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  Subjects -> ENGINEERING (Total: 2298 journals)
    - CHEMICAL ENGINEERING (192 journals)
    - CIVIL ENGINEERING (192 journals)
    - ELECTRICAL ENGINEERING (104 journals)
    - ENGINEERING (1209 journals)
    - ENGINEERING MECHANICS AND MATERIALS (385 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (69 journals)
    - MECHANICAL ENGINEERING (92 journals)

ENGINEERING (1209 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 252)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 26)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 11)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 40)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 5)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 17)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 8)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 27)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 270)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 195)
Composites Part B : Engineering     Hybrid Journal   (Followers: 276)
Composites Science and Technology     Hybrid Journal   (Followers: 191)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 29)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 6)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 32)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 7)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        1 2 3 4 5 6 7 | Last

Journal Cover AIChE Journal
  [SJR: 1.122]   [H-I: 120]   [32 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0001-1541 - ISSN (Online) 1547-5905
   Published by John Wiley and Sons Homepage  [1589 journals]
  • Stochastic Back-off Algorithm for Simultaneous Design, Control and
           Scheduling of Multi-product Systems under Uncertainty
    • Authors: Robert W. Koller; Luis A. Ricardez-Sandoval, Lorenz T. Biegler
      Abstract: An algorithm that employs the back-off method to provide optimal solutions for integration of design, control, and scheduling for multi-product systems is presented, featuring a flexibility and feasibility analysis. The algorithm employs Monte Carlo (MC) sampling to generate a large number of random realizations, and simulate the system to determine feasibility. Back-off terms are determined and incorporated into a new flexibility analysis to approximate the effect of stochastic uncertainty and disturbances. Through successive iterations, the algorithm converges, terminating on a solution that is robust to a specified level of process variability due to stochastic realizations in the disturbances and uncertain parameters. The proposed algorithm has been successfully applied to a multi-product continuous stirred tank reactor for which optimal design, control, and scheduling decisions are identified, subject to stochastic uncertainty and disturbance. The present approach has been compared to a critical-set (multi-scenario) method showing the benefits and limitations of both approaches. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-17T11:45:41.009039-05:
      DOI: 10.1002/aic.16092
       
  • Ecosystems as Unit Operations for Local Techno-Ecological Synergy:
           Integrated Process Design with Treatment Wetlands
    • Authors: Varsha Gopalakrishnan; Bhavik R. Bakshi
      Abstract: Despite the critical importance of ecological systems for sustaining all chemical and manufacturing processes, process design has kept nature outside its system boundary. Recent efforts for sustainable process design aim to reduce environmental impact, but no design method considers the capacity of ecosystems to supply the goods and services that are needed to sustain a process. Overcoming this deficiency of conventional process design is essential to transform the chemical industry into an activity that respects ecological constraints and results in a net positive societal impact. As an important step toward meeting this goal, this work expands the boundary of process design to include ecosystems as unit operations in traditional design. Similar to tasks performed by conventional unit operations, ecological processes perform ecosystem functions resulting in goods and services required by the technological system. The goal behind designing integrated techno-ecological process flowsheets is to balance the ecosystem service demand of technological systems with the ecosystem service supply of ecological systems. Systems are optimized to balance the demand and supply subject to unit operation level constraints of technological and ecological systems, and interactions between detailed process level variables and ecological variables are explored. The Techno-Ecological Synergy (TES) Design method is developed and applied to a biofuel production system, considering ecosystem services like water provisioning and water quality regulation provided by wetland ecosystems. Comparing the integrated TES design with conventional techno-centric design shows that TES design can result in net positive impact manufacturing: a case where the ecosystem service supply is equal to or exceeds the demand, with little or no compromises in process profitability. These results should encourage close integration between technological and ecological systems while designing sustainable processes, and identify many challenges for developing TES of individual processes and across the life cycle. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-17T11:43:42.742612-05:
      DOI: 10.1002/aic.16093
       
  • Highly Efficient Methane Reforming over a Low-loading Ru/γ-Al2O3 Catalyst
           in a Pd-Ag Membrane Reactor
    • Authors: David S. A. Simakov; Yuriy Román-Leshkov
      Abstract: Natural gas can be reformed to syngas (CH4 + H2O = CO + 3H2), at temperatures above 850 °C. Membrane catalytic reformers can provide high CH4 conversions at temperatures below 650 °C, by separating H2 from the reactive mixture. Traditional Ni-based catalysts suffer from low activity at low temperatures and deactivate rapidly by coking, particularly at low steam/carbon ratios. In this study, an ultra-low loading (0.15 wt%) Ru/γ-Al2O3 catalyst was implemented in a lab-scale membrane reformer, using a supported 5μm Pd-Ag film membrane. Methane conversions above 90% were achieved at 650 °C, 8 bar, and H2O/CH4 = 2, 3 with contact times of ca. 10 s. The system generated up to 3.5 mol of ultra-pure H2 per mol of CH4 fed, with a maximum power density of 0.9 kW/L. No significant deactivation was observed after 200 h time on stream, even when using low H2O:CH4 ratios. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-17T11:43:05.959442-05:
      DOI: 10.1002/aic.16094
       
  • Continuous-Time Formulations for the Optimal Planning of Multiple
           Refracture Treatments in a Shale Gas Well
    • Authors: Diego C. Cafaro; Markus G. Drouven, Ignacio E. Grossmann
      Abstract: This work presents a continuous-time optimization model for planning multiple refracture treatments over the lifespan of a shale gas well. We demonstrate that continuous-time models can handle multiple restimulations very efficiently, increasing the net present value of the well development and refracturing plan. Well productivity is represented by a piecewise hyperbolic function, which accounts for when and how often the well has been refractured. We illustrate the application and effectiveness of the proposed approach for both the maximization of the total gas recovered and the maximization of the net present value. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-17T11:41:41.24767-05:0
      DOI: 10.1002/aic.16095
       
  • Impact of Diversity of Morphological Characteristics and Reynolds number
           on Local Hemodynamics in Basilar Aneurysms
    • Authors: Marjan Rafat; Mahsa Dabagh, Martin Heller, James D. Rabinov, Howard A. Stone, Amanda Randles, Debra T. Auguste
      Abstract: Morphological and hemodynamic parameters have been suggested to affect the rupture of cerebral aneurysms, but detailed mechanisms of rupture are poorly understood. The purpose of our study is to determine criteria for predicting the risk of aneurysm rupture, which is critical for improved patient management. Existing aneurysm hemodynamics studies generally evaluate limited geometries or Reynolds numbers (Re), which are difficult to apply to a wide range of patient-specific cases. We focused on the association between hemodynamic characteristics and morphology. We assessed several two-dimensional (2D) and three-dimensional (3D) idealized and physiological geometries to characterize the hemodynamic landscape between flow patterns. The impact of morphology on velocity and wall shear stress (WSS) profiles were evaluated. We found that slight changes in aneurysm geometry or Re result in significant changes in the hemodynamic and WSS profiles. Our systematic mapping and non-dimensional analysis qualitatively identify hemodynamic conditions that may predispose aneurysms to rupture. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-12T11:05:22.297615-05:
      DOI: 10.1002/aic.16091
       
  • A Square-Force Cohesion Model and its Extraction from Bulk Measurements
    • Authors: Peiyuan Liu; Casey Q. LaMarche, Kevin M. Kellogg, Christine M. Hrenya
      Abstract: Accurate modeling of interparticle forces in DEM is critical to predicting the rheology of cohesive particles. Rigorous cohesion models usually include parameters associated with particle surface roughness. However, both roughness measurement and its distillation into appropriate model parameters remain challenging. We propose a square-force cohesion model, where cohesive force remains constant until a cut-off separation, above which cohesion vanishes. We demonstrate the square-force model is a valid surrogate of more rigorous models. Specifically, when two parameters of square-force model are chosen to match the two key quantities governing dense and dilute flows, namely maximum cohesive force and critical cohesive energy31, respectively, DEM results using square-force and more rigorous models show good agreement. For practical application of the square-force model to lightly cohesive systems, a method is established to extract its parameters via defluidization, enabling determination of particle-particle cohesion from simpler bulk measurements than complicated and expensive scans on individual grains. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:21:07.514719-05:
      DOI: 10.1002/aic.16089
       
  • Globally Optimal Linear Approach to the Design of Heat Exchangers Using
           Threshold Fouling Modeling
    • Authors: Julia C. Lemos; André L. H. Costa, Miguel J. Bagajewicz
      Abstract: This article presents a method for the mathematical optimization of the design of heat exchangers including fouling rate modeling for the tube-side. The description of the fouling rate in crude preheat trains of petroleum distillation units is commonly based on threshold models (Ebert-Panchal model and its variants). Our formulation of the design problem employs a mixed integer linear programing approach; therefore the solution is the global optimum and common nonconvergence drawbacks of mixed-integer nonlinear programming models are totally avoided. Three different examples are employed to compare the proposed approach with an optimization procedure using fixed fouling resistances. The results indicate that in two problems was possible to obtain design solutions associated to smaller heat exchangers. Additionally, three case studies are also explored to discuss how fouling is related to crude types, pressure drop manipulation, and energy integration. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:59.068084-05:
      DOI: 10.1002/aic.16083
       
  • Experimental Investigation of Particle Migration in Suspension Flow
           through Bifurcating Microchannels
    • Authors: Bhaskar Jyoti Medhi; Vipin Agrawal, Anugrah Singh
      Abstract: Experimental measurements of velocity and concentration profiles were carried out to study transport of non-colloidal suspension in bifurcating micro channels for both diverging and converging flow conditions using a combination of Mirco Particle Image Velocimetry (PIV) and Particle Tracking Velicimetry (PTV) techniques. Migration of particles across the streamline was observed and symmetric velocity and concentration profile in the inlet branch becomes asymmetric in the daughter branches. Further migration of particles towards the center of the channel in the outlet branch make the profiles again symmetric. The evolution of velocity and concentration profiles was observed to be different in the symmetric and asymmetric bifurcation channels. The comparison of the streamlines for the fluid and the particles showed significant deviation near the bifurcation region. This may explain why there is unequal flow and particle partitioning during flow of suspension in asymmetric bifurcating channels as reported in many previous studies. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:57.069458-05:
      DOI: 10.1002/aic.16084
       
  • 3D Simulation of the Time-dependent Fluid Flow and Fouling Behavior in an
           Industrial Hollow Fiber Membrane Module
    • Authors: Liwei Zhuang; Gance Dai, Zhen-liang Xu
      Abstract: A novel three-dimensional CFD model has been developed on the basis of fluid flow in the shell and lumen sides, and permeation and fouling behavior in the porous membrane zone. The simulated 25-minute dead-end outside-in filtration process showed that the energy consumed by the inlet manifold decreases during the constant pressure filtration. The velocity and pressure distributions in the module change with time. Flux distribution both in the axial and radial directions becomes increasingly more uniform, so does the cake distribution. Flux distribution and cake distribution inter-adjust each other in different modes. A correlation equation has been developed to describe the relationship between the volumetric flow rate and accumulated water production. The correlation equation with simple experiment enables the dynamic evolution of energy consumed by shell inlet manifold to be presented, which can be the criterion of how well the shell inlet manifold or module has been designed. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:53.190384-05:
      DOI: 10.1002/aic.16090
       
  • A Study of Film Thickness and Hydrodynamic Entrance Length in Liquid
           Laminar Film Flow along a Vertical Tube
    • Authors: Hongxia Gao; Xiao Luo, Ding Cui, Xiayi Hu, Ardi Hartono, Hallvard F. Svendsen, Zhiwu Liang
      Abstract: The liquid film thickness and hydrodynamic entrance length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt% MEA and 40 wt% sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq.16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empirical model and an improved minimal surface model have been firstly proposed for calculation of the hydrodynamic entrance length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the hydrodynamic entry length on the gas-liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film length (y) and the hydrodynamic entrance length (λE) is lower than 10. However, it should be noted that the hydrodynamic entrance length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:46.94143-05:0
      DOI: 10.1002/aic.16081
       
  • Influence of Normal Contact Force Model on Simulations of
           Sphero-cylindrical Particles
    • Authors: Rohit Kumar; Avik Sarkar, William Ketterhagen, Bruno Hancock, Jennifer Curtis, Carl Wassgren
      Abstract: This paper investigates how the choice of elastic normal contact force model affects predictions from DEM simulations of sphero-cylindrical particles. Three force models were investigated: (1) a Hertzian force model (HFM) which assumes a circular contact area; (2) a linear force model (LFM) with a constant stiffness; and (3) a modified Hertzian force model (MFM) that accounts for various contact areas and contact transitions. With the MFM, transitions between contact area types must be accounted for otherwise discontinuities in the contact force can occur. It is found that simple force models (HFM, LFM) can be substituted for more accurate force models if only force data and bulk properties are of interest. However, if more detailed contact information, such as contact area, contact overlap, contact duration, or collision frequency are needed, for example in population balance models and transient liquid bridge modeling, then a more accurate force model should be used. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:39.716576-05:
      DOI: 10.1002/aic.16082
       
  • Liquid-Liquid-Solid Mass Transfer and Phase Behavior of Heterogeneous
           Etherification of Glycerol with Isobutene
    • Authors: Jingjun Liu; Bolun Yang
      Abstract: Previous experiments observed auto-acceleration in the etherification of glycerol with isobutene. This paper engaged to uncover the reason for this phenomenon via investigating the heterogenicity, including liquid-liquid phase equilibrium and liquid-liquid-solid mass transfer, of the reaction system. Phase behavior analysis showed that the reaction mixture separates into two liquid phases during the whole course of the reaction. The produced mono ethers of glycerol thermodynamically promote the homogenization of the two liquid phases. The modeling results of liquid-liquid-solid mass transfer indicated that the resistance of mass transfer is insignificant during the reaction. The bulk compositions of the two liquid phases are very close to their corresponding equilibrium compositions. An increase of isobutene concentration in the reaction phase is believed to lead all reactions speeding up. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:20:34.597975-05:
      DOI: 10.1002/aic.16080
       
  • On the Mechanisms of Secondary Flows in a Gas Vortex Unit
    • Authors: Kaustav Niyogi; Maria M. Torregrosa, Vladimir N. Shtern, Guy B. Marin, Geraldine J. Heynderickx
      Abstract: The hydrodynamics of secondary flow phenomena in a disc-shaped gas vortex unit (GVU) is investigated using experimentally validated numerical simulations. The simulation using ANSYS FLUENT® v.14a reveals the development of a backflow region along the core of the central gas exhaust, and of a counterflow multi-vortex region in the bulk of the disc part of the unit. Under the tested conditions, the GVU flow is found to be highly spiraling in nature. Secondary flow phenomena develop as swirl becomes stronger. The backflow region develops first via the swirl-decay mechanism in the exhaust line. Near-wall jet formation in the boundary layers near the GVU end-walls eventually results in flow reversal in the bulk of the unit. When the jets grow stronger the counterflow becomes multi-vortex. The simulation results are validated with experimental data obtained from Stereoscopic Particle Image Velocimetry and surface oil visualization measurements. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:17:01.37428-05:0
      DOI: 10.1002/aic.16087
       
  • Lattice Boltzmann Simulation of Asymptotic Longitudinal Mass Dispersion in
           Reconstructed Random Porous Media
    • Authors: Chen Yang; Yixiong Lin, Gérald Debenest, Akira Nakayama, Ting Qiu
      Abstract: In order to research macroscopic mass transport characteristics of porous media, a lattice Boltzmann method (LBM) approach was utilized to calculate asymptotic longitudinal mass dispersion. In this study, a D2Q9 model with multi-relaxation-time (MRT) collision operator, which is appropriate for incompressible flow with a high Péclet number without refining the lattice, was chosen. With respect to the microstructure of porous media, random placement (RP) method was applied to obtain randomly positioned particles. Based on the exhausted numerical results presented in the study, a new correlation of longitudinal mass dispersion was established. By comparing with available experimental data in the literature, reasonable agreements are observed in a wide porosity range from 0.3 to 0.7, indicating the validity of the proposed correlation. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:16:14.217384-05:
      DOI: 10.1002/aic.16088
       
