JournalTOCs

Emission Control Science and Technology
Journal Prestige (SJR): 0.731

Citation Impact (citeScore): 2
Number of Followers: 1

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2199-3629 - ISSN (Online) 2199-3637
Published by Springer-Verlag

[2469 journals]

Influence of Global Operating Parameters on the Reactivity of Soot
Particles from Direct Injection Gasoline Engines
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract The aim of this study is to investigate the impact of global operating parameters, e.g., engine speed, brake mean effective pressure, and air–fuel ratio, of a turbocharged 4-cylinder GDI engine on the reactivity of soot particles against oxidation. The knowledge of soot reactivity is crucial for optimizing gasoline particulate filter regeneration strategies and is, consequently, a key parameter for reducing fuel consumption and CO2 emissions. In this work, time-resolved in-cylinder soot concentrations and exhaust particle size distributions are measured by using two-color pyrometry, engine exhaust particle sizer and smoke meter, respectively. Reactivity against oxidation by molecular oxygen is determined by temperature programmed oxidation analysis. To derive a physicochemical explanation for varying soot reactivity, the morphological and nanostructural primary particle structure of collected samples is analyzed using high-resolution electron microscopy and image analysis algorithms. The results reveal that engine operating parameters affect soot reactivity differently. While engine speed has only a slight effect, a reduction of air/fuel ratio (λ < 1.0) or an increase of BMEP > 10 bar significantly reduces the soot oxidation reactivity. These findings give evidence, that the quality of the fuel/air mixture is a significant parameter influencing soot reactivity. Measured soot concentrations substantiate the hypothesis that low-sooty homogeneous premixed combustion of a homogeneous fuel/air mixture favors formation of high-reactive soot particle fractions. Reactive soot particle aggregates are composed of multiple soot fractions of different reactivity. Reactive primary particles are composed of short graphene-like layers and vice versa, providing a physicochemical explanation for varying soot reactivity depending on engine operating conditions.
  PubDate: 2022-05-11
In-use Emission Measurements from Two High-Speed Passenger Ferries
Operating in California with Tier 2 and Tier 3 Marine Diesel Engines
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Marine diesel engines operating in ferries and other commercial harbor craft (CHC) represent a significant fraction of near-source health risk to port and coastal communities, and emissions must be reduced to protect public health and meet federal national ambient air quality standards. In this study, we measured in-use particulate matter (PM) and gaseous emissions — including carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), and nitrogen dioxide (NO2) from two high-speed passenger ferries in the San Francisco Bay Area: one equipped with tier 2 engines with 18,096 h, the other equipped with tier 3 marine engines with 6392 h at the commencement of the study. Whereas marine engines are certified by United States (US) Environmental Protection Agency (EPA) over the ISO 8178 E3 steady-state cycle, we used portable emissions measurement systems (PEMS) to measure emissions during normal revenue service, which includes some transient and some steady-state operation. Measured real-world emissions were below relevant certification limits for CO, NOx, and PM; average in-use NOx emissions were 4.62 and 3.62 g/bhp-h for the tier 2 and tier 3 engine, respectively, CO emissions were 1.55 and 1.60 g/bhp-h for the tier 2 and tier 3 engine, respectively, and PM emissions were 0.044 g/bhp-h for the tier 3 engine. The ferry with tier 3 engines was also equipped with an aftermarket selective catalytic reduction (SCR) system designed to further reduce NOx emissions to levels below the certification level of the engine. However, due to a diesel exhaust fluid (DEF) dosing malfunction, no appreciable NOx reductions were recorded during the testing. The SCR system was designed with a platinum-group metal oxidation catalyst to reduce ammonia slip, which may have contributed to the observed 76% reduction in CO, 74% reduction in PM, and 23% increase in the NO2/NOx ratio. Findings from this study suggest certification data are good predictors of real-world emissions from tier 2 and tier 3 marine engines and underscore the need to properly maintain and operate SCR systems.
