AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processe...AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.展开更多
The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This re...The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This researchlays the groundwork for our future studies,which will focus on photovoltaic thermal applications.These nanofluidsconsist of water and nanoparticles of alumina(Al_(2)O_(3)),titanium dioxide(TiO_(2)),and copper(Cu),exploringvolumetric concentrations ranging from 0%to 4%for each type of nanoparticle,and up to 10%for total mixtures.The developed model accounts for complex interactions between the nanoparticles and the base fluid,as well assynergistic effects resulting from the coexistence of different nanoparticles.Detailed simulations have shownexceptional agreement with experimental results,reinforcing the credibility of our approach in accurately capturingthe thermophysical behavior of these hybrid nanofluids.Based on these results,our study proposes significantadvancements in the design and optimization of nanofluids for cooling applications in solar panels.These developmentsare crucial for improving the efficiency of solar installations by mitigating overheating effects,providinga solid foundation for practical applications in this rapidly evolving field.展开更多
Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively ...Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.展开更多
A program CALTPP(CALculation of ThermoPhysical Properties)is developed in order to provide various thermophysical properties such as diffusion coefficient,interfacial energy,thermal conductivity,viscosity and molar vo...A program CALTPP(CALculation of ThermoPhysical Properties)is developed in order to provide various thermophysical properties such as diffusion coefficient,interfacial energy,thermal conductivity,viscosity and molar volume mainly as function of temperature and composition.These thermophysical properties are very important inputs for microstructure simulations and mechanical property predictions.The general structure of CALTPP is briefly described,and the CALPHAD-type models for the description of these thermophysical properties are presented.The CALTPP program contains the input module,calculation and/or optimization modules and output module.A few case studies including(a)the calculation of diffusion coefficient and optimization of atomic mobility,(b)the calculation of solid/liquid,coherent solid/solid and liquid/liquid interfacial energies,(c)the calculation of thermal conductivity,(d)the calculation of viscosity,and(e)the establishment of molar volume database in binary and ternary alloys are demonstrated to show the features of CALTPP.It is expected that CALTPP will be an effective contribution in both scientific research and education.展开更多
Thermophysical parameters are the main parameters affecting the utilization efficiency of shallow geothermal energy. Based on the research and evaluation data of shallow geothermal energy in capital cities of China, t...Thermophysical parameters are the main parameters affecting the utilization efficiency of shallow geothermal energy. Based on the research and evaluation data of shallow geothermal energy in capital cities of China, this paper analyzes the differences between two testing methods and finds that data measured in in-situ thermal conductivity test is closer to the actual utilization. This paper analyzes the influencing factors of thermophysical parameters from lithology, density, moisture content and porosity: The thermal conductivity coefficient of bedrock is generally higher than Quaternary system loose bed soil; as for the coefficient of bedrock, dolomite, shale and granite are higher while gabbro, sandstone and mudstone are lower; as for the coefficient of loose bed, pebble and gravel are higher while clay and silt are lower. As the particle size of sand decreases, the thermal conductivity coefficient declines accordingly. The thermal conductivity coefficient increases linearly with growing density and decreases in logarithm with growing moisture content as well as porosity; specific heat capacity decreases in logarithm with growing density, increases in power exponent with growing moisture content and decreases linearly with growing porosity. The thermal conductivity coefficient is high when hydrodynamic condition is good and vice versa. The conclusions of this paper have guiding significance for the research, evaluation and development of shallow geothermal energy in other areas.展开更多
In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties...In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications. The examined thermophysical properties and structural characterization, including material anisotropy, coupled with the results of previous measurements of the mechanical properties of both Al2O3 reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions. Microscopic examinations (LM, SEM) were carried out to reveal the range of morphological homogeneity of the microstructure, the anisotropy of the filament band distribution, and simultaneously the adhesive behavior of the metal/fbier interface. The 3D morphology of the chosen microstructure components was revealed by computed tomography. The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced, on the one hand, by the geometry of its internal microstructure, i.e. spatial distribution and volume fraction of the Al2O3 reinforcing filaments and, on the other hand, by a very good compatibility obtained between the individual metal prepreg components.展开更多
