Specific Heat Capacity of A2FeCoO6-δ (A = Ca or Sr)

A2FeCoO6-δ (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr2FeCoO6-δ is found to be the highest, and that of Ca2FeCoO6-δ is the lowest while CaSrFeCoO6-δ shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca2FeCoO6-δ to CaSrFeCoO6-δ to Sr2FeCoO6-δ.

Effects of crystallization on low-temperature specific heat capacity of Cu_(60)Zr_(20)Hf_(10)Ti_(10) bulk metallic glass

The specific heat capacities of Cu60Zr20Hfl0Til0 bulk metallic glass （BMG） and crystallized alloys were measured from 2 to 101 K. The effect of crystallization on the specific heat capacity of the BMG was studied. The effects of crystallization and the relationship between local modes and boson peak in the BMG were discussed. The specific heat capacity deviates from the simple Debye behaviors, showing the presence of local harmonic modes （Einstein oscillator） in the BMG and the crystallized alloy. Model calculation includes the contribution of one Debye mode and two Einstein modes for the BMG, one Debye mode and one Einstein mode for the crystallized alloy, showing an adequate description of the experimental data.

Investigation on specific heat capacity and thermal behavior of sodium hydroxyethyl sulfonate

The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.

Utilization of Machine Learning Methods in Modeling Specific Heat Capacity of Nanofluids

Nanofluids are extensively applied in various heat transfer mediums for improving their heat transfer characteristics and hence their performance.Specific heat capacity of nanofluids,as one of the thermophysical properties,performs principal role in heat transfer of thermal mediums utilizing nanofluids.In this regard,different studies have been carried out to investigate the influential factors on nanofluids specific heat.Moreover,several regression models based on correlations or artificial intelligence have been developed for forecasting this property of nanofluids.In the current review paper,influential parameters on the specific heat capacity of nanofluids are introduced.Afterwards,the proposed models for their forecasting and modeling are proposed.According to the reviewed works,concentration and properties of solid structures in addition to temperature affect specific heat capacity to large extent and must be considered as inputs for the models.Moreover,by using other effective factors,the accuracy and comprehensive of the models can be modified.Finally,some suggestions are offered for the upcoming works in the relevant topics.

Thermal Behavior, Specific Heat Capacity and Adiabatic Time-to-explosion of GDN

A new compound, [（NH2）2C=NH2]＋N（NO2）2-（GDN）, was prepared by mixing ammonium dinitramide （ADN） and guanidine hydrochloride in water. The thermal behavior of GDN was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy（E） and pre-exponential constant（A） of the exothermic decomposition stage of GDN were 118.75 kJ/mol and 10^10.86 s^-1, respectively. The critical temperature of the thermal explosion（Tb） of GDN was 164.09 ℃. The specific heat capacity of GDN was determined with the Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity was 234.76 J·mol^-1·K^-1 at 298.15 K. The adiabatic time-to-explosion of GDN was also calculated to be a certain value between 404.80 and 454.95 s.

Characteristic of specific heat capacity of NiTi alloy phases

The specific heat capacity of NiTi alloy at constant pressure using MDSC (Modulated differential scanning calorimeter) was determined. It was found that the variation tendencies of the specific heat capacity for different phases are different. The fitting equations of the specific heat capacity for martensite and austenite phases were presented. Then, a reason, based on thermodynamic point of view, was proposed to explain the difference of the specific heat capacity between martensitic and austenitic phases. Finally, compared with the specific heat capacity of pure Ni and Ti, it was found that the specific heat capacity of NiTi alloy is inherent to that of pure Ti. When the specific heat capacity of NiTi alloy is calculated by Neuman Kopp, in the temperature region of phase transformation and the temperature higher than 400 K, the results are not desirable.[

Effects of Diesel Concentration on the Thermal Conductivity,Specific Heat Capacity and Thermal Diffusivity of Diesel-Contaminated Soil