  PubDate: 2022-05-06
Effect of Rare-Earth (La, Nd, Pr, Y) Doping on the Properties of
X-Y-Ce-Zr-O and X-Y-Z-Ce-Zr-O Nanodispersions for GPF Applications
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract The effect of different rare-earth dopants (Nd, Y, La, Pr) and their combination on the final properties of CeO2-ZrO2 mixed oxide nanodispersions for gasoline particulate filter applications was investigated. The presence of additional two or three dopants improves the thermal stability as they were found to maintain their cubic (c) or pseudo-cubic (t″) phase symmetry after high temperature ageing at 1150°C in contrast to the pure ceria–zirconia reference samples. Doping also improved the surface area and porosity and the thermal stability towards sintering of primary particles. It was observed that La/Pr sample shows initial mesoporosity and the highest thermal stability. A clear link between structural/thermal stability and the oxygen storage performance could be made. The rare-earth doped samples showed improved reduction ability and were reduced in H2 at temperatures 591-597°C compared to pure ceria–zirconia samples (616-617°C). Furthermore, they were also able to be partially re-oxidized at 50°C whereas the pure ceria–zirconia samples were not. This could be explained by the improved oxygen mobility in the t″ phase for doped materials. Tested samples showed good catalytic performance in the reaction of soot oxidation by TG-DTA. SEM imaging of coated cordierite particulate filters showed that the nanodispersions were coated in a manner that eliminated the small pores in the filter wall and reduced the size of the larger pores. According to literature analysis, these coating characteristics would offer improved performance in relation to filtration efficiency and backpressure.
  PubDate: 2022-04-20
Implications of Hydrated Ash on Filtration Efficiency and Performance of
Particulate Filters (DPF, GPF, and SCRF)—a Perspective
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Particulate filters are used to meet current and future emission-control standards for particle mass and particle number requirements. However, with vehicle operation, non-combustible material (termed as “ash”) collects in the filter leading to an increase in ∆P, lower fuel economy, reduced soot storage space, and lower conversion rates for exhaust gases such as HC, NO, and NO2. In most cases, CaSO4 originating from detergent formulations in the lubricant forms the major component of inorganic ash; CaSO4 undergoes hydration cycles forming gypsum, along with semi-/hemi-hydrates through a series of transformations that are a function of temperature, time, and humidity. The exact nature of these transformations and the interaction of hydrated species with the filter substrate are poorly understood. The current work highlights the recent serendipitous discovery of hydrated ash structures and their deleterious effects on the filter and informs the automotive emission control community about the strategies for effective management of the filter.
  PubDate: 2022-04-12
Experimental and Modeling Study of NO and NO2 Storage and Release
Characteristics of a Diesel-Cold Start Catalyst
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract A 2013 6.7L Cummins ISB (209 kW) diesel engine was used to quantify the NO, NO2, and NOx storage and release performance of the diesel cold start catalyst (dCSC™). The NOx storage experiments were performed over a range of temperatures from 80 to 250°C and NOx release experiments were performed at temperatures from 200 to 450°C. A 2-D diesel cold start catalyst (d-CSC) model was developed to predict NO, NO2 storage, and release characteristics along with the temperature distribution within diesel cold start catalyst (d-CSC) and the pressure drop across the d-CSC. This d-CSC model was calibrated using eight runs of experimental data that consisted of storage temperatures ranging from 80 to 250°C and release temperatures ranging from 200 to 450°C. The validation results show that the new d-CSC model can predict 200-s NOx storage and total NOx release capacity with a maximum root mean square (RMS) error of 0.02 and 0.10 NO2 g/L of substrate, respectively. The NO2/NOx ratio RMS error was within 24%. The RMS temperature errors for storage and release phases were within 3°C and the pressure drop model error was within 0.2 kPa. It is found that the dCSC™ shows significant low temperature NOx storage capability with a peak storage occurring from 125 to 150°C. The rapid NOx release was observed at temperatures above 200°C which is well within the operating range of the aftertreatment system after cold start period.