  • Experimental investigation of the morphology of salt deposits from drying
           sessile droplets by white-light interferometry
    • Authors: F. Sondej; M. Peglow, A. Bück, E. Tsotsas
      Abstract: This study presents a new approach to investigate the drying behavior and the structure of deposit resulting from drying of solid containing micro droplets. It is shown that deposit structure (porosity and “footprint”) depends on drying conditions. This dependency may contribute to better understanding of particle-forming processes, such as fluidized bed coating. In the framework of this study, sessile droplets containing sodium benzoate dissolved in water were dried on thin glass plates in a small drying chamber. The drying conditions (temperature, moisture content and flow rate of drying gas) and material parameters (solid content of solution) were systematically varied. The drying rate of droplets was determined from the moisture balance of the drying gas. The final 3D shape of dried sessile droplets was measured using white-light interferometry and transformed into a 2D profile using a Monte Carlo method. Moreover the mean porosity of dried droplets was calculated. By comparison of structural information and process conditions it is shown that the drying process may have a large influence on deposit structure. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:15:34.490529-05:
      DOI: 10.1002/aic.16085
       
  • Flow Distribution of Hydrocarbon Fuel in Parallel Mini-Channels Heat
           Exchanger
    • Authors: Yu Chen; Zhiliang Lei, Tianhao Zhang, Quan Zhu, Zewei Bao, Qiyi Zhang, Xiang-Yuan Li
      Abstract: In this paper, the flow distribution of the Chinese No. 3 jet fuel in parallel mini-channels heat exchanger under high temperature condition was investigated. The models of PFR and choked flow were established based on the real fluid model. The formation mechanism of flow maldistribution of the fuel in the freely-distributed channels was studied. It was found that: under low heat flux, the slight flow rate deviation will be spontaneously eliminated; under high heat flux, the slight deviation of flow rate and heat flux will be enlarged and result in the channel with smaller flow rate entering the coking region. The feasibility and influence factors of the control method of flow distribution based on choked flow were discussed. The experimental results indicated that the mini-channels fuel-cooled plate with choked flow could maintain uniform flow distribution when the total fuel outlet temperature reached 1035 K. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T11:10:30.909323-05:
      DOI: 10.1002/aic.16086
       
  • Non-homogeneous flow of micellar solutions: A kinetic - network theory
           approach
    • Authors: J. Paulo García-Sandoval; A. Martín del Campo, F. Bautista, O. Manero, Jorge E. Puig
      Abstract: The rheological behavior of micellar solutions is analyzed under non-homogeneous velocity and stress flow conditions. The framework is based on the extended irreversible thermodynamics and the transient network formulation coupled to the underlying kinetics embodying two relevant processes: formation of wormlike chains from a free micellar solution through a thermally activated process and their flow induced degradation. The second kinetic process consists in the formation of entanglements from the free wormlike chains and their flow-induced breakage. These processes are modeled in a coupled kinetic scheme constituted by a set of reversible kinetic equations describing the evolution in average of the three microstates (free short rod-like micelles, free wormlike chains and entangled wormlike chains) that reflect the complexity of macromolecular interactions. The predictions of the shear stress and first normal stress difference as a function of shear-rate under banded flow are in good agreement with experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-06T10:40:26.871744-05:
      DOI: 10.1002/aic.16079
       
  • Non-spherical particles in a pseudo-2D fluidized bed: Experimental study
    • Authors: Vinay V. Mahajan; Tim M.J. Nijssen, Kay A. Buist, J. A. M. Kuipers, Johan T. Padding
      Abstract: Fluidization is widely used in industries and has been extensively studied, both experimentally and theoretically, in the past. However, most of these studies focus on spherical particles while in practice granules are rarely spherical. Particle shape can have a significant effect on fluidization characteristics. It is therefore important to study the effect of particle shape on fluidization behaviour in detail. In this study, experiments in pseudo-2D fluidized beds are used to characterize the fluidization of spherocylindrical (rod-like) Geldart D particles of aspect ratio 4. Pressure drop and optical measurement methods (DIA, PIV, PTV) are employed to measure bed height, particle orientation, particle circulation, stacking and coordination number. The commonly used correlations to determine the pressure drop across a bed of non-spherical particles are compared to experiments. Experimental observations and measurements have shown that rod-like particles are prone to interlocking and channelling behaviour. Well above the minimum fluidization velocity, vigorous bubbling fluidization is observed, with groups of interlocked particles moving upwards, breaking up, being thrown high in the freeboard region and slowly raining down as dispersed phase. At high flowrates, a circulation pattern develops with particles moving up through the center and down at the walls. Particles tend to orient themselves along the flow direction. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-05T10:50:43.158868-05:
      DOI: 10.1002/aic.16078
       
  • The pH, Temperature and Protein Structure Effect on β-Lactoglobulin A and
           B Separation in Anion-Exchange Chromatography
    • Authors: Gorgi Pavlova; James T. Hsua
      Abstract: The effect of pH and temperature on separating a mixture of similar proteins, namely β-lactoglobulin A (LGA) and β-lactoglobulin B (LGB) in anion-exchange chromatography is explored. The proteins carry a slight difference in negative charge at basic pH, providing a separation basis on an Q Sepharose Fast Flow anion-exchange resin. They were separated at different temperatures and pH values, and the separation factor was evaluated. The experimental results were matched to a theoretical model to compute the equilibrium constant KA. The data shows that an increase in temperature and pH leads to an increase in the retention time of the proteins. The results were correlated with the net charge of the molecule for the separation so that the elution can be simulated for any condition that was studied. The tertiary structures of LGA and LGB are analyzed to illustrate the structure effect on the separation. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-05T10:50:20.515597-05:
      DOI: 10.1002/aic.16077
       
  • Issue Information
    • Abstract: Cover illustration. Li-LSX zeolite is the sorbent of choice for air separation via pressure swing adsorption (PSA). Due to the rapidly rising Li cost, it is desirable to minimize Li use. Li cations occupy Sites I' and II (SI' and SII) preferentially, and only cations on SIII are used for adsorption. Mixed LiCa-LSX with only a few %Li show better PSA performance compared to Ca-LSX and only slightly lower performance than pure Li-LSX. Image edited by Franklin Epiepang, University of Michigan. 10.1002/aic.16032
      PubDate: 2018-01-03T13:52:06.604144-05:
      DOI: 10.1002/aic.15898
       
  • A Regime Map for the Normal Surface Impact of Wet and Dry Agglomerates
    • Authors: Mohammad Khalilitehrani; Joakim Olsson, Farin Daryosh, Anders Rasmuson
      Abstract: The normal surface impacts of wet and dry agglomerates are simulated in a DEM framework. While the impact behavior of dry agglomerates has been addressed previously, similar studies on wet agglomerate impact are missing. We show that by adding a small amount of liquid the impact behavior changes significantly.The impact behavior of the agglomerates at different moisture contents and impact energies are analyzed through post-impact parameters and coupled to their microscopic and macroscopic properties. While increasing the impact energy breaks more inter-particle bonds and intensifies damage and fragmentation, increasing the moisture content is found to provide the agglomerates with higher deformability and resistance against breakage. It is shown that the interplay of the two latter parameters together with the agglomerate structural strength creates various impact scenarios, which are classified into different regimes and addressed with a regime map. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-03T10:42:01.559243-05:
      DOI: 10.1002/aic.16072
       
  • Revealing Low Temperature Microwave-assisted Pyrolysis Kinetic Behaviors
           and Dielectric Properties of Biomass Components
    • Authors: Hu Luo; Li-Wei Bao, Ling-Zhao Kong, Yu-Han Sun
      Abstract: The kinetic characteristics of microwave-assisted pyrolysis of biomass components were investigated in a self-designed microwave TGA using the KAS model and the master plot method. Compared with conventional pyrolysis, the initial decomposition temperatures of biomass components were reduced by 50-100°C and the fastest weight loss regions were shifted to lower temperatures. The average apparent activation energies of cellulose, hemicellulose and lignin were 47.82, 44.81 and 51.54 kJ/mol, respectively. Analysis with master plot method suggested the MAP of cellulose followed the 2-D diffusion reaction model, while hemicellulose and lignin could be interpreted by 3rd order-based and 3-D diffusion model. The change of dielectric properties was consistent with the weight loss behaviors of biomass components during the pyrolysis process. The increase of dielectric properties with temperature can lead to a thermal gradient and “hot spots” within biomass, which accelerated the pyrolysis process at low temperatures and reduced the apparent activation energy. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-03T10:41:54.278231-05:
      DOI: 10.1002/aic.16073
       
  • Heat Transfer Intensification for Retrofitting Heat Exchanger Networks
           with Considering Exchanger Detailed Performances
    • Authors: Ming Pan; Igor Bulatov, Robin Smith
      Abstract: The challenging of this work is to present a thorough study of implementing heat transfer intensification in heat exchanger network (HEN) retrofitting, including all details of exchanger geometry, stream bypassing and splitting, temperature-variation of properties, LMTD and its correction, and pressure drops. This leads to very complex mixed integer nonlinear programming (MINLP) problems rarely reported before. By adopting the MILP-based iterative approach proposed in the earlier work (Pan et al. in 2013), temperature-variation of properties, LMTD and its correction are initialised to parameters at first, and the rest nonlinear terms are then linearized and expressed as first order Taylor series expansions. Finally, two iteration loops are executed to find optimal solutions. A small-scale motivating problem and an industrial scale problem are presented to demonstrate the validity and efficiency of the proposed methods. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-03T10:41:40.632147-05:
      DOI: 10.1002/aic.16075
       
  • On the construction of binary mixture p-x and T-x diagrams from isochoric
           thermodynamics∗
    • Authors: Ian H. Bell; Ulrich K. Deiters
      Abstract: In this work we describe how to efficiently and reliably calculate p-x and T-x diagrams for binary mixtures of fluids. The method is based on the use of the Helmholtz energy density as the fundamental thermodynamic potential. Through the use of temperature and molar concentrations of the components as the independent variables, differential relationships can be constructed along the phase envelope surface, and this system of differential equations is then integrated to construct isotherms and isobars cutting through the phase envelope.The use of the Helmholtz energy density as the fundamental potential allows several models to be considered in this formalism, including cubic equations of state (Peng-Robinson, GC-VTPR, etc.) as well as high-accuracy multifluid equations of state (the so-called GERG mixture model). Examples of each class are presented, demonstrating the flexibility of this method. Source code, examples, and comprehensive analytic derivatives are provided in the supplemental material. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-03T10:41:32.191932-05:
      DOI: 10.1002/aic.16074
       
  • Enhanced Water Flux through Graphitic Carbon Nitride Nanosheets Membrane
           by Incorporating Polyacrylic Acid
    • Authors: Yanjie Wang; Lingfei Liu, Jian Xue, Jiamin Hou, Li Ding, Haihui Wang
      Abstract: Membranes assembled from two-dimensional (2D) layered materials have shown potential use in water purification. Recently, a 2D graphitic carbon nitride (g-C3N4) nanosheets membrane exhibit considerable separation performance in water purification. In this study, to further improve this water separation performance, polyacrylic acid (PAA) was introduced to tune the nanochannels formed between the g-C3N4 nanosheets. The fabricated g-C3N4-PAA hybrid membranes possessed higher water flux without sacrificing much rejection rate compared with that of the g-C3N4 membrane; however noticeable fouling was observed upon addition of the PAA into the membrane composite structure. In addition, the effect of PAA on the morphology, surface hydrophilicity, separation performance, and antifouling properties of the g-C3N4 membrane were examined in detail. Overall, incorporating PAA into the g-C3N4 nanosheets membrane was an effective and convenient method to improve the water separation performance, which could promote the application of the 2D g-C3N4 nanosheets membrane in practical ultrafiltration processes. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-03T10:41:04.62055-05:0
      DOI: 10.1002/aic.16076
       
  • CO2 Capture by Methanol, Ionic Liquid, and Their Binary Mixtures:
           Experiments, Modeling, and Process Simulation
    • Authors: Mohsen Taheri; Chengna Dai, Lei Zhigang
      Abstract: The CO2 solubility data in the ionic liquid (IL) 1-allyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide, methanol (MeOH), and their mixture with different combinations at temperatures of (313.2, 333.2, and 353.2 K) and pressures up to 6.50 MPa were measured experimentally. New group binary interaction parameters of the predictive UNIFAC-Lei model, which has been continually advanced by our group, were introduced by correlating the experimental data of this work and the literature. The consistency between experimental data and predicted results proves the reliability of UNIFAC-Lei model for CO2-IL-organic solvent systems. The newly obtained parameters were incorporated into the UNIFAC property model of Aspen Plus software to optimize a conceptual process developed for the purification of a CO2-containing gas stream. The simulation results indicate that the use of IL either mixed with MeOH or purely considerably lowers the process power consumption, and improves the process performance in terms of CO2 capture rate and solvent loss. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-02T10:10:41.785233-05:
      DOI: 10.1002/aic.16070
       
  • Solubilities of Solid n-Alkanes in Methane: Data Analysis and Models
           Assessment
    • Authors: Marco Campestrini; Paolo Stringari
      Abstract: This paper reviews the results of experiments underway since 1950 studying the solid solubility of n-alkanes (from ethane up to n-triacontane) in methane and the factors influencing the global phase equilibrium behavior of the related binary mixtures.The methodology used consists of a series of comparisons of data in the composition-temperature and pressure-temperature diagrams. The kind of global phase diagram of the binary mixtures of methane referred to in the present article is found to be dependent of the ratio between the triple-point temperature of the generic n-alkane and the critical-point temperature of methane.The Peng-Robinson (1976), Predictive Soave-Redlich-Kwong, and Predictive Peng-Robinson (1978) equations of state have been applied and compared with respect to the calculation of bivariant, univariant, and invariant equilibrium data involving solid n-alkanes in binary mixture with methane. The fugacities of the solid n-alkanes have been calculated by means of the so-called classic approach. This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-02T10:10:37.398384-05:
      DOI: 10.1002/aic.16071
       
  • Issue Information - Table of Contents
    • Pages: 405 - 405
      PubDate: 2018-01-03T13:52:09.139938-05:
      DOI: 10.1002/aic.15897
       
  • Experimental Measurement and Thermodynamic Modeling of Cyclopentane
           Hydrates with NaCl, KCl, CaCl2 or NaCl-KCl Present
    • Authors: S. Ho-Van; B. Bouillot, J. Douzet, S. Maghsoodloo, J.M. Herri
      Abstract: Consistent phase equilibrium data for cyclopentane hydrates in presence of salts are vitally important to many industries, with particular interest to the field of hydrate-based water separation via cyclopentane hydrate crystallization such as desalination. However, there are very little experimental equilibrium data, and no thermodynamic prediction tools. Hence, we set up a method to generate a great deal of much needed equilibrium data for cyclopentane hydrates in diverse saline solutions with a wide range of salt concentrations. Our method does furnish verified, reliable and accurate equilibrium data. Plus, three thermodynamic approaches are developed to predict equilibrium, and provide tools for simulations, by considering the kind of salt and concentrations. All three models are in very good accordance with experimental data. One method, using a new correlation between occupancy factor and water activity, might be the best way to obtain consistent, quick and accurate dissociation temperatures of cyclopentane hydrate in brine. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T10:30:46.662499-05:
      DOI: 10.1002/aic.16067
       
  • On reduced modeling of mass transport in wavy falling films
    • Authors: P. Bandi; S. Groß, Y. Heng, W. Marquardt, A. Mhamdi, M. Modigell, A. Reusken, L. Zhang
      Abstract: In many industrial units such as packing columns, falling film reactors, etc., the liquid phase is designed as a falling film. It is well known that the mass and heat transfer in laminar wavy film flows is significantly enhanced compared to flat films. The kinetic phenomena underlying the increase in mass and heat transfer are, however, still not fully understood. For an efficient design of falling film units, computational models that account for these enhanced transport mechanisms are of key importance. In this paper, we present a reduced modeling approach based on a long-wave approximation to the fluid dynamics of the film. Furthermore, we introduce a new 2D high-resolution laser-induced luminescence measurement technique. Both in the numerical simulation results and in the high-resolution 2D-concentration measurements obtained in the experiments we observe similar patterns of high concentrations locally, especially in the areas close to the wave hump. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T10:30:43.927612-05:
      DOI: 10.1002/aic.16065
       
  • Nanospace-Confined Synthesis of Coconut-like SnS/C Nanospheres for
           High-Rate and Stable Lithium-Ion Batteries
    • Authors: Zongnan Deng; Hao Jiang, Yanjie Hu, Chunzhong Li, Yu Liu, Honglai Liu
      Abstract: Coconut-like monocrystalline SnS/C nanospheres are developed as anode materials for lithium-ion batteries (LIBs) by a micro-evaporation-plating strategy in confined nanospaces, achieving reversible capacities as high as 936 mAh g−1 at 0.1 A g−1 after 50 cycles and 830 mAh g−1 at 0.5 A g−1 for another 250 cycles. The remarkably improved electrochemical performances can be mainly attributed to their unique structural features, which can perfectly combine the advantages of the face-to-face contact of core/shell nanostructure and enough internal void space of yolk/shell nanostructure, and therefore well-addressing the pivotal issues related to SnS low conductivity, sluggish reaction kinetics and serious structure pulverization during the lithiation/delithiation process. The evolutionary process of the nanospheres is clearly elucidated based on experimental results and a multiscale kinetic simulation combining the microscopic reaction-diffusion equation and the mesoscopic theory of crystal growth. Furthermore, a LiMn2O4//SnS/C full cell is assembled, likewise exhibiting excellent electrochemical performance. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T10:30:40.251797-05:
      DOI: 10.1002/aic.16068
       