A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on cas...A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on casting solidification temperature field, microstructure and hardness has been investigated. The results show that the solidification rate decreases inversely with the coating thickness when the coating contains silica sol, zircon powder, mullite powder and defoaming agent. In contrast, the solid cooling rate increases as the coating thickness increases. However, the solidification rate and solid cooling rate of the casting produced by the existing IC and the improved IC are very similar when the coating thickness is 5 mm, so the microstructure and hardness of a container corner fitting produced by the improved IC and the existing IC are similar. The linear regression equation for the grain size （d） and cooling rate （v） of the castings is d= -0.41v＋206.1. The linear regression equation for the content of pearlite （w） and solid cooling rate （t） is w=1.79t ＋ 6.71. The new improved IC can greatly simplify the process and decrease the cost of production compared with the existing IC. Contrasting with LI=C, container corner fittings produced by the new improved IC have fewer defects and better properties. It was also found that the desired microstructure and properties can be obtained by changing the thermophysical property and thickness of the coating.展开更多
The calculation of thermophysical properties of stainless steel castings and its application to casting simulation is discussed. It is considered that accurate thermophysical properties of the casting alloys are neces...The calculation of thermophysical properties of stainless steel castings and its application to casting simulation is discussed. It is considered that accurate thermophysical properties of the casting alloys are necessary for the valid simulation of the casting processes. Although previous thermophysical calculation software requires a specific knowledge of thermodynamics, the calculation method proposed in the present study does not require any special knowledge of thermodynamics, but only the information of compositions of the alloy. The proposed calculator is based on the CALPHAD approach for modeling of multi-component alloys, especially in stainless steels. The calculator proposed in the present study can calculate thermophysical properties of eight-component systems on an iron base alloy(Fe-C-Si-Cr-Mn-Ni-Cu-Mo), and several Korean standard stainless steel alloys were calculated and discussed. The calculator can evaluate the thermophysical properties of the alloys such as density, heat capacity, enthalpy, latent heat, etc, based on full Gibbs energy for each phase. It is expected the proposed method can help casting experts to devise the casting design and its process easily in the field of not only stainless steels but also other alloy systems such as aluminum, copper, zinc, etc.展开更多
Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will...Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will affect the energy storage efficiency of MPCM.The incorporation of TiO_(2)nanoparticles into MPCM can alleviate supercooling.In this work,octadecyltrimethoxysilane(ODTMS)was used to modify the solid nucleating agent TiO_(2)(m-TiO_(2))to improve its compatibility with n-Octadecane.Then,MPCM based on m-TiO_(2)nucleating agent,melamine-formaldehyde resin(MF)shell material,and n-Octadecane core material was prepared.Differential scanning calorimetry(DSC)results demonstrate that the supercooling degree(ΔT)of MPCM(MPCM-02)decreases to 0℃with a tiny level of 0.25 wt%m-TiO_(2),while the MPCM with unmodified TiO_(2)is 6.1℃and the MPCM without nucleating agent is 4.1℃.Besides,the phase change enthalpy(ΔHm)and encapsulation efficiency(E)of MPCM-02 remain at 183.7 J/g and 95.3%,respectively.Finally,phase change composite materials with photothermal conversion capabilities were constructed by MXenes,MPCM,and polyurethane acrylate(PUA).When 1 wt%MXenes and 30 wt%MPCM were incorporated into PUA matrix,the thermal conductivity and surface temperature after 1200s of infrared light irradiation were 48.8%and 8.2℃higher than pure PUA matrix.These results demonstrate the good solar energy storage capabilities of the MPCM,which possesses promising application potential in the field of solar energy thermal management and human thermal regulation.展开更多
In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical propertie...In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and CaCl2.mNH3 + Ti. It reveals that the thermophysical properties in this measurement would be the valuable design factors to develop energy and H2 storage systems utilizing natural resources such as solar energy.展开更多
A possible way to increase thermal conductivity of working fluids, while keeping pressure drop at acceptable levels, is through nanofluids. Nanofluids are nano-sized particles dispersed in conventional working fluids....A possible way to increase thermal conductivity of working fluids, while keeping pressure drop at acceptable levels, is through nanofluids. Nanofluids are nano-sized particles dispersed in conventional working fluids. A great number of materials have potential to be used in nanoparticles production and then in nanofluids;one of them is Multi-Walled Carbon Nano Tubes (MWCNT). They have thermal conductivity around 3000 W/mK while other materials used as nanoparticles like CuO have thermal conductivity of 76.5 W/mK. Due to this fact, MWCNT nanoparticles have potential to be used in nanofluids production, aiming to increase heat transfer rate in energy systems. In this context, the main goal of this paper is to evaluate from the synthesis to the experimental measurement of thermal conductivity of nanofluid samples based on functionalized (-OH) MWCNT nanoparticles. They will be analyzed nanoparticles with different functionalization degrees (4% wt, 6% wt, and 9% wt). In addition, it will be quantified other thermophysical properties (dynamic viscosity, specific heat and specific mass) of the synthetized nanofluids. So, the present work can contribute with experimental data that will help researches in the study and development of MWCNT nanofluids. According to the results, the maximum increment obtained in thermal conductivity was 10.65% in relation to the base fluid (water).展开更多
Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entr...Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entropy of fusion, thermal expansion coefficient and thermal diffusivity are experimentally investigated with differential scanning cMorimetry, dilatometry and laser flash methods. The NiFeCoCrCu HEAs contain a face- centered cubic high-entropy phase plus a minor interdendritic （Cu） phase and display a lower entropy of fasion and the Vickers hardness. The NiFeCoCrAl HEAs consist of two body-centered cubie high-entropy phases with coarse dendritic structures and show higher entropy of fusion and the Vickers hardness. Both the thermal expansion coefficient and the thermal diffusivity of the former Cu-doped alloy are signitieantly larger than those of the latter At-doped M1oy. Although the temperature dependence of thermal diffusivity is similar for both HEAs, it is peculiar that the thermal expansion curve of the NiFeCoCrAl alloy exhibits an inflexion at temperatures of 860-912 K.展开更多
In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values...In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values of normal spectral emissivity of the alloys are in between or higher than those of the pure constituent components. Experiments were conducted on the alloy systems Ni-Ti and Au-Ni. Their emissivity as well as electrical resistivity and enthalpy as a function of temperature is presented.展开更多
The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expans...The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expansion coefficient, specific heat, thermal diffusivity and thermal conductivity were experimentally obtained as a function of temperature. The thermal expansion coefficient was determined at temperatures of 20°C to 1200°C in a dilatometer DIL 402 PC. The specific heat was determined on a differential scanning calorimeter at temperatures between 300°C and 1200°C. The diffusivity and thermal conductivity were determined in the temperature range 100°C to 800°C in a 457 LFA diffusivimeter using laser flash technique. The thermal expansion coefficient remained approximately with constant value of 8.5 × 10-6 K-1 and suffered two falls reaching values -25 × 10-6 K-1 and -50 × 10-6 K-1 in the stages of heating and cooling respectively. It was observed for this material, minimum and maximum values of specific heat equal to 0.571 J/gK and 1.084 J/gK at temperatures of 300°C and 720°C, respectively. The behavior of thermal diffusivity and thermal conductivity in the temperature range 100°C to 800°C tends to decrease with increasing temperature. Based on the measured properties, computational modeling of the temperature field can be numerically obtained with better accuracy.展开更多
By using compression factors of real gas and the Vilia equations and considering the variation of the thermophysical parameters of the mois air with its temperature, this paper develops the calculating equations of th...By using compression factors of real gas and the Vilia equations and considering the variation of the thermophysical parameters of the mois air with its temperature, this paper develops the calculating equations of the thermophysical para leters of the moist air at high temperature ranging from 100℃- 200℃. It is convenient to calculate the thermophysical parameters and the thermophysical processes of the moist air at high temperature.展开更多
In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equat...In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered potential.According to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered system.Using the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free energy.Our results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum ring.We also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the system.Our results are discussed in detail.展开更多
The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element met...The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element method and the finite difference method). By matching the theoretical calculation to an experiment, the nonlinear problem was analyzed and the variable thermophysical parameters concerned was evaluated. The analysis procedure and the evaluation of the parameters were presented in detail. The result of the study showed that by using the method as described in the paper, it was possible to determine the variable (with respect to temperature, moisture content and freezing state) thermophysical parameters which were unknown or difficult to measure as long as the governing equations for a considered process were available. The method can significantly reduces the experiment efforts for determining thermophysical parameters which arc very complicated to measure. The determined variable of the effective heat conductivity of wood particle material was given in the paper. The error of the numerical calculation was also estimated by the comparison with a matched experiment.展开更多
