Journal articles: 'Thermophysical model'

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Markkanen, J., and J. Agarwal. "Thermophysical model for icy cometary dust particles." Astronomy & Astrophysics 643 (October 27, 2020): A16. http://dx.doi.org/10.1051/0004-6361/202039092.

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Context. Cometary dust particles are subjected to various forces after being lifted off the nucleus. These forces define the dynamics of dust, trajectories, alignment, and fragmentation, which, in turn, have a significant effect on the particle distribution in the coma. Aims. We develop a numerical thermophysical model that is applicable to icy cometary dust to study the forces attributed to the sublimation of ice. Methods. We extended the recently introduced synoptic model for ice-free dust particles to ice-containing dust. We introduced an additional source term to the energy balance equation accounting for the heat of sublimation and condensation. We use the direct simulation Monte Carlo approach with the dusty gas model to solve the mass balance equation and the energy balance equation simultaneously. Results. The numerical tests show that the proposed method can be applied for dust particles covering the size range from tens of microns to centimetres with a moderate computational cost. We predict that for an assumed ice volume fraction of 0.05, particles with a radius, r ≫ 1 mm, at 1.35 AU, may disintegrate into mm-sized fragments due to internal pressure build-up. Particles with r < 1 cm lose their ice content within minutes. Hence, we expect that only particles with r > 1 cm may demonstrate sustained sublimation and the resulting outgassing forces.

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SOZONOV, Maxim V., Alexander N. BUSYGIN, Andrey N. BOBYLEV, and Anatolii A. KISLITSYN. "THERMOPHYSICAL MODEL OF A MEMRISTOR-DIODE MICROCHIP." Tyumen State University Herald. Physical and Mathematical Modeling. Oil, Gas, Energy 7, no. 4 (2021): 62–78. http://dx.doi.org/10.21684/2411-7978-2021-7-4-62-78.

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The most popular models of memristor, based on the principle of formation and breakage of conductive filaments in memristive layer, are applied to consideration of a single memristor. However, consideration of a full-fledged microchip with many memristors may be also interesting. In this case, it is very important to determine the thermal mode of work of the device, in particular, to determine if it needs cooling and how the microchip architecture affects on the nature of heat transfer. At the same time, the proposed model should be quite simple, since modeling of conductive filaments in each memristor greatly complicates work with the model and requires large computational resources. In this paper a thermophysical model of the microchip based on a memristor-diode crossbar created at the REC “Nanotechnology” at Tyumen State University is presented. The model takes into account Joule heating and convective heat transfer. A feature of the model is a simplified determination of memristor state by the resistivity value of memristive layer from the data of the current-voltage characteristic of a real memristor sample. Simulation is carried out in the ANSYS software package. Within the framework of the model, self-consistent electrical and thermophysical problems are solved in a non-stationary setting. The temperature fields and graphs of the temperature versus time were obtained for various operating modes. The results obtained are in good agreement with similar data from other studies published in the literature. The model shows itself well in various operating modes, both in modes with memristor state switching process and without it. The presented model can be used at the design stage to take into account the features of the microchip architecture, which can significantly affect the thermal state of microchip operating modes.

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Selivanova, Z. M., and K. V. Skomorokhov. "Identification of the Measuring Situation when Determining Thermal Properties of Solid Materials under Uncertainty." Vestnik Tambovskogo gosudarstvennogo tehnicheskogo universiteta 27, no. 4 (2021): 516–27. http://dx.doi.org/10.17277/vestnik.2021.04.pp.516-527.

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The main factors characterizing the uncertainty of the measuring situation during thermophysical measurements are considered. An approach is proposed for determining the parameters of the thermophysical properties of materials and the measurement error under uncertainty. A conceptual model of the formation of a measuring environment for an intelligent information-measuring system of thermophysical properties of materials in a situation of uncertainty has been created. The solution of the optimization problem of identification of the measuring situation when determining the thermophysical properties of solid materials of various ranges of thermal conductivity is presented. An information model has been developed to identify a measurement situation in an intelligent information and measurement system operating under conditions of uncertainty.

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Franke, Martin M., Michael Hilbinger, Astrid Heckl, and Robert F. Singer. "Effect of Thermophysical Properties and Processing Conditions on Primary Dendrite Arm Spacing of Nickel-Base Superalloys – Numerical Approach." Advanced Materials Research 278 (July 2011): 156–61. http://dx.doi.org/10.4028/www.scientific.net/amr.278.156.

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This paper presents the results of an investigation on the interrelationship between thermophysical properties, processing conditions and primary dendrite arm spacing for a nickel-base superalloy. The research was realized for CMSX-4, directionally solidified in a Bridgman furnace. For a systematic, fast and cost-efficient investigation numerical finite element models were applied. The numerical model, composed of thermophysical material data, geometric data and boundary conditions, was calibrated and experimentally validated. Microstructural parameters of the castings were determined for a broad range of processing conditions and varying thermophysical properties in order to study general influences. Withdrawal speed, furnace temperature, enthalpy of fusion, solidification range, heat conductivity and specific heat were varied accordingly. The primary dendrite arm spacing is predominantly influenced by withdrawal speed and furnace temperature, but shows only a weak dependency on thermophysical properties.

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Parvizi, Negar, Falamarz Akbari, Mohammad Mehdi Alavianmehr, and Delara Mohammad-Aghaie. "Thermophysical properties of biodiesel fuels from modified perturbed hard trimer chain equation of state." High Temperatures-High Pressures 51, no. 1 (2022): 3–26. http://dx.doi.org/10.32908/hthp.v51.1099.

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In the present study, a modified version of the perturbed hard trimer chain equation of state was employed to predict thermophysical properties of fatty acid methyl ester (FAME) and fatty acid ethyl ester (FAEE) systems. The thermophysical properties in question are liquid density, vapor pressure, heat capacity, viscosity and thermal conductivity. The predictive power of the model has been assessed by calculating the aforementioned thermophysical properties and comparing with experimental ones as well as other models. Typically, the overall average absolute relative deviation (AARD in %) of the predicted densities for 1665 data points was found to be 2.57%. Simplicity and good agreement between the experimental data and those calculated from the present model, are the reasons for applicability of proposed model with sufficient accuracy for engineering applications. The capability of this new equation of state in predicting both thermodynamic and transport properties simultaneously with good accuracies is really prominent.

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Spencer, John R. "A rough-surface thermophysical model for airless planets." Icarus 83, no. 1 (January 1990): 27–38. http://dx.doi.org/10.1016/0019-1035(90)90004-s.

