Thermophysical Parameters Research Articles

Study of the Resistance of Lithium-Containing Ceramics to Helium Swelling

The paper presents the results of studies of the resistance of lithium ceramics to helium swelling during its accumulation in the structure of the near-surface layer, and the identification of the three types of lithium ceramics most resistant to radiation degradation: Li4SiO4, Li2TiO3, and Li2ZrO3. The simulation of helium swelling under high-dose irradiation was carried out by irradiation with He2+ ions with fluences of 1 × 1016 ion/cm2–5 × 1017 ion/cm2, which allows for simulating the implanted helium accumulation with a high concentration in the damaged surface layer (about 500 nm thick). The samples were irradiated at a temperature of 1000 K, the choice of which was determined by the possibility of simulating radiation damage as close as possible to real operating conditions. Such accumulation can result in the formation of gas-filled bubbles. Through the application of X-ray phase analysis, indentation testing, and thermophysical parameter assessments, it was ascertained that among the three ceramic types, Li4SiO4 ceramics exhibit the highest resistance to helium-induced swelling. These ceramics experienced less significant alterations in their properties compared to the other two types. An analysis of the correlation between the structural and strength parameters of lithium-containing ceramics revealed that the most significant changes occur when the volumetric swelling of the crystal lattice becomes the dominant factor in structural alterations. This phenomenon is manifested as an accelerated degradation of strength characteristics, exceeding 10%. At the same time, analysis of these alterations in the stability of thermophysical parameters to the accumulation of structural distortions revealed that, regardless of the type of ceramics, the degradation of thermophysical properties is most pronounced under high-dose irradiation (above 1017 ion/cm2).

Assessing r2SCAN meta-GGA functional for structural parameters, cohesive energy, mechanical modulus, and thermophysical properties of 3d, 4d, and 5d transition metals.

The recent development of accurate and efficient semilocal density functionals on the third rung of Jacob's ladder of density functional theory, such as the revised regularized strongly constrained and appropriately normed (r2SCAN) density functional, could enable rapid and highly reliable prediction of the elasticity and temperature dependence of thermophysical parameters of refractory elements and their intermetallic compounds using the quasi-harmonic approximation (QHA). Here, we present a comparative evaluation of equilibrium cell volumes, cohesive energy, mechanical moduli, and thermophysical properties (Debye temperature and thermal expansion coefficient) for 22 transition metals using semilocal density functionals, including the local density approximation (LDA), Perdew-Burke-Ernzerhof (PBE) and PBEsol generalized gradient approximations (GGAs), and the r2SCAN meta-GGA. PBEsol and r2SCAN deliver the same level of accuracies for structural, mechanical, and thermophysical properties. PBE and r2SCAN perform better than LDA and PBEsol for calculating cohesive energies of transition metals. Among the tested density functionals, r2SCAN provides an overall well-balanced performance for reliably computing cell volumes, cohesive energies, mechanical properties, and thermophysical properties of various 3d, 4d, and 5d transition metals using QHA. Therefore, we recommend that r2SCAN could be employed as a workhorse method to evaluate thermophysical properties of transition metal compounds and alloys in high throughput workflows.

Thermal Storage Performance of a Shell and Tube Phase Change Heat Storage Unit with Different Thermophysical Parameters of the Phase Change Material

The thermal storage performance of shell and tube phase change heat storage units is greatly influenced by the thermophysical parameters of the phase change material (PCM). Therefore, we use numerical simulations to examine how the thermal storage capability of shell and tube phase change heat storage units is affected by thermophysical parameters such as specific heat capacity, thermal conductivity, and latent heat of phase change. The findings indicate that while the rate of temperature increase and the rate of the PCM melting both slow down as specific heat capacity increases, the overall heat storage increases. Within the specified range of parameters, the average rate of heat storage increases by approximately 4% for every 50% increase in specific heat capacity. The PCM’s rate of temperature rise slows down and its overall heat storage capacity rises throughout the middle stage of the phase change heat storage process as the latent heat of phase change grows. The average heat storage rate increases by approximately 6% and 22% for every 50% increase in latent heat and thermal conductivity, respectively. Notably, when the thermal conductivity is enhanced by a factor of 1.5, the average heat storage rate experiences an almost 50% increase. The thermal conductivity of the PCM has a negligible impact on total heat storage. The choice and use of the PCM in shell and tube phase change heat storage heat exchangers has a theoretical and empirical foundation thanks to this work.

EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND THERMAL PERFORMANCE OF PARABOLIC TYPE SOLAR COLLECTOR WITH RIBBED SURFACE TEXTURE FOR CLEAN ENERGY EXTRACTION

This paper examines the performance of a parabolic type solar collector (PTSC) that uses both plain tube and ribbed surface textured tube channels for elevating the water temperature used for various applications. The performance of a solar water heater is evaluated experimentally. During the experiment, the solar radiation intensity and the feed water flow rate of 1.0 kg/min to 5.0 kg/min in steps of 1 kg/min are taken into consideration for analyzing the effect of ribbed textured tubes on the thermal effectiveness, frictional factor, convective transfer of heat, Reynolds number, and the Nusselt number of the PTSC. Furthermore, the overall performance of the PTSC is analyzed considering the above thermo-physical parameters. Based on the result of this study, at a flow rate of 3.0 kg/min, the thermal efficiency is found to be enhanced by about 28.25%, the friction factor is augmented by about 0.23%, the convective heat transfer coefficient is improved by 24.22%, and the Nusselt number is increased by about 26.32%. On average, an overall improvement in the performance of 8.25% is observed for the ribbed textured tube than that of the plain tube. The experimental error analysis shows that the standard deviation for both plain and ribbed textured tubes is in the range of 3.2, which is in the acceptable limit.

Thermomechanical modeling of the shearing process during fine blanking of quenched and tempered steel

In order to develop an alloy design for fine blanking of deformation mechanism-based sheet metal materials such as high manganese steel, knowledge of the temperature during the shearing process is required. Thermomechanical modeling of shear zone temperature requires consideration of contact heat transfer, which depends on stress state as well as temperature. This paper deals with a methodology for calibrating the contact heat transfer coefficient during fine blanking using indirect temperature measurements. For this purpose, a thermomechanically coupled finite element (FE) model was designed considering thermoviscoplasticity, temperature-dependent physical and thermophysical parameters as well as a steady-state calibrated contact heat transfer coefficient. Experimental fine blanking tests were carried out to validate the model using force, die roll and thermography measurements based on varied blanking velocities. The thermomechanically coupled FE modeling showed a sufficiently accurate correspondence regarding the experimentally determined blanking force, die roll as well as sheared surface temperature. Thermographically determined sheared surface temperatures allowed calibration of locally different contact heat transfer coefficients as a simplified approach under steady-state conditions.

FEM model optimization study of mechanical properties and material selection in stamping process

Abstract This paper establishes a finite element model of stamping and forming and proposes solution algorithms for static and dynamic forces. The finite element simulation of the hot stamping process is carried out to analyze the thermophysical parameters of BR1500HS ultra-high-strength steel sheet material and H13 steel mold material. Set the temperatures of austenitic material in the transfer process and molding process, obtain the rheological stress data of BR1500HS ultra-high-strength steel plate during plastic deformation at high temperature, and determine the basic mechanical properties of the material at high temperature. A geometric finite element model of thermal-force-phase coupling of the hot stamping and forming process is established to simulate the temperature field change of the steel plate during the hot stamping and forming process by combining the process conditions and process parameters. At the same time, the ultra-high-strength boron steel 22MnB5 is selected to simulate the hot forming and tempering process of U-shaped parts made of high-strength steel sheet material, and the feasibility of the finite element model is verified. Different hot stamping process parameters are set to analyze the forming quality of both BR1500HS ultra-high strength steel and ultra-high-strength boron steel 22MnB5. When the stamping speed is increased from 50mm/s to 100mm/s, the maximum equivalent force of BR1500HS ultra-high strength steel decreases, and thus, when the stamping speed is 100mm/s and the holding time is 5s, the part forming performance is better, which meets the requirements of the gradient performance hot stamping process.