The influence of pressure and temperature on the thermodynamic properties of MgCu intermetallic compound was investigated by quasi-harmonic Debye model approximation.The equation of state(EoS)parameters has performed ...The influence of pressure and temperature on the thermodynamic properties of MgCu intermetallic compound was investigated by quasi-harmonic Debye model approximation.The equation of state(EoS)parameters has performed using plane-wave pseudopotential(PW-PP)approach in the framework of the density functional theory(DFT)and the generalized gradient approximation(GGA)for the exchange-correlation functional.Our results agree well with other data of the literature.The finite temperature thermophysical properties under pressure up to 16 GPa and high temperature up to 800 K,respectively were determined.Our results of the thermophysical properties are also agree very well with other data of the literature,where for example at ambient temperature,the deviation between our obtained value(11.05 Cal mol^(−1)K^(−1))of C V,and the theoretical value(11.21 Cal mol^(−1)K^(−1))reported in the literature is only around 1.44%.The finite temperature thermophysical properties were found varied monotonically with either temperature or pressure.Compared with other materials previously studied,similar behaviors were observed.展开更多
A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductiv...A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductivity and effective absorption coefficient of semitransparent materials.For the direct model,the spherical harmonic method and the finite volume method are used to solve the coupled conduction-radiation heat transfer problem in an absorbing,emitting,and non-scattering 2D axisymmetric gray medium in the background of laser flash method.For the identification part,firstly,the temperature field and the incident radiation field in different positions are chosen as observables.Then,a traditional identification model based on PSO algorithm is established.Finally,multilayer ANNs are built to fit and replace the direct model in the traditional identification model to speed up the identification process.The results show that compared with the traditional identification model,the time cost of the hybrid identification model is reduced by about 1 000 times.Besides,the hybrid identification model remains a high level of accuracy even with measurement errors.展开更多
基金National Key Research and Development Program of China(2022YFB3504402,2023YFB3610101)。
文摘AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.
文摘The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This researchlays the groundwork for our future studies,which will focus on photovoltaic thermal applications.These nanofluidsconsist of water and nanoparticles of alumina(Al_(2)O_(3)),titanium dioxide(TiO_(2)),and copper(Cu),exploringvolumetric concentrations ranging from 0%to 4%for each type of nanoparticle,and up to 10%for total mixtures.The developed model accounts for complex interactions between the nanoparticles and the base fluid,as well assynergistic effects resulting from the coexistence of different nanoparticles.Detailed simulations have shownexceptional agreement with experimental results,reinforcing the credibility of our approach in accurately capturingthe thermophysical behavior of these hybrid nanofluids.Based on these results,our study proposes significantadvancements in the design and optimization of nanofluids for cooling applications in solar panels.These developmentsare crucial for improving the efficiency of solar installations by mitigating overheating effects,providinga solid foundation for practical applications in this rapidly evolving field.
基金This work was financially supported by the Austrian "Forschungsfrderungsgesellschaft mbH", Krntner Strasse 21-23, 1010 Vienna, under contract No. 810999.
文摘Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.
基金The financial supports from the National Natural Science Foundation of China(Grant Nos.51671219 and 51429101)National Key Research and Development Plan(Grant No.2016YFB0701202)are greatly acknowledged.The work of GK was supported by nano-Ginop Project GINOP-2.3.2-15-2016-00027 in the framework of the Szechenyi 2020 program,supported by the European Union.
文摘A program CALTPP(CALculation of ThermoPhysical Properties)is developed in order to provide various thermophysical properties such as diffusion coefficient,interfacial energy,thermal conductivity,viscosity and molar volume mainly as function of temperature and composition.These thermophysical properties are very important inputs for microstructure simulations and mechanical property predictions.The general structure of CALTPP is briefly described,and the CALPHAD-type models for the description of these thermophysical properties are presented.The CALTPP program contains the input module,calculation and/or optimization modules and output module.A few case studies including(a)the calculation of diffusion coefficient and optimization of atomic mobility,(b)the calculation of solid/liquid,coherent solid/solid and liquid/liquid interfacial energies,(c)the calculation of thermal conductivity,(d)the calculation of viscosity,and(e)the establishment of molar volume database in binary and ternary alloys are demonstrated to show the features of CALTPP.It is expected that CALTPP will be an effective contribution in both scientific research and education.