  PubDate: 2022-02-23
  DOI: 10.1007/s40825-022-00208-7
Experimental and Numerical Analysis of an Innovative Mixer Geometry for
Urea Injection in SCR Applications
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Selective catalytic reduction (SCR), based on the injection of urea-water-solution (UWS), is one of the prevailing and more effective approaches to reduce NOx emissions in diesel engines. To improve the performance and durability of the system, it is crucial to develop reliable simulation tools able to correctly describe not only the urea conversion into ammonia and the mixing with exhaust gases but also the possible formation of solid deposits along with the engine’s exhaust line. In the present paper, two different exhaust systems for off-road applications are analyzed, both of them consisting of a diesel oxidation catalyst (DOC) followed by a diesel particulate filter (DPF), a UWS injection and a mixing device, and an SCR catalyst. Two alternative UWS mixing subsystems are evaluated, including a newly developed design. A 3D-CFD numerical analysis is carried out to assess the performance of both systems in terms of pressure drop, UWS spray, and liquid film development, in addition to flow velocities and species concentration uniformities at SCR catalyst inlet. A detailed analysis of droplet impingement on walls and liquid film development is enabled, thanks to a conjugate heat transfer (CHT) approach. Moreover, a deposit risk index is used to identify the areas of the systems where urea deposit formation is expected. Eventually, numerical results are compared with experiments on one operating condition chosen as the most challenging in terms of exhaust temperature and flow rate, both in terms of systems NOx conversion efficiency and deposit formation, showing a satisfactory agreement, thus paving the way to use the proposed synergetic numerical and experimental approach to further optimize the design and the system’s performance.
  PubDate: 2022-02-05
  DOI: 10.1007/s40825-022-00207-8
AdSCR Systems (Adsorption + Selective Catalytic Reduction): Analysis
of the Influence of H2O and CO2 on Low Temperature NOx Emission Reduction
Performances
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract The removal of NOx from low-temperature diesel engine emissions still represents a big challenge in view of the upcoming more stringent worldwide regulations. In our previous studies, we proved the ability of novel AdSCR (Adsorption + Selective Catalytic Reduction) systems, based on the combination of a chemical trapping compound and a conventional SCR catalyst, to trap cold start NOx emissions and to desorb and simultaneously reduce them with ammonia at higher temperature. In the present work, we extend the investigation of Cu-CHA + BaO/Al2O3 systems under more realistic conditions, focusing on the impact of H2O and CO2. The experimental results reveal a reduction of the AdSCR system performances with respect to dry and CO2-free conditions. Despite this, the system is still able to store and reduce NOx. The NOx storage capacity on barium oxide is more affected by the presence of CO2 than by H2O. However, H2O hinders the NO oxidative activation in the zeolite cages, which is a fundamental step in order to be able to trap NOx on the storage material at low temperature. We further demonstrate that the detrimental effect of H2O can be mitigated by small amounts of NO2 in the gaseous feed or by including a 13X zeolite guard bed prior to the AdSCR bed.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00204-3
Numerical Prediction of Particulate Matter (PM) Collection Efficiency,
Loading, and Flow Characteristics in Partially Damaged Particulate Filters
with Different PM Size Classes
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract The objective of the current study is to numerically predict the collection efficiency, particulate matter (PM) loading, pressure drop, and flow characteristics in partially damaged or unplugged filters. Five different PM size classes with mean particle diameters ranging from 25 to 300 nm are considered for loading the filter. These PM classes are transported in the computational domain as scalars and collected in the filter through Brownian diffusion and interception mechanisms. Four different partially damaged filters with varying damaged cross-sections in the outlet face of the filter are considered. Five different exhaust gas flow rates from 50 to 300 kg/h with a transient soot loading condition are considered, which leads to different temporal and spatial soot cake evolutions as well as a different total soot mass in the filter. As expected, plugged filter sections have higher filtration efficiencies which increases monotonically with soot accumulation. For damaged segment, however, efficiency is nonmonotonic and depends strongly on particle size, loading, and prevailing flow conditions. The collection efficiency of damaged segments is less than 40% at all flow rates and damaged cross-sections considered in this study. The overall filter efficiency