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. T...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.展开更多
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 prope...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.展开更多
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 secon...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.展开更多
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...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.展开更多
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 diffe...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.[展开更多
A<sub>2</sub>FeCoO<sub>6-δ</sub> (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 ...A<sub>2</sub>FeCoO<sub>6-δ</sub> (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 Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> 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 Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.展开更多
The distinctive specific heat capacity of nanofluids presents opportunities for enhancing heat transfer efficiency and plays a pivotal role in the design of nanoscale devices.Existing research often overlooks the infl...The distinctive specific heat capacity of nanofluids presents opportunities for enhancing heat transfer efficiency and plays a pivotal role in the design of nanoscale devices.Existing research often overlooks the influence of particle size and nanostructures on the specific heat capacity of nanofluids.Therefore,this paper provides a comprehensive survey that encompasses synthesis techniques,measurement methodologies,predictive models,and influential parameters affecting the specific heat capacity of nanofluids.Empirical investigations have consistently shown that the specific heat capacity of nanofluids typically increases with a reduction in particle size,primarily due to surface and size effects.Furthermore,the specific heat capacity of nanofluids is significantly influenced by temperature and concentration.However,due to the complex interplay of surface effects,temperature gradients,and pressure gradients within nanofluids,the specific heat capacity exhibits nonlinear behavior,thereby complicating the research landscape.展开更多
In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined...In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined water.In this work,we employed the method of molecular dynamics(MD)simulation to calculate the specific heat capacity at constant volume and coordination number of water molecules confined in carbon nanotubes(CNTs)under different conditions(T=600-700 K,P=21.776 and 25 MPa,CNT diameter=0.949-5.017nm).The results showed that near the critical point,the specific heat capacity at constant volume of confined water was lower than that of bulk water,and the energy fluctuation showed a trend of first increasing and then remaining unchanged with the increase of temperature and CNT diameter.Among them,the saturation point of temperature is 650 K(reduced pressure P_(r)=1)and 660 K(P_(r)=1.15),and the saturation point of CNT diameter is 2.034 nm.Additionally,the pseudo-critical temperature of confined water was the same as bulk water,and it increased with the increase of critical pressure.Moreover,with the increase of CNT diameter,the coordination number of confined water increased rapidly,and reaches the saturation state when the CNT diameter is 2.034 nm.This investigation revealed the mass and energy characteristics of nano-confined water near the critical point,which could provide guidance for the critical phase transition of nano-confined water.展开更多
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 ...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.展开更多
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 variat...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.展开更多
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 （...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.展开更多
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 appr...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.展开更多
The thermal behavior,non-isothermal thermal decomposition reaction kinetics and specific heat capacity of hexanitro-hexaazaisowurtzitane(HNIW)were studied by differential scanning calorimeter(DSC)and Micro-DSCIapparat...The thermal behavior,non-isothermal thermal decomposition reaction kinetics and specific heat capacity of hexanitro-hexaazaisowurtzitane(HNIW)were studied by differential scanning calorimeter(DSC)and Micro-DSCIapparatus,The kinetic parameters of the thermal decomposition reaction(the apparent activation energy(E,)and pre-exponential factor(A))were calcu-lated by non-isothermal DSC curves.The results show that the differential mlechanism function and values of E,and A of the ther-mal decomposition reaction of HNIW are 3(1-a)[-ln(1-a)]"·,155.04 kJ·mol^(-1)and 10""s^(-1),respectively.The critical tem-perature of thermal explosion of the title compound is 226.60℃.The entropy of activation(AS·),enthalpy of activation(AH·)and free energy of activation(AG·)of this reaction are 11.60J·mol·K^(-1),152.04 kJ·mol^(-1)and 146.29 kJ·mol^(-1),respec-tively.The equation of specific heat capacity of HNIW with temperature is C,=0.2472+0.002705992Tin the temperature range of 283 K to 343K.The values of self-accelerating decomposition temperature,adiabatic time-to-maximum decomposition rate and adiabatic time-to-explosion are 486.5K,54.81s and 54.31s,respectively.Thermal sensitivity probability density distribution curve of HNIW is constructed.展开更多
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 slowl...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.展开更多
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 fl...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.展开更多
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 a...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.展开更多
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 resu...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.展开更多
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 me...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.展开更多
As a promising new energy source, natural gas hydrates (NGHs) have attracted wide attention. The thermophysical properties of NGHs are of great significance to their exploitation. This work summarizes the progress of ...As a promising new energy source, natural gas hydrates (NGHs) have attracted wide attention. The thermophysical properties of NGHs are of great significance to their exploitation. This work summarizes the progress of laboratory measurements and models of NGH thermophysical parameters, such as phase equilibrium, thermal conductivity, dissociation enthalpy, thermal diffusivity, and specific heat capacity. The advantages and disadvantages of measurement methods, numerical models, typical experimental data, and characteristics are discussed. The measurement accuracy of hydrate phase equilibrium is closely related to the estimation (or prediction) of the temperature (pressure), at which gas hydrate may decompose, as well as the heating rate, pores, residual water, ice and additive, etc., affect the sample quality as well as the thermal conductivity. The randomness of hydrate nucleation and growth leads to the uncertainty of hydrate distribution in sediments, which directly affects the accuracy of thermophysical property prediction models. Moreover, some future perspectives are suggested.展开更多
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...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.展开更多
基金Project(082102230035)supported by the Foundation of Science and Technology Department of Henan Province,China
文摘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.
