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International Journal of Thermophysics
Journal Prestige (SJR): 0.417  Citation Impact (citeScore): 1 Number of Followers: 7  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1572-9567 - ISSN (Online) 0195-928X Published by Springer-Verlag  [2468 journals]
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- Correction: Di-Alkyl Adipates as New Phase Change Material for Low
Temperature Energy Storage-
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PubDate: 2023-12-04
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- Measurement of Thermal Transport in Solids with the Hot Disc Method
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Abstract: Abstract This experimental method was first proposed in 1991 and is presently being used for determining thermal conductivity, thermal diffusivity, thermal effusivity, and volumetric heat capacity of solids. Under special and well-controlled conditions, it is possible to measure thermal conductivity over approximately six orders of magnitude at temperatures ranging from 25 K up to 1500 K. A feature of this method is the possibility to obtain both the thermal conductivity and thermal diffusivity from one single transient recording and in that way to open up convenient measurements of thermal transport of certain anisotropic materials. A further advantage of using a transient method relates to the possibility to eliminate the influence of the contact resistances always present between the heating element, functioning also as the temperature recorder, and the surface of the substrate under investigation. This review will touch upon the limitations of the method with an estimation of the measuring uncertainty together with a discussion on the influence of the difference between the experimental arrangement and the assumption made in the development of the analytical theory used for analyzing the experimentally recorded data. The method has turned out to be useful not only in measurements of the thermal transport but also for special quality control situations. It is used in both academic institutions and in industrial laboratories and has so far generated some 5000 scientific papers in international journals.
PubDate: 2023-12-01
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- Editor’s Preface for the Special Issue in Honor of Professor Roland
Span’s 60th Birthday-
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PubDate: 2023-11-27
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- A Falling Body High-Pressure Viscometer
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Abstract: Abstract This paper describes the construction, working equations, and operation of a semi-automated high-pressure falling body viscometer used in the pressure range 0.1 MPa to 400 MPa and at temperatures between 255 K and 368 K. The viscometer employs self-centering sinkers, each a hollow cylinder with a solid hemispherical face. This results in a viscosity-independent sinker calibration constant. With sinkers of different diameters, a broad range of Reynolds numbers is accessible. The dependence of the calibration constants (A) on sinker clearance (c), A ∝ c−3, conforms with theory. It has been used for both high and low viscosity molecular liquids and viscous ionic liquids. It is hoped that a complete description may be of use to others wishing to build and operate such an instrument.
PubDate: 2023-11-27
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- Modeling Thermodynamic Properties of Mixtures of CO2 + O2 in the Allam
Cycle by Equations of State-
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Abstract: Abstract Different equations of state (EOS) were applied for describing thermodynamic properties of the system \(\text {CO}_{2} + \text {O}_{2},\) which is important for the Allam cycle: cubic EOS (Soave–Redlich–Kwong, Peng–Robinson), molecular-based EOS (PC-SAFT, PCP-SAFT, SAFT-VR Mie, polar soft-SAFT, BACKONE, sCPA), and multiparameter EOS (GERG-2008, EOS-CG). The pure component models were taken from the literature. The results for the mixture were compared to experimental data from the literature for two cases: (i) the thermodynamic properties of the mixture were modeled using predictive mixing and combination rules; (ii) additional binary interaction parameters were fitted to experimental data for improving the performance. In the predictive mode (i), the best results were obtained with molecular-based EOS. In the adjusted mode (ii) the best results were obtained with the multi-parameter GERG-2008 EOS and EOS-CG.