High energy consumption is a serious issue associated with in situ thermal desorption(TD)remediation of sites contaminated by petroleum hydrocarbons(PHs).The knowledge on the thermophysical properties of contaminated soil can help predict accurately the transient temperature distribution in a remediation site,for the purpose of energy conservation.However,such data are rarely reported for PH-contaminated soil.In this study,by taking diesel as a representative example for PHs,soil samples with constant dry bulk density but different diesel mass concentrations ranging from 0% to 20% were prepared,and the variations of their thermal conductivity,specific heat capacity and thermal diffusivity were measured and analyzed over a wide temperature range between 0℃ and 120℃.It was found that the effect of diesel concentration on the thermal conductivity of soil is negligible when it is below 1%.When diesel concentration is below 10%,the thermal conductivity of soil increases with raising the temperature.However,when diesel concentration becomes above 10%,the change of the thermal conductivity of soil with temperature exhibits the opposite trend.This is mainly due to the competition between soil minerals and diesel,because the thermal conductivity of minerals increases with temperature,whereas the thermal conductivity of diesel decreases with temperature.The analysis results showed that,compared with temperature,the diesel concentration has more significant effects on soil thermal conductivity.Regardless of the diesel concentration,with the increase of temperature,the specific heat capacity of soil increases,while the thermal diffusivity of soil decreases.In addition,the results of a control experiment exhibited that the relative differences of the thermal conductivity of the soil samples containing the same concentration of both diesel and a pure alkane are all below 10%,indicating that the results obtained with diesel in this study can be extended to the family of PHs.A theoretical prediction model was proposed based on cubic fractal and thermal resistance analysis,which confirmed that diesel concentration does have a significant effect on soil thermal conductivity.For the sake of practical applications,a regression model with the diesel concentration as a primary parameter was also proposed.

Effect of temperature-dependent rock thermal conductivity and specific heat capacity on heat recovery in an enhanced geothermal system

The modeling of heat recovery from an enhanced geothermal system(EGS)requires rock thermal parameters as inputs such as thermal conductivity and specific heat capacity.These parameters may encounter significant variations due to the reduction of rock temperature during heat recovery.In the present study,we investigate the effect of temperature-dependent thermal conductivity and specific heat capacity on the thermal performance of EGS reservoirs.Equations describing the relationships between thermal conductivity/specific heat capacity and temperature from previous experimental studies were incorporated in a field-scale single-fracture EGS model.The modeling results indicate that the increase of thermal conductivity caused by temperature reduction accelerates thermal conduction from rock formations to fracture fluid,and thus improves thermal performance.The decrease of specific heat capacity due to temperature reduction,on the contrary,impairs the thermal performance but the impact is smaller than that of the increase of thermal conductivity.Due to the opposite effects of thermal conductivity increase and specific heat capacity decrease,the overall effect of temperature-dependent thermal parameters is relatively small.Assuming constant thermal parameters measured at room temperature appears to be able to provide acceptable predictions of EGS thermal performance.

Determination of the Specific Heat Capacity of RE（Et2dtc）3（phen） by Microcalorimetry

A calculation formula for determining the specific heat capacity of solid compound with an improved RD496-Ⅲ microcalorimeter was derived. The calorimetric constant and precision determined by the Joule effect were （63.901±0.030）μV/mW and 0.3% at 298.15 K, respectively, and the total disequilibrium heat has been measured by the Peltier effect. The specific heat capacities of two standard substances （benchmark benzoic acid and α-Al2O3） were obtained with this microcalorimeter, and the differences between their calculated values and literature values were less than 0.4%. Similarly, the specific heat capacities of thirteen solid complexes, RE（Et2dtc）3（phen） （RE=La, Pr, Nd, Sm-Lu, Et2dtc： diethyldithiocarbamate ion, phen： 1,10-phenanthroline） were gained, and their total deviations were within 1.0%. These values were plotted against the atomic numbers of rare-earth, which presents tripartite effect, suggesting a certain amount of covalent character in the bond of RE^3＋and ligands, according to Nephelauxetic effect of 4f electrons of rare earth ions.