基金supported by Development and Use of Shallow Part Geothermal Energy below the Earth Surface and Research on Geothermal Reinjection Technology, the Basic Research Funding Project (SK201501)
文摘Thermophysical parameters are the main parameters affecting the utilization efficiency of shallow geothermal energy. Based on the research and evaluation data of shallow geothermal energy in capital cities of China, this paper analyzes the differences between two testing methods and finds that data measured in in-situ thermal conductivity test is closer to the actual utilization. This paper analyzes the influencing factors of thermophysical parameters from lithology, density, moisture content and porosity: The thermal conductivity coefficient of bedrock is generally higher than Quaternary system loose bed soil; as for the coefficient of bedrock, dolomite, shale and granite are higher while gabbro, sandstone and mudstone are lower; as for the coefficient of loose bed, pebble and gravel are higher while clay and silt are lower. As the particle size of sand decreases, the thermal conductivity coefficient declines accordingly. The thermal conductivity coefficient increases linearly with growing density and decreases in logarithm with growing moisture content as well as porosity; specific heat capacity decreases in logarithm with growing density, increases in power exponent with growing moisture content and decreases linearly with growing porosity. The thermal conductivity coefficient is high when hydrodynamic condition is good and vice versa. The conclusions of this paper have guiding significance for the research, evaluation and development of shallow geothermal energy in other areas.
文摘In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications. The examined thermophysical properties and structural characterization, including material anisotropy, coupled with the results of previous measurements of the mechanical properties of both Al2O3 reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions. Microscopic examinations (LM, SEM) were carried out to reveal the range of morphological homogeneity of the microstructure, the anisotropy of the filament band distribution, and simultaneously the adhesive behavior of the metal/fbier interface. The 3D morphology of the chosen microstructure components was revealed by computed tomography. The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced, on the one hand, by the geometry of its internal microstructure, i.e. spatial distribution and volume fraction of the Al2O3 reinforcing filaments and, on the other hand, by a very good compatibility obtained between the individual metal prepreg components.
文摘A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on casting solidification temperature field, microstructure and hardness has been investigated. The results show that the solidification rate decreases inversely with the coating thickness when the coating contains silica sol, zircon powder, mullite powder and defoaming agent. In contrast, the solid cooling rate increases as the coating thickness increases. However, the solidification rate and solid cooling rate of the casting produced by the existing IC and the improved IC are very similar when the coating thickness is 5 mm, so the microstructure and hardness of a container corner fitting produced by the improved IC and the existing IC are similar. The linear regression equation for the grain size （d） and cooling rate （v） of the castings is d= -0.41v＋206.1. The linear regression equation for the content of pearlite （w） and solid cooling rate （t） is w=1.79t ＋ 6.71. The new improved IC can greatly simplify the process and decrease the cost of production compared with the existing IC. Contrasting with LI=C, container corner fittings produced by the new improved IC have fewer defects and better properties. It was also found that the desired microstructure and properties can be obtained by changing the thermophysical property and thickness of the coating.
文摘The calculation of thermophysical properties of stainless steel castings and its application to casting simulation is discussed. It is considered that accurate thermophysical properties of the casting alloys are necessary for the valid simulation of the casting processes. Although previous thermophysical calculation software requires a specific knowledge of thermodynamics, the calculation method proposed in the present study does not require any special knowledge of thermodynamics, but only the information of compositions of the alloy. The proposed calculator is based on the CALPHAD approach for modeling of multi-component alloys, especially in stainless steels. The calculator proposed in the present study can calculate thermophysical properties of eight-component systems on an iron base alloy(Fe-C-Si-Cr-Mn-Ni-Cu-Mo), and several Korean standard stainless steel alloys were calculated and discussed. The calculator can evaluate the thermophysical properties of the alloys such as density, heat capacity, enthalpy, latent heat, etc, based on full Gibbs energy for each phase. It is expected the proposed method can help casting experts to devise the casting design and its process easily in the field of not only stainless steels but also other alloy systems such as aluminum, copper, zinc, etc.
基金supported by the National Natural Science Foundation of China(No.U20A20299)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985)the support from the Scientific and Technological Innovation Strategy Program of Guangdong Province:Guangdong-Hong Kong-Macao Technology Cooperation Funding Scheme(No.2022A0505030026).