PubDate: 2023-11-27
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- Optical $$n(p,\ T_{90})$$ Measurement Suite 1: He, Ar, and N $$_2$$
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Abstract: Abstract An \(n(p,\ T_{90})\) measurement suite is reported for the gases helium, argon, and nitrogen. The methodology is optical refractive-index gas metrology, operating at laser wavelength \(633\ {\text {nm}}\) and covering the temperature range \((293< T < 433)\ {\text {K}}\) and pressures \(p < 0.5\ {\text {MPa}}\) . The measurement suite produces several things of thermophysical interest. First, the helium dataset deduces the effective compressibility of the apparatus with a relative standard uncertainty of \(1.3 \times 10^{-4}\) . Next, the argon dataset determines \(T - T_{90}\) with a relative standard uncertainty of about \(3\ \upmu {\text {K}}{\cdot }{\text {K}}^{-1}\) . (The implementation is relative primary thermometry; \(T - T_{90}\) is the difference between thermodynamic temperature and ITS-90.) Finally, the nitrogen dataset estimates the temperature dependence of polarizability within \(3.5\ \%\) relative standard uncertainty. As a by-product of the nitrogen and argon measurements, values of the second density virial coefficient \(B_{\rho }(T)\) are derived with uncertainties smaller than those of previous experiments. More broadly, the work enables conversion of a measured refractivity at known temperature to optical pressure within \(3.5\ \upmu {\text {Pa}}{\cdot }{\text {Pa}}^{-1}\) across the stated range, albeit traceable to the diameter of a piston-gage.
PubDate: 2023-11-23
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- Highly Accurate Densities and Isobaric and Isochoric Heat Capacities of
Compressed Liquid Water Derived from New Speed of Sound Measurements-
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Abstract: Abstract Comprehensive and accurate measurements of the speed of sound in liquid water are reported. The measurements were carried out by a double-path-length pulse-echo technique and cover the temperature range from 273.65 K to 368.15 K with pressures up to 100 MPa. The relative expanded ( \({ k}=2\) ) uncertainties are 2.1 mK in temperature, 45 parts-per-million (ppm) in pressure, and between 40 ppm and 70 ppm in speed of sound. Furthermore, values for the density and specific isobaric and isochoric heat capacities were derived from the speed of sound data in the measured temperature range up to 100 MPa by the method of thermodynamic integration. Very accurate values for the derived properties were obtained by using density data of Takenaka and Masui (Metrologia 27:165–171, 1990) and isobaric heat capacity data of Osborne et al. (J Res Natl Bur Stand 23:197, 1939) at ambient pressure as initial values in combination with an accurate correlation of our speed of sound. The relative expanded ( \({ k}=2\) ) uncertainties of the derived properties are 2 ppm in density, 0.11% in isobaric heat capacity, and 0.12% in isochoric heat capacity. The experimental speeds of sound and derived properties are compared with experimental data of other authors from the literature, the IAPWS-95 (International Association of the Properties of Water and Steam) formulation for the thermodynamic properties of water, and a recent equation of state for supercooled water.
PubDate: 2023-11-20
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- Modeling Mixtures with PCP-SAFT: Insights from Large-Scale Parametrization
and Group-Contribution Method for Binary Interaction Parameters-
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Abstract: Abstract Vapor/liquid equilibria of mixtures are of utmost importance in the design of chemical processes. Because of the combinatorial complexity of mixtures, the available experimental data are small when considering the large molecular space. To fill this knowledge gap, molecular equations of state like PCP-SAFT show promise due to their explicit consideration of intermolecular interactions that can be transferred to mixtures. In this work, we comprehensively assess and exploit PCP-SAFT for modeling phase equilibria of mixtures. First, we provide binary interaction parameters for 7861 binary systems for which pure-component parameters and experimental data are available. Bubble and dew point pressures are described with a median deviation of 2.3 %. Secondly, we adjust a matrix of binary group/group interaction parameters for the homosegmented and heterosegmented group-contribution (GC) methods for PCP-SAFT. Among 1389 mixtures that can be described with the GC methods, the median deviation in bubble and dew point pressures are 6.4 % for the homosegmented approach and 5.1 % for the heterosegmented approach. The detailed analysis shows the importance of hydrogen bonds in mixtures of non-self-associating components with self-associating components. The parametrization is only possible by introducing a fast numerical method to calculate the derivative of bubble and dew point pressures with respect to arbitrarily many model parameters. The approach leverages reverse mode automatic differentiation (backpropagation), the same method used in machine learning to regress millions of model parameters to large datasets.