Characterization of rock thermophysical properties and factors affecting thermal conductivity−A case study of Datong Basin,China

Rock thermal physical properties play a crucial role in understanding deep thermal conditions,modeling the thermal structure of the lithosphere,and discovering the evolutionary history of sedimentary basins.Recent advancements in geothermal exploration,particularly the identification of high-temperature geothermal resources in Datong Basin,Shanxi,China,have opened new possibilities.This study aims to characterize the thermal properties of rocks and explore factors influencing thermal conductivity in basins hosting high-temperature geothermal resources.A total of 70 groups of rock samples were collected from outcrops in and around Datong Basin,Shanxi Province.Thermal property tests were carried out to analyze the rock properties,and the influencing factors of thermal conductivity were studied through experiments at different temperature and water-filled states.The results indicate that the thermal conductivity of rocks in Datong,Shanxi Province,typically ranges from 0.690 W/(m·K)to 6.460 W/(m·K),the thermal diffusion coefficient ranges from 0.441 mm^(2)/s to 2.023 mm^(2)/s,and the specific heat capacity of the rocks ranges from 0.569 KJ/(kg·℃)to 1.117 KJ/(kg·°C).Experimental results reveal the impact of temperature and water saturation on the thermal conductivity of the rock.The thermal conductivity decreases with increasing temperature and rises with high water saturation.A temperature correction formula for the thermal conductivity of different lithologies in the area is proposed through linear fitting.The findings from this study provide essential parameters for the assessment and prediction,development,and utilization of geothermal resources in the region and other basins with typical high-temperature geothermal resource.

Calculation of the Heat Energy Needed for Melting of the Ice Formed from Bounded Water in the Wood

An engineering approach for the calculation of the specific heat energy needed for melting of the ice, which is created from the freezing of hygroscopically bounded water in the wood, qbw, has been suggested. The approach, together with the equation that presents it, includes mathematical descriptions of the density of frozen wood in the hygroscopic diapason, Pw, and of the specific heat capacity of the ice formed from the bounded water in the wood, cbw for the calculation of Pw, cbw and qbw according to the suggested approach a software program has been prepared in the calculation environment of Visual Fortran. Using the program computations have been carried out for the determination ofpw, cbw and qbw, of oak, pine, beech and poplar frozen wood with initial temperature in the range from -20℃ to -2℃, at which the thawing of the ice from the bounded water is completed, and with moisture content in the hygroscopic range during wood defrosting. Based on the obtained results, a very simple and easy for use equation for the calculation of qbw depending only on the wood moisture content and on the content of non-frozen water in the wood at given initial wood temperature has been suggested.

Synthesis,Crystal Structure and Thermal Analysis of N-(2,3-Dimethyl-phenyl)-N'-(methoxyl formyl)thiourea

N-（2,3-Dimethyl-phenyl）-N＇-（methoxyl formyl）thiourea was synthesized by the reacting of 2,3-dimethylaniline,potassium thiocyanate（KSCN） and methyl chloroformate（ClCOOCH 3）.Single crystal was obtained by slowly evaporation solvent at room temperature.The structure was characterized by elemental analysis,IR and X-ray crystalography.The compound crystallized：a triclinic system with space group Pī,a=0.83440（12） nm,b=0.89113（13） nm,c=0.93015（13） nm,α=76.548（2） o,β=63.906（2） o,γ=82.538（2） o,V=0.60379（15） nm 3,Z=2,D c =1.311 mg/m 3,F（000）=252,μ=0.256 mm-1,R 1 =0.0379,wR 2 =0.0919.The specific heat capacity of the title compound was determined by a Micro-DSC method,and the specific heat capacity was 1.25 J·g-1 ·K-1 at 298.15 K.Thermodynamic functions,relative to those at the standard temperature of 298.15 K,were calculated via thermodynamic relationship.The thermal behavior of the title compound under a non-isothermal condition was studied by differential scanning calorimetry/thermogravimetric（DSC/TG） method.There was an obvious endothermic peak in the DSC curve,the peak temperature was 479.43 K.The compound mass loss was 89.94% observed from the TG curve.