  • Determination of Crystalline Thermodynamics and behavior of Anthracene in
           different Solvents
    • Authors: Cui-ping Ye; Xiao-xiao Ding, Wen-ying Li, Hai Mu, Wei Wang, Jie Feng
      Abstract: To screen suitable solvents for anthracene crystallization, the solubilities of anthracene and metastable zone width were determined in four different solvents, N,N-dimethyl formamide (DMF), xylene, tetrachloroethylene, and diethylene glycol dimethyl ether from 30 to 80°C at atmospheric pressure using a self-made crystallizer. The cooling modes, solvents, and the effects of carbazole on the solvent crystallization process of anthracene were also investigated. The composition of mother liquors and solid products were measured by gas chromatography, the solids were analyzed by scanning electron microscope, X-ray diffractometer, differential scanning calorimetry, granulometer, and fluorescence spectrometer. The results showed that a uniform anthracene crystal was obtained when using DMF under the forced circulation cooling mode. Solid solution of anthracene and carbazole was initially detected in solvent crystallization. The existence of carbazole in solution has an obvious effect on the crystal morphology of anthracene, to some extent, is beneficial to the crystal growth of anthracene. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T10:30:36.40887-05:0
      DOI: 10.1002/aic.16069
       
  • Solvent-free polymer emulsification inside a twin screw extruder
    • Authors: A. Goger; M.R. Thompson, J.L. Pawlak, M.A. Arnould, D.J.W. Lawton
      Abstract: Solvent-free extrusion emulsification (SFEE) is new technique for a twin screw extruder to prepare sub-micron sized particles (100-500 nm) without using hazardous solvents. The particle size is reliant upon the thickness of striated lamellae, which can be monitored rheologically based on the viscosity change occurring at the SFEE process. The lamellae coarsening rate is predominantly affected by the interfacial energy of the system when a surfactant is added but shows stronger dependency on viscosity change when interfacial growth between the polymer and water phases is solely determined by the end-groups conversion into carboxylate species. For this latter case, the dissolution of the sodium hydroxide species and the kinetics of end-groups conversion prove to be rate-limiting phenomena to generating thinner striated lamellae. Additionally, the ionic strength of the system is notably important to the viscosity response and particle size produced, particularly when surfactant is not added. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-22T10:10:30.019902-05:
      DOI: 10.1002/aic.16066
       
  • Convex Relaxations for Global Optimization Under Uncertainty Described by
           Continuous Random Variables
    • Authors: Yuanxun Shao; Joseph K. Scott
      Abstract: This article considers nonconvex global optimization problems subject to uncertainties described by continuous random variables. Such problems arise in chemical process design, renewable energy systems, stochastic model predictive control, etc. Here, we restrict our attention to problems with expected-value objectives and no recourse decisions. In principle, such problems can be solved globally using spatial branch-and-bound. However, branch-and-bound requires the ability to bound the optimal objective value on subintervals of the search space, and existing techniques are not generally applicable because expected-value objectives often cannot be written in closed-form. To address this, this article presents a new method for computing convex and concave relaxations of nonconvex expected-value functions, which can be used to obtain rigorous bounds for use in branch-and-bound. Furthermore, these relaxations obey a second-order pointwise convergence property, which is sufficient for finite termination of branch-and-bound under standard assumptions. Empirical results are shown for three simple examples. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-21T10:46:48.450981-05:
      DOI: 10.1002/aic.16064
       
  • Dynamics and Scaling of Explosion Cratering in Granular Media
    • Authors: Ming Gao; Xiao Liu, Luana Pasetti Vanin, Ting-Pi Sun, Leonardo Gordillo, Xiang Cheng
      Abstract: Granular cratering is a ubiquitous phenomenon occurring in various natural and industrial contexts. Although impact-induced granular cratering has been extensively studied, fewer experiments have been conducted on granular cratering via low-energy explosions. Here, we study the dynamics and scaling of explosion granular cratering by injecting short pulses of pressurized air in quasi-two-dimensional granular media. Through an analysis of the dynamics of explosion processes at different explosion pressures, explosion durations and burial depths, we identify two regimes, the bubbling and the eruption regimes, in explosion granular cratering. Our experiments explore the distinctive dynamics and crater morphologies of these regimes and show the energy scaling of the size of explosion craters. We compare high-energy and low-energy explosion cratering as well as explosion and impact cratering in terms of their energy scalings. Our work illustrates complex granular flows in explosion cratering and provides new insights into the general scaling of granular cratering processes. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-19T08:27:00.634136-05:
      DOI: 10.1002/aic.16063
       
  • Rheological properties and structure of step- and chain-growth gels
           concentrated above the overlap concentration
    • Authors: Matthew D. Wehrman; Andrew Leduc, Holly E. Callahan, Michelle S. Mazzeo, Mark Schumm, Kelly M. Schultz
      Abstract: Cross-linked polymeric gels are widely used in applications ranging from biomaterial scaffolds to additives in enhanced oil recovery. Despite this, fundamental understanding of the effect of polymer concentration and reaction mechanism on the scaffold structure is lacking. We measure scaffold properties and structure during gelation using multiple particle tracking microrheology. To determine the effect of concentration, we measure gelation as polymer interactions are increased in the backbone precursor solution: below, at and above the overlap concentration, c*. To determine structural changes due to the gelation mechanism, we measure gelation between the same polymers undergoing both step- and chain-growth reactions using self-assembling maleimide:thiol and photo-initiated acrylate:thiol chemistries, respectively. We determine the critical relaxation exponent, n, a measure of structure. n decreases with increasing concentration, indicating a change from a percolated (c 
      PubDate: 2017-12-18T10:30:21.502207-05:
      DOI: 10.1002/aic.16062
       
  • Eulerian-Lagrangian Simulations of Settling and Agitated Dense
           Solid-Liquid Suspensions – Achieving Grid Convergence
    • Authors: J.J. Derksen
      Abstract: Eulerian-Lagrangian simulations of solid-liquid flow have been performed. The volume-averaged Navier-Stokes equations have been solved by a variant of the lattice-Boltzmann method; the solids dynamics by integrating Newton's second law for each individual particle. Solids and liquid are coupled via mapping functions. The application is solids suspension in a mixing tank operating in the transitional regime (the impeller-based Reynolds number is 4,000), an overall solids volume fraction of 10% and a particle-liquid combination with an Archimedes number of 30. In this application, the required grid resolution is dictated by the liquid flow and we thus need freedom to choose the particle size independent of the grid spacing. Preliminary hindered settling simulations show that the proposed Eulerian-Lagrangian mapping strategy indeed offers this independence. The subsequent mixing tank simulations generate grid-independent results. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T11:20:32.511175-05:
      DOI: 10.1002/aic.16061
       
  • Simulation of Shale Gas Transport and Production with Complex Fractures
           using Embedded Discrete Fracture Model
    • Authors: Wei Yu; Yifei Xu, Malin Liu, Kan Wu, Kamy Sepehrnoori
      Abstract: The goal of this study is to develop a new model to simulate gas and water transport in shale nanopores and complex fractures. We first derive a new gas diffusivity equation to consider multiple important physical mechanisms such as gas desorption, gas slippage and diffusion, and non-Darcy flow. For complex fractures, we implement a state-of-the-art embedded discrete fracture model (EDFM). We verify this numerical model against a commercial reservoir simulator for shale gas simulation with multiple planar fractures. After that, we perform a series of simulation studies to investigate the impacts of complex gas transport mechanisms and various fracture geometries on well performance. The critical parameters controlling well performance are identified. The simulation results reveal that modeling of gas production from complex fractures as well as modeling important gas transport mechanisms in shale gas reservoirs is extremely significant. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T11:20:28.910288-05:
      DOI: 10.1002/aic.16060
       
  • Monetizing Shale Gas to Polymers under Mixed Uncertainty: Stochastic
           Modeling and Likelihood Analysis
    • Authors: Chang He; Ming Pan, Bingjian Zhang, Qinglin Chen, Fengqi You, Jingzheng Ren
      Abstract: This paper presents a novel framework based on stochastic modeling methods and likelihood analysis to address large-scale monetization processes of converting shale gas to polymers under the mixed uncertainties of feedstock compositions, estimated ultimate recovery, and economic parameters. A new stochastic data processing strategy is developed to quantify the feedstock variability through generating the appropriate number of scenarios. This strategy includes the Kriging-based surrogate model, sample average approximation and the integrated decline-stimulate analysis curve. The feedstock variability is then propagated through performing a detailed techno-economic modeling method on distributed-centralized conversion network systems. Uncertain economic parameters are incorporated into the stochastic model to estimate the maximum likelihood of performance objectives. The proposed strategy and models are illustrated in four case studies with different plant locations and pathway designs. The results highlight the benefits of the hybrid pathway as it is more amenable to reducing the economic risk of the projects. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T11:16:27.67898-05:0
      DOI: 10.1002/aic.16058
       
  • Extracting Dynamic Features with Switching Models for Process Data
           Analytics and Application in Soft Sensing
    • Authors: Yanjun Ma; Biao Huang
      Abstract: In recent decades, soft sensors have been profoundly studied and successfully applied to predict critical process variables in real-time. While dealing with various application scenarios, data-driven methods with representation learning possess great potentials. Latent features are formulated in these approaches to predict outputs from correlated input variables. In this study, a probabilistic framework of feature extraction is proposed in the context of process data analysis. To address switching behaviours in industrial processes, multiple emission models are utilized to construct latent space. To address temporal correlations from continuously operating processes, a dynamic model is implemented in latent space. Bayesian learning strategy is then developed for parameters estimation, where modelling preferences and uncertainties from multiple models are considered. The effectiveness and practicability of the proposed feature extraction algorithm are illustrated through numerical simulations, as well as an industrial case study. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-15T11:16:01.49727-05:0
      DOI: 10.1002/aic.16059
       
  • Dynamic Catalytic Adsorptive Desulfurization of Real Diesel over
           Ultra-Stable and Low-Cost Silica Gel supported TiO2
    • Authors: Xiaoling Ren; Zewei Liu, Lei Dong, Guang Miao, Neng Liao, Zhong Li, Jing Xiao
      Abstract: The work aims to develop dynamic ultra-deep catalytic adsorptive desulfurization of real diesel using ultra-stable and low-cost silica gel supported TiO2. A two-stage dynamic breakthrough model was built to describe the CADS process, varied with H/R ratio and O/S ratio. The desulfurization capacity reached 1.3 mg-S/g-A at the breakthrough concentration of 5 ppm-S. Various types of silica gel were screened as the substrate for TiO2, and the textural/acidic properties and CADS capacity were correlated in high relevancy. The effectiveness of diverse oxidants on CADS and the oxidation path were elucidated via combined experiment/simulation. Adsorption enthalpy derived from fitted isotherm data was calculated as 33.4 kJ/mol. The TiO2/silica gel-based sorbent demonstrated remarkable recyclability/stability in 10 cycles. This work provides an effective and economic route to eliminate the trace amount of stubborn sulfur compounds in low-sulfur diesel, which can be potentially implemented as the final polishing step for ultra-clean diesel production. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:44.823274-05:
      DOI: 10.1002/aic.16055
       
  • Towards a continuous synthesis of porous carbon xerogel beads
    • Authors: David Eskenazi; Patrick Kreit, Jean-Paul Pirard, Philippe Compère, Nathalie Job
      Abstract: A continuous process for producing porous carbon xerogel beads has been developed. It consists in injecting a pre-cured aqueous solution of resorcinol and formaldehyde on top of a column filled with hot oleic acid. The latter is pumped on the top of the column and fed at the bottom, generating an upward flow that can be adjusted to match the terminal velocity of the settling beads. Thus, the bead residence time in the column can be adjusted to match the gelation time, allowing the beads to solidify before reaching the bottom of the vessel. The obtained beads are subsequently dried and pyrolyzed.The developed experimental setup proved the continuous synthesis of porous carbon beads is possible. Nevertheless, the shaping process caused various texture changes of the porous carbon, which mainly yields macropores instead of micro and mesopores. This process also leads to the build-up of a denser skin around the beads. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:40.993442-05:
      DOI: 10.1002/aic.16056
       
  • Surface Nonuniformities in Latex Paints due to Evaporative Mechanisms
    • Authors: K.B. Sutton; C.B. Clemons, K.L. Kreider, J.P. Wilber, G.W. Young
      Abstract: A model is developed for predicting long-wavelength nonuniformities in the thickness of drying latex paint films. The model includes the effects of temperature, latex particle volume fraction, surface surfactant density, bulk surfactant density, and several material and environmental factors. After the model is simplified by applying the lubrication approximation, equations for spatially independent base state solutions are derived. The base state solutions describe a drying latex paint film of uniform thickness. The equations for the base states are solved numerically and a linear stability analysis is conducted. This analysis indicates that evaporation, slow surfactant kinetics, low initial surface tension, substrate permeability, and high initial latex particle volume fractions destabilize the uniform film, while fast surfactant kinetics, high initial surface tension, and high viscosity are stabilizing. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:33.285414-05:
      DOI: 10.1002/aic.16057
       
  • Multi-Dimensional Modeling of a Microfibrous Entrapped Cobalt Catalyst
           Fischer-Tropsch Reactor Bed
    • Authors: M. S. Challiwala; B. A. Wilhite, M. M. Ghouri, N. O. Elbashir
      Abstract: Thermal management of highly-exothermic Fischer-Tropsch-Synthesis has been a challenging bottleneck limiting the radial dimension of the Packed-Bed (PB) reactor tube to 1.5”-ID. In this work, a computational demonstration of a novel Microfibrous-Entrapped-Cobalt-Catalyst (MFECC) in mitigating hotspot formation has been evaluated. Specifically, a 2-D model was developed in COMSOL®, validated with experimental data and subsequently employed to demonstrate scale-up of the FTS bed from 0.59” – 4”ID. Significant hot-spot of 102.39 K in PB was reduced to 9.4 K in MFECC bed under gas-phase at 528.15 K and 2 MPa. Improvement in heat-transfer within the MFECC bed facilitates higher productivities at low space velocities (≥1000 1/h) corresponding to high CO-conversion (≥90%). Additionally, the MFECC reactor provides an 8-fold increase in the reactor ID at hotspots≤30 K with CO% conversions≥90%. This model was developed for a typical FTS cobalt-based catalyst where CO2 production is negligible. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-12T15:41:18.867483-05:
      DOI: 10.1002/aic.16053
       
  • Synthesis of Ni Nanoparticles with Controllable Magnetic Properties by
           Atmospheric Pressure Microplasma Assisted Process
    • Authors: Liangliang Lin; Sergey A. Starostin, R. Lavrijsen, Wei Zhang, Sirui Li, Volker Hessel
      Abstract: An atmospheric pressure microplasma technique is demonstrated for the gas phase synthesis of Ni nanoparticles by plasma-assisted nickelocene dissociation at different conditions. The dissociation process and the products are characterized by complementary analytical methods to establish the relationship between operational conditions and product properties. The innovation is to show proof-of-principle of a new synthesis route which offers access to less costly and less poisonous reactant, a higher quality product, and a simple, continuous and pre/post treatment-free manner with chance for fine-tuning “in-flight”. Results show that Ni nanoparticles with controllable magnetic properties are obtained, in which flexible adjustment of product properties can be achieved by tuning operational parameters. At the optimized condition only fcc Ni nanoparticles are formed, with saturation magnetization value of 44.4 mAm2/g. The upper limit of production rate for Ni nanoparticles is calculated as 4.65 × 10−3 g/h using a single plasma jet, but the process can be scaled-up through a microplasma array design. In addition, possible mechanisms for plasma-assisted nickelocene dissociation process are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-12T15:41:06.40549-05:0
      DOI: 10.1002/aic.16054
       