is evaluated as the sum of flow averaged filtration efficiencies of both plugged and unplugged sections. The overall filter efficiency is less than 100% and this efficiency decreases from filter-1 to filter-4 as the damaged filter section contributes to the efficiency loss. Spatial and temporal evolution of soot cake is different in damaged and undamaged sections. Strong nonuniform soot distribution is observed in the partially damaged filters in both the axial and radial direction. One objective of the current study is to analyze the overall filter collection efficiency with respect to the percentage of damage, which as a result will assist in the roadworthiness studies, on-board diagnostic studies, or periodic technical inspection of the filters or damaged filters.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00195-1
Light-off Investigation of Oxymethylene Ether (OME) Considering the
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Synthetic fuels and fuel blends like OMEs can contribute to tank-to-wheel CO2 emission savings. At the same time, it is known that these fuels have a lower exhaust temperature compared to conventional diesel. This effect has major impact on the exhaust after-treatment system, particularly in cold start conditions. This paper investigates the light-off behavior of exhaust gases containing OMEs by temperature-programmed oxidation experiments using a state-of-the-art oxidation catalyst. The main side product of catalytic oxidation of OMEs between 100 °C and the oxidation temperature T50, which was around 160 °C, was shown to be formaldehyde. While alkane oxidation, in this case heptane, was little influenced by OME oxidation, the oxidation temperature T50 of CO increases by more than 10 °C by OME addition. Nitrogen monoxide impeded the oxidation of OME in a similar way to the other components investigated. Due to the amount of FA produced and its toxicity, it could be concluded that it is necessary to heat up exhaust after-treatment systems of OME diesel engines even faster than conventional diesel exhaust after-treatment systems. The relatively high reactivity of OME on oxidation catalyst can be used by active thermal management approaches.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00202-5
Backpressure Prediction for Flow-Through Monoliths and Wall-Flow Filters
Using 1-Dimensional Models: Entrance Effect Pressure Change, Developing
Flow and Validation Using Length-Varying Techniques
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Backpressure prediction for flow-through monoliths (FTMs) and particulate filters (PFs) has been investigated. Backpressure data for model validation was measured as a function of part length by progressively shortening the parts. The experimental setup has fixed pressure at the inlet and zero exit pressure change, so varying the length of an FTM is equivalent to measuring the pressure along the channels, enabling separation of along-channel and entrance contributions to backpressure. With PFs, the PF becomes a partial PF after the first cut; testing in both orientations doubles the available data. Full and partial PFs are governed by the same differential equations, so this partial PF data can be used to validate the balance equations of a full PF. CFD results for a channel with an upstream contraction were also used for model validation. Equations for predicting the pressure drop due to flow contraction into the part are developed and validated. How to combine equations for pressure drop due to flow contraction and that along channels to give an accurate backpressure prediction for an FTM is considered. The length-varying technique enables different models proposed for PFs to be discriminated against. An approach for including the effect of developing flow in PFs is proposed; this includes a definition for dimensionless length for PFs, which is validated against literature CFD results.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00198-y
Comparative Study of SO2 and SO2/SO3 Poisoning and Regeneration of Cu/BEA
and Cu/SSZ-13 for NH3 SCR
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Two copper-exchanged zeolites, Cu/SSZ-13 and Cu/BEA, were studied as catalysts for the selective reduction of NOx by NH3 (NH3-SCR). Their activities for standard SCR (NOx = NO) and fast SCR (NOx = 50% NO + 50% NO2) were measured before and after sulfur poisoning at 250 °C. The effect of 30 ppm SO2 and a mixture of 24 ppm SO3 + 6 ppm SO2 was evaluated. The repetition of subsequent activity measurements served as regeneration method in SCR conditions. SO2 deactivated Cu/SSZ-13 whereas Cu/BEA was only moderately affected. SO3 led to stronger deactivation of both catalysts than SO2. However, also for this case, the Cu/BEA was significantly less affected than Cu/SSZ-13, even though Cu/BEA contained larger amount of stored sulfur. One possible reason for this could be the large pores of Cu/BEA, where the sulfur species possibly resulted in less sterical hindrance than in the small pore SSZ-13 structure. NH3 temperature-programmed desorption (NH3-TPD) showed no loss of storage sites upon sulfur treatment and subsequent regeneration. Partial activity recovery was observed after a period in SCR conditions at 400 °C and 500 °C. Temperature at 300 °C was insufficient to regenerate the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of NO adsorption suggested that SO2 interacts with the ZCuOH sites on Cu/SSZ-13, causing the strong poisoning.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00203-4