文摘Microencapsulation of phase change materials(MPCM)is an effective way to achieve solar energy management.However,the crystallization of phase change materials(PCMs)in microcapsules will produce supercooling,which will affect the energy storage efficiency of MPCM.The incorporation of TiO_(2)nanoparticles into MPCM can alleviate supercooling.In this work,octadecyltrimethoxysilane(ODTMS)was used to modify the solid nucleating agent TiO_(2)(m-TiO_(2))to improve its compatibility with n-Octadecane.Then,MPCM based on m-TiO_(2)nucleating agent,melamine-formaldehyde resin(MF)shell material,and n-Octadecane core material was prepared.Differential scanning calorimetry(DSC)results demonstrate that the supercooling degree(ΔT)of MPCM(MPCM-02)decreases to 0℃with a tiny level of 0.25 wt%m-TiO_(2),while the MPCM with unmodified TiO_(2)is 6.1℃and the MPCM without nucleating agent is 4.1℃.Besides,the phase change enthalpy(ΔHm)and encapsulation efficiency(E)of MPCM-02 remain at 183.7 J/g and 95.3%,respectively.Finally,phase change composite materials with photothermal conversion capabilities were constructed by MXenes,MPCM,and polyurethane acrylate(PUA).When 1 wt%MXenes and 30 wt%MPCM were incorporated into PUA matrix,the thermal conductivity and surface temperature after 1200s of infrared light irradiation were 48.8%and 8.2℃higher than pure PUA matrix.These results demonstrate the good solar energy storage capabilities of the MPCM,which possesses promising application potential in the field of solar energy thermal management and human thermal regulation.
文摘In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and CaCl2.mNH3 + Ti. It reveals that the thermophysical properties in this measurement would be the valuable design factors to develop energy and H2 storage systems utilizing natural resources such as solar energy.
文摘A possible way to increase thermal conductivity of working fluids, while keeping pressure drop at acceptable levels, is through nanofluids. Nanofluids are nano-sized particles dispersed in conventional working fluids. A great number of materials have potential to be used in nanoparticles production and then in nanofluids;one of them is Multi-Walled Carbon Nano Tubes (MWCNT). They have thermal conductivity around 3000 W/mK while other materials used as nanoparticles like CuO have thermal conductivity of 76.5 W/mK. Due to this fact, MWCNT nanoparticles have potential to be used in nanofluids production, aiming to increase heat transfer rate in energy systems. In this context, the main goal of this paper is to evaluate from the synthesis to the experimental measurement of thermal conductivity of nanofluid samples based on functionalized (-OH) MWCNT nanoparticles. They will be analyzed nanoparticles with different functionalization degrees (4% wt, 6% wt, and 9% wt). In addition, it will be quantified other thermophysical properties (dynamic viscosity, specific heat and specific mass) of the synthetized nanofluids. So, the present work can contribute with experimental data that will help researches in the study and development of MWCNT nanofluids. According to the results, the maximum increment obtained in thermal conductivity was 10.65% in relation to the base fluid (water).
基金Supported by the National Natural Science Foundation of China under Grant Nos 51571163,51371150,51271150 and 51327901
文摘Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entropy of fusion, thermal expansion coefficient and thermal diffusivity are experimentally investigated with differential scanning cMorimetry, dilatometry and laser flash methods. The NiFeCoCrCu HEAs contain a face- centered cubic high-entropy phase plus a minor interdendritic （Cu） phase and display a lower entropy of fasion and the Vickers hardness. The NiFeCoCrAl HEAs consist of two body-centered cubie high-entropy phases with coarse dendritic structures and show higher entropy of fusion and the Vickers hardness. Both the thermal expansion coefficient and the thermal diffusivity of the former Cu-doped alloy are signitieantly larger than those of the latter At-doped M1oy. Although the temperature dependence of thermal diffusivity is similar for both HEAs, it is peculiar that the thermal expansion curve of the NiFeCoCrAl alloy exhibits an inflexion at temperatures of 860-912 K.
基金This work is financially supported by the "Austrian Science Fund - FWF", Sensengasse 1, 1090 Vienna, under contract No. P15055
文摘In a previous paper it was shown that the normal spectral emissivity at 684.5 nm of a binary alloy can be lower than that of the pure constituent components. For the actual probes it was found that the observed values of normal spectral emissivity of the alloys are in between or higher than those of the pure constituent components. Experiments were conducted on the alloy systems Ni-Ti and Au-Ni. Their emissivity as well as electrical resistivity and enthalpy as a function of temperature is presented.