  • Limiting Flux in Microfiltration of Colloidal Suspensions by Focusing on
           Hydrodynamic Forces in Viscous Sublayer
    • Authors: Ryo Makabe; Kazuki Akamatsu, Shin-ichi Nakao
      Abstract: Cross-flow microfiltration tests were performed on colloidal suspensions under turbulence conditions. By changing the particle diameter, flow rate, and channel height in the membrane housing to measure limiting fluxes, the influence of each parameter on the limiting flux was assessed from the viewpoint of hydrodynamic forces exerted on a particle in the viscous sublayer. In analyzing all the data taken, we found that the particle Reynolds number calculated from the limiting flux is proportional to the 1.5-power of that calculated from the flow rate at the boundary between the viscous sublayer and the intermediate layer. This fact indicates that the limiting flux can be determined in situations where the drag force exerted by the flux is balanced by the lift force in the viscous sublayer. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:55.882106-05:
      DOI: 10.1002/aic.16050
       
  • Model fitting of sorption kinetics data: Rectification of misapplications
           overlooked
    • Authors: Yifeng Huang; Muhammad U. Farooq, Shuixiu Lai, Panida Sampranpiboon, Xiaodong Wang, Wei Huang, Xianshe Feng
      Abstract: When the model fitting of sorption kinetics data was carried out using linearized pseudo second order rate equations based on constant Qe corresponding to equilibrium sorption, the instantaneous driving force for sorption was underestimated, resulting in an erroneous overestimation of the rate constant. To resolve the issue, a rectification of the model fitting was proposed by accounting for the concentration dependence of Qe in the model equation based on the fact that Qe in the equation represents the sorption capacity at that instant as sorption proceeded with time. The rectified approach was validated with experimental data for various sorption systems reported in the literature. It was shown that the rectification yielded true sorption rate constant that characterizes the relationship between sorption rate and solute concentration, thereby resolving the issues associated with the original approach where the specific rate constant was found to depend on solute concentration and sorption time. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:51.887542-05:
      DOI: 10.1002/aic.16051
       
  • Heat Transfer Characteristics of Polymer Hollow Fiber Heat Exchanger for
           Vaporization Application
    • Authors: Jun Liu; Hong Guo, Xingxing Zhi, Lei Han, Kai Xu, Hailei Li, Baoan Li
      Abstract: The heat transfer characteristics of polymer hollow fiber heat exchanger were investigated by analysing the heat transfer coefficient (HTC) and the heat transfer resistance (HTR) distributions of both the lumen side and the shell side. The influences of the fiber wall thickness and the polymer thermal conductivity on the heat transfer performance were studied numerically based on the experimental validated simulation model. It is found that the original overall HTC value is below 1032 W/m2·K and the HTR is focus on the fiber wall. However, if enhancing the polymer thermal conductivity to be higher than 1.0 W/m·K and/or lowering the fiber wall thickness to be less than 0.1 mm, the overall HTC could be improved to over 2000 W/m2·K, which indicates that the fiber wall HTR is no longer the limiting factor of the polymer hollow fiber heat exchanger applications. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:37.500975-05:
      DOI: 10.1002/aic.16049
       
  • Mass Transfer Coefficient of Tubular Ultrafiltration Membranes under
           High-Flux Conditions
    • Authors: Kazuki Akamatsu; Keita Ishizaki, Shotaro Yoshinaga, Shin-ichi Nakao
      Abstract: The effect of suction flow on the mass transfer coefficient of tubular ultrafiltration membranes, in particular that under a high flux condition, was studied. We pointed out that Nsh is proportional to NRe 0.875 NSc 0.25 under turbulent conditions, and that the proportional constant, b, exceeds 0.023 when the effect of suction flow is not negligible. We conducted the velocity variation method using ultrafiltration membranes with MWCOs of 20k and 100k and dextrans having molecular weights of 40,000 and 70,000 at the conditions where NRe exceeded 3.6 × 103. We demonstrated that the effect of suction flow includes not only flux but also the diffusion coefficient of solute, and that the ratio of the flux to the diffusion coefficient, expressed as NPew, is an important index. Finally, we concluded that b = 0.023 when NPew is smaller than 2.23 × 103, giving the Deissler equation itself, and that b=2.04×10-6×NPew1.21 when NPew exceeds 2.23 × 103. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:05:23.128217-05:
      DOI: 10.1002/aic.16052
       
  • A Full-condition Monitoring Method for Nonstationary Dynamic Chemical
           Processes with Cointegration and Slow Feature Analysis
    • Authors: Chunhui Zhao; Biao Huang
      Abstract: Chemical processes are in general subject to time variant conditions because of load changes, product grade transitions, or other causes, resulting in typical nonstationary dynamic characteristic. It is of a considerable challenge for process monitoring to consider all possible operation conditions simultaneously including multifarious steady states and dynamic switchings. In the present work, a novel full-condition monitoring strategy is proposed based on both cointegration analysis (CA) and slow feature analysis (SFA) with the following considerations: (1) Despite that the operation conditions may vary over time, they may follow certain equilibrium relations that extend beyond the current time; (2) there may exist certain dynamic relations that stay invariant under normal process operation despite process may operate at different operating conditions. To monitor both equilibrium and dynamic relations, in the proposed method, nonstationary variables are separated from stationary variables first. Then by CA and SFA, the long-term equilibrium relation is distinguished from the specific relation held by the current conditions from both static and dynamic aspects. Various monitoring statistics are designed with clear physical interpretation. It can distinguish between the changes of operation conditions and real faults by checking deviations from equilibrium relation and deviations from the specific relation. Case study on a chemical industrial scale multiphase flow experimental rig shows the validity of the proposed full-condition monitoring method. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-06T15:25:32.357672-05:
      DOI: 10.1002/aic.16048
       
  • Combined Effects of Soot Load and Catalyst Activity on the Regeneration
           Dynamics of Catalytic Diesel Particulate Filters
    • Authors: Valeria Di Sarli; Almerinda Di Benedetto
      Abstract: The combined effects of soot load and catalyst activity on the regeneration dynamics of a catalytic diesel particulate filter have been investigated through transient CFD-based simulations of soot combustion in a single-channel configuration. The soot load was changed by varying the amount of soot accumulated as cake layer, while keeping the amount of soot trapped inside the catalytic wall constant.Substantially uniform soot combustion that allows reasonably fast regeneration of the filter under controlled temperature conditions has been simulated only in the absence of cake and at relatively low catalyst activity. Conversely, in the presence of cake, numerical predictions have shown that, regardless of both soot load and catalyst activity, fast regeneration always occurs by propagation of sharp reaction fronts that result in high temperature rises.These findings highlight the importance of avoiding the cake formation, while properly optimizing the catalyst activity, to conduct an effective regeneration of catalytic filters. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-05T07:55:41.670631-05:
      DOI: 10.1002/aic.16047
       
  • Influence of Mixing Performance on Polymerization of Acrylamide in
           Capillary Microreactors
    • Authors: Yang Song; Minjing Shang, Guangxiao Li, Luo Zheng-Hong, Yuanhai Su
      Abstract: Non-living free radical polymerization of acrylamide was chosen as a model reaction to investigate the effect of mixing performance on the polymerization in capillary microreactors. The polymerization rate was enhanced by increasing the volumetric flow rate and the reaction temperature at a constant residence time. However, higher temperatures led to lower Mn and larger PDI. The reaction mixture viscosity increased significantly during the polymerization. Both diffusion and dispersion coefficients were calculated in order to evaluate the mixing performance in microreactors. The capillary microreactor with a larger inner diameter led to higher monomer conversions, lower Mn and larger PDI compared to the capillary microreactor with a smaller inner diameter, which could be explained through a heat balance analysis for the polymerization and the dispersion effect. Moreover, it was found that the addition of a pre-mixing stage minimized the effect of insufficient mixing between the initiators and the monomers on the polymerization. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:31:21.040339-05:
      DOI: 10.1002/aic.16046
       
  • Multilevel Monte Carlo Applied to Chemical Engineering Systems Subject to
           Uncertainty
    • Authors: Grigoriy Kimaev; Luis A. Ricardez-Sandoval
      Abstract: The aim of this study is to evaluate the performance of Multilevel Monte Carlo (MLMC) sampling technique for uncertainty quantification in chemical engineering systems. Three systems (a mixing tank, a wastewater treatment plant and a ternary distillation column, all subject to uncertainty) were considered. The expected values of the systems' observables were estimated using MLMC, Power Series and Polynomial Chaos expansions, and standard Monte Carlo (MC) sampling. The MLMC technique achieved results of significantly greater accuracy than other methods at a lower computational cost than standard MC. This study highlights the nuances of adapting the MLMC technique to chemical engineering systems and the advantages of using MLMC for uncertainty quantification. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:31:11.300659-05:
      DOI: 10.1002/aic.16045
       
  • Simulation of Gas Separation Using Partial Element Stage Cut Modeling of
           Hollow Fiber Membrane Modules
    • Authors: Sina Gilassi; Seyed Mohammad Taghavi, Denis Rodrigue, Serge Kaliaguine
      Abstract: A mathematical model is developed to simulate a gas separation process using a hollow fiber membrane module. In particular, a new numerical technique is introduced based on flash calculation. Such analysis allows identifying the required membrane properties needed to reach module performance of interest. This model is validated for six different gas separation cases taken from literature. Then, the validated model is used to investigate the effect of O2 and N2 permeances on O2 recovery and O2 mole fraction in the permeate stream. A realistic two-stage air enrichment process is also proposed for O2 production using an industrial module with different fibers numbers. Moreover, this model is used to simulate a natural gas purification process using a single unit to determine the required membrane separation area and CH4 loss. Finally, a two-stage process is proposed to equally enhance CH4 retentate mole fraction and decrease CH4 loss. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:30:41.921538-05:
      DOI: 10.1002/aic.16044
       
  • Extending the Range of COSMO-SAC to High Temperatures and High Pressures
    • Authors: Christian L. Silveira; Stanley I. Sandler
      Abstract: In this paper we extend the range of the predictive Gibbs energy of solvation model, COSMO-SAC, to large ranges of density, pressure and temperature for very nonideal mixtures by combining it with an equation of state using the Wong-Sandler mixing rule. We compare the accuracy of isothermal vapor-liquid equilibria (VLE) calculations based on using the predictive COSMO-SAC model and separately the correlative NRTL model, each combined with three different forms of the Peng-Robinson equation of state (PREOS). All the models considered require the value of the EOS mixing rule binary parameter kij. The NRTL model also requires three other parameters obtained from correlation low pressure VLE data. We show that the PRSV + COSMO-SAC model, with its one adjustable parameter obtained from low temperature data leads good predictions at much higher temperatures and pressures. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-01T11:06:26.182402-05:
      DOI: 10.1002/aic.16043
       
  • Enhanced CO2 Separation Performance for Tertiary Amine-silica Membranes
           via Thermally Induced Local Liberation of CH3Cl
    • Authors: Liang Yu; Masakoto Kanezashi, Hiroki Nagasawa, Norihiro Moriyama, Henji Ito, Toshinori Tsuru
      Abstract: A facile method for the fabrication of amine-silica membranes with enhanced CO2 separation performance was proposed via the thermally induced liberation of small molecules from quaternary ammonium salt. Quaternary ammonium-silica (QA-SiO1.5) xerogel powders/films were fabricated via sol-gel processing and their thermal stability was systematically studied using TG-MS, FTIR, EDS, and PALS analysis. CO2 sorption performances of QA-SiO1.5 derived xerogel powders were quantitatively compared after assigning their relevant parameters to a dual-mode sorption model. The gas permeation performances of membranes derived from QA-SiO1.5 were evaluated in terms of kinetic diameter and temperature dependence of gas permeance, and activation energy (Ep) required for gas permeation. The results indicate that liberation of the CH3Cl molecules from these membranes significantly improved both CO2 permeation and CO2/N2 separation capabilities. Therefore, the present study provides insight that should be useful in the development of high-performance CO2 separation membranes via the effect of the thermally induced liberation of small molecules. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:40:55.024476-05:
      DOI: 10.1002/aic.16040
       
  • Stem Cell Biomanufacturing under Uncertainty: A Case Study in Optimizing
           Red Blood Cell Production
    • Authors: Ruth Misener; Mark C. Allenby, María Fuentes-Garí, Karan Gupta, Thomas Wiggins, Nicki Panoskaltsis, Efstratios N. Pistikopoulos, Athanasios Mantalaris
      Abstract: As breakthrough cellular therapy discoveries are translated into reliable, commercializable applications, effective stem cell biomanufacturing requires systematically developing and optimizing bioprocess design and operation. This manuscript proposes a rigorous computational framework for stem cell biomanufacturing under uncertainty. Our mathematical tool kit incorporates: high-fidelity modeling; single- and multivariate sensitivity analysis; global topological superstructure optimization; robust optimization. We quantitatively demonstrate the advantages of the proposed bioprocess optimization framework using, as a case study, a dual hollow fiber bioreactor producing red blood cells from progenitor cells. The optimization phase reduces the cost by a factor of 4 and the price of insuring process performance against uncertainty is approximately 15% over the nominal optimal solution. Mathematical modeling and optimization can guide decision making; we quantitatively evaluate the possible commercial impact of this cellular therapy using the disruptive technology paradigm. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:40:33.501778-05:
      DOI: 10.1002/aic.16042
       
  • Hydrodynamics in a Jet Bubbling Reactor: Experimental Research and
           Mathematical Modeling
    • Authors: Zhengliang Huang; Haotong Wang, Yun Shuai, Tianqi Guo, Musango Lungu, Yao Yang, Jingdai Wang, Yongrong Yang
      Abstract: The radial distribution of liquid velocity in the axial direction of a jet bubbling reactor has been measured by experimentation. Three different typical flow structures controlled by liquid jet, gas bubbling and liquid jet coupled with bubbling are observed. A tank in series model is established on this basis. Calculated values in each region are in good agreement with measured values in jet, bubbling and wall effect controlled areas. Axial flow rate, radial exchange rate and jet controlled volume η are analyzed from energy input aspect under different ug and uj. Simulation results indicate that under the synergetic action of the liquid jet and gas bubbling effect, jet controlled area exhibits a “spindle” structure, and its size decreases with the increase of ug. When gas input power occupies about 67% of total energy consumption, the best synergy of liquid jet and gas bubbling is obtained. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:35:36.521727-05:
      DOI: 10.1002/aic.16041
       
  • An Innovative Unit Operation of Particle Separation/Classification by
           Irradiating Low-Frequency Ultrasound into Water
    • Authors: Hiroya Muramatsu; Takayuki Saito
      Abstract: By irradiating kHz-band ultrasound, submillimeter- or millimeter-size particles that were dispersed in water with dissolved gases flocculated into a spherically flocculated particle swarm (SFPS). Acoustic cavitation-oriented bubbles caused by the irradiation played essential roles in the formation of the SFPS. Unprecedented and promising phenomena were observed: the particles were separated based on their diameters through the precise control of the ultrasound irradiation, and the SFPS was easily manipulated by using a motion-controlled stick. We discuss the relationship between the sound-pressure profiles and the manipulable range of the SFPS; i.e., the effectively manipulable range was limited by the sound-pressure profile. By means of manipulation control, we demonstrate the particle classification by particle diameters. On the basis of these findings, we propose an example of a practical application of this technique. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:40.100345-05:
      DOI: 10.1002/aic.16039
       
  • Numerical and Experimental Evaluation of Heat Transfer in Helically
           Corrugated Tubes
    • Authors: David J. Van Cauwenberge; Jens N. Dedeyne, Jens Floré, Kevin M. Van Geem, Guy B. Marin
      Abstract: The enhancement of convective heat transfer in single-phase heat transfer through the use of helicoidally corrugated tubes has been studied numerically. By comparing the large eddy simulation (LES) results with detailed Stereo-PIV and Liquid Crystal Thermography measurements obtained at the von Karman Institute for Fluid Dynamics (VKI), a validated numerical framework was obtained. Heat transfer enhancements of 83-119% were seen, at the cost of pressure losses that were approximately 5.6 to 6.7 times higher than for a bare tube. In order to extrapolate the results to industrial Reynolds numbers at which experimental data is scarce, the simulation data was used to develop an improved near-wall Reynolds stress transport model (RSTM) that more accurately describes the heat flux vector. Comparison of both global and local flow characteristics at different Reynolds numbers confirms that the approach allows more accurate predictions over a wider range of design and operating parameters than using two-equation turbulence models, while the computational cost is still significantly lower than LES. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:37.154999-05:
      DOI: 10.1002/aic.16038
       