基金This work was supported by College of Engineering and Technology,the American University of the Middle East,Kuwait.Homepage:https://www.aum.edu.kw.
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China(No.20803058)Xi’an Scientific and Technical Plan Foundation, China(No.YF07106).
文摘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.
文摘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.[
文摘A<sub>2</sub>FeCoO<sub>6-δ</sub> (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 Sr<sub>2</sub>FeCoO<sub>6-δ</sub> is found to be the highest, and that of Ca<sub>2</sub>FeCoO<sub>6-δ</sub> is the lowest while CaSrFeCoO<sub>6-δ</sub> 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 Ca<sub>2</sub>FeCoO<sub>6-δ</sub> to CaSrFeCoO<sub>6-δ</sub> to Sr<sub>2</sub>FeCoO<sub>6-δ</sub>.
基金financially supported by the National Natural Science Foundation of China(52176061,51876040)Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)Project of Jiangsu Provincial Six Talent Peaks。
文摘The distinctive specific heat capacity of nanofluids presents opportunities for enhancing heat transfer efficiency and plays a pivotal role in the design of nanoscale devices.Existing research often overlooks the influence of particle size and nanostructures on the specific heat capacity of nanofluids.Therefore,this paper provides a comprehensive survey that encompasses synthesis techniques,measurement methodologies,predictive models,and influential parameters affecting the specific heat capacity of nanofluids.Empirical investigations have consistently shown that the specific heat capacity of nanofluids typically increases with a reduction in particle size,primarily due to surface and size effects.Furthermore,the specific heat capacity of nanofluids is significantly influenced by temperature and concentration.However,due to the complex interplay of surface effects,temperature gradients,and pressure gradients within nanofluids,the specific heat capacity exhibits nonlinear behavior,thereby complicating the research landscape.
基金financially supported by the National Key R&D Program of China(2020YFA0714400)the Fundamental Research Funds for the Central Universities(xzy022023036)。
文摘In the field of nano energy,investigating the specific heat capacity and coordination number of nano-confined water is highly significant for gaining a better understanding of the energy and microstructure of confined water.In this work,we employed the method of molecular dynamics(MD)simulation to calculate the specific heat capacity at constant volume and coordination number of water molecules confined in carbon nanotubes(CNTs)under different conditions(T=600-700 K,P=21.776 and 25 MPa,CNT diameter=0.949-5.017nm).The results showed that near the critical point,the specific heat capacity at constant volume of confined water was lower than that of bulk water,and the energy fluctuation showed a trend of first increasing and then remaining unchanged with the increase of temperature and CNT diameter.Among them,the saturation point of temperature is 650 K(reduced pressure P_(r)=1)and 660 K(P_(r)=1.15),and the saturation point of CNT diameter is 2.034 nm.Additionally,the pseudo-critical temperature of confined water was the same as bulk water,and it increased with the increase of critical pressure.Moreover,with the increase of CNT diameter,the coordination number of confined water increased rapidly,and reaches the saturation state when the CNT diameter is 2.034 nm.This investigation revealed the mass and energy characteristics of nano-confined water near the critical point,which could provide guidance for the critical phase transition of nano-confined water.