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Zhang, Chunping, Mohammad Jahazi, and Paloma Isabel Gallego. "On the Impact of Microsegregation Model on the Thermophysical and Solidification Behaviors of a Large Size Steel Ingot." Metals 10, no. 1 (January 2, 2020): 74. http://dx.doi.org/10.3390/met10010074.

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The impact of microsegregation models on thermophysical properties and solidification behaviors of a high strength steel was investigated. The examined microsegregation models include the classical equilibrium Lever rule, the extreme non-equilibrium Scheil-Gulliver, as well as other treatments in the intermediate regime proposed by Brody and Flemings, Clyne and Kurz, Kobayashi and Ohnaka. Based on the comparative analyses performed on three representative regions with varied secondary dendrite arm spacing sizes, the classical equilibrium Lever rule and non-equilibrium Scheil scheme were employed to determine the thermophysical features of the studied steel, using the experimentally verified models from literature. The evaluated thermophysical properties include effective thermal conductivity, specific heat capacity and density. The calculated thermophysical data were used for three-dimensional simulation of the casting and solidification process of a 40 metric ton steel ingot, using FEM code Thercast®. The simulations captured the full filling, the thermo-mechanical phenomena and macro-scale solute transport in the cast ingot. The results demonstrated that Lever rule turned out to be the most reasonable depiction of the physical behavior of steel in study in large-size cast ingot and appropriate for the relevant macrosegregation simulation study. The determination of the model was validated using the experimentally measured top cavity dimension, the thermal profiles on the mold outside surface by means of thermocouples, and the carbon distribution patterns via mass spectrometer analysis.

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Magri, Christopher, Ellen S. Howell, Ronald J. Vervack, Michael C. Nolan, Yanga R. Fernández, Sean E. Marshall, and Jenna L. Crowell. "SHERMAN, a shape-based thermophysical model. I. Model description and validation." Icarus 303 (March 2018): 203–19. http://dx.doi.org/10.1016/j.icarus.2017.11.025.

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Osokin, N. I., R. S. Samoylov, A. V. Sosnovskiy, S. A. Sokratov, and V. A. Zhidkov. "Model of the influence of snow cover on soil freezing." Annals of Glaciology 31 (2000): 417–21. http://dx.doi.org/10.3189/172756400781820282.

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AbstractA mathematical model of snow-cover influence on soil freezing, taking into account the phase transition layer, water migration in soil, frost heave and ice-layer formation, has been developed. The modeled results are in good agreement with data observed in natural conditions. The influence of a possible delay between the time of negative temperature establishment in the air and the beginning of snow accumulation, and possible variations of the thermophysical properties of snow cover in the wide range previously reported were investigated by numerical experiments. It was found that the delay could change the frozen-soil depth up to 2–3 times, while different thermophysical characteristics of snow changed the resulting freezing depth 4–5 times.

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Bhardwaj, Purvee. "Structural and Thermophysical Properties of Cadmium Oxide." ISRN Thermodynamics 2012 (April 9, 2012): 1–4. http://dx.doi.org/10.5402/2012/798140.

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We have studied the structural and thermophysical properties of cadmium oxide (CdO), using the Three-Body Potential (TBP) model. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and related volume collapses obtained from this model show a generally good agreement with available experimental others data. The thermophysical properties like molecular force constant, Debye temperature, and so forth, of CdO are also reported.

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Feistel, R., G. M. Marion, R. Pawlowicz, and D. G. Wright. "Thermophysical property anomalies of Baltic seawater." Ocean Science 6, no. 4 (November 18, 2010): 949–81. http://dx.doi.org/10.5194/os-6-949-2010.

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Abstract. While the thermodynamic properties of Standard Seawater are very well known, the quantitative effect of sea salt composition anomalies on various properties is difficult to estimate since comprehensive lab experiments with the various natural waters are scarce. Coastal and estuarine waters exhibit significant anomalies which also influence to an unknown amount the routine salinity calculation from conductivity measurements. Recent numerical models of multi-component aqueous electrolytes permit the simulation of physical chemical properties of seawater with variable solute composition. In this paper, the FREZCHEM model is used to derive a Gibbs function for Baltic seawater, and the LSEA_DELS model to provide estimates for the conductivity anomaly relative to Standard Seawater. From additional information such as direct density measurements or empirical salinity anomaly parameterisation, the quantitative deviations of properties between Baltic and Standard Seawater are calculated as functions of salinity and temperature. While several quantities show anomalies that are comparable with their measurement uncertainties and do not demand special improvement, others exhibit more significant deviations from Standard Seawater properties. In particular density and sound speed turn out to be significantly sensitive to the presence of anomalous solute. Suitable general correction methods are suggested to be applied to Baltic Sea samples with known Practical Salinity and, optionally, directly determined density.

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Feistel, R., G. M. Marion, R. Pawlowicz, and D. G. Wright. "Thermophysical property anomalies of Baltic seawater." Ocean Science Discussions 7, no. 3 (June 30, 2010): 1103–208. http://dx.doi.org/10.5194/osd-7-1103-2010.

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Abstract. While the thermodynamic properties of Standard Seawater are very well known, the quantitative effect of sea salt composition anomalies on various properties is difficult to estimate since comprehensive lab experiments with the various natural waters are scarce. Coastal and estuarine waters exhibit significant anomalies which also influence to an unknown amount the routine salinity calculation from conductivity measurements. Recent numerical models of multi-component aqueous electrolytes permit the simulation of physical chemical properties of seawater with variable solute composition. In this paper, the FREZCHEM model is used to derive a Gibbs function for Baltic seawater, and the LSEA_DELS model to provide estimates for the conductivity anomaly relative to Standard Seawater. From additional information such as direct density measurements or empirical salinity anomaly parameterisation, the quantitative deviations of properties between Baltic and Standard Seawater are calculated as functions of salinity and temperature. While several quantities show anomalies that are comparable with their measurement uncertainties and do not demand special improvement, others exhibit more significant deviations from Standard Seawater properties. In particular density and sound speed turn out to be significantly sensitive to the presence of anomalous solute. Suitable general correction methods are suggested to be applied to Baltic Sea samples with known Practical Salinity and, optionally, directly determined density.

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Panthi, Narayan, Indra Bhandari, and Ishwar Koirala. "Thermophysical behavior of mercury-lead liquid alloy." Papers in Physics 14 (April 1, 2022): 140005. http://dx.doi.org/10.4279/pip.140005.