Adaptability Study on the Equations of State for Calculating the Thermophysical Parameters of Hydrogen-Enriched Natural Gas

Adaptability Study on the Equations of State for Calculating the Thermophysical Parameters of Hydrogen-Enriched Natural Gas

Analysis of thermal properties of main sedimentary rocks in the Beijing area

The Beijing area is abundant in geothermal resources, yet there has been limited research on the thermal properties of rocks and their influencing factors. This paper focuses on the thermal properties of sedimentary rocks in the region, conducting experimental analysis to investigate these properties and their influencing factors. The experiment involved collecting primary sedimentary rock outcrop samples from around Beijing, testing the thermophysical parameters of 48 samples using a Hot Disk thermal constant analyzer. By combining this data with the standard stratum profile and historical information about Beijing, the thermal conductivity of the formation was calculated using the harmonic mean method, allowing for an analysis of the thermal properties of primary sedimentary rocks in the study area. The results indicate that overall distribution of thermal conductivity for sedimentary rocks in the Beijing area ranges from 1.48 to 6.55 W/(m·K), while thermal diffusivity ranges from 0.76 × 10−6 to 4.04 × 10−6 m2/s, and specific heat distribution ranges from 0.57 to 2.52MJ/(m3·K). Furthermore, according to harmonic mean calculations, it was found that Jixian formation exhibits the highest thermal conductivity value, whereas Triassic formation displays the lowest. This study on the thermal properties of sedimentary rocks provides valuable insights for the geothermal field research in the Beijing area.

Methodological approach to determining the area of air recycling on metro lines with double track tunnels

The article discusses the issues of operating existing metro lines with double-track tunnels. Significant differences between average annual, average monthly and extreme values of outdoor air temperature affecting the thermodynamic and thermophysical parameters of the mine atmosphere of subway tunnels, both in Russia and abroad, are analyzed. The results of a comprehensive analysis of the conditions that determine the temperature regime of the lines of double-track tunnels are presented. Air recirculation in the tunnels has been determined considering climatic conditions. Engineering and technical calculations have been carried out in metro tunnels when the seasonal periods of their operation change. Each of these periods is characterized by its own temperature, for example, for the winter period these are: average winter temperatures, temperatures of the coldest month, the coldest five-day period. The obtained results of the research work will make it possible to select the amount of air for each specific variant of the year, which will ensure, during the operation of this kind of metro lines, the standard thermodynamic parameters of the air environment, both in underground stations and in metro tunnels, and possibly lead to a positive economic effect.

Analysis of thermophysical parameters of solar water desalination plant with an external camera

In this work, an analysis of the thermophysical processes taking place inside a specially designed chamber with a geometry different from other works was carried out. This process is designed in COMSOL Multiphysics software. Boundary conditions were investigated for ambient temperature of 293.15 K and solar radiation of 1000 W/m2. The process was taken as natural convection. In this case, the flow of air with high humidity inside the solar water heater was analyzed. It can be seen that the air temperature rises to 450 K. At the same time, the speed of moist air inside the chamber, heat flow and other thermophysical quantities were determined and analyzed.

A numerical and statistical study to determine the effect of thermophysical properties of phase change material for lithium-ion battery thermal management

Lithium-ion batteries’ performance is quite sensitive to temperature, leading to capacity fade, acceleration of aging effect, and possible thermal runaway. The temperature of lithium-ion batteries increases under operating conditions of high discharge rates. The heat released by the battery can be effectively removed using phase change material (PCM). The thermophysical properties of the PCM affect the heat removal performance of the PCM. In this study, the effect of thermophysical parameters such as thermal conductivity, latent heat, specific heat, and density on maximum battery temperature and battery temperature uniformity was numerically investigated. The dominant factors for PCM to prevent temperature increase in a prismatic LiMn2O4 lithium-ion battery were identified by orthogonal design to improve the thermophysical properties of PCM. The thermophysical properties of PCM were changed by incorporating the expanded graphite. Based on what was observed in the current study, the influence of the thermal conductivity of PCM was higher than other thermophysical properties, while the influence of the latent heat on both maximum battery temperature and temperature uniformity was negligible. Density was the second crucial factor that could help reduce the maximum battery temperature and keep the temperature distribution uniform. The results obtained from this study can allow the design of effective battery thermal management systems by improving the thermophysical properties of the PCM.