PubDate: 2023-11-20
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- EOS-CG-2021: A Mixture Model for the Calculation of Thermodynamic
Properties of CCS Mixtures-
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Abstract: Abstract Thermodynamic properties for CCS-relevant mixtures can be calculated with the fundamental equation of state presented in this work over wide ranges of pressure, temperature, and composition for gas, liquid, and supercritical states, as well as for phase equilibria. The mixture model is formulated in terms of the Helmholtz energy and is based on the EOS-CG model of Gernert and Span (J Chem Thermodyn 93:274, 2016]. The new model presented here (EOS-CG-2021) is an update and extension of the previous version, and covers the following sixteen components: carbon dioxide, water, nitrogen, oxygen, argon, carbon monoxide, hydrogen, methane, hydrogen sulfide, sulfur dioxide, monoethanolamine, diethanolamine, hydrogen chloride, chlorine, ammonia, and methyl diethanolamine. Previously published elements of the model are summarized, and new elements are validated and analyzed with the use of comparisons to experimental data and by assessing the physical and extrapolation behavior of the equations. A comprehensive study on the representation of multicomponent mixture data was carried out to show the high accuracy and application range of the EOS-CG-2021.
PubDate: 2023-11-16
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- Viscosity Measurements on Natural Gas: Re-evaluation
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Abstract: Abstract Previous experimental viscosity data for natural gas, published by Schley et al. (Int J Thermophys 25:1623, 2004) and originally obtained using a vibrating-wire viscometer in the temperature range between 260 K and 320 K, were re-evaluated after an improved re-calibration. For this purpose, a new reference value for the viscosity of argon at 298.15 K and at zero density, proposed by Vogel et al. (Mol Phys 108:3335, 2010) and further updated by Hellmann (Private communication, University of the Federal Armed Forces Hamburg, Hamburg, 2020), was applied. In addition, the density computed from the measured temperatures and pressures was determined using the equation of state by Kunz and Wagner (J Chem Eng Data 57:3032, 2012) instead of employing a calculation according to the International Standard ISO 12213 nowadays out of date.
PubDate: 2023-11-16
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- Group Contribution Method for the Residual Entropy Scaling Model for
Viscosities of Branched Alkanes-
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Abstract: Abstract In this work it is shown how the entropy scaling paradigm introduced by Rosenfeld (Phys Rev A 15:2545–2549, 1977, https://doi.org/10.1103/PhysRevA.15.2545) can be extended to calculate the viscosities of branched alkanes by group contribution methods (GCM), making the technique more predictive. Two equations of state (EoS) requiring only a few adjustable parameters (Lee–Kesler–Plöcker and PC-SAFT) were used to calculate the thermodynamic properties of linear and branched alkanes. These EOS models were combined with first-order and second-order group contribution methods to obtain the fluid-specific scaling factor allowing the scaled viscosity values to be mapped onto the generalized correlation developed by Yang et al. (J Chem Eng Data 66:1385–1398, 2021, https://doi.org/10.1021/acs.jced.0c01009) The second-order scheme offers a more accurate estimation of the fluid-specific scaling factor, and overall the method yields an AARD of 10 % versus 8.8 % when the fluid-specific scaling factor is fit directly to the experimental data. More accurate results are obtained when using the PC-SAFT EoS, and the GCM generally out-performs other estimation schemes proposed in the literature for the fluid-specific scaling factor.
PubDate: 2023-11-16
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- Correction to: Fundamental Equation of State for Fluid Tetrahydrofuran
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PubDate: 2023-11-13
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- Thermal Performances of Myristic Acid/Bentonite/Graphene Composite Phase
Change Materials-
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Abstract: Abstract In this work, composite phase change materials (CPCM) containing myristic acid (MA), bentonite, and graphene were prepared by melt blending method, where MA is phase change material (PCM), bentonite is supporting material, and graphene is thermal conductivity enhancer. The CPCM containing 50 wt% MA can still maintain the stable morphology during phase change process. The chemical structure, crystal structure and microstructures of CPCM were examined by Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. Differential scanning calorimeter (DSC) analysis indicate that the melting enthalpy is 94 to 97 J·g−1. Thermogravimetric analysis (TGA) demonstrates good thermal stability of the CPCM. Thermal conductivity of the CPCM with 3 wt% graphene can reach 1.09 W⋅(m⋅K)−1, that is 2.37 times that of MA/bentonite. Experimental results indicate that the CPCM have significant improvement with regard to stability and thermal conductivity as compared to the pristine PCM. Moreover, the CPCM still remain good thermal properties after undergoing 100 thermal cycles.