Influence of V2O5 and AlF3 on Microstructure of Acicular Mullite Diesel
Particulate Filter Along with Soot Oxidation Kinetics
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract In current research, aluminium oxide and silicon dioxide are used as raw materials for fabricating main structures of mullite diesel particulate filters. The variable substances applied to develop acicular mullite structure are titanium dioxide, aluminium fluoride, and vanadium oxide. Carbon black was used to create pores in mullite diesel particulate filters with 35 to 45% porosity based on the sintering temperature of 1300°C. The images of the filter’s porous surface microstructure were investigated using scanning electron microscopy. Vanadium oxide and aluminium fluoride play important roles in growth of acicular shape and acicular size for membrane, respectively. Acicular size of membrane varies from a hundred nano-meters to the submicron in needle diameter. The relation of all factors between pore size, porosity, surface roughness, and pin-shape microstructure can be controlled by additional amounts of additives. From Raman spectroscopy analysis, the soot formation of carbon black’s micro and nanostructure are acceptable to simulate diesel soot particles. In line with these results, carbon black was successfully used as a substitute of real engine soot in soot kinetics reactivity. In addition, the oxidation kinetics of soot particles on mullite and acicular mullite membrane were investigated by using tight contact in isothermal and loose contact in non-isothermal thermo-gravimetric analysis. The calculated apparent activation energies of soot oxidation with isothermal technique on mullite and acicular mullite membrane are approximately 213 and 141 kJ/mol while those values calculated with non-isothermal technique are 118 and 76 kJ/mol, respectively.
  PubDate: 2021-12-01
  DOI: 10.1007/s40825-021-00201-6
The Effect of Variable Overlap and Primary Particle Size on Fractal-Like
Aggregate Mobility Diameter and Effective Density
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract It is well-known that the structural properties of soot aggregates determine their behavior in the atmosphere and depend on their morphology. Previous work on the field has been focused on examining the impact of the critical features such as size, polydispersity, or overlap between primary particles separately. However, aggregates formed in real processes have complex, irregular shapes and they usually consist of monomers of variable size and overlap. In this study, fractal aggregates of different sizes and/or overlap extent are computationally generated using fractal properties relevant to soot and the proposed expressions include the effect of both phenomena. It is shown that both the mobility diameter and the effective density are increasing proportionally with the level of polydispersity, while the mobility diameter is reduced as overlap coefficient augments, leading to higher effective densities. The mobility diameter is taken as the projected area-equivalent diameter for the free molecular regime and an expression is suggested for its dependence from the aggregate’s structural properties. Furthermore, a universal effective density equation as proposed taking into account the effect of variable primary particle sizes and the existence of penetration between adjacent monomers.
  PubDate: 2021-11-30
  DOI: 10.1007/s40825-021-00206-1
Investigation of CO Deactivation of Passive NOx Adsorption on La Promoted
Pd/BEA
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Passive NOx adsorption (PNA) is a method, in which NOx can be stored at low temperatures and released at higher temperatures where the urea decomposition is functional during selective catalytic reduction (i.e., above 180–200 °C). We have studied the promotion of Pd/BEA with La as a PNA in the presence of high CO concentration. Both the reference and promoted samples exhibited a significant loss of NOx adsorption/desorption capacity after multiple cycles using 4000 ppm CO. However, already after 5 cycles, 99% of the NOx released between 200 and 400 °C was lost for Pd/BEA, compared to only 64% for Pd-La/BEA, which thereafter was stable. XPS and O2-TPD clearly showed that the Pd species were influenced by La. The PNA deactivation in the presence of CO could be related to Pd reduction followed by migration and the formation of more PdOx clusters, as observed by O2-TPD analysis. Interestingly, significantly more PdOx clusters formed on Pd/BEA after 10 cycles compared to Pd-La/BEA.