Nanoparticle Shape Effects of Aligned Magnetohydrodynamics Mixed Convection Flow of Jeffrey Hybrid Nanofluid over a Stretching Vertical Plate

This study investigates the nanoparticle shape effects of aligned magnetohydrodynamics (MHD) mixed convection flow of Cu-Al2O3/water-EG Jeffrey hybrid nanofluid over a stretching vertical plate. Five different shapes of nanoparticles which are spherical, cylindrical, blades, bricks, and platelets are considered in this study. The governing equations in the form of Partial Differential Equations (PDEs) had been reduced to nonlinear Ordinary Differential Equations (ODEs) by using similarity transformation. The solver bvp4c in MATLAB software was applied to numerically solve the dimensionless governing equations towards the physical parameters which are aligned angle of magnetic field, interaction of magnetic field, mixed convection, Deborah number, volume fraction of nanoparticles, and nanoparticle shape factor. The effects of nanoparticle shapes and other relevant thermophysical parameters on fluid velocity, temperature, skin friction coefficient and Nusselt number are discussed in tables and figures. In comparison of all shapes, this study found that blade shaped nanoparticles have the highest values of skin friction coefficient and Nusselt number. The parameters blobid0.pngblobid1.pngblobid2.png and blobid3.png decrease the velocity profiles but increase the temperature profiles.

Atomistic-Continuum Study of an Ultrafast Melting Process Controlled by a Femtosecond Laser-Pulse Train.

In femtosecond laser fabrication, the laser-pulse train shows great promise in improving processing efficiency, quality, and precision. This research investigates the influence of pulse number, pulse interval, and pulse energy ratio on the lateral and longitudinal ultrafast melting process using an experiment and the molecular dynamics coupling two-temperature model (MD-TTM model), which incorporates temperature-dependent thermophysical parameters. The comparison of experimental and simulation results under single and double pulses proves the reliability of the MD-TTM model and indicates that as the pulse number increases, the melting threshold at the edge region of the laser spot decreases, resulting in a larger diameter of the melting region in the 2D lateral melting results. Using the same model, the lateral melting results of five pulses are simulated. Moreover, the longitudinal melting results are also predicted, and an increasing pulse number leads to a greater early-stage melting depth in the melting process. In the case of double femtosecond laser pulses, the pulse interval and pulse energy ratio also affect the early-stage melting depth, with the best enhancement observed with a 2 ps interval and a 3:7 energy ratio. However, pulse number, pulse energy ratio, and pulse interval do not affect the final melting depth with the same total energies. The findings mean that the phenomena of melting region can be flexibly manipulated through the laser-pulse train, which is expected to be applied to improve the structural precision and boundary quality.

РАСЧЕТ ЭЛЕМЕНТОВ ЖЕЛЕЗОБЕТОННЫХ КОНСТРУКЦИЙ НА ОГНЕСТОЙКОСТЬ И ОГНЕСОХРАННОСТЬ В ПРОГРАММНОМ КОМПЛЕКСЕ СТАРКОН.

RCDiagra software as a part of the domestic STARKON software is presented. The software is designed to perform fire resistance and fire safety analysis of reinforced concrete beams and columns. The strength analysis is based on the nonlinear deformation theory and enables to take into account non-stationary thermal effects changing the concrete and reinforcement properties. To determine the ultimate strength, elastic modulus for concrete and reinforcement, ultimate relative deformations, a thermal analysis is performed in accordance with SP 468.1325800.2019 and MDS 21-2.2000. The thermal engineering analysis solve the problem of determining the temperature field in the beam cross-section under non-stationary thermal action, depending on the boundary conditions and thermophysical parameters of the material. It is assumed that the coefficients of thermal conductivity and specific heat capacity of concrete depend on the current temperature at the crosssection points.

Determining the dynamic characteristics of a class B fire in the case of extinguishing by water spray