PubDate: 2023-11-10
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- Thickness and Roughness Effect of Pr2NiO4+δ Coating on the Normal
Spectral Emittance-
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Abstract: Abstract Pr2NiO(4+δ) coatings of rare earth nickelate oxide were prepared through RF magnetron co-sputtering, combined with an appropriate heat treatment. The study focused on optimizing the growth conditions to enhance the thermal emittance of the coatings, taking into account the influence of thickness and roughness. The research findings revealed interesting insights. Firstly, by analyzing room temperature infrared reflectivity and studying the temperature dependence of the normal spectral emittance in the range of 500 cm−1 to 5500 cm−1, it was observed that the total emittance increased as the coating thickness increased. However, this increase tended to approach a saturation value at higher thicknesses. Additionally, the study demonstrated that a coating thickness of 2.8 μm was sufficient to effectively shield the substrate's infrared thermal response. This suggests the potential application of these coatings for thermal management purposes. Furthermore, the influence of roughness on the emittance was predominantly observed in the spectral range of 1200 cm−1 to 3600 cm−1. This finding highlights the importance of considering surface roughness when designing coatings for optimal thermal properties. In summary, the research provided valuable insights into the growth conditions and the impact of thickness and roughness on the thermal emittance of Pr2NiO4+δ coatings. These findings contribute to the development of improved materials for thermal management and related applications.
PubDate: 2023-11-10
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- Investigation of the Density Dependence of the Influence Parameter
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Abstract: Abstract In chemical engineering, interfacial properties play an important role in the design of thermal separation units and also in product design. Two important surface properties are the surface tension between fluid phases and the adsorption of fluids on solids. Of the various ways of describing and calculating these properties, density gradient theory (DGT) is by far the least computationally demanding. However, while surface tension is well described by DGT, adsorption is typically not. One possible reason for this is the constant known as the influence parameter of DGT. This parameter has a real physical meaning—it is the second moment of the direct correlation function—and should therefore depend on the density. In this contribution the density dependence of the influence parameter is investigated. Both, the surface tension between liquid and vapor and the adsorption of vapor or gas on solids of the Lennard–Jones truncated and shifted fluid, are calculated and compared with molecular simulation data. A functional form is identified which retains most of the accuracy of the surface tension while greatly improving the description of the adsorption.
PubDate: 2023-11-10
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- Correction to: Vapor Pressures, Densities, and PC-SAFT Parameters for 11
Bio-compounds-
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PubDate: 2023-11-09
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- A Numerical Algorithm for Calculating Critical Points and Its Application
to Predictive Mixture Models and Binary CO $$_2$$ Mixtures-
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Abstract: Abstract The use of supercritical fluids in technical applications requires an accurate knowledge of their critical points. For mixtures, these can deviate significantly and without a linear dependency from the critical points of its individual pure components. Since even small amounts of admixture can have noticeable effects, this not only concerns blends of targeted compositions, but also unintentional mixtures for example caused by impurities. Within this work, a method for the calculation of critical points is presented which focuses on numerical robustness promoting a fast and reliable generation of results. Implemented into the thermodynamic property software TREND, with its mixture modeling capabilities, the method allows a flexible combination of different equations of state and mixture models which also includes predictive approaches. Against the background of an increasing relevance of mixtures based on supercritical CO \(_2\) (sCO \(_2\) ) for energy applications, critical lines are calculated and compared against experimental results for selected sCO \(_2\) -based mixtures recently considered for power plant applications. Herein, several combinations of equations of state (EoS) and mixture models are compared. Critical lines are calculated for the first time in this work with the combination of the multi-fluid mixture model with excess Gibbs energy ( \(g^\text {E}\) ) models. It was found that the critical lines calculated with the combination of the multi-fluid mixture model with the \(g^\text {E}\) -model COSMO-SAC yields good predictive results for the investigated CO \(_2\) mixtures.