文摘The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expansion coefficient, specific heat, thermal diffusivity and thermal conductivity were experimentally obtained as a function of temperature. The thermal expansion coefficient was determined at temperatures of 20°C to 1200°C in a dilatometer DIL 402 PC. The specific heat was determined on a differential scanning calorimeter at temperatures between 300°C and 1200°C. The diffusivity and thermal conductivity were determined in the temperature range 100°C to 800°C in a 457 LFA diffusivimeter using laser flash technique. The thermal expansion coefficient remained approximately with constant value of 8.5 × 10-6 K-1 and suffered two falls reaching values -25 × 10-6 K-1 and -50 × 10-6 K-1 in the stages of heating and cooling respectively. It was observed for this material, minimum and maximum values of specific heat equal to 0.571 J/gK and 1.084 J/gK at temperatures of 300°C and 720°C, respectively. The behavior of thermal diffusivity and thermal conductivity in the temperature range 100°C to 800°C tends to decrease with increasing temperature. Based on the measured properties, computational modeling of the temperature field can be numerically obtained with better accuracy.
文摘By using compression factors of real gas and the Vilia equations and considering the variation of the thermophysical parameters of the mois air with its temperature, this paper develops the calculating equations of the thermophysical para leters of the moist air at high temperature ranging from 100℃- 200℃. It is convenient to calculate the thermophysical parameters and the thermophysical processes of the moist air at high temperature.
文摘In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered potential.According to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered system.Using the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free energy.Our results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum ring.We also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the system.Our results are discussed in detail.
文摘The coupled heat and moisture transfer in a freezing process of wood particle material was mathematically modeled in the paper. The models were interactively solved by using the numerical method(the finite element method and the finite difference method). By matching the theoretical calculation to an experiment, the nonlinear problem was analyzed and the variable thermophysical parameters concerned was evaluated. The analysis procedure and the evaluation of the parameters were presented in detail. The result of the study showed that by using the method as described in the paper, it was possible to determine the variable (with respect to temperature, moisture content and freezing state) thermophysical parameters which were unknown or difficult to measure as long as the governing equations for a considered process were available. The method can significantly reduces the experiment efforts for determining thermophysical parameters which arc very complicated to measure. The determined variable of the effective heat conductivity of wood particle material was given in the paper. The error of the numerical calculation was also estimated by the comparison with a matched experiment.
文摘The influence of pressure and temperature on the thermodynamic properties of MgCu intermetallic compound was investigated by quasi-harmonic Debye model approximation.The equation of state(EoS)parameters has performed using plane-wave pseudopotential(PW-PP)approach in the framework of the density functional theory(DFT)and the generalized gradient approximation(GGA)for the exchange-correlation functional.Our results agree well with other data of the literature.The finite temperature thermophysical properties under pressure up to 16 GPa and high temperature up to 800 K,respectively were determined.Our results of the thermophysical properties are also agree very well with other data of the literature,where for example at ambient temperature,the deviation between our obtained value(11.05 Cal mol^(−1)K^(−1))of C V,and the theoretical value(11.21 Cal mol^(−1)K^(−1))reported in the literature is only around 1.44%.The finite temperature thermophysical properties were found varied monotonically with either temperature or pressure.Compared with other materials previously studied,similar behaviors were observed.
基金supported by the Fundamental Research Funds for the Central Universities (No.3122020072)the Multi-investment Project of Tianjin Applied Basic Research(No.23JCQNJC00250)。
文摘A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductivity and effective absorption coefficient of semitransparent materials.For the direct model,the spherical harmonic method and the finite volume method are used to solve the coupled conduction-radiation heat transfer problem in an absorbing,emitting,and non-scattering 2D axisymmetric gray medium in the background of laser flash method.For the identification part,firstly,the temperature field and the incident radiation field in different positions are chosen as observables.Then,a traditional identification model based on PSO algorithm is established.Finally,multilayer ANNs are built to fit and replace the direct model in the traditional identification model to speed up the identification process.The results show that compared with the traditional identification model,the time cost of the hybrid identification model is reduced by about 1 000 times.Besides,the hybrid identification model remains a high level of accuracy even with measurement errors.