The object of this study is a class B fire, which is extinguished with sprayed water. The subject of the study is the characteristics of class B fires when they are extinguished with sprayed water. Diffusion burning of a flammable liquid is considered as such a fire, and its extinguishing is carried out by cooling the flame. Heat and oxygen balance equations are used to build a mathematical model describing the fire extinguishing process. The components of the heat balance equation are the power of heat during heat release due to the chemical reaction of liquid combustion and the power of heat dissipated to the environment. The second component takes into account heat removal due to radiation, convection, and evaporation. The component of removed heat due to evaporation takes into account the Sreznevsky constant. The mathematical model that describes the process of extinguishing a class B fire is built in the class of models belonging to differential equations with constant coefficients. Analytical expressions were obtained for these static and dynamic coefficients, which include thermophysical, kinematic, and geometric parameters of the flame and fire extinguishing agent. To determine these characteristics, the constructed mathematical fire model was transformed using the integral Laplace transform. The dynamic characteristics of the fire were obtained in the time domain – the transient function of the fire, and in the frequency domain – the amplitude-frequency and phase-frequency characteristics of the fire. It is shown that the parameters of these dynamic characteristics should be determined experimentally. Experimental methods for determining parameters of dynamic fire characteristics have been devised. The presence of dynamic characteristics of class B fire makes it possible to spread the proven methods of the theory of control systems to design effective fire extinguishing systems

Sensitivity analysis for MHD bionanofluid slip flow model in fluid-permeable plate

Diagnostic and therapeutic purpose on human healthcare is moving to a trend of combined engineering principles and design concepts. It is therefore beneficial to refine the study on thermodynamic properties of bionanofluid towards a better state of diagnoses and treatments. This paper aims to determine the characteristics of a magnetohydrodynamics (MHD) bionanofluid slip flow model in a fluid-permeable plate. A Buongiorno mathematical model describing steady two-dimensional MHD bionanofluid slip flow across a permeable plate is constructed. Numerical analysis by shooting technique and sensitivity analysis under the principle of RSM is configured to determine the correlation between input parameters and output responses. The relationship between the four parameters of interest namely skin friction coefficient, local Nusselt number, local Sherwood number and local density of motile microorganism with respective velocity, temperature, nanoparticle concentration and microorganism density distributions to the selected input parameters are investigated. Skin friction coefficient and local density of motile microorganism increase with suction and Schmidt number respectively, signifying positive sensitivity. Local Sherwood number is conditionally more sensitive to Brownian motion parameter or else Lewis number. While, local Nusselt number is always gaining negative sensitivity from Lewis number, thermophoresis and Brownian motion parameters. Extensive numerical studies on boundary layer problem have been done; yet this is the first study invoking sensitivity analysis to discuss the sensitivity of parameters of interest to the input thermophysical parameters.

Effects of CO2 variable thermophysical properties and phase behavior on CO2 geological storage: A numerical case study

CO2 injection into the reservoir can effectively reduce greenhouse gas emissions. The thermophysical parameters and phase behavior of CO2 are highly sensitive to pressure and temperature, resulting in drastic change in wellbore and reservoir, and thus affecting the CO2 storage effect. To study the impact of CO2 thermophysical properties and phase behavior on CO2 geological storage, we established a fully coupled 1D+3D wellbore coupled 3D reservoir model. Based on the analysis of non–isothermal flow characteristics, CO2 thermophysical properties and phase behavior, the influence of engineering parameters on the key factors of CO2 geological storage is discussed. The findings indicate that the density and thermal capacity of CO2 are the most important thermophysical parameters that affect wellhead pressure and bottomhole temperature respectively. The efficiency of CO2 storage is greatly influenced by the density and viscosity of CO2, more so than any other thermophysical parameters. CO2 phase behavior and permeability change increase CO2 seepage capacity by 3.50 % and 8.79 % respectively. Engineering parameters will affect the thermophysical properties and permeability of bottom–hole CO2, thereby affecting the injectability and storage efficiency of CO2. This research can offer suggestions and theoretical groundwork for the improved design of CO2 geological storage.

Cooling efficiency of thermochromic asphalt pavement material and its contribution to field performance enhancement of asphalt mixture

The thermochromic asphalt pavement material (TAPM) has the potential to bilaterally regulate the pavement temperature according to seasonal environment, which is beneficial to heat island effect mitigation and pavement performance enhancement. However, studies on quantifying the cooling efficiency and verifying the field performance of TAPM are still limited. This study aims to more extensively verify the cooling efficiency of TAPM in different climatic regions and to reveal its cooling mechanism in the field. The key thermophysical parameter, solar albedo, of TAPM was back-calculated using an interpolation methodology to match the numerical simulation results with the specimen temperature data monitored experimentally. The cooling efficiency of TAPM in broader climatic regions was demonstrated through the numerical simulation combined with real meteorological conditions. In view of the cooling characteristics of TAPM as well as the temperature dependency attribute of asphalt mixture, various field performance properties of TAPM were characterized. It was found that at a temperature larger than 31 ℃, the solar albedo of TAPM is 0.30, which is six times larger than that of the conventional asphalt pavement material, indicating a strong reflection ability to solar radiation. The average temperature reduction of TAPM compared with the conventional asphalt pavement material in different regions is 6.26 ℃ with a standard deviation of 0.79 ℃, demonstrating the effective, universal and stable cooling effect of TAPM in summer across China. The cooling function of TAPM contributes to the improvement of high-temperature stability, aging resistance and low-temperature cracking performance of asphalt mixture. Therefore, it is necessary to consider the unique cooling function of TAPM for a more objective evaluation of its field performance.