PubDate: 2023-11-07
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- The Magnetic Suspension Balance: 40 Years of Advancing Densimetry and
Sorption Science-
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Abstract: Abstract This paper reviews the 40-year evolution and application of the magnetic suspension balance (MSB) and discusses some challenging issues of the technique. An MSB, as defined herein, is a magnetic suspension coupling (MSC) connected to an analytical balance. With an MSC, an object can be weighed in a different environment than the balance itself, making it possible for contactless weighing. Over the past 40 years, the MSB has been commonly used in research areas requiring accurate object weighings, notably gas density measurements by MSB-based densimeters and gas adsorption measurements by MSB-based sorption analyzers. More than 15 MSB-based densimeters have been built to date; these are generally called two-sinker densimeter and single-sinker densimeter. They have produced highly accurate density data of many pure fluids and fluid mixtures. These data serve as the basis for the development of reference equations of state, which play an essential role in various industrial and scientific areas. Moreover, such systems are central to the metrology program of many countries. The MSB technique is also very successful in adsorption science: more than 85 MSB-based sorption analyzers have been set up in over 20 countries. The number of new MSB-based sorption analyzers, and peer-reviewed publications resulting from them, are both increasing exponentially since 2004. They have produced highly reliable gas adsorption data at high pressures for many applications, mainly in the energy and environmental sectors. Although further development of innovative instruments based on the MSB is threatened by the proprietary nature of MSB technology, the development will continue, e.g., toward cryogenic measurements and a more compact design.
PubDate: 2023-11-07
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- A Helmholtz Energy Equation of State for
cis-1-Chloro-2,3,3,3-tetrafluoro-1-propene [R-1224yd(Z)]-
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Abstract: Abstract A fundamental equation of state expressed explicitly in the Helmholtz energy is presented for R-1224yd(Z), an environmentally friendly refrigerant for centrifugal chillers, high-temperature heat pumps, and organic Rankine cycles. The equation of state is based on consistent experimental data for the critical parameters, vapor pressures, saturated liquid and vapor densities, \((p, \rho , T)\) behavior, vapor-phase sound speeds, liquid-phase sound speeds, and ideal-gas isobaric heat capacities. The equation is valid at temperatures from the triple-point temperature (157.8 K) to 473 K and pressures up to 35 MPa. In the valid range, expected relative uncertainties ( \(k=2\) ) of the equation are 0.04 % for vapor pressures, 0.1 % for saturated liquid densities, 2 % for saturated vapor densities, 0.05 % for liquid densities, 0.3 % for vapor densities, 0.02 % for vapor-phase sound speeds, and 0.04 % for liquid-phase sound speeds, except in the critical region, where more significant uncertainties of up to 2 % are sometimes observed in densities. The equation exhibits reasonable behavior in the critical and extrapolated regions; this is demonstrated by several plots of derived properties over wide ranges of temperature and pressure.
PubDate: 2023-11-06
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- Liquid Viscosity and Density of Squalane and Squalane with Dissolved
Carbon Dioxide at Temperatures From (298.15 to 548.15) K-
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Abstract: Abstract The thermophysical properties of CO2 + alkane mixtures involved in Fischer–Tropsch (FT) synthesis process are attracting attention. In this work, the viscosity and density of squalane and binary mixture of squalane with dissolved carbon dioxide were measured by using a vibrating-wire apparatus. The measurements were performed at temperatures from (298.15 to 548.15) K and pressures up to 10 MPa for squalane, and over the temperature range from (308.15 to 548.15) K and at pressures up to approximately 6 MPa for CO2 + squalane under CO2-saturated conditions. The estimated combined expanded uncertainties are 2.2% and 0.24% for viscosity and density, respectively, with a confidence level of 0.95 (k = 2). The results show that the dissolution of CO2 in squalane widens the density range and reduces greatly the viscosity when compared to pure squalane at the experimental temperature and pressure ranges. In addition, the experimental data of viscosity and density were correlated using the modified Tait-Andrade equation and Tait equation, respectively. The correlations developed in this work for both pure squalane and CO2 + squalane mixture are in good agreement with the experimental results.
PubDate: 2023-11-06
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