TiN振动和热力学性质的第一性原理研究

基于平面波赝势的第一性原理方法,对TiN的B1(NaCl)和B2(CsCl)以及B3(闪锌矿)复合结构的力学性能以及焓与压力之间的关系进行了研究,并讨论了它们的相对稳定性.通过研究分析可知,TiN在347 GPa左右时会发生从B1到B2的结构相变,在-17.5 GPa左右时会发生从B1到B3的结构相变.由声子频率对压强的依赖关系可知频率和带隙随着压力的增加而增加.另外高温区TiN的热膨胀系数受温度的影响较小.     

Thermodynamic and Mechanical Properties of Skeletal Muscle Contraction

Thermodynamic parameters such as the change of entropy, internal energy, and enthalpy were calculated as a function of the relative skeletal muscle strain within the framework of a proposed thermodynamic model. A value for the Young’s modulus for the skeletal muscle was also estimated. The obtained theoretical values are in a good agreement with available experimental results for the frog skeletal muscle contraction.     

Database of Thermodynamic Properties for Aqueous Organic Compounds

Results are presented from a project undertaken to develop a database for properties of organic compounds relevant for geochemistry and environmental chemistry. The database includes critically assessed standard thermodynamic properties in aqueous solution, properties of pure compounds at ambient conditions, and bibliographic references. All information stored in the databases is accessible through a web interface, which includes calculation modules for evaluating properties at elevated temperatures and pressures. The basic structure of the databases and the web interface design are described.     

The Calculation of Thermodynamic Properties of Ga-Sb Binary Liquid Alloys

In this paper, the activities of componentsof Ga-Sb system have been calculated from itsphase diagram by using computer program CABPD(calculating activities from binary phasediagrams) presented by us in previous paper.The excess free energy of liquid solution canbe expressed as:ΔG_m=X_(Ga)X_(Sb)(4392+17022X_(Sb)-15138X_(Sb)) J/mol In order to verify the reliability ofcalculated results, a discriminant has beenproposed.     

HFCs混合制冷剂热力性质的研究

为了利用PR方程和Huron-Vidal混合规则对三元混合制冷剂的热力性质进行精确计算,通过对10组二元HFCs混合制冷剂的汽液相平衡实验数据进行热力学关联,得出了相应的NRTL模型参数,由优选得到的过量Gibbs自由能NRTL模型的相互作用系数预测了构成R407C和R404A的三元混合制冷剂R32／R125／R134a以及R125／R143a／R134a的汽液相平衡,结果表明,泡点压力实验值和计算值的算术平均相对偏差小于0．42％,各组分的汽相组成实验值和计算值基本吻合。最后还应用相关热力性质分别对R32／R125和R407C进行了理论制冷循环分析计算并和其他模型的计算结果进行了比较。     

金属纳米微粒热力学性能的形状效应

金属纳米微粒的热力学性能不仅依赖于纳米微粒的尺寸,还依赖于纳米微粒的形状.介绍了作者建立的描述纳米微粒形状效应的理论模型,该模型能够预测微粒形状对其结合能、熔解温度、过热、熔解熵、