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Thermophysical properties of compound forming binary liquid mercury-lead alloy at temperature 600 K have been reported as a function of concentration by considering HgPb2 complex using different modelling equations. The thermodynamic properties such as the Gibbs free energy, enthalpy of mixing, chemical activity of each component, and microscopic properties such as concentration fluctuation in long-wavelength limit and Warren-Cowley short range order parameter of the alloy are studied by quasi-chemical approximation. This research paper places additional emphasis on the interaction energy parameters between the atoms of the alloy. The theoretical and experimental data are compared to determine the model’s validity. Compound formation model, statistical mechanical technique, and improved derivation of the Butler equation have all been used to investigate surface tension. The alloy’s viscosity is investigated using the Kozlov-Ronanov-Petrov equation, the Kaptay equation, and the Budai-Benko-Kaptay model. The study depicts a weak interaction of the alloy, and the theoretical thermodynamic data derived at 600 K are in good agreement with the experimental results. The surface tension is slightly different in the compound formation model than in the statistical mechanical approach and the Butler equation at greater bulk concentrations of lead. The estimated viscosities in each of the three models are substantially identical.

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PAPARI, MOHAMMAD MEHDI, JALIL MOGHADASI, SOUDABEH NIKMANESH, ELHAM HOSSEINI, and ALI BOUSHEHRI. "MODELING THERMOPHYSICAL PROPERTIES OF NOBLE GAS INVOLVED MIXTURES." International Journal of Computational Methods 08, no. 01 (March 2011): 19–39. http://dx.doi.org/10.1142/s0219876211002393.

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The present work involves in determining isotropic and effective pair potential energy of binary gas mixtures of Kr–Xe , Kr–C2H6 , Xe–C2H6 , Kr–C3H8 , and Xe–C3H8 from thermophysical properties consisting of viscosity and second virial coefficients through inversion method. Typically, the calculated intermolecular potential energy of Kr–Xe system has compared with HFD model potential reported in literature. A desirable harmony between our model potential and HFD model has been obtained. In order to assess the potential energies obtained, transport properties including viscosity, diffusion, thermal diffusion factor, and thermal conductivity of aforementioned mixtures were predicted using the calculated models potential. The deviation percentage of the calculated viscosity and thermal conductivity of above-mentioned mixtures from the literature values are, respectively, within ±2%, ±3%.

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Sulochana. C and T. Prasanna Kumar. "Heat Transfer of SWCNT-MWCNT Based Hybrid Nanofluid Boundary Layer Flow with Modified Thermal Conductivity Model." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 92, no. 2 (March 12, 2022): 13–24. http://dx.doi.org/10.37934/arfmts.92.2.1324.

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Thermal conductivity is one of the important thermophysical property of nanofluid in enhancing heat transfer. To analyse heat transfer in boundary layer problems thermal diffusivity coefficient along with embedded nano particle thermophysical values will be used via various thermal conductivity models. Many thermal conductivity models are being utilised for theoretical analysis of heat transfer behaviour such as Maxwell model, Hamilton crosser model etc. In this current communication we are analysing the thermal properties of carbon nanotubes by embedding modified Xue thermal conductivity model. Momentum, energy and nano particle volume fraction equations are turned into differential equation of single variable by using appropriate similarity transformation and solved by numerical scheme shooting method. Skin friction, Nusselt numbers for mono particle nanofluid, hybrid nanofluid are computed for distinct physical parameters and it is observed that heat transfer rate is improved with SWCNT-MWCNT as compared to SWCNT.

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Alarifi, Ibrahim M., Hoang M. Nguyen, Ali Naderi Bakhtiyari, and Amin Asadi. "Feasibility of ANFIS-PSO and ANFIS-GA Models in Predicting Thermophysical Properties of Al2O3-MWCNT/Oil Hybrid Nanofluid." Materials 12, no. 21 (November 4, 2019): 3628. http://dx.doi.org/10.3390/ma12213628.

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The main purpose of the present paper is to improve the performance of the adaptive neuro-fuzzy inference system (ANFIS) in predicting the thermophysical properties of Al2O3-MWCNT/thermal oil hybrid nanofluid through mixing using metaheuristic optimization techniques. A literature survey showed that the use of an artificial neural network (ANN) is the most widely used method, although there are other methods that showed better performance. Moreover, it was found in the literature that artificial intelligence methods have been widely used for predicting the thermal conductivity of nanofluids. Thus, in the present study, genetic algorithms (GAs) and particle swarm optimization (PSO) have been utilized to search and determine the antecedent and consequent parameters of the ANFIS model. Solid concentration and temperature were considered as input variables, and thermal conductivity, dynamic viscosity, heat transfer performance, and pumping power in both the internal laminar and turbulent flow regimes were the outputs. In order to evaluate and compare the performance of the models, two statistical indices of root mean square error (RMSE) and determination coefficient (R) were utilized. Based on the results, both of the models are able to predict the thermophysical properties appropriately. However, the ANFIS-PSO model had a better performance than the ANFIS-GA model. Finally, the studied thermophysical properties were developed by the trained ANFIS-PSO model.

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Çobanoğlu, Nur, and Ziya Haktan Karadeniz. "Effect of Nanofluid Thermophysical Properties on the Performance Prediction of Single-Phase Natural Circulation Loops." Energies 13, no. 10 (May 15, 2020): 2523. http://dx.doi.org/10.3390/en13102523.

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Specifying nanofluids’ thermophysical properties correctly is crucial for correct interpretation of a system’s thermo-hydraulic performance and faster market-uptake of nanofluids. Although, experimental and theoretical studies have been conducted on nanofluids’ thermophysical properties; their order-of-magnitude change is still a matter of debate. This numerical study aims to reveal the sensitivity of single phase natural circulation loops (SPNCL), which are the passive systems widely used in solar thermal and nuclear applications, to thermophysical property inputs by evaluating the effects of measured and predicted nanofluid thermophysical properties on the SPNCL characteristics and performance for the first time. Performance and characteristics of an SPNCL working with water-based-Al2O3 nanofluid (1–3 vol.%) for heating applications is evaluated for different pipe diameters (3–6 mm). The thermal conductivity effect on SPNCL characteristics is found to be limited. However, viscosity affects the SPNCL characteristics significantly for the investigated cases. In this study, Grm ranges are 1.93 × 107–9.45 × 108 for measured thermophysical properties and 1.93 × 107–9.45 × 108 for predicted thermophysical properties. Thermo-hydraulic performance is evaluated by dimensionless heat transfer coefficients which is predicted within an error band of ±7% for both the predicted and measured thermophysical properties of the data. A Nu correlation is introduced for the investigated SPNCL model, which is useful for implementing the SPNCL into a thermal system.