Heat treatment of ground surface using an electric arc plasma generator

The article presents a generalization of the results of experimental and theoretical studies on the intensive thermal effect on the surface of foundations from cohesive soils (as opposed to deep heat treatment) using an electric arc generator of low-temperature plasma (plasmatron). A plasmatron with massive consumable electrodes made of borosilicated graphite and a wide "blurred" plasma torch was used for heat treatment. Physical and mathematical modeling of the thermal effect on the surface of clay soil by a moving high-temperature source has been performed. For the first time, a special installation was manufactured and experimental studies were carried out on the heat treatment of ground surfaces on the site with an electric arc plasma torch. It is established that the effective heat flux density reaches 2.5-.3.5 kW/cm2. The main part of the thermal energy for the used plasmatron enters the material due to radiant heat transfer. An analytical mathematical model of the temperature field of a three-dimensional semi-bounded body in the technological process under consideration is given by an essentially nonlinear boundary value problem for a nonlinear heat equation with nonlinear boundary conditions of the second kind. When solving thermophysical problems, the ground semi-bounded space was considered as a quasi-homogeneous medium having a constant initial temperature and initial thermophysical parameters that change in the process of temperature increase. The effective values of the thermophysical characteristics were determined on the basis of experimental data. Calculations and experiments have shown that the temperature boundary leading to significant changes in the structural properties of soils drops to a depth of 4-6 cm from the surface, despite the boiling of the ground melt with a temperature of 2500 ...2800 K on the ground surface. Therefore, a new technological principle of heat treatment is proposed, which consists in building up the ground melt in layers of 4-5 cm up from the initial surface. The impossibility of obtaining a positive effect even with the use of a powerful high-temperature source of exposure in the case of traditional surface heat treatment technology has been confirmed. The new plasma technology of surface heat treatment of ground surfaces to the stage of silicate melt allows to obtain a common layer of the required thickness. At the same time, the efficiency of surface heat treatment is significantly increased. The new technology of layer-by-layer surface deposition reduces cracking in the layer when the melt cools, but does not eliminate this negative process.

Effects of Composition Variations on Mechanochemically Synthesized Lithium Metazirconate-Based Ceramics and Their Resistance to External Influences

The study examines the influence of variations in the compositions of components for the production of lithium-containing ceramics based on lithium metazirconate obtained by the method of mechanochemical grinding and subsequent thermal sintering. For component variation, two compositions were used, consisting of zirconium dioxide (ZrO2) and two distinct types of lithium-containing materials: lithium perchlorate (LiClO4·3H2O) and lithium carbonate (Li2CO3). Adjusting the concentration of these components allowed for the production of two-phase ceramics with varying levels of impurity phases. Using X-ray phase analysis methods, it was determined that the use of LiClO4·3H2O results in the formation of a monoclinic phase, Li2ZrO3, with impurity inclusions in the orthorhombic phase, LiO2. On the other hand, when Li2CO3 is used, the resulting ceramics comprise a mixture of two phases, Li2ZrO3 and Li6Zr2O7. During the studies, it was established that the formation of impurity inclusions in the composition of ceramics leads to an increase in the stability of strength properties with varying mechanical test conditions, as well as stabilization of thermophysical parameters and a decrease in thermal expansion during long-term high-temperature tests. It has been established that in the case of two-phase ceramics Li2ZrO3/Li6Zr2O7 in which the dominance of the Li6Zr2O7 phase is observed during high-temperature mechanical tests, a more pronounced decrease in resistance to cracking is observed, due to thermal expansion of the crystal lattice.