Thermal conductivity of Al-Gd-TM glass-forming alloys

Thermal diffusivity, specific heat capacity and thermal conductivity of AI86Gd6TM8 （TM = Cu, Ni, Co, Fe, Mn, Cr, Ti, Zr, Mo, Ta） glass-forming alloys in the temperature range of 300-880 K were determined by laser flash method. The temperatures of endothermic and exothermic reactions of the alloys were determined by differential scanning calorimetry method. The alloys were prepared by conventional arc-melting technique under helium atmosphere. All the alloys studied exhibit strong supercooling of the liquidus temperatures up to 80 K, which indicates their good glass-forming ability. The specific heat capacity of the alloys achieves the Dulong-Petit＇s value in the temperature range of 350-550 K except Als6CrsGd6 and Als6ZrsGd6 compositions. The values of both thermal diffusivity and thermal conductivity of the alloy studied are significantly lower than those for pure aluminum. It is found that embedding 14% （mole fraction） of transition elements （Gd＋TM） in the aluminum matrix leads to significant decrease in the absolute magnitudes of both thermal diffusivity and thermal conductivity in crystalline state. The thermal conductivity of glass-forming Als6Gd6TMs alloys is strongly affected by directed chemical bonding between alloy components.

Research of Mechanical and Thermal Properties of Composite Material Based on Gypsum and Straw

This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum and reinforcing natural fibers.The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum.From this composite material,high-strength plasterboards could then be produced,which meet the higher demands of users than conventional gypsum plasterboards.For their production,natural waste materials would be used efficiently.As part of the development of new building materials,it is necessary to specify essential characteristics for their later use in civil engineering.Crushed wheat straw and three gypsum classes with strengths G2(2 MPa)—gypsum Class I.,G5(5 MPa)—gypsum Class II.and G16(16 MPa)—gypsum Class III.were used to create the test samples.Samples were made with different ratios of the two ingredients,with the percentages of straw being 0%,2.5%,and 5%for each gypsum grade.The first part of the article describes how the increasing proportion of straw affects the composite’s mechanical properties(flexural strength and compressive strength).The second part of the article focuses on the change of thermal properties(thermal conductivity and specific heat capacity).The last part of the article mentions the verification of the fire properties(single-flame source fire test and gross heat of combustion)of this composite material.The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength(up to 56.49%in the 3.series of gypsum Class II.)and compressive strength(up to 80.27%in the 3.series of gypsum Class III.)and an improvement in the specific heat capacity and thermal conductivity(up to 31.40%in the 3.series).This composite material is thus not suitable for the production of high-strength plasterboards,but its reduced mechanical properties do not prevent its use for interior plasters.Based on the performed fire tests,it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2.From an ecological point of view,it is advantageous to use a composite material with a higher straw content.

Research on influence factors of rock-soil thermal properties by laboratory test

In order to discover the relation between rock-soil thermal properties and strata during the process of engineering investigation,the authors studied the measuring principle of Thermal Conductivity Scanner( TCS)and measured the thermal properties of 45 drilling samples from Qinghai with TCS in the laboratory. The results show that the specific heat capacity( SHC) decreases while the thermal conductivity( TC) increases with the increase of the depth. With the lithological change,the specific heat capacity and thermal conductivity have the opposite trend. The depth and lithology have a greater influence on the thermal conductivity than the specific heat capacity.

Improved Thermophysical Properties of Developed Ternary Nitrate-Based Phase Change Material Incorporated with MXene as Novel Nanocomposites

In this study,nanocomposite of ternary nitrate molten salt induced with MXene is developed.LiNO3-NaNO3-KNO3 with wt%of 35:12:53 and 35:10:55 are produced and doped with MXene in the wt%of 0.2,0.5,1.0,and 1.5.FTIR result indicates the composites had no chemical reaction occurred during the preparation.UV-VIS analysis shows the absorption enhancement with respect to the concentration of MXene.Thermogravimetric analysis(TGA)was used to measure the thermal stability of the LiNO_(3)-NaNO_(3)-KNO_(3) induced with MXene.The ternary molten salts were stable at temperature range of 600–700°C.Thermal stability increases with the addition of MXene.1.5 wt%of MXene doped with LiNO_(3)-NaNO_(3)-KNO_(3) with wt%35:10:55 and 35:12:53,increases the thermal stability from 652.13°C to 731.49°C and from 679.82°C to 684.57°C,respectively.Using thermophysically enhanced molten salt will increase the efficiency of CSP.