  PubDate: 2021-11-25
  DOI: 10.1007/s40825-021-00205-2
Cold-Start Modeling and On-Line Optimal Control of the Three-Way Catalyst
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract We present a three-way catalyst (TWC) cold-start model, calibrate the model based on experimental data from multiple operating points, and use the model to generate a Pareto-optimalcold-start controller suitable for implementation in standard engine control unit hardware. The TWC model is an extension of a previously presented physics-based model that predicts carbon monoxide, hydrocarbon, and nitrogen oxides tailpipe emissions. The model axially and radially resolves the temperatures in the monolith using very few state variables, thus allowing for use with control-policy based optimal control methods. In this paper, we extend the model to allow for variable axial discretization lengths, include the heat of reaction from hydrogen gas generated from the combustion engine, and reformulate the model parameters to be expressed in conventional units. We experimentally measured the temperature and emission evolution for cold-starts with ten different engine load points, which was subsequently used to tune the model parameters (e.g. chemical reaction rates, specific heats, and thermal resistances). The simulated cumulative tailpipe emission modeling error was found to be typically − 20% to + 80% of the measured emissions. We have constructed and simulated the performance of a Pareto-optimal controller using this model that balances fuel efficiency and the cumulative emissions of each individual species. A benchmark of the optimal controller with a conventional cold-start strategy shows the potential for reducing the cold-start emissions.
  PubDate: 2021-10-12
  DOI: 10.1007/s40825-021-00199-x
Emission Reduction Efficiency Analysis Based on Characteristics of Vehicle
Emissions
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract With the rapid increase in vehicle ownership, exhaust pollution has become one of the important sources of air pollution in China. In this study, a MAHA METDH 6.3 exhaust gas test experimental platform was developed, and an emission model suitable for coupling with real-time road conditions was established based on large-scale vehicle emission test data. Based on traffic big data such as traffic volume, average vehicle speed, and vehicle model distribution, ArcGIS was used to select the road network information in the study area and combined with the emission model to realize the spatial distribution of line sources of vehicle emissions. Finally, based on the road network simulation model built by VISSIM, the emission changes caused by the two measures of trunk line optimization and new energy vehicle development were simulated and analyzed. The results show that the spatial distribution characteristics of vehicle exhaust pollutants in Zhangdian District are closely related to road type. Taking trunk line optimization measures and developing new energy vehicles have a certain reduction effect on vehicle emissions in Zhangdian District. This study lays a foundation for proposing targeted measures to reduce motor vehicle emissions based on big traffic operation data.
  PubDate: 2021-10-05
  DOI: 10.1007/s40825-021-00200-7
Modelling Investigation of the Thermal Treatment of Ash-Contaminated
Particulate Filters
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract This paper investigates the impact of thermal treatment on the pressure drop of particulate filters containing ash deposits. A one-dimensional model has been developed and applied to describe the deposition of soot and ash particles, and estimate the spatial distribution of the deposits in such filters. Phenomenological models have been developed to describe the potential sintering and cracking of the ash deposits caused by thermal treatment of the filter. The model results are in good agreement with experimental measurements of the reduction in the pressure drop in thermally treated filters. It was found that crack formation in the ash layer can lead to significant reduction of the pressure drop at relatively low temperatures. Sintering of ash deposits in the wall and the ash plug also contributes towards a decrease in filter pressure drop at higher temperatures. This work is the first attempt to model the impact of the thermal treatment of ash in particulate filters in order to support the development of future ash management strategies. The cracking of the ash layer during the thermal treatment has been identified to be the most critical effect for pressure drop reduction.