  • Catalytic Partial Oxidation of CH4 over Bimetallic Ni-Re/Al2O3: Kinetic
           determination for Application in Microreactor
    • Authors: Kuson Bawornruttanaboonya; Navadol Laosiripojana, Arun S. Mujumdar, Sakamon Devahastin
      Abstract: The activity of a novel Ni-Re/Al2O3 catalyst toward partial oxidation of methane was investigated in comparison with a precious-metal Rh/Al2O3 catalyst. Reactions involving CH4/O2/Ar, CH4/H2O/Ar, CH4/CO2/Ar, CO/O2/Ar and H2/O2/Ar were performed to determine the kinetic expressions based on indirect partial oxidation scheme. A mathematical model comprising of Ergun equation as well as mass and energy balances with lumped indirect partial oxidation network was applied to obtain the kinetic parameters and then used to predict the reactant and product concentrations as well as temperature profiles within a fixed-bed microreactor. H2 and CO production as well as H2/CO2 and CO/CO2 ratios from the reaction over Ni-Re/Al2O3 catalyst were higher than those over Rh/Al2O3 catalyst. Simulation revealed that much smoother temperature profiles along the microreactor length were obtained when using Ni-Re/Al2O3 catalyst. Steep hot-spot temperature gradients, particularly at the entrance of the reactor, were, on the other hand, noted when using Rh/Al2O3 catalyst. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:22.472597-05:
      DOI: 10.1002/aic.16037
       
  • Magnetic Resonance Imaging of Gas-Solid Fluidization with Liquid Bridging
    • Authors: C. M. Boyce; A. Penn, K. P. Pruessmann, C. R. Müller
      Abstract: Magnetic resonance imaging is used to generate snapshots of particle concentration and velocity fields in gas-solid fluidized beds into which small amounts of liquid are injected. Three regimes of bed behavior (stationary, channeling and bubbling) are mapped based on superficial velocity and liquid loading. Images are analyzed to determine quantitatively the number of bubbles, the bubble diameter, bed height and the distribution of particle speeds under different wetting conditions. The cohesion and dissipation provided by liquid bridges cause an increase in the minimum fluidization velocity and a decrease in the number of bubbles and fast particles in the bed. Changes in liquid loading alter hydrodynamics to a greater extent than changes in surface tension or viscosity. Keeping U/Umf at a constant value of 1.5 produced fairly similar hydrodynamics across different wetting conditions. The detailed results presented provide an important dataset for assessment of the validity of assumptions in computational models. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:06:04.060573-05:
      DOI: 10.1002/aic.16036
       
  • Analysis of North-American Tight Oil Production
    • Authors: Raul Velascoa; Palash Panja, Manas Pathak, Milind Deo
      Abstract: North-American tight oil production has been on the rise due to the introduction of new drilling and hydraulic fracturing technologies. Such advances have dramatically changed the conventional understanding of the hydrocarbon recovery process. A dimensionless study of tight oil production across the United Sates in plays such as the Bakken, Niobrara, Eagle Ford, Woodford, Bone Spring, and Wolfcamp shed light on some of these recovery processes. Production from any well, regardless of geologic attributes and operating conditions, fits into a universal curve during its initial productive period. Subsequently, production becomes a strong function of hydrocarbon thermodynamics and multiphase flow. Results from this analysis help rank important parameters that affect oil recovery in terms of how wells are operated and the reservoir's intrinsic geological and fluid properties. Furthermore, production results are combined with a simple dimensionless economic analysis to determine optimal fracture configurations independent of oil price environment. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:00:56.000202-05:
      DOI: 10.1002/aic.16034
       
  • Simulation and Modeling of Segregating Rods in Quasi-2D Bounded Heap Flow
    • Authors: Yongzhi Zhao; Hongyi Xiao, Paul B. Umbanhowar, Richard M. Lueptow
      Abstract: Many products in the chemical and agricultural industries are pelletized in the form of rod-like particles that often have different aspect ratios. However, the flow, mixing, and segregation of non-spherical particles such as rod-like particles are poorly understood. Here, we use the discrete element method (DEM) utilizing super-ellipsoid particles to simulate the flow and segregation of rod-like particles differing in length but with the same diameter in a quasi-2D one-sided bounded heap. The DEM simulations accurately reproduce the segregation of size bidisperse rod-like particles in a bounded heap based on comparison with experiments. Rod-like particles orient themselves along the direction of flow, though bounding walls influence the orientation of the smaller aspect ratio particles. The flow kinematics and segregation of bidisperse rods having identical diameters but different lengths are similar to spherical particles. The segregation velocity of one rod species relative to the mean velocity depends linearly on the concentration of the other species, the shear rate, and a parameter based on the relative lengths of the rods. A continuum model developed for spherical particles that includes advection, diffusion, and segregation effects accurately predicts the segregation of rods in the flowing layer for a range of physical control parameters and particle species concentrations. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:00:31.548838-05:
      DOI: 10.1002/aic.16035
       
  • Robust Stabilization of a Two-Stage Continuous Anaerobic Bioreactor System
    • Authors: Zhaoyang Duan; Costas Kravaris
      Abstract: This paper studies the problem of stabilizing a two-stage continuous bioreactor system. A simple dynamic model of the system is first introduced based on a detailed mass balance model, and then used to derive a constant-yield controller to stabilize the system at given design steady state conditions. Using Lyapunov stability analysis, this control law is proved to guarantee stability of the closed loop system over the entire positive orthant. Simulation results show the successful performance of the controller. The control law is proved to be robust with respect to errors in the kinetic parameters and in the inlet feed concentration, in the sense of preserving its stability region. Performance of the control system can be enhanced if a feedforward measurement of the inlet feed concentration can be incorporated in the control law. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:55:41.235266-05:
      DOI: 10.1002/aic.16033
       
  • Mixed-Cation LiCa-LSX Zeolite with Minimum Lithium for Air Separation
    • Authors: Franklin E. Epiepang; Xiong Yang, Jianbo Li, Yingshu Liu, Ralph T. Yang
      Abstract: The aim of this work was to reduce/minimize Li in Li-LSX by replacing the 70% Li+ cations in Li-LSX that are bonded to the interior or inaccessible sites which are not used for adsorption. Thus, mixed-cation LiCa-LSX containing minimum lithium were prepared by exchanging small fractions of Li+ into Ca-LSX, followed by dehydration under mild conditions to avoid migration/equilibration of Li+ cations. Comparisons of adsorption isotherms of N2/O2 and heats of adsorption for the LiCa-LSX samples with that for pure-cation Li-LSX and Ca-LSX provided strong evidence that significant amounts of these Li+ cations indeed remained on the exposed sites (SIII). The mixed-cation LiCa-LSX samples were compared against the pure-cation Ca-LSX and Li-LSX based on their performance for oxygen production by PSA, via model simulation. The results showed that the mixed-cation LiCa-LSX samples yielded significantly higher O2 product productivities at the same product purity and recovery than their pure-cation precursor (Ca-LSX). This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:55:36.79446-05:0
      DOI: 10.1002/aic.16032
       
  • Modeling of Circulating Fluidized Beds systems for post-combustion CO2
           capture via Temperature Swing Adsorption
    • Authors: Stefano E. Zanco; Matteo Gazzani, Matteo C. Romano, Isabel Martínez, Marco Mazzotti
      Abstract: The technology of circulating uidized beds (CFB) is applied to temperature swing adsorption (TSA) processes for post-combustion CO2 capture employing a commercial zeolite sorbent. Steady state operation is simulated through a one-dimensional model, which combines binary adsorption with the CFB dynamics. Both single step and multi-step arrangements are investigated. Extensive sensitivity analyses are performed varying the operating conditions, in order to assess the inuence of the main operational parameters. The results reveal a neat superiority of multi-step configurations over the standard one, in terms of both separation performance and efficiency. Compared to fixed-bed TSA systems, CFB TSA features a high compactness degree. However, product purity levels are limited compared to the best performing fixed-bed processes, and heat management within the system appears to be a major issue. As regards energy efficiency, CFB systems place themselves in between the most established absorption-based technologies and the fixed-bed TSA. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:50:38.062582-05:
      DOI: 10.1002/aic.16029
       
  • Feedback control of proppant bank heights during hydraulic fracturing for
           enhanced productivity in shale formations
    • Authors: Prashanth Siddhamshetty; Joseph Sang-II Kwon, Shuai Liu, Peter P. Valkó
      Abstract: In hydraulic fracturing of shale formations, compared to conventional reservoirs, the fracturing fluid injected is of low-viscosity and hence during pumping the proppant settles significantly, forming a proppant bank. Motivated by this consideration, we initially develop a high-fidelity process model of hydraulic fracturing to describe the dominant proppant settling behavior during hydraulic fracturing. Second, a novel remeshing strategy is developed to handle the high computational requirement due to moving boundaries. Third, a section-based optimization method is employed to obtain key fracture design parameters for enhanced productivity in shale formations subject to given fracturing resources. Fourth, a reduced-order model is constructed to design a Kalman filter and to synthesize a real-time model-based feedback control system by explicitly taking into account actuator limitations, process safety and economic considerations. We demonstrate that the proposed control scheme can regulate the uniformity of proppant bank heights along the fracture at the end of pumping. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:50:30.307892-05:
      DOI: 10.1002/aic.16031
       
  • Optimal PID Controller Tuning using Stochastic Programming Techniques
    • Authors: Jose A. Renteria; Yankai Cao, Alexander W. Dowling, Victor M. Zavala
      Abstract: We argue that stochastic programming provides a powerful framework to tune and analyze the performance limits of controllers. In particular, stochastic programming formulations can be used to identify controller settings that remain robust across diverse scenarios (disturbances, set-points, and modeling errors) observed in real-time operations. We also discuss how to use historical data and sampling techniques to construct operational scenarios and inference analysis techniques to provide statistical guarantees on limiting controller performance. Under the proposed framework, it is also possible to use risk metrics to handle extreme (rare) events and stochastic dominance concepts to conduct systematic benchmarking studies. We provide numerical studies to illustrate the concepts and to demonstrate that modern modeling and local/global optimization tools can tackle large-scale applications. The proposed work also opens the door to data-based controller tuning strategies that can be implemented in real-time operations. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-11T09:50:21.698851-05:
      DOI: 10.1002/aic.16030
       
  • Optimal Operation of Batch Enantiomer Crystallization: From Ternary
           Diagrams to Predictive Control
    • Authors: Caio Felippe Curitiba Marcellos; Helen Durand, Joseph Sang-II Kwon, Amaro Gomes Barreto, Paulo Laranjeira da Cunha Lage, Maurício Bezerra de Souza, Argimiro Resende Secchi, Panagiotis D. Christofides
      Abstract: In this work, the modeling and control of batch crystallization for racemic compound forming systems is addressed in a systematic fashion. Specifically, a batch crystallization process is considered for which the initial solution has been pre-enriched in the desired enantiomer to enable crystallization of only the preferred enantiomer. A method for determining desired operating conditions (composition of the initial pre-enriched solution and temperature to which the mixture must be cooled for maximum yield) for the batch crystallizer based on a ternary diagram for the enantiomer mixture in a solvent is described. Subsequently, it is shown that the information obtained from the ternary diagram, such as the maximum yield attainable from the process due to thermodynamics, can be used to formulate constraints for an optimization-based control method to achieve desired product characteristics such as a desired yield. The proposed method is demonstrated for the batch crystallization of mandelic acid in a crystallizer with a fines trap that is seeded with crystals of the desired enantiomer. The process is controlled with an optimization-based controller to minimize the ratio of the mass of crystals obtained from nuclei to the mass obtained from seeds while maintaining the desired enantioseparation. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-10T11:05:24.444146-05:
      DOI: 10.1002/aic.16028
       
  • More Comprehensive 3D Modeling of Clay-like Material Drying
    • Authors: M. Heydari; K. Khalili, S. Y. Ahmadi-Brooghani
      Abstract: Drying process plays an important role in the manufacturing of many products such as ceramic, kitchenware and building materials, some of which have complex 3D geometry. To deal with many restrictions found in literatures, a 3D numerical approach was used to describe the drying process of a porous Clay-like material. The problem investigated involves highly coupled equations considering heat, mass and mechanical aspects. The model is validated through the comparison of experimental measurements with simulation result. Simulation results show that increasing the initial moisture content and reducing the initial temperature have the same privilege and without significant increase in drying time, it reduces slightly the amount of maximum stress but delays the occurrence time of maximum stress. The non-uniform heat expansion induced stresses are very small in comparison to non-uniform moisture shrinkage induced stresses and can be neglected in drying simulation. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-10T10:10:20.229176-05:
      DOI: 10.1002/aic.16027
       
  • Numerical Simulation on Flow Behaviour of Twin-liquid Films over a
           Vertical Plate with an Open Window
    • Authors: Hanguang Xie; Jianguang Hu, Gance Dai
      Abstract: A novel element for gas–liquid contact, a plate with rectangular windows was designed to enhance absorption process. Coexistence and interaction of wall-bounded films and confined free films named as “twin-liquid films” were observed on the plate. VOF method was used to simulate its flow behavior. Flow phenomena such as flow around a step-in, jet impingement, varicose waves, and sinuous waves were observed. Different from thin films flow on an unperforated plate, larger mean velocity, thinner film thickness, more intensive capillary waves, and stronger vorticity on the free surfaces were detected inside the window, and the disturbances could propagate over the whole plate. Three-dimensional simulation results generally agreed with our experimental observations and further demonstrated complex wavy structures both inside and outside the window. The results would broaden traditional knowledge of liquid films flow and clarify the mechanism of mass transfer intensification for the plate with windows. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:42.379766-05:
      DOI: 10.1002/aic.16021
       
  • Materials Genomics-Guided Ab Initio Screening of MOFs with Open Copper
           Sites for Acetylene Storage
    • Authors: Ce Zhang; Youshi Lan, Xiangyu Guo, Qingyuan Yang, Chongli Zhong
      Abstract: Discovering high-performance metal-organic frameworks (MOFs) with open metal sites has become an increasingly hot research topic in the field of safe storage and transportation of acetylene. Following the concept of Materials Genomics proposed recently, a database of 502 experimental MOFs was built by searching the structures deposited in the CSD with the dicopper paddle-wheel node Cu2(COO)4 as the characteristic materials gene. On the basis of the developed ab initio force field, a high-throughput computational screening was conducted to examine the property-performance relationships of MOFs containing Cu-OMS for C2H2 storage at ambient conditions. The optimal ranges of the structural and energetic features for the design of such MOFs were suggested. From our computational screening, three potentially promising MOFs were identified which exhibit a performance outperforming those MOFs reported experimentally so far with record high gravimetric C2H2 uptakes, both in the total and deliverable adsorption capacities. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:34.030147-05:
      DOI: 10.1002/aic.16025
       
  • DEM Study on the Discharge Characteristics of Lognormal Particle Size
           Distributions from a Conical Hopper
    • Authors: Ya Zhao; Shiliang Yang, Liangqi Zhang, Jia Wei Chew
      Abstract: This study employs the discrete element method (DEM) to investigate the impact of the widths of lognormal particle size distributions (PSDs) with the same mean particle diameter on hopper discharge behaviors, namely, discharge rate, particle velocities and size-segregation. Results reveal that (i) the hopper discharge rate decreases as PSD width increases; (ii) the mean discharge rates are constant with time, but the fluctuations increase as the PSD width increases; (iii) the overall size-segregation increases with PSD width; (iv) the overall mean particle diameters of the narrower PSDs do not exceed the initial mean of 5 mm, whereas that of wider ones do; (v) the relationship between PSD width and particle velocities is non-monotonic with no consistent trends; and (vi) no direct correlation exists between particle velocity and size-segregation. The results here provide valuable insights on the behavior of the prevalent polydisperse mixtures in hoppers. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:30.637498-05:
      DOI: 10.1002/aic.16026
       
  • Studies on Mild Catalytic Synthesis of Methyl Acrylate via One-Step Aldol
           Reaction
    • Authors: Gang Wang; Chidchon Sararuk, Zeng-xi Li, Chun-shan Li, Hui Wang, Suo-jiang Zhang
      Abstract: One-step catalytic synthesis of methyl acrylate from methyl acetate and trioxane, with 90.7% yield and 91.8% selectivity, was realized at 10°C-25°C. NMR analysis confirmed the ester enolization with generation of [i-Pr2EtN-H]+[TfO]- in the presence of i-Pr2EtN and Bu2BOTf, which was affected by solvent and base. The depolymerization of trioxane into formaldehyde was catalyzed by Bu2BOTf. The in-situ catalytic mechanism and efficiency of [i-Pr2EtN-H]+[TfO]- was determined and analyzed. Mechanism-based kinetic and thermodynamic studies were conducted for better understanding of this route. Also the primary process design and product separation simulation were carried out. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T01:15:52.329623-05:
      DOI: 10.1002/aic.16022
       