Determination of Thermal Physical Properties

In this paper, the parallel wire techniques for determining thermal physical properties inchtding thermal conductivity, thermal diffusivity and specfic heat capacity were proposed. The theoretical basis, the apparatus and procedure, the technical data for not only normal refractory but also carbon-containing materials were also introduced.

An approach of the internal friction-dependent temperature changes for conventional and pure biogenic lubricating greases

This work investigated the temperature changes inside the bulk of lubricating greases under controlled high-shear stress conditions(250-500 s-1).For this purpose,a newly developed temperature-measuring cell called Calidus was successfully tested.The temperature changes(ΔT)have been related to the greases'components(thickener,base oil-type,and composition)and the structural degradation of the lubricating greases.Furthermore,a theoretical approach was proposed for calculating the internal temperature change of lubricating greases during shear stress.All greases showed an internal temperature profile characterised by a sudden rise inΔT within the first 4 h from starting the test and subsequentΔT decay until it reaches the steady state value.Furthermore,it was found that greases C1 and C5,formulated with lithium and calcium soap,respectively,with different soap content(16.1 wt%and 9.7 wt%,respectively),but the same base castor oil,showed the highest value of the maximumΔT,c.a.3.2 K,and the most drastic drop ofΔT.These greases showed both the highest specific densities and heat capacities.In addition,they showed the lowest ratio of expended energies(Rtee),which means more structural degradation in the stressed grease.On the contrary,the grease C3,with 13 wt%of Li-soap but the lowest base oil's viscosity,showed the lowest maximumΔT and the temperature profile was characterised by a moderate variation ofΔT along the test.The biogenic grease B3 developed a low-temperature change in the group of pure bio-genic greases close to grease C3.

Investigation on thermophysical properties of reactive powder concrete

The thermophysical properties,such as thermal conductivity,thermal diffusivity,specific heat capacity and linear thermal expansion of reactive powder concrete(RPC) with different steel fiber volumetric fractions are investigated by means of high temperature tests. The thermophysical characteristics of RPC with different fiber volumes under different temperatures are analyzed and compared with those of the common high-strength concrete and high-performance concrete. The empirical relationships of thermophysical properties with temperature and fiber volume are identified. By the heat transfer and solid physics methods,the microscopic physical mechanism of heat transfer process and heat conduction properties of RPC are investigated,and the theoretical formulas of specific heat capacity and thermal expansion coefficient are derived,respectively. The effects of temperature and steel fibers on the specific heat capacity and the thermal expansion coefficient are quantitatively analyzed and the discriminant conditions are provided. It is shown that the experimental results are consistent with the theoretical prediction.

Thermal Property Measurements of a Large Prismatic Lithium-ion Battery for Electric Vehicles

Because of the high cost of measuring the specific heat capacity and the difficulty in measuring the thermal conductivity of prismatic lithium-ion batteries,two devices with a sandwiched core of the sample-electric heating film-sample were designed and developed to measure the thermal properties of the batteries based on Fourier's thermal equation.Similar to electrical circuit modeling,two equivalent thermal circuits were constructed to model the heat loss of the self-made devices,one thermal-resistance steady circuit for the purpose of measuring the thermal conductivity,the other thermal-resistance-capacitance dynamic circuit for the purpose of measuring the specific heat capacity.Using the analytic method and recursive least squares,the lumped model parameters of these two thermal circuits were extracted to estimate the heat loss and correct the measured values of the self-made devices.Compared to the standard values of the reference samples of the glass and steel plates,the measured values were corrected to improve the measurement accuracies beyond 95% through steady thermal-circuit modeling.Compared to the measured value of the specific heat capacity of the battery sample at 50% state of charge using the calorimeter,the measured value using the self-made device was corrected in order to elevate the measurement accuracy by about 90% through dynamic thermal-circuit modeling.As verified through the experiments,it was reliable,convenient,and low cost for the proposed methodology to measure the thermal properties of prismatic lithium-ion batteries.