  PubDate: 2021-09-18
  DOI: 10.1007/s40825-021-00197-z
Impact of Different Synthesis Methods on the Low-Temperature Deactivation
of Cu/SAPO-34 for NH3-SCR Reaction
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract SAPO-34 were synthesized using three structure-directing agents (SDAs), i.e., tetraethylammonium hydroxide (TEAOH), triethylamine (TEA), and morpholine (MO). These SAPO-34 supports were used to prepare Cu/SAPO-34 catalysts via two different Cu-exchange methods: incipient wetness impregnation (IWI) and solid-state ion exchange (SSIE). The catalytic performance of Cu/SAPO-34(TEAOH, TEA, MO) catalysts prepared with IWI and SSIE before and after exposure to water vapor at 70 °C was systemically examined, and their deactivation behavior during low-temperature NH3-SCR reaction was studied. These catalysts were characterized by XRD, BET, ICP-SFMS, SEM/EDX, solid-state NMR, CO-DRIFTS, NO-DRIFTS, and H2-TPR. The various characterization findings for the Cu/SAPO-34 catalysts suggest that the distribution of different Cu2+ species and the mobility of Cu2+ in chabazite (CHA) structure are important for the low-temperature deactivation and regeneration behaviors of the Cu/SAPO-34(TEAOH, TEA, MO)-IWI and -SSIE during the NH3-SCR reaction. Thus, it has been determined that the choice of SDA and Cu-exchange method is vital to design of an efficient Cu/SAPO-34 catalyst that is highly active during a NH3-SCR reaction and has a high tolerance for the low-temperature deactivation caused by exposure to water vapor.
  PubDate: 2021-09-01
  DOI: 10.1007/s40825-020-00182-y
Evaluation of a Catalyzed Diesel Particulate Filter Coated by a Novel
Silver-Based Catalyst Using Mining Diesel Engines
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract A silver-based catalyst was loaded on a commercial ceramic wall-flow filter to produce a prototype catalyzed diesel particulate filter (CDPF). The effectiveness of the prototype CDPF for soot removal from the engine exhaust was quantified by the balance point temperature (BPT) during the engine test using a heavy-duty mining diesel engine. The determination of the CDPF balance point temperature revealed its high passive regeneration performance. Emission tests using a medium-duty mining diesel engine demonstrated that the catalyst coating of the CDPF assisted CO and total hydrocarbon (THC) combustion as well as NO2 reduction within a wide temperature range. The average effectiveness of the particulate matter (PM) mass removal was found to be greater than 85% while keeping the back pressure within the application requirements for the tested engine. The engine test results showed the potential for the lower cost, silver-based, prototype CDPF to oxidize PM effectively during normal operation conditions. Further, the improvement it provides in passive regeneration would lower fuel consumption and related CO2 emissions by avoiding active regeneration cycles or decreasing their frequency.
  PubDate: 2021-09-01
  DOI: 10.1007/s40825-021-00186-2
Influence of Preparation Conditions on Platinum and Palladium Catalysts
Supported on Anodically Oxidized Stainless Steel Wire Meshes for CO
Oxidation
- Free pre-print version: Loading...
  Rate this result: What is this?
  
  Please help us test our new pre-print finding feature by giving the pre-print link a rating.
  A 5 star rating indicates the linked pre-print has the exact same content as the published article.
  
  Abstract: Abstract Washcoat-free catalysts capable of operation in high-temperature combustion exhaust streams were produced via anodically oxidized stainless steel mesh catalysts supports with platinum and palladium as the catalytically active species. Except for the least aggressive anodic treatment, this methodology created catalysts that were more active and stable than catalysts prepared without anodic oxidation. In general, increasing the current during anodic oxidation resulted in increased activity at high temperatures, likely by improving surface roughening, which reduced the impact of steam-enhanced sintering. Treatment with acid with relative medium acidity resulted in catalysts with superior activity and stability. This increase in activity at moderate current has been attributed to increased metal uptake and in the platinum to palladium ratio, which increased to nearly a 1:1 ratio for the most active catalysts, as well more oxide growth relative to surface dissolution. Also, the most active catalyst displayed excellent stability during an extended 100-h time-on-stream test.
  PubDate: 2021-09-01
  DOI: 10.1007/s40825-021-00196-0