  • Synthesis of Ternary Distillation Process Structures Featuring Minimum
           Utility Cost Using the IDEAS Approach
    • Authors: Hiroshi Takase; Shinji Hasebe
      Abstract: A synthesis method for ternary distillation process structures is proposed on the basis of the infinite-dimensional state-space (IDEAS) approach. The proposed synthesis procedure consists of two steps. At the first step, the utility cost is minimized. The result of the first step contains many tiny flows among the modules because the number of flows is not included in the objective function. Then, at the second step, an evolutionary procedure for process simplification is executed. In this step, the weighted sum of flow rates is minimized recursively while updating the weights at each iteration. The practical process structure is finally determined from the result of the second simplification step. The developed synthesis procedure was applied to the separation problem of a ternary mixture consisting of benzene, toluene, and o-xylene. It demonstrated that the proposed procedure provides a process whose liquid composition profile is quite similar to that of a Petlyuk column. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T01:15:39.984478-05:
      DOI: 10.1002/aic.16023
       
  • A Comparative Kinetics Study of CO2 Absorption into Aqueous DEEA/MEA and
           DMEA/MEA Blended Solutions
    • Authors: Wusan Jiang; Xiayi Hu, Xiao Luo, Hongxia Gao, Zhiwu Liang, Bin Liu, Paitoon Tontiwachwuthikul
      Abstract: The kinetics of CO2 absorption into aqueous solutions of N,N-diethylethanolamine (DEEA), and N,N-dimethylethanolamine (DMEA), and their blends with monoethanolamine (MEA) have been studied in a stopped-flow apparatus. The kinetics experiments were carried out at the concentrations of DEEA and DMEA varying from 0.075 to 0.175 kmol/m3 respectively, and that of MEA ranging between 0.0075 and 0.0175 kmol/m3, over the temperature range of 293K to 313K. Two kinetics models are proposed to interpret the reaction in the blended amine systems and the results show that the model which incorporates the base-catalyzed hydration mechanism and termolecular mechanism resulted in a better prediction. Furthermore, the kinetics behaviors of CO2 absorption into two blended systems are comprehensively discussed according to their molecular structures. It can be concluded that the interaction between tertiary amines and primary amines as well as the alkyl chain length of tertiary amines have a significant influence on the kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-07T17:38:46.095241-05:
      DOI: 10.1002/aic.16024
       
  • Uncertainty-Conscious Methodology for Process Performance Assessment in
           Biopharmaceutical Drug Product Manufacturing
    • Authors: Gioele Casola; Christian Siegmund, Markus Mattern, Hirokazu Sugiyama
      Abstract: This work presents an uncertainty-conscious methodology for the assessment of process performance—e.g., run time—in the manufacturing of biopharmaceutical drug products. The methodology is presented as an activity model using the type 0 integrated definition (IDEF0) functional modelling method, which systematically interconnects information, tools, and activities. In executing the methodology, a hybrid stochastic–deterministic model that can reflect operational uncertainty in the assessment result is developed using Monte Carlo simulation. This model is used in a stochastic global sensitivity analysis to identify tasks that had large impacts on process performance under the existing operational uncertainty. Other factors are considered, such as the feasibility of process modification based on Good Manufacturing Practice, and tasks to be improved is identified as the overall output. In a case study on cleaning and sterilization processes, suggestions were produced that could reduce the mean total run time of the processes by up to 40%. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-06T17:21:56.05222-05:0
      DOI: 10.1002/aic.16020
       
  • A Branch and Bound Algorithm to Solve Large-Scale Multi-Stage Stochastic
           Programs with Endogenous Uncertainty
    • Authors: Brianna Christian; Selen Cremaschi
      Abstract: The growth in computation complexity of multistage stochastic programs (MSSPs) with problem size often prevents its application to real-world size problems. We present two variants of branch-and-bound algorithm, which reduce the resource requirements for the generation and solution of large-scale MSSPs with endogenous uncertainty. Both variants use Knapsack-problem based Decomposition Algorithm12 to generate feasible solutions and primal bounds. First variant (PH-KDA) uses a progressive hedging dual-bounding approach; the second (OSS-KDA) solves the MSSP removing all non-anticipativity constraints. Both variants were employed to solve several instances of the pharmaceutical clinical trial planning problem. The first iteration of both algorithms provide a feasible solution, and a primal bound and a dual bound for the problem. Although the dual-bounds of OSS-KDA were generally weaker than PH-KDA, they are generated considerably faster. For the seven-product case the OSS-KDA generated a solution with a gap of 9.92% in 115 CPU seconds. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-06T17:21:53.693542-05:
      DOI: 10.1002/aic.16019
       
  • Insight in Kinetics from Pre-edge Features using Time Resolved in situ XAS
    • Authors: N.V.R.A. Dharanipragada; Vladimir V. Galvita, Hilde Poelman, Lukas C. Buelens, Alessandro Longo, Guy B. Marin
      Abstract: The kinetics of reduction of a 10wt%Fe2O3-MgAl2O4 spinel were investigated using XRD and time resolved Fe-K QXANES. The Rietveld refinement of the XRD pattern showed the replacement of Al with Fe in the spinel structure and the formation of MgFeAlOx. The XANES pre-edge feature was employed to study the reduction kinetics during H2-TPR (Temperature Programmed Reduction) up to 730°C. About 55% of the Fe3+ in MgFeAlOx was reduced to Fe2+. A shrinking core model, which takes into account both solid-state diffusion via an oxygen diffusion coefficient, and gas-solid reaction through a reaction rate coefficient, was applied. The activation energy for chemical reaction showed a linear dependence on the conversion, increasing from 104 kJ/mol to 126 kJ/mol over the course of material reduction. The good accordance between the shrinking core model description and the experimental data indicates that XANES pre-edge features can be used to correlate changes in material structure and reaction kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-27T10:35:26.233322-05:
      DOI: 10.1002/aic.16017
       
  • Joint Capacity Planning and Distribution Network Optimization of Coal
           Supply Chains under Uncertainty
    • Authors: Rui-Jie Zhou; Li-Juan Li
      Abstract: A two-stage stochastic integer programming model is developed to address the joint capacity planning and distribution network optimization of multi-echelon coal supply chains (CSCs) under uncertainty. The proposed model not only introduces the uses of compound real options in sequential capacity planning, but also considers uncertainty induced by both risks and ambiguities. Both strategic decisions (i.e., facility locations and initial investment, service assignment across the entire CSC, and option holding status) and scenario-based operational decisions (i.e., facility operations and capacity expansions, outsourcing policy, and transportation and inventory strategies) can be simultaneously determined using the model. By exploiting the nested decomposable structure of the model, we develop a new distributed parallel optimization algorithm based on non-convex generalized Bender decomposition and Lagrangean relaxation to mitigate the computation resource limitation. One of the main CSCs in China is studied to demonstrate the applicability of the proposed model and the performance of the algorithm. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-22T05:55:25.758985-05:
      DOI: 10.1002/aic.16012
       
  • Two-Step Continuous Production of Monodisperse Colloidal Ellipsoids at
           Rates of One Gram per Day
    • Authors: Joseph A. Ferrar; Leonid Pavlovsky, Yanliang Liu, Eric Viges, Michael J. Solomon
      Abstract: We report a two-step process for the continuous production of monodisperse polystyrene colloidal ellipsoids of aspect ratios up to 6.8 at rates that exceed 1.0 g per day, an improvement upon previously reported synthetic batch processing rates of nearly a factor of 20. This scale up is accomplished by continuous evaporative processing of a polymer solution into an elastomeric film embedded with colloidal spheres. Subsequently, the film is continuously elongated at a temperature that stretches the embedded spheres into ellipsoids. The method is used to deform initially 1.0 μm diameter spheres into ellipsoids of aspect ratio 1.27 ± 0.15, 3.31 ± 0.44, 3.91 ± 0.72, 4.14 ± 0.47, and 6.77 ± 1.01. The particle production rate reported here opens new possibilities for applications of monodisperse ellipsoids, such as self-assembly and optical characterization of complex crystalline unit cells, as well as rheological characterization of dilute gels and dense suspensions. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:06:30.057101-05:
      DOI: 10.1002/aic.16009
       
  • DEM-PBM modeling of abrasion dominated ribbon breakage
    • Authors: Simone Loreti; Chuan-Yu Wu, Gavin Reynolds, Jonathan Seville
      Abstract: In dry granulation, fine cohesive powders are compacted into large multi-particle entities, i.e., briquettes, flakes or ribbons. The powder compaction is generally followed by milling, a size reduction process, which is crucial to obtain the desired granule size or properties. Abrasion and impact are two primary mechanisms of comminution in ribbon milling, but they are not completely understood. The aim of this paper was hence to investigate numerically the fragmentation process induced by abrasion during ribbon milling. The discrete element method (DEM) was employed to simulate abrasion tests, for which three-dimensional parallelepiped ribbons were generated using auto-adhesive elastic spheres. The fragmentation rate, and the fragments size and number were determined for various surface energies and abrasive velocities. The DEM results showed that the mass-equivalent fragment size distributions were bi-modal, similar to the experimental observations and the numerical results for impact-dominated ribbon milling reported in the literature. In addition, two quantities were determined from the DEM analysis, i.e. the number of large fragments and the fraction of fines, which was then integrated into the population balance models (PBM) so that a DEM-PBM multiscale modeling framework was developed to predict the granule size distribution during ribbon milling. The DEM-PBM results were compared with the experimental results reported in the literature, and a broad agreement was obtained, implying the proposed DEM-PBM can be used to analyse the ribbon milling behavior. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-13T10:55:31.869796-05:
      DOI: 10.1002/aic.16005
       
  • An interfacial curvature distribution model and phase inversion
    • Authors: A. Vikhansky
      Abstract: The state of the two-phase system is described by the interfacial curvature distribution. A phenomenological closure model is proposed for the exact (unclosed) equations. Parameters of the model are related to the existing correlations for drop size in stirred flows. If water is dispersed in oil, the curvature has a uni-modal distribution with a positive mode. When a control parameter, e.g., water volume fraction is increasing, the distribution becomes bi-modal with both negative and positive values. After a while, the phase inversion occurs, and the distribution becomes uni-modal with a negative mode. Going in the other direction the phase inversion happens at lower volume fraction of water, i.e., there is an ambivalent region, where both phases might be in the dispersed state. The model implies, that even if the conditions for phase inversion are met, there might be a significant delay before the new morphology is established. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-06T17:50:21.172204-05:
      DOI: 10.1002/aic.15992
       
  • Modeling and Prediction of Protein Solubility using the Second Osmotic
           Virial Coefficient
    • Authors: Marcel Herhut; Christoph Brandenbusch, Gabriele Sadowski
      Abstract: The development of a precipitation or crystallization step requires knowing the solubility of the target protein and its crystallization behavior in aqueous solutions at different pH, temperatures and in the presence of precipitating agents, especially salts. Within this work, a solubility model for proteins based on the second osmotic virial coefficient B22 is developed. For this, a relation between protein solubility and B22 was combined with the extended DLVO model. This solubility model was then used to model and also predict the protein solubility of lysozyme and monoclonal antibody for different salts, salt concentrations, and pH. The modeled as well predicted B22 and protein solubility data of lysozyme in the presence of sodium chloride and sodium p-toluenesulfonate and of a monoclonal antibody in the presence of ammonium sulfate at different pH shows good agreement with experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-01T10:42:19.405106-05:
      DOI: 10.1002/aic.15944
       
  • Confinement of a polymer chain: An entropic study by Monte Carlo method
    • Authors: Flavia Ruggiero; Rosaria Aruta, Paolo Antonio Netti, Enza Torino
      Pages: 416 - 426
      Abstract: The properties of macromolecules in presence of an interface could be considerably modified due to confinement effects. When phase separations are performed in nanoconfined domains, the concurrent presence of high-energy interfaces and conformational entropy constraints of the macromolecules causes profound differences in polymer aggregation behavior. Here, thermodynamics of a polymer chain in solution, confined by a three-dimensional cubic interface, is studied by means of Monte Carlo method, focusing on the chain conformational entropy penalty arising from the excluded volume effects. The presented method might become a general tool for a preliminary evaluation of the thermodynamic effects due to the confinement of a polymer system. Further, the interface effects on Thermally Induced Phase Separation (TIPS) of polymer solutions, confined by High-Pressure Homogenization, are experimentally studied, regarding final morphologies. It is confirmed how peculiar polymer morphologies are obtained only when the TIPS develops under nanoconfinement degrees above a threshold one. © 2017 American Institute of Chemical Engineers AIChE J, 64: 416–426, 2018
      PubDate: 2017-09-08T07:31:47.690068-05:
      DOI: 10.1002/aic.15951
       
  • Gravitational discharge of fine dry powders with asperities from a conical
           hopper
    • Authors: Hui Lu; Jia Zhong, Gui-Ping Cao, Hai-Feng Liu
      Pages: 427 - 436
      Abstract: The effects of particle properties, especially the surface roughness and particle type, on the gravity discharge rate and flow behavior of fine dry powders from a conical hopper are studied in detail. The van der Waals force is considered to dominate the discharge of small particles, while the empty annulus effect dominates the discharge of large particles. To predict the van der Waals force between two rough spherical particles, a model based on Rumpf theory is adopted. The effect of surface roughness can be reflected by Bond number Bog which is correlated with discharge rate. By modifying the powder bed porosity and Beverloo constant, the discharge rates of fine dry powders can be well predicted by an empirical correlation. Finally, not only the ratio of hopper outlet size to particle size D0/dp but also the Bond number Bog is found to be an important indicator to determine the powder flowability. © 2017 American Institute of Chemical Engineers AIChE J, 64: 427–436, 2018
      PubDate: 2017-09-12T10:15:48.6213-05:00
      DOI: 10.1002/aic.15954
       
  • The effect of liquid bridge model details on the dynamics of wet fluidized
           beds
    • Authors: Mingqiu Wu; Johannes G. Khinast, Stefan Radl
      Pages: 437 - 456
      Abstract: Wet fluidized beds of particles in small periodic domains are simulated using the CFD-DEM approach. A liquid bridge is formed upon particle-particle collisions, which then ruptures when the particle separation exceeds a critical distance. The simulations take into account both surface tension and viscous forces due to the liquid bridge. We perform a series of simulations based on different liquid bridge formation models: (1) the static bridge model of Shi and McCarthy, (2) a simple static version of the model of Wu et al., as well as (3) the full dynamic bridge model of Wu et al. We systematically compare the differences caused by different liquid bridge formation models, as well as their sensitivity to system parameters. Finally, we provide recommendations for which systems a dynamic liquid bridge model must be used, and for which application this appears to be less important. © 2017 American Institute of Chemical Engineers AIChE J, 64: 437–456, 2018
      PubDate: 2017-09-13T11:16:15.496578-05:
      DOI: 10.1002/aic.15947
       
  • Quantitative and qualitative studies of microorganisms involved in
           full-scale autotrophic nitrogen removal performance
    • Authors: Barbara Muñoz-Palazon; Alejandro Rodriguez-Sanchez, Antonio Castellano-Hinojosa, Jesus Gonzalez-Lopez, Mark C. M. van Loosdrecth, Riku Vahala, Alejandro Gonzalez-Martinez
      Pages: 457 - 467
      Abstract: Autotrophic nitrogen removal systems have been implemented at full-scale and provide an efficient way for nitrogen removal from industrial and urban wastewaters. Our study present qualitative and quantitative analysis of archaeal and bacterial amoA genes and Candidatus Brocadiales bacteria analyzed in six full-scale autotrophic nitrogen removal bioreactors. The results showed that ammonium oxidizing bacteria (AOB) were detected in all bioreactors. However, ammonium oxidizing archaea (AOA) were detected only in the non-aerated technologies. Conversely, different Candidatus Brocadiales phylotypes appeared due to differences in influent wastewater composition and hydraulic retention time (HRT). In the same terms multivariate redundancy analysis confirmed that AOA was positively correlated with temperature, ammonium concentration and low HRT. However, AOB population was positively correlated with pH, temperature, and dissolved oxygen concentration. Our data suggested a correlation between the microorganisms involved in the nitrogen removal performance and the operational conditions in the different full-scale bioreactors. © 2017 American Institute of Chemical Engineers AIChE J, 64: 457–467, 2018
      PubDate: 2017-08-25T23:05:32.23751-05:0
      DOI: 10.1002/aic.15925
       