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Hamm, M., I. Pelivan, M. Grott, and J. de Wiljes. "Thermophysical modelling and parameter estimation of small Solar system bodies via data assimilation." Monthly Notices of the Royal Astronomical Society 496, no. 3 (June 20, 2020): 2776–85. http://dx.doi.org/10.1093/mnras/staa1755.

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ABSTRACT Deriving thermophysical properties such as thermal inertia from thermal infrared observations provides useful insights into the structure of the surface material on planetary bodies. The estimation of these properties is usually done by fitting temperature variations calculated by thermophysical models to infrared observations. For multiple free model parameters, traditional methods such as least-squares fitting or Markov chain Monte Carlo methods become computationally too expensive. Consequently, the simultaneous estimation of several thermophysical parameters, together with their corresponding uncertainties and correlations, is often not computationally feasible and the analysis is usually reduced to fitting one or two parameters. Data assimilation (DA) methods have been shown to be robust while sufficiently accurate and computationally affordable even for a large number of parameters. This paper will introduce a standard sequential DA method, the ensemble square root filter, for thermophysical modelling of asteroid surfaces. This method is used to re-analyse infrared observations of the MARA instrument, which measured the diurnal temperature variation of a single boulder on the surface of near-Earth asteroid (162173) Ryugu. The thermal inertia is estimated to be 295 ± 18 $\mathrm{J\, m^{-2}\, K^{-1}\, s^{-1/2}}$, while all five free parameters of the initial analysis are varied and estimated simultaneously. Based on this thermal inertia estimate the thermal conductivity of the boulder is estimated to be between 0.07 and 0.12,$\mathrm{W\, m^{-1}\, K^{-1}}$ and the porosity to be between 0.30 and 0.52. For the first time in thermophysical parameter derivation, correlations and uncertainties of all free model parameters are incorporated in the estimation procedure that is more than 5000 times more efficient than a comparable parameter sweep.

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Toleubekov, K. O., A. S. Khazhidinov, and A. S. Akaev. "MODELING OF THE INDUCTION HEATING FOR IMITATION DECAY HEAT IN THE CORIUM DURING THE INTERACTION WITH HEAT-RESISTANT MATERIALS." NNC RK Bulletin, no. 1 (May 1, 2021): 9–14. http://dx.doi.org/10.52676/1729-7885-2021-1-9-14.

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This work is devoted to modeling of the induction heating the corium melts pouring on in the trap. The results nonstationary thermophysical calculation of the temperature field of the corium and refractory blocks of the melt trap are presented in the article. In the process of work, 2D model of the selected the melt trap area was created in the program ANSYS and the thermophysical model was validated by comparison the calculated and experimental data of the experiment.

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Müller, Thomas G. "ISO: Asteroid Results and Thermophysical Modeling." Highlights of Astronomy 13 (2005): 749–51. http://dx.doi.org/10.1017/s1539299600017019.

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AbstractThrough a recently developed thermophysical model, observations from the Infrared Space Observatory (ISO) were combined with visual photometry, lightcurves, close-up observations and direct measurement. In this way, many applications were possible, ranging from simple diameter and albedo determination of serendipitously seen asteroids to sophisticated studies of mineralogic aspects and regolith properties, like emissivity, roughness or thermal inertia for well-known asteroids. The possibility to combine all sources of information in one single model lead also to a better understanding of thermophysical effects, like beaming or the before/after opposition effect. Thus, the mineralogic signatures can be recognized easier and asteroid data from infrared surveys and individual IR photometry can be interpreted more accurately, even in cases where shape or rotational behaviour are not known. Some well-studied asteroids are now even considered as excellent far-infrared calibrators.

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Pawar, Pooja, and Sadhna Singh. "Structural and elastic behavior of aluminum pnictides with temperature effect." International Journal of Modern Physics B 33, no. 30 (December 10, 2019): 1950365. http://dx.doi.org/10.1142/s021797921950365x.

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A realistic interaction potential model (RIPM) has been formulated to theoretically predict the pressure-induced phase transition, elastic properties and thermophysical properties of AlAs and AlSb, including temperature effect (300 K). This model exhibits a better agreement with the available experimental rather than theoretical data for obtained calculations of phase transition pressures and volume collapses. We have achieved elastic moduli, anisotropy factor, Poisson’s ratio, Kleinman parameter, on the basis of the calculated elastic constants. Apparently, this is the first time when thermophysical properties of these compounds are explored at temperature effect by using a single model. Our results are justified by available measured and other reported data which support the validity of our model.

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Baranovskii, V. M., S. V. Temnikova, A. V. Cherenkov, T. P. Zeleneva, and Yu V. Zelenev. "Predicting the Thermophysical Properties of Polymer Composites using Model Representations." International Polymer Science and Technology 31, no. 11 (November 2004): 5–12. http://dx.doi.org/10.1177/0307174x0403101102.

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Liang, Zhi, and Hai-Lung Tsai. "Calculation of thermophysical properties for CO2gas using anab initiopotential model." Molecular Physics 108, no. 10 (May 20, 2010): 1285–95. http://dx.doi.org/10.1080/00268971003670873.

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Dasheev, D. E., N. N. Smirnyagina, A. E. Lapina, and A. S. Milonov. "Thermophysical model of electron beam boriding of carbon steel St3." Journal of Physics: Conference Series 1393 (November 2019): 012079. http://dx.doi.org/10.1088/1742-6596/1393/1/012079.

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Kambhatla, Pravin Kashyap, Odelu Ojjela, and Samir Kumar Das. "Viscoelastic model of ethylene glycol with temperature-dependent thermophysical properties." Journal of Thermal Analysis and Calorimetry 135, no. 2 (June 19, 2018): 1257–68. http://dx.doi.org/10.1007/s10973-018-7476-4.

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Shkaeva, N. V., D. S. Kosyakov, T. E. Skrebets, and Yu N. Sazanov. "Thermophysical properties of model compounds of the lignin structural unit." Russian Chemical Bulletin 65, no. 10 (October 2016): 2504–8. http://dx.doi.org/10.1007/s11172-016-1614-6.

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Restrepo, Albeiro, Gary D. Bent, and H. Harvey Michels. "Solution theory model for thermophysical properties of refrigerant/lubricant mixtures." AIChE Journal 55, no. 12 (December 2009): 3241–47. http://dx.doi.org/10.1002/aic.11944.