基金financially supported by the National Key Research and Development Program (project No.2019YFC1805700,program No.2019YFC1805701)。
文摘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.
基金greatly acknowledge the National Key Research and Development Program of China(No.2021YFA0716000)the China National Petroleum Corporation-Peking University Strategic Cooperation Project of Fundamental Research.
文摘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.
基金Project supported by the National Natural Science Foundation of China （No. 20271036）, the Foundation of Education Committee of Shaanxi Province （No. 01JK229） and the National State Doctoral Foundation.
文摘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.
文摘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.
基金The National Nature Science Foundation of China(21173163)
文摘The thermal behavior,non-isothermal thermal decomposition reaction kinetics and specific heat capacity of hexanitro-hexaazaisowurtzitane(HNIW)were studied by differential scanning calorimeter(DSC)and Micro-DSCIapparatus,The kinetic parameters of the thermal decomposition reaction(the apparent activation energy(E,)and pre-exponential factor(A))were calcu-lated by non-isothermal DSC curves.The results show that the differential mlechanism function and values of E,and A of the ther-mal decomposition reaction of HNIW are 3(1-a)[-ln(1-a)]"·,155.04 kJ·mol^(-1)and 10""s^(-1),respectively.The critical tem-perature of thermal explosion of the title compound is 226.60℃.The entropy of activation(AS·),enthalpy of activation(AH·)and free energy of activation(AG·)of this reaction are 11.60J·mol·K^(-1),152.04 kJ·mol^(-1)and 146.29 kJ·mol^(-1),respec-tively.The equation of specific heat capacity of HNIW with temperature is C,=0.2472+0.002705992Tin the temperature range of 283 K to 343K.The values of self-accelerating decomposition temperature,adiabatic time-to-maximum decomposition rate and adiabatic time-to-explosion are 486.5K,54.81s and 54.31s,respectively.Thermal sensitivity probability density distribution curve of HNIW is constructed.
基金Supported by the National Natural Science Foundation of China(No.20571060)the Natural Science Foundation of Shaanxi Province,China(No.2007B08)
文摘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.
基金Project(13-02-96036) supported by RFBR and the Government of Sverdlovsk Region of Russia
文摘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.
基金This article was financed from the budget of the Student Grant Competition VSB-TUO(Registration No.SGS SP2020/135)This article has been elaborated in the framework of scholarship of the City of Ostrava(RRC/2806/2019)+1 种基金in the framework of the grant programme“Support for Science and Research in the Moravia-Silesia Region 2018”(RRC/10/2018)financed from the budget of the Moravian-Silesian Region.
文摘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.
基金grateful to Minister of higher education under Fundamental Research Grant Scheme(FRGS)No.FRGS/1/2019/TK07/UMP/02/3Universiti Malaysia Pahang(www.ump.edu.my)for the financial support provided under the Grant,RDU192209.
文摘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.
基金Supported by National High Technology Research and Development Program of China(863 Project)(No.2012AA052801)National Natural ScienceFoundation of China(No.41372239)Specialized Research Fund for the Doctoral Program of Higher Education(No.20110061110055)
文摘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.
基金funded by the National Natural Science Foundation of China(52074165)Natural Science Foundation of Shandong Province(ZR2019MEE116,ZR2020ME187)Source Innovation Special Project of Qingdao West Coast New Area(2020-93).
文摘As a promising new energy source, natural gas hydrates (NGHs) have attracted wide attention. The thermophysical properties of NGHs are of great significance to their exploitation. This work summarizes the progress of laboratory measurements and models of NGH thermophysical parameters, such as phase equilibrium, thermal conductivity, dissociation enthalpy, thermal diffusivity, and specific heat capacity. The advantages and disadvantages of measurement methods, numerical models, typical experimental data, and characteristics are discussed. The measurement accuracy of hydrate phase equilibrium is closely related to the estimation (or prediction) of the temperature (pressure), at which gas hydrate may decompose, as well as the heating rate, pores, residual water, ice and additive, etc., affect the sample quality as well as the thermal conductivity. The randomness of hydrate nucleation and growth leads to the uncertainty of hydrate distribution in sediments, which directly affects the accuracy of thermophysical property prediction models. Moreover, some future perspectives are suggested.
文摘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.