  • Dynamic modeling and simulations of the behavior of a fixed-bed
           reactor-exchanger used for CO2 methanation
    • Authors: Rasmey Try; Alain Bengaouer, Pierre Baurens, Christian Jallut
      Pages: 468 - 480
      Abstract: A multidimensional heterogeneous and dynamic model of a fixed-bed heat exchanger reactor used for CO2 methanation has been developed in this work that is based on mass, energy and momentum balances in the gas phase and mass and energy balances for the catalyst phase. The dynamic behavior of this reactor is simulated for transient variations in inlet gas temperature, cooling temperature, gas inlet flow rate, and outlet pressure. Simulation results showed that wrong-way behaviors can occur for any abrupt temperature changes. Conversely, temperature ramp changes enable to attenuate and even fade the wrong-way behavior. Traveling hot spots appear only when the change of an operating condition shifts the reactor from an ignited steady state to a non-ignited one. Inlet gas flow rate variations reveal overshoots and undershoots of the reactor maximum temperature. © 2017 American Institute of Chemical Engineers AIChE J, 64: 468–480, 2018
      PubDate: 2017-09-05T11:10:46.179263-05:
      DOI: 10.1002/aic.15874
       
  • Nonlinear robust optimization for process design
    • Authors: Yuan Yuan; Zukui Li, Biao Huang
      Pages: 481 - 494
      Abstract: A novel robust optimization framework is proposed to address general nonlinear problems in process design. Local linearization is taken with respect to the uncertain parameters around multiple realizations of the uncertainty, and an iterative algorithm is implemented to solve the problem. Furthermore, the proposed methodology can handle different categories of problems according to the complexity of the problems. First, inequality-only constrained optimization problem as studied in most existing robust optimization methods can be addressed. Second, the proposed framework can deal with problems with equality constraint associated with uncertain parameters. In the final case, we investigate problems with operation variables which can be adjusted according to the realizations of uncertainty. A local affinely adjustable decision rule is adopted for the operation variables (i.e., an affine function of the uncertain parameter). Different applications corresponding to different classes of problems are used to demonstrate the effectiveness of the proposed nonlinear robust optimization framework. © 2017 American Institute of Chemical Engineers AIChE J, 64: 481–494, 2018
      PubDate: 2017-09-12T10:25:46.48771-05:0
      DOI: 10.1002/aic.15950
       
  • Modular methanol manufacturing from shale gas: Techno-economic and
           environmental analyses of conventional large-scale production versus
           small-scale distributed, modular processing
    • Authors: Minbo Yang; Fengqi You
      Pages: 495 - 510
      Abstract: This article presents comparative techno-economic and environmental analyses of four representative shale gas monetization options, namely, conventional shale gas processing, large-scale methanol manufacturing, modular methanol manufacturing with shale gas supplied by pipelines, and modular methanol manufacturing with consideration of plant relocation. We first present shale gas supply models for the four gas monetization options. Next, the process designs for shale gas processing and methanol manufacturing from shale gas are described. We develop detailed process simulation models for shale gas processing and methanol manufacturing with different scales using raw shale gas extracted from the Marcellus, Eagle Ford, and Bakken shale plays. On this basis, techno-economic analyses and environmental impact analyses are conducted for the four shale gas monetization options to systematically compare their economic and environmental performances based on the same conditions. The results show that modular methanol manufacturing is more economically competitive than conventional shale gas processing, although it leads to higher environmental impacts. Besides, modular methanol manufacturing is better than large-scale methanol manufacturing for raw shale gas produced from distributed, remote wells from both economic and environmental perspectives. © 2017 American Institute of Chemical Engineers AIChE J, 64: 495–510, 2018
      PubDate: 2017-09-17T14:25:34.348224-05:
      DOI: 10.1002/aic.15958
       
  • A flowsheet model for the development of a continuous process for
           pharmaceutical tablets: An industrial perspective
    • Authors: Salvador García-Muñoz; Adam Butterbaugh, Ian Leavesley, Leo Francis Manley, David Slade, Sean Bermingham
      Pages: 511 - 525
      Abstract: A dynamic model of a continuous direct compression process for pharmaceutical tablets is presented. The objective is to assess the impact of the variability from the feeder system on the concentration of drug in the powder in the feed frame of a tablet press. The model is based on principles of dispersed flow from the reaction engineering field. An estimability analysis was performed to understand the impact of the available measurements on the estimated parameters and suggest better ways to approach the parametrization. Predictions are successfully contrasted with experimental data. The model is used to produce residence time distributions at different process conditions and a graphical representation of the allowable range of disturbances in the feeders that can be mitigated by the process. The model was used in support of the method development for an online near infrared sensor. © 2017 American Institute of Chemical Engineers AIChE J, 64: 511–525, 2018
      PubDate: 2017-09-25T13:15:29.890902-05:
      DOI: 10.1002/aic.15967
       
  • Plasma assisted nitrogen oxide production from air: Using pulsed powered
           gliding arc reactor for a containerized plant
    • Authors: Bhaskar S. Patil; F. J. J. Peeters, Gerard J. van Rooij, J. A. Medrano, Fausto Gallucci, J. Lang, Qi Wang, Volker Hessel
      Pages: 526 - 537
      Abstract: The production of NOx from air and air + O2 is investigated in a pulsed powered milli-scale gliding arc (GA) reactor, aiming at a containerized process for fertilizer production. Influence of feed mixture, flow rate, temperature, and Ar and O2 content are investigated at varying specific energy input. The findings are correlated with high-speed imaging of the GA dynamics. An O2 content of 40–48% was optimum, with an enhancement of 11% in NOx production. Addition of Ar and preheating of the feed resulted in lower NOx production. Lower flow rates produced higher NOx concentrations due to longer residence time in the GA. The volume covered by GA depends strongly on the gas flow rate, emphasizing that the gas flow rate has a major impact on the GA dynamics and the reaction kinetics. For 0.5 L/min, 1.4 vol % of NOx concentration was realized, which is promising for a containerized process plant to produce fertilizer in remote locations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 526–537, 2018
      PubDate: 2017-08-31T14:16:58.678505-05:
      DOI: 10.1002/aic.15922
       
  • Fenton-like degradation of rhodamine B over highly durable Cu-embedded
           alumina: Kinetics and mechanism
    • Authors: Yiyi Sheng; Yang Sun, Jing Xu, Jie Zhang, Yi-Fan Han
      Pages: 538 - 549
      Abstract: Cu-embedded mesoporous alumina, as a Fenton-like catalyst prepared via a sol-gel method, showed excellent activity and durability for the degradation of refectory compounds. The origin of active sites for the generation of hydroxyl radicals (•OH) were thoroughly studied using multitechniques. Cu, as the only active element, could be penetrated into the bulk of alumina and some Cu atoms were embedded into the framework. The dynamic structure of surface Cu species (the variety of Cu+/Cu2+ ratio) during the reaction were determined as well. Furthermore, the structure plasticity of catalyst has proved by optimizing preparation and reaction conditions. A 98.53% degradation of RhB was recorded within 30 min, following a pseudo-first-order reaction rate expression. Electron spin resonance spectra and •OH scavenging experiments have confirmed that •OH is the main reactive oxidant for the elimination of RhB. By the surface-enhanced Raman spectroscopy and gas chromatography-mass spectrometer results, plausible pathways of RhB degradation were elaborated. © 2017 American Institute of Chemical Engineers AIChE J, 64: 538–549, 2018
      PubDate: 2017-08-31T14:21:32.732601-05:
      DOI: 10.1002/aic.15937
       
  • La-hexaaluminate for synthesis gas generation by Chemical Looping Partial
           Oxidation of Methane Using CO2 as Sole Oxidant
    • Authors: Yanyan Zhu; Weiwei Liu, Xueyan Sun, Xiaoxun Ma, Yu Kang, Xiaodong Wang, Junhu Wang
      Pages: 550 - 563
      Abstract: Chemical looping partial oxidation of methane using a sole CO2 oxidant (CL-POM-CO2) is an emerging technology for synthesis gas generation and CO2 utilization, which is highly dependent on an oxygen carrier (OC). In this work, Fe-substituted La-hexaaluminate as the OC was found to exhibit good reactivity and stability during 50 periodic CH4/CO2 redox cycles due to the formation of magnetoplumbite La-hexaaluminate structure with the introduction of La. Deeper reduction for synthesis gas generation did not destroy the La-hexaaluminate structure via a charge compensation mechanism, which increased CH4 reactivity and further improved CO2 utilization under subsequent re-oxidation. In the La-hexaaluminate structure, O6-Fe3+(Oh) was highly active for the total oxidation of methane, while O5-Fe3+(Tr) and O4-Fe3+(Th) selectively oxidized CH4 to synthesis gas. The sole CO2 oxidant only selectively recovered O5-Fe3+(Tr) and O4-Fe3+(Th), and thus is more favorable for improving synthesis gas selectivity than O2/air, which offers an attractive opportunity for CO2 utilization. © 2017 American Institute of Chemical Engineers AIChE J, 64: 550–563, 2018
      PubDate: 2017-09-01T11:05:41.142555-05:
      DOI: 10.1002/aic.15942
       
  • Automated measurements of gas-liquid mass transfer in micropacked bed
           reactors
    • Authors: Jisong Zhang; Andrew R. Teixeira, Klavs F. Jensen
      Pages: 564 - 570
      Abstract: Gas-liquid mass transfer in micropacked bed reactors is characterized with an automated platform integrated with in-line Fourier transform infrared spectroscopy. This setup enables screening of a multidimensional parameter space underlying absorption with chemical reaction. Volumetric gas-liquid mass-transfer coefficients (kLa) are determined for the model reaction of CO2 absorption in a methyl diethanolamine/water solution. Parametric studies are conducted varying gas and liquid superficial velocities, packed bed dimensions and packing particle sizes. The results show that kLa values are in the range of 0.12∼0.39 s−1, which is about one-to-two orders of magnitude larger than those of conventional trickle beds. An empirical correlation predicts kLa in micropacked bed reactors in good agreement with experimental data. © 2017 American Institute of Chemical Engineers AIChE J, 64: 564–570, 2018
      PubDate: 2017-09-05T11:10:37.495303-05:
      DOI: 10.1002/aic.15941
       
  • Organocatalyzed Beckmann rearrangement of cyclohexanone oxime in a
           microreactor: Kinetic model and product inhibition
    • Authors: Chencan Du; Jisong Zhang, Guangsheng Luo
      Pages: 571 - 577
      Abstract: The kinetic study of Beckmann rearrangement of cyclohexanone oxime catalyzed by trifluoroacetic acid and acetonitrile in a microreactor is presented in this article. Parametric studies are conducted varying temperature, ratio of trifluoroacetic acid to acetonitrile, and concentration of cyclohexanone oxime. The inhibition effect of ɛ-caprolactam in this reaction system is firstly reported. A comprehensive mathematic kinetic model considering the product inhibition effect of caprolactam has been developed in the temperature range of 368–391 K, which agrees well with the experimental results across a broad experimental parameter space. In addition, kinetic study indicates that the esterification of cyclohexanone oxime and transposition reaction of the intermediate are both supposed to be the rate-determining steps, and in this catalyst system, the ratio of trifluoroacetic acid and acetonitrile mainly influences the reaction rate and the activation energy of the transposition step. The developed model could provide much reliable knowledge for industrial application. © 2017 American Institute of Chemical Engineers AIChE J, 64: 571–577, 2018
      PubDate: 2017-09-12T10:15:33.394936-05:
      DOI: 10.1002/aic.15946
       
  • Multiscale modeling of methane catalytic partial oxidation: From the
           mesopore to the full-scale reactor operation
    • Authors: Jorge E. P. Navalho; José M. C. Pereira, José C. F. Pereira
      Pages: 578 - 594
      Abstract: A multiscale methodology combining three different reactor length-scales is presented to investigate the role of the catalyst internal pore structure and metal loading and dispersion on the catalyst layer and full-scale reactor performances. At the catalyst level, the methodology involves pore-scale simulations in the three-dimensional mesopore and macropore space. The information gathered at the catalyst level is delivered to the full-scale reactor model. The methodology is applied to a honeycomb reactor performing methane partial oxidation considering reaction kinetics described through a detailed multistep reaction mechanism. Realistic mesopore and macropore structures were reconstructed and combined to form specific bidisperse porous washcoat layers. The study shows that species effective diffusivities vary significantly but not in the same proportion for different structures. For structures featuring poor transport characteristics, the integral methane conversion and hydrogen selectivity are strongly affected while the reactor temperatures increase substantially. © 2017 American Institute of Chemical Engineers AIChE J, 64: 578–594, 2018
      PubDate: 2017-09-21T09:41:32.248262-05:
      DOI: 10.1002/aic.15945
       
  • A theory of ultradeep hydrodesulfurization of diesel in stacked-bed
           reactors
    • Authors: Teh C. Ho
      Pages: 595 - 605
      Abstract: Hydrodesulfurization catalysts have two types of active sites for hydrogenation and hydrogenolysis reactions. While hydrogenation sites are more active for desulfurizing refractory sulfur species, they are more susceptible to organonitrogen inhibition than hydrogenolysis sites. In contrast, hydrogenolysis sites are more resistant to organonitrogen inhibition but are less active for desulfurizing refractory sulfur species. This dichotomy is exploited to develop an ultradeep hydrodesulfurization stacked-bed reactor comprising two catalysts of different characteristics. The performance of such a catalyst system can be superior or inferior to that of either catalyst alone. A mathematical model is constructed to predict the optimum stacking configuration for maximum synergies between the two catalysts. The best configuration provides the precise environment for the catalysts to reach their full potentials, resulting in the smallest reactor and minimum hydrogen consumption. Model predictions are consistent with experimental results. A selectivity-activity diagram is developed for guiding the development of stacked-bed catalyst systems. © 2017 American Institute of Chemical Engineers AIChE J, 64: 595–605, 2018
      PubDate: 2017-09-23T20:50:38.875073-05:
      DOI: 10.1002/aic.15969
       
  • Gas drying with ionic liquids
    • Authors: Jingli Han; Chengna Dai, Zhigang Lei, Biaohua Chen
      Pages: 606 - 619
      Abstract: The gas drying technology with ionic liquids (ILs) was systematically studied ranging from the molecular level to industrial scale. The COSMO-RS model was first used to screen the suitable IL and provide theoretical insights at the molecular level. Toward CO2 gas dehydration, we measured the CO2 solubility in single [EMIM][Tf2N] and in the [EMIM][Tf2N] + H2O mixture, as well as the vapor-liquid equilibrium (VLE) of [EMIM][Tf2N] + H2O system, to justify the applicability of UNIFAC model. Based on the thermodynamic study, the rigorous equilibrium (EQ) stage mathematical model was established for process simulation. The gas drying experiment with IL was also performed and the water content in gas product can be reduced to 375 ppm. It was confirmed that a less flow rate of absorbent, a higher CO2 recovery ratio and a much lower energy consumption can be achieved with IL than with the conventional triethylene glycol (TEG). © 2017 American Institute of Chemical Engineers AIChE J, 64: 606–619, 2018
      PubDate: 2017-08-29T09:56:01.293375-05:
      DOI: 10.1002/aic.15926
       
  • Economic assessment of carbon capture by minichannel absorbers
    • Authors: Ziqiang Yang; Tariq S. Khan, Mohamed Alshehhi, Yasser F. AlWahedi
      Pages: 620 - 631
      Abstract: In this work, a physio-economic model supported by lab-scale experiments assessing the economic viability of minichannel based carbon capture units is presented. The net present value of (capital and operating) costs (NPVC) ensued throughout the plant life is selected as the benchmarking parameter. An optimization problem is formulated and solved with the objective of minimizing the NPVC of the unit subject to constraints imposed by the physics of absorption and pressure drop limits; both of which are captured via experimentally deduced empirical correlations. The results show that the minichannel absorbers are economically competitive to conventional systems for low capacity CO2 capture achieving savings ranging from ∼50% to 3% for plant capacities ranging from 5 to 50 MMSCFD, respectively, primarily due to their lower capital costs. At higher plant capacities, the higher operating costs of the minichannel units dominate their NPVC and as such lead them to lose their competitiveness. © 2017 American Institute of Chemical Engineers AIChE J, 64: 620–631, 2018
      PubDate: 2017-08-31T14:15:57.641669-05:
      DOI: 10.1002/aic.15919
       