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Kravchenko, Igor N., Yurii A. Kuznetsov, Vladimir V. Goncharenko, and Larisa V. Kalashnikova. "Investigation of Influence of Plasma Spraying Process Parameters on the Level of Residual Stresses." Key Engineering Materials 864 (September 2020): 198–203. http://dx.doi.org/10.4028/www.scientific.net/kem.864.198.

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The method to determine thermal fields considering dependence of thermophysical and mechanical properties of coating materials and a base from the temperature, the running of plastic deformations and stresses relaxation at plasma spraying is suggested. The mathematical model of calculation of thermal field with moving boundary considering nonlinear feature of coating growth at layer-by-layer deposition and dependences from thermophysical properties of materials of the system «coating-base» is developed. The model application helps to estimate the effect of the parameters of plasma spraying process on the level of the residual stresses in the increased coatings.

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Aman, Sidra, Syazwani Mohd Zokri, Zulkhibri Ismail, Mohd Zuki Salleh, and Ilyas Khan. "Casson Model of MHD Flow of SA-Based Hybrid Nanofluid Using Caputo Time-Fractional Models." Defect and Diffusion Forum 390 (January 2019): 83–90. http://dx.doi.org/10.4028/www.scientific.net/ddf.390.83.

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In this paper MHD flow of Casson hybrid nanofluids are investigated with Caputo time-fractional derivative. Alumina (Al) and copper (Cu) are used as nanoparticles in this study with heat, mass transfer and MHD flow over a vertical channel in a porous medium. The problem is modeled using Caputo fractional derivatives and thermophysical properties of hybrid nanoparticles. The influence of concerned parameters is investigated physically and graphically on the heat, concentration and flow. The effect of volume fraction on thermal conductivity of hybrid nanofluids is observed.

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Davidsson, Björn J. R., and Sona Hosseini. "Implications of surface roughness in models of water desorption on the Moon." Monthly Notices of the Royal Astronomical Society 506, no. 3 (August 2, 2021): 3421–29. http://dx.doi.org/10.1093/mnras/stab1360.

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ABSTRACT The observed presence of water molecules in the dayside lunar regolith was an unexpected discovery and remains poorly understood. Standard thermophysical models predict temperatures that are too high for adsorbed water to be stable. We propose that this problem can be caused by the assumption of locally flat surfaces that is common in such models. Here, we apply a model that explicitly considers surface roughness, and accounts for solar illumination, shadows cast by topography, self-heating, thermal reradiation, and heat conduction. We couple the thermophysical model to a model of first-order desorption of lunar surface water and demonstrate that surface roughness substantially increases the capability of the Moon to retain water on its sunlit hemisphere at any latitude, and within 45○ of the poles, at any time of the lunar day. Hence, we show that lunar surface roughness has a strong influence on lunar water adsorption and desorption. Therefore, it is of critical importance to take account of surface roughness to get an accurate picture of the amount of water on the Moon’s surface and in its exosphere.

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Liang, J. F., J. K. Yu, and Y. Q. Quan. "Thermophysical Properties of Aluminum Infiltrated Silicon Carbide for Electronic Packaging." Materials Science Forum 475-479 (January 2005): 1755–58. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1755.

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The effects of interfacial thickness and temperature on thermal conductivity and CTEs of Al/SiC packaging materials were investigated. The interfacial thermal conductivity and thickness have significant influence on the thermal conductivity of the Al/SiC packaging materials, while the SiC size has slight influence on that of the Al/SiC packaging materials. The experiment results of thermal conductivity are similar to Hassleman model and simulation results. Schapery model can be used to calculate the CTEs of composites when temperatures are lower(50~100°C) and Kerner model can be used when temperatures are higher(300~450°C). The CTEs of composites will increase more quickly than that by three models when temperatures are between 100°C and 300°C.

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Jawahery, Sudi, Ville-Valtteri Visuri, Stein O. Wasbø, Andreas Hammervold, Niko Hyttinen, and Martin Schlautmann. "Thermophysical Model for Online Optimization and Control of the Electric Arc Furnace." Metals 11, no. 10 (October 5, 2021): 1587. http://dx.doi.org/10.3390/met11101587.

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A dynamic, first-principles process model for a steelmaking electric arc furnace has been developed. The model is an integrated part of an application designed for optimization during operation of the furnace. Special care has been taken to ensure that the non-linear model is robust and accurate enough for real-time optimization. The model is formulated in terms of state variables and ordinary differential equations and is adapted to process data using recursive parameter estimation. Compared to other models available in the literature, a focus of this model is to integrate auxiliary process data in order to best predict energy efficiency and heat transfer limitations in the furnace. Model predictions are in reasonable agreement with steel temperature and weight measurements. Simulations indicate that industrial deployment of Model Predictive Control applications derived from this process model can result in electrical energy consumption savings of 1–2%.

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Ignatova, Elena. "Information modeling of windows with the account of thermophysical characteristics." MATEC Web of Conferences 144 (2018): 04014. http://dx.doi.org/10.1051/matecconf/201814404014.

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The task of improving the buildings energy efficiency is one of the most important tasks in the design of buildings. The buildings energy efficiency can be improved by rational choice of building structures and reduction of the heat transfer. Significant heat transfer of a building occurs through the windows. At the design stage of a building, it is necessary to estimate the magnitude of a heat transfer of different windows. Currently the designers are increasingly using the technology of building information modeling (BIM). 3D-model of the building consists of models of structural elements, which contain information about the different geometric, physical, technological and other characteristics of the structure. The aim of this work is to develop a parametric information model of the window taking into account its heat transfer resistance. In this paper the design of window units with one, two and three sashes are discussed. The value of window-reduced resistance to a heat transfer is calculated inside the window information model and is presented in the table. The method can be applied to different window design. Thermophysical parameter of the window information model can be used to assess the energy costs of operating the building.

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Koczyk, Halina. "SELECTION OF THERMOPHYSICAL PROPERTIES OF HEAT STORAGE WALL." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, no. 4 (December 31, 2002): 281–85. http://dx.doi.org/10.3846/13923730.2002.10531289.

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The paper discusses a method of the multilayered heat storage wall. Initial data: walls are multilayered, heat conductivity process is considered being one-dimensional, climatic factors and power supplied are periodic functions of time. In the paper mathematical and numerical models are presented. A mathematical model is constituted of a system of differential equations which describe heat conduction in material layers, equation of heat balance and boundary conditions system. Solving equations with regard to unknown property which has been recognized as a crucial parameter in the task one can obtain a real numeric value of the parameter. The paper is illustrated by the nomograms of calculated accumulating layer thickness and the scheme of an algorithm designed to calculate the thickness of accumulating layer.