  • Chemical solvent in chemical solvent: A class of hybrid materials for
           effective capture of CO2
    • Authors: Feng-Feng Chen; Kuan Huang, Jie-Ping Fan, Duan-Jian Tao
      Pages: 632 - 639
      Abstract: Amino acid ionic liquids (AAILs) are chemical solvents with high reactivity to CO2. However, they suffer from drastic increase in viscosity on the reaction with CO2, which significantly limits their application in the industrial capture of CO2. In this work, 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) which also exhibits chemical affinity to CO2 but low viscosity, and its viscosity does not increase drastically after CO2 absorption, was proposed as the diluent for AAILs to fabricate hybrid materials. The AAIL+[emim][Ac] hybrids were found to display enhanced kinetics for CO2 absorption, and their viscosity increase after CO2 absorption are much less significant than pure AAILs. More importantly, owing to the fact that [emim][Ac] itself can absorb large amount of CO2, the AAIL+[emim][Ac] hybrids still have high absolute capacities of CO2. Such hybrid materials consisting of a chemical solvent plus another chemical solvent are believed to be a class of effective absorbents for CO2 capture. © 2017 American Institute of Chemical Engineers AIChE J, 64: 632–639, 2018
      PubDate: 2017-09-12T10:20:30.64237-05:0
      DOI: 10.1002/aic.15952
       
  • Adsorption separation of R134a, R125, and R143a fluorocarbon mixtures
           using 13X and surface modified 5A zeolites
    • Authors: Darshika K. J. A. Wanigarathna; Bin Liu, Jiajian Gao
      Pages: 640 - 648
      Abstract: We report a facile method for the adsorption separation of fluorocarbon blends containing tetrafluoroethane (R134a), pentafluoroethane (R125) and trifluoroethane (R143a) refrigerants into their pure components using commercial 13X zeolite and pore-size modified 5A zeolite under ambient condition. Based on the measured R134a, R125, and R143a pure gas equilibrium adsorption isotherms, the adsorption capacity varies in the order of R134a > R143a > R125 on 13X zeolite. The mixed gas breakthrough experiments reveal that 13X zeolite selectively adsorbs R134a over R125 and R143a. By running two adsorption cycles, it is possible to obtain R134a with ultrahigh purity. Furthermore, through chemical modification of tetraethyl orthosilicate (TEOS), the pore size of 5A zeolite could be successfully narrowed to the extent to just adsorb R125 while excluding R143a. The modified 5A zeolite was utilized to separate refrigerant mixtures containing R125 and R143a into their pure components. © 2017 American Institute of Chemical Engineers AIChE J, 64: 640–648, 2018
      PubDate: 2017-09-14T01:50:45.132873-05:
      DOI: 10.1002/aic.15955
       
  • A systematic method to synthesize all dividing wall columns for
           n-component separation—Part I
    • Authors: Gautham Madenoor Ramapriya; Mohit Tawarmalani, Rakesh Agrawal
      Pages: 649 - 659
      Abstract: We present an easy-to-use step-wise procedure to synthesize an initial-dividing wall column (i-DWC) from any given n-component basic distillation column sequence or its thermally coupled derivative. The procedure to be used is dependent on the nature of the distillation column sequence that is to be converted into a DWC, and comprises of an intuitive set of steps that we demonstrate through examples. It is noteworthy that, even for a ternary distillation, 15 potentially useful DWCs, some of which had been missing from the literature, have now been identified. This work significantly expands the search space of useful DWCs to separate any given multicomponent mixture. © 2017 American Institute of Chemical Engineers AIChE J, 64: 649–659, 2018
      PubDate: 2017-09-26T11:50:37.040051-05:
      DOI: 10.1002/aic.15964
       
  • A systematic method to synthesize all dividing wall columns for
           n-component separation: Part II
    • Authors: Gautham Madenoor Ramapriya; Mohit Tawarmalani, Rakesh Agrawal
      Pages: 660 - 672
      Abstract: We present a simple rule that, for the first time, enables exhaustive enumeration of dividing wall columns (DWCs) corresponding to any given thermally coupled distillation column-configuration. With the successive application of our rule, every partition in a DWC can be extended all the way to the top and/or to the bottom of a column without losing thermodynamic equivalence to the original thermally coupled configuration. This leads to easy-to-operate DWCs with possible control/regulation of each and every vapor split by external means. As a result, we conclude that any given DWC can be transformed into a thermodynamically equivalent form that is easy-to-operate, and hence, there always exists at least one easy-to-operate DWC for any given thermally coupled distillation. Our method of enumerating and identifying easy-to-operate DWCs for an attractive thermally coupled configuration will contribute toward process intensification by providing ways to implement efficient and low-cost multicomponent distillations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 660–672, 2018
      PubDate: 2017-09-26T11:50:26.362995-05:
      DOI: 10.1002/aic.15963
       
  • Ultrasound–assisted synthesis and characterization of polymethyl
           methacrylate/reduced graphene oxide nanocomposites
    • Authors: Maneesh Kumar Poddar; Sushobhan Pradhan, Vijayanand S. Moholkar, Mohammad Arjmand, Uttandaraman Sundararaj
      Pages: 673 - 687
      Abstract: This article reports ultrasound–assisted synthesis of polymethyl methacrylate (PMMA)/reduced graphene oxide (RGO) nanocomposites by in situ emulsion polymerization coupled with in situ reduction of graphene oxide. The thermal degradation kinetics of the nanocomposites was also assessed with Criado and Coats-Redfern methods. Intense microconvection generated by ultrasound and cavitation results in uniform dispersion of RGO in the polymer matrix, which imparts markedly higher physical properties to resulting nanocomposites at low (≤1.0 wt %) RGO loadings, as compared to nanocomposites synthesized with mechanical stirring. Some important properties of the PMMA/RGO nanocomposites synthesized with sonication (with various RGO loadings) are: glass transition temperature (0.4 wt %) = 124.5°C, tensile strength (0.4 wt %) = 40.4 MPa, electrical conductivity (1.0 wt %) = 2 × 10−7 S/cm, electromagnetic interference shielding effectiveness (1.0 wt %) = 3.3 dB. Predominant thermal degradation mechanism of nanocomposites (1.0 wt % RGO) is 1D diffusion with activation energy of 111.3 kJ/mol. © 2017 American Institute of Chemical Engineers AIChE J, 64: 673–687, 2018
      PubDate: 2017-08-30T06:30:55.413712-05:
      DOI: 10.1002/aic.15936
       
  • Novel semi-interpenetrating network structural phase change composites
           with high phase change enthalpy
    • Authors: Yuang Zhang; Jinghai Xiu, Bingtao Tang, Rongwen Lu, Shufen Zhang
      Pages: 688 - 696
      Abstract: High phase change enthalpy, controllable temperature, and stable shape can expand the application of phase change materials (PCMs) in energy storage. In this study, a series of novel form-stable PCMs with high phase change enthalpy (169–195 J/g) and controllable temperature (45.3–61.4°C) were prepared. The PCMs exhibited a semi-interpenetrating polymer network (semi-IPN) structure resulting from the combination of polyethylene glycol (PEG) and a three-dimensional (3-D) network gel. The gel itself featured an inherent phase change characteristic and a 3-D network structure. Thus, it improved the phase transition enthalpy of the materials and facilitated the formation of a semi-IPN that endowed the materials with excellent form-stable properties. In addition, the latent heat of the composites (169–195 J/g) is much higher than most of the previously reported composites using PEG as phase change component (68–132 J/g). © 2017 American Institute of Chemical Engineers AIChE J, 64: 688–696, 2018
      PubDate: 2017-09-12T10:05:49.957998-05:
      DOI: 10.1002/aic.15956
       
  • Model for the outer cavity of a dual-cavity die with parameters determined
           by two-dimensional finite-element analysis
    • Authors: Kenneth J. Ruschak; Steven J. Weinstein
      Pages: 708 - 716
      Abstract: A coating die forms liquid layers of uniform thickness for application to a substrate. In a dual-cavity coating die an outer cavity and slot improves flow distribution from an inner cavity and slot. A model for axial flow in the outer cavity must consider the ever-present cross flow. A 1-D equation for the pressure gradient for a power-law liquid is obtained as a small departure from a uniform flow distribution and no axial flow. The equation contains a shape factor dependent on cavity shape, Reynolds number, and power-law index. The shape factor for five triangular cavity shapes is obtained by finite-element analysis and correlated for application to die design up to the onset of flow recirculation which arises at the junction of the cavity and outer slot. The performance of the combined cavity and slot is considered and the most effective design determined. © 2017 American Institute of Chemical Engineers AIChE J, 64: 708–716, 2018
      PubDate: 2017-08-25T23:00:54.32771-05:0
      DOI: 10.1002/aic.15927
       
  • Chaotic mixing in a barrier-embedded partitioned pipe mixer
    • Authors: Seon Yeop Jung; Kyung Hyun Ahn, Tae Gon Kang, Gi Taek Park, Sang Ug Kim
      Pages: 717 - 729
      Abstract: Inspired by the partitioned pipe mixer (PPM), a barrier-embedded partitioned pipe mixer (BPPM) is designed and analyzed using a numerical simulation scheme. The BPPM is a static mixer, composed of orthogonally connected rectangular plates with a pair of barriers, which divide, stretch, and fold fluid elements, leading to chaotic mixing via the baker's transformation. The aspect ratio of the plate (α) and the dimensionless height of the barrier (β) are chosen as design parameters to conduct a parameter study on the mixing performance. The flow characteristics and mixing performance are analyzed using the cross-sectional velocity vectors, Poincaré section, interface tracking, and the intensity of segregation. The results indicate that several designs of the BPPM significantly enhance the PPM's mixing performance. The best BPPMs are identified with regard to compactness and energy consumption. © 2017 American Institute of Chemical Engineers AIChE J, 64: 717–729, 2018
      PubDate: 2017-08-25T22:56:06.892833-05:
      DOI: 10.1002/aic.15929
       
  • Dynamic formation and scaling law of hollow droplet with gas/oil/water
           system in dual-coaxial microfluidic devices
    • Authors: Fu-Ning Sang; Zhuo Chen, Yun-Dong Wang, Jian-Hong Xu
      Pages: 730 - 739
      Abstract: Based on the one-step microfluidic method of producing hollow droplet with thin film, this article studies the effect of water and oil flow rate, gas pressure, and viscosity of aqueous phase on the dynamic formation and size of hollow droplet by analyzing large amounts of data acquired automatically. The results show that the filling stage of hollow droplet is similar to that of microbubble formation, while the necking stage is similar to that of droplet formation process. Furthermore, based on the data and mathematical model describing droplet formation mechanism, a filling stage model including Capillary number of continuous phase is developed. Considering the dynamic interface breakup and displacement of droplet in necking stage, a necking stage model is developed. The results show that the model results considering filling and necking stage fit well with the experimental data, and the relative error is less than 5%. Finally, the same model with parameters is used to predict the size of hollow droplet with other systems and devices, and the model is proved to be relative precise in our experimental conditions. The results presented in this work provide a more in-depth understanding of the dynamic formation and scaling law of hollow droplet with G/L/L systems in microfluidic devices. © 2017 American Institute of Chemical Engineers AIChE J, 64: 730–739, 2018
      PubDate: 2017-08-25T08:55:37.56018-05:0
      DOI: 10.1002/aic.15930
       
  • Experiments on breakup of bubbles in a turbulent flow
    • Authors: Jiří Vejražka; Mária Zedníková, Petr Stanovský
      Pages: 740 - 757
      Abstract: The breakup of air bubbles in a turbulent water flow is studied experimentally. Water flows from a nozzle array, generating intense turbulence, and then flows downward through a cell. The velocity field is measured by PIV, and the local dissipation rate is estimated using a large-eddy PIV technique. Bubbles (1.8 to 5 mm) are injected in the bottom of the cell and rise toward the region of intense turbulence, where they break. The time spent by bubbles in various zones without breaking and the number of breakups are evaluated, providing information about the breakup frequency. The number of daughter bubbles and their size distribution are determined. The number of daughters depends on a Weber number 2ρϵ2/3D′5/3/σ, where ϵ is the turbulent energy dissipation rate, D′ is the mother particle size, ρ and σ are the liquid density and surface tension. The daughter size distribution is a function of their number. © 2017 American Institute of Chemical Engineers AIChE J, 64: 740–757, 2018
      PubDate: 2017-08-31T13:51:21.662627-05:
      DOI: 10.1002/aic.15935
       
  • Effects of compositional variations on CO2 foam under miscible conditions
    • Authors: Siavash Kahrobaei; Kai Li, Sebastien Vincent-Bonnieu, Rouhollah Farajzadeh
      Pages: 758 - 764
      Abstract: Foam can mitigate the associated problems with the gas injection by reducing the mobility of the injected gas. The presence of an immiscible oleic phase can adversely affect the foam stability. Nevertheless, under miscible conditions gas and oil mix in different proportions forming a phase with a varying composition at the proximity of the displacement front. Therefore, it is important to understand how the compositional variations of the front affect the foam behavior. In this study through several core-flood experiments under miscible condition, three different regimes were identified based on the effects of the mixed-phase composition on CO2 foam-flow behavior: In Regime 1 the apparent viscosity of the in-situ fluid was the highest and increased with increasing xCO2. In Regime 2 the apparent viscosity increased with decreasing xCO2. In Regime 3 the apparent viscosity of the fluid remained relatively low and insensitive to the value of xCO2. © 2017 American Institute of Chemical Engineers AIChE J, 64: 758–764, 2018
      PubDate: 2017-08-31T14:21:51.359178-05:
      DOI: 10.1002/aic.15938
       
  • Settling and re-entrainment of wax particles in near-gelling systems
    • Authors: Seetharaman Navaneetha Kannan; Nagu Daraboina, Rama Venkatesan, Cem Sarica
      Pages: 765 - 772
      Abstract: Under near-gelling conditions, the precipitated wax particles can settle down due to gravity and form a bed at the bottom of the pipeline. During restart, the settled waxy bed can increase the pressure drop significantly, and the necessity for pigging and/or addition of chemicals has to be determined to re-entrain settled wax particles. A laboratory-scale flow loop, first of its kind, has been built and used to understand the settling and re-entrainment behavior. The experimental results confirmed the settling of precipitated wax in a pipe under quiescent conditions when the oil temperature falls between wax appearance temperature and pour point. During restart, complete re-entrainment was attained after reaching a critical flow rate. Solid transport models were able to predict reasonably good results in agreement with experiments. This work emphasizes the importance of understanding the behavior of waxy crude oil during production shutdown and design appropriate startup strategies. © 2017 American Institute of Chemical Engineers AIChE J, 64: 765–772, 2018
      PubDate: 2017-09-14T02:01:33.497248-05:
      DOI: 10.1002/aic.15948
       
  • Flow of viscoelastic surfactants through porous media
    • Authors: S. De; S. P. Koesen, R. V. Maitri, M. Golombok, J. T. Padding, J. F. M. van Santvoort
      Pages: 773 - 781
      Abstract: We compare the flow behavior of viscoelastic surfactant (VES) solutions and Newtonian fluids through two different model porous media having similar permeability: (a) a 3D random packed bed and (b) a microchannel with a periodically spaced pillars. The former provides much larger flow resistance at the same apparent shear rate compared to the latter. The flow profile in the 3D packed bed cannot be observed since it is a closed system. However, visualization of the flow profile in the microchannel shows strong spatial and temporal flow instabilities in VES fluids appear above a critical shear rate. The onset of such elastic instabilities correlates to the flow rate where increased flow resistance is observed. The elastic instabilities are attributed to the formation of transient shear induced structures. The experiments provide a detailed insight into the complex interplay between the pore scale geometry and rheology of VES in the creeping flow regime. © 2017 American Institute of Chemical Engineers AIChE J, 64: 773–781, 2018
      PubDate: 2017-09-19T11:50:29.246127-05:
      DOI: 10.1002/aic.15960
       
  • Flow field design and optimization of high power density vanadium flow
           batteries: A novel trapezoid flow battery
    • Authors: Meng Yue; Qiong Zheng, Feng Xing, Huamin Zhang, Xianfeng Li, Xiangkun Ma
      Pages: 782 - 795
      Abstract: Vanadium flow battery (VFB) is one of the preferred techniques for efficient large-scale energy storage applications. The key issue for its commercialization is cost reduction, which can be achieved by developing high power density VFB stacks. One of the effective strategies for developing high power density stacks is to enhance the mass transport by performing flow field design. Based on the maldistribution characteristics of concentration polarization inside a conventional rectangular flow battery (RFB), a novel trapezoid flow battery (TFB) was first proposed. Furthermore, a practical and general strategy, consisting of a stepping optimization method and an arithmetic progression model, has been developed for the TFB's structure optimization. By combining numerical simulation with charge-discharge test of the magnified stacks, it was verified that mass transport enhancement and performance improvement of the optimized TFB, with significant increments in voltage efficiency and electrolyte utilization, allowed it to possess great superiority over the RFB. © 2017 American Institute of Chemical Engineers AIChE J, 64: 782–795, 2018
      PubDate: 2017-09-20T08:35:31.271686-05:
      DOI: 10.1002/aic.15959
       
 
 
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