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Durdán, Milan, Ján Kačur, Marek Laciak, and Patrik Flegner. "Thermophysical Properties Estimation in Annealing Process Using the Iterative Dynamic Programming Method and Gradient Method." Energies 12, no. 17 (August 25, 2019): 3267. http://dx.doi.org/10.3390/en12173267.

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In annealing, steel coils should be heated and consequently cooled according to the technological prescription defined for the annealed type of steel. It is appropriate to develop the systems and methods for estimation of the steel coil inner temperature for that reason. The proposal for such a system of indirect measurement of inner temperature is described in this study. This system, in the form of the mathematical model, is developed based on the theory of heat transfer and needs thermophysical parameters as inputs. In many cases, the thermophysical properties are difficult to access or unknown for the specific composition of the material being processed. In this paper, two optimization methods were applied to estimate two thermophysical properties. The application of the iterative dynamic programming method is aimed to estimate optimal thermal diffusivity. The verification of this method was performed on 11 laboratory measurements. The algorithm of the gradient method was used for estimating thermal conductivity and was verified on seven operational measurements. Results show that the optimized values of thermophysical properties increased the accuracy of the steel coil inner temperature estimation in the locations nearer to the steal coil central axis.

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Smirnov, Vitalii A., and Aleksandr V. Repko. "Workpiece Temperature Variations During Flat Peripheral Grinding." Management Systems in Production Engineering 26, no. 2 (June 1, 2018): 93–98. http://dx.doi.org/10.1515/mspe-2018-0015.

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Abstract The paper presents the results of researches of temperature variations during flat peripheral grinding. It is shown that the temperature variations of the workpiece can reach 25...30% of the average values, which can lead to some thermal defects. A nonlinear two-dimensional thermophysical grinding model is suggested. It takes into account local changes in the cutting conditions: the fluctuation of the cut layer and the cutting force, the thermal impact of the cutting grains, and the presence of surface cavities in the intermittent wheel. For the numerical solution of the problem, the method of finite differences is adapted. Researches of the method stability and convergence are made, taking into account the specific nature of the problem. A high accuracy of the approximation of the boundary conditions and the nonlinear heat equation is provided. An experimental verification of the proposed thermophysical model was carried out with the use of installation for simultaneous measurement of the grinding force and temperature. It is shown that the discrepancy between the theoretical and experimental values of the grinding temperature does not exceed 5%. The proposed thermophysical model makes it possible to predict with high accuracy the temperature variations during grinding by the wheel periphery.

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Srivastava, Anurag, and Bhoopendra Dhar Diwan. "Pressure-induced phase transition and thermophysical properties of cubic refractory metal nitrides: theory." Canadian Journal of Physics 91, no. 1 (January 2013): 27–33. http://dx.doi.org/10.1139/cjp-2012-0149.

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The present paper reports the structural stability, pressure-induced phase transition, and thermophysical properties for refractory metal nitrides (viz: TiN, ZrN, HfN, VN, NbN, and TaN) computed using a three-body force potential model. The structural phase transitions from a parental NaCl (B1) type phase to the most stable CsCl (B2) type phase has been observed in the pressure range 162–370 GPa. Study includes the computation of thermophysical properties (U, f, θD, υ0,γ, β, αV/CV), where some of the properties are being reported for the first time on these materials.

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Zenk, Christopher H., Steffen Neumeier, Nicole M. Engl, Suzana G. Fries, Oleksandr Dolotko, Martin Weiser, Sannakaisa Virtanen, and Mathias Göken. "Intermediate Co/Ni-base model superalloys — Thermophysical properties, creep and oxidation." Scripta Materialia 112 (February 2016): 83–86. http://dx.doi.org/10.1016/j.scriptamat.2015.09.018.

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Freile, Ramiro, and Mark Kimber. "Influence of molten salt-(FLiNaK) thermophysical properties on a heated tube using CFD RANS turbulence modeling of an experimental testbed." EPJ Nuclear Sciences & Technologies 5 (2019): 16. http://dx.doi.org/10.1051/epjn/2019027.

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In a liquid fuel molten salt reactor (MSR) a key factor to consider upon its design is the strong coupling between different physics present such as neutronics, thermo-mechanics and thermal-hydraulics. Focusing in the thermal-hydraulics aspect, it is required that the heat transfer is well characterized. For this purpose, turbulent models used for FLiNaK flow must be valid, and its thermophysical properties must be accurately described. In the literature, there are several expressions for each material property, with differences that can be significant. The goal of this study is to demonstrate and quantify the impact that the uncertainty in thermophysical properties has on key metrics of thermal hydraulic importance for MSRs, in particular on the heat transfer coefficient. In order to achieve this, computational fluid dynamics (CFD) simulations using the RANS k-ω SST model were compared to published experiment data on molten salt. Various correlations for FLiNaK’s material properties were used. It was observed that the uncertainty in FLiNaK’s thermophysical properties lead to a significant variance in the heat coefficient. Motivated by this, additional CFD simulations were done to obtain sensitivity coefficients for each thermophysical property. With this information, the effect of the variation of each one of the material properties on the heat transfer coefficient was quantified performing a one factor at a time approach (OAT). The results of this sensitivity analysis showed that the most critical thermophysical properties of FLiNaK towards the determination of the heat transfer coefficient are the viscosity and the thermal conductivity. More specifically the dimensionless sensitivity coefficient, which is defined as the percent variation of the heat transfer with respect to the percent variation of the respective property, was −0.51 and 0.67 respectively. According to the different correlations, the maximum percent variations for these properties is 18% and 26% respectively, which yields a variation in the predicted heat transfer coefficient as high as 9% and 17% for the viscosity and thermal conductivity, respectively. It was also demonstrated that the Nusselt number trends found from the simulations were captured much better using the Sieder Tate correlation than the Dittus Boelter correlation. Future work accommodating additional turbulence models and higher fidelity physics will help to determine whether the Sieder Tate expression truly captures the physics of interest or whether the agreement seen in the current work is simply reflective of the single turbulence model employed.

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Sur, Anirban, and Randip K. Das. "Numerical Modeling and Thermal Analysis of an Adsorption Refrigeration System." International Journal of Air-Conditioning and Refrigeration 23, no. 04 (December 2015): 1550033. http://dx.doi.org/10.1142/s2010132515500339.

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The aim of this paper is to develop a complete, precise and simple numerical model based on the thermophysical properties of an adsorptive cooling system (using activated carbon–methanol pair), analyze and discuss the heat and mass transfer processes and identify the parameters which influence the system performance. In the design of adsorption refrigeration system, the characteristics of both adsorbate–adsorbent pairs and system operating conditions are very important. So in this model, different thermophysical properties of working pair such as, specific heat, density, isosteric heat of adsorption and desorption, and different temperatures of the system are considered. A simulation code, written in FORTRAN, is carried out. The performance of the system is assessed in terms of refrigeration effect and coefficient of performance (COP).

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Zuev, A. V., Yu P. Zarichnyak, and D. Ya Barinov. "MEASUREMENT OF THERMOPHYSICAL PROPERTIES RIGID FIBER INSULATION." Proceedings of VIAM, no. 2 (2021): 88–98. http://dx.doi.org/10.18577/2307-6046-2021-0-2-88-98.

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Describes a mathematical model for processing the results of measurements of thermal conductivity of highly porous fibrous materials of thermal protection. The results and some methodological features of measuring the thermal conductivity of rigid thermal insulation based on refractory oxide fibers are presented. The possibility of measurements taking into account the anisotropy of properties is investigated. The stiffness of the thermal insulation at the fiber contacts is provided by the binder. Thermal conductivity was measured by the stationary method on cylindrical samples in a wide temperature range from 20 to 1700 °C in various gaseous media.

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Skorov, Yu, H. U. Keller, S. Mottola, and P. Hartogh. "Near-perihelion activity of comet 67P/Churyumov–Gerasimenko. A first attempt of non-static analysis." Monthly Notices of the Royal Astronomical Society 494, no. 3 (April 4, 2020): 3310–16. http://dx.doi.org/10.1093/mnras/staa865.

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ABSTRACT The observed rate of water production of comet 67P/Churyumov–Gerasimenko near its perihelion can be approximated by a very steep power function of the heliocentric distance. Widely used thermophysical models based on a static dust layer on top of the icy/refractory matrix are poorly consistent with these observations. We analyse published model results and demonstrate that thermophysical models with a uniform and static ice free layer do not reproduce the observed steep water production rates of 67P near perihelion. Based on transient thermal modeling we conclude that the accelerated gas activity can be explained assuming that the active area fraction near the south pole is increased. The deeper penetration of the heat wave during polar day (no sunset) can activate sublimation through thicker inert dust layers. This can also lead to removal of thicker dust layers and consequently to an expansion of the active area.

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Hanimann, Lucian, Luca Mangani, Ernesto Casartelli, Damian Vogt, and Marwan Darwish. "Real Gas Models in Coupled Algorithms Numerical Recipes and Thermophysical Relations." International Journal of Turbomachinery, Propulsion and Power 5, no. 3 (August 3, 2020): 20. http://dx.doi.org/10.3390/ijtpp5030020.

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In the majority of compressible flow CFD simulations, the standard ideal gas state equation is accurate enough. However, there is a range of applications where the deviations from the ideal gas behaviour is significant enough that performance predictions are no longer valid and more accurate models are needed. While a considerable amount of the literature has been written about the application of real gas state equations in CFD simulations, there is much less information on the numerical issues involved in the actual implementation of such models. The aim of this article is to present a robust implementation of real gas flow physics in an in-house, coupled, pressure-based solver, and highlight the main difference that arises as compared to standard ideal gas model. The consistency of the developed iterative procedures is demonstrated by first comparing against results obtained with a framework using perfect gas simplifications. The generality of the developed framework is tested by using the parameters from two different real gas state equations, namely the IAPWS-97 and the cubic state equations state equations. The highly polynomial IAPWS-97 formulation for water is applied to a transonic nozzle case where steam is expanded at transonic conditions until phase transition occurs. The cubic state equations are applied to a two stage radial compressor setup. Results are compared in terms of accuracy with a commercial code and measurement data. Results are also compared against simulations using the ideal gas model, highlighting the limitations of the later model. Finally, the effects of the real gas formulations on computational time are compared with results obtained using the ideal gas model.

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Novakovic, Rada, Simona Delsante, and Donatella Giuranno. "Design of Composites by Infiltration Process: A Case Study of Liquid Ir-Si Alloy/SiC Systems." Materials 14, no. 20 (October 13, 2021): 6024. http://dx.doi.org/10.3390/ma14206024.

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The design of processing routes involving the presence of the liquid phase is mainly associated with the knowledge of its surface and transport properties. Despite this need, due to experimental difficulties related to high temperature measurements of metallic melts, for many alloy systems neither thermodynamic nor thermophysical properties data are available. A good example of a system lacking these datasets is the Ir-Si system, although over the last fifty years, the structures and properties of its solid phases have been widely investigated. To compensate the missing data, the Gibbs free energy of mixing of the Ir-Si liquid phase was calculated combining the model predicted values for the enthalpy and entropy of mixing using Miedema’s model and the free volume theory, respectively. Subsequently, in the framework of statistical mechanics and thermodynamics, the surface properties were calculated using the quasi-chemical approximation (QCA) for the regular solution, while to obtain the viscosity, the Moelwyn-Hughes (MH) and Terzieff models were applied. Subsequently, the predicted values of the abovementioned thermophysical properties were used to model the non-reactive infiltration isotherm of Ir-Si (eutectic)/SiC system.

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Balestra, P., F. Giannetti, G. Caruso, and A. Alfonsi. "New RELAP5-3D Lead and LBE Thermophysical Properties Implementation for Safety Analysis of Gen IV Reactors." Science and Technology of Nuclear Installations 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/1687946.

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The latest versions of RELAP5-3D©code allow the simulation of thermodynamic system, using different type of working fluids, that is, liquid metals, molten salt, diathermic oil, and so forth, thanks to the ATHENA code integration. The RELAP5-3D©water thermophysical properties are largely verified and validated; however there are not so many experiments to generate the liquid metals ones in particular for the Lead and the Lead Bismuth Eutectic. Recently, new and more accurate experimental data are available for liquid metals. The comparison between these state-of-the-art data and the RELAP5-3D©default thermophysical properties shows some discrepancy; therefore a tool for the generation of new properties binary files has been developed. All the available data came from experiments performed at atmospheric pressure. Therefore, to extend the pressure domain below and above this pressure, the tool fits a semiempirical model (soft sphere model with inverse-power-law potential), specific for the liquid metals. New binary files of thermophysical properties, with a detailed mesh grid of point to reduce the code mass error (especially for the Lead), were generated with this tool. Finally, calculations using a simple natural circulation loop were performed to understand the differences between the default and the new properties.

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Chyhryn, Serafym. "Modelling and Analysis of Plate Heat Exchangers for Flexible District Heating Systems." Energies 12, no. 21 (October 30, 2019): 4141. http://dx.doi.org/10.3390/en12214141.

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Seamless integration of district heating (DH) and power systems implies their flexible operation, which extends their typical operational boundaries and, thus, affects performance of key components, such as plate heat exchangers (PHXs). Despite that the heat transfer in a PHX is regulated by mass flows, flexible operation and demand variations cause shifts in temperature levels, which affects the system operation and must be efficiently accounted for. In this paper, an overall heat transfer coefficient (OHTC) model with direct relation to temperature is proposed. The model is based on a linear approximation of thermophysical components of the forced convection coefficient (FCC). On one hand, it allows to account for temperature variations as compared to mass flow-based models, thus, improving accuracy. On the other hand, it does not involve iterative lookup of thermophysical properties and requires fewer inputs, hence, reducing computational effort. The proposed linear model is experimentally verified on a laboratory PHX against estimated correlations for FCC. A practical estimation procedure is proposed based on component data. Additionally, binding the correlation to one of varying parameters shows reduction in the heat transfer error. Finally, operational optimization test cases for a basic DH system demonstrate better performance of the proposed models as compared to those previously used.

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Khabibullin, I. L., and G. A. Nigametuanova. "THERMOMECHANICAL MODEL FOR DETERMINING THE STABILITY OF THE PERMAFROST ZONE SLOPES." Oil and Gas Studies, no. 1 (March 1, 2018): 42–48. http://dx.doi.org/10.31660/0445-0108-2018-1-42-48.

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The authors of the article propose a model for determining the stability of the permafrost zone slopes, which includes mechanical and thermophysical components. The developed model for determining the stability of slopes in the process of thawing permafrost allows assess slope stability factor depending on the time and the set of parameters: thermal and mechanical properties of soil making up the slope, the components of the radiation balance, the exposure, and the angle of slope, etc.

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Yu, Liangliang, and Jianghui Ji. "Thermophysical Characteristics of OSIRIS-REx Target Asteroid (101955) Bennu." Proceedings of the International Astronomical Union 10, S318 (August 2015): 218–20. http://dx.doi.org/10.1017/s1743921315006985.

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AbstractIn this work, we investigate the thermophysical properties, including thermal inertia, roughness fraction and surface grain size of OSIRIS-REx target asteroid (101955) Bennu by using a thermophysical model with the recently updated 3D radar-derived shape model (Nolan et al., 2013) and mid-infrared observations (Müller et al. 2012, Emery et al., 2014). We find that the asteroid bears an effective diameter of 510+6−40 m, a geometric albedo of 0.047+0.0083−0.0011, a roughness fraction of 0.04+0.26−0.04, and thermal inertia of 240+440−60 Jm−2s−0.5K−1 for our best-fit solution. The best-estimate thermal inertia suggests that fine-grained regolith may cover a large portion of Bennu's surface, where a grain size may vary from 1.3 to 31 mm. Our outcome suggests that Bennu is suitable for the OSIRIS-REx mission to return samples to Earth.

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Gorbynov, V. A., S. G. Andrianov, and S. S. Konovaltseva. "Assessment of radiation heat transfer influence on parameters of temperature fields of various design fuel rods." Vestnik IGEU, no. 2 (April 30, 2021): 23–31. http://dx.doi.org/10.17588/2072-2672.2021.2.023-031.

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VVER-1000 reactors use cylindrical smooth-core fuel rods. Previously, a model to determe the fuel rod temperature field in a two-dimensional problem statement has been developed and verified. However, modelling assumptions do not consider the influence of variable thermophysical properties, radiation heat transfer, and the opening in the fuel rod on the final parameters of the temperature fields. The impact assessment is an urgent task to improve the economic efficiency of the fuel cycle and the capacity of power units. To develop models and study the features of energy release in nuclear reactors, a numerical package of thermophysical modeling COMSOL Multiphysics software is used. The simulation of temperature fields is performed based on the heat equation with an internal heat source, under the boundary conditions of the second kind at the ends of the fuel rod and the boundary conditions of the third kind on the side surface of the rod. Аn axisymmetric model in two-dimensional problem statement and a three-dimensional model of the fuel rod are developed. The temperature distribution fields are determined by the finite element method. The results of calculations of various design fuel rods are presented. The results have showen that the radiation heat transfer significantly affects the maximum fuel temperature (UO2). The impact degree of variability of thermophysical properties and radiation heat transfer is determined. It was found that the temperature characteristics under different specified conditions have a difference in the range of 15,5–282,0 K (0,8–14,4 %). The developed models are reliable and confirmed by the previously verified model, the characteristics of the fuel assembly used on the VVER-1000 units. The results presented can be used for mathematical modeling of heat transfer processes, both during the modernization of the equipment in operation, and during the development, design, and operation, which will increase the efficiency of electric energy generation at the power unit of a nuclear power plant.

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FUKUYAMA, H., M. WATANABE, and M. ADACHI. "Recent studies on thermophysical properties of metallic alloys with PROSPECT: Excess properties to construct a solution model." High Temperatures-High Pressures 49, no. 1-2 (2020): 197–210. http://dx.doi.org/10.32908/hthp.v49.851.

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We have developed the system PROSPECT for measuring thermophysical properties at high temperature. Precise thermophysical measurements provide accurate excess functions, which represent non-ideality of solutions. We use excess functions to discuss solution models on the basis of electronic structure and thermodynamics. Pd-Fe systems show positive excess volume VE with negative excess Gibbs energy GE. The phase diagrams of these systems have common features with those of other Pd-X and Pt-X systems (where X is Fe, Ni, Co, or Cu), which means they all have order-disorder transitions. The correlation between VE and GE is discussed in terms of the electronic structure of the alloys, and an energy diagram is proposed to understand this correlation. The excess heat capacity CpE of Fe-Ni melts is positive over a whole composition range and a wide temperature range. We estimate the temperature dependences of the excess enthalpy HE and excess entropy SE of Fe-Ni melts from CpE. The Lupis-Elliott rule is satisfied for HE and SE with positive CpE.

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Journal articles on the topic 'Thermophysical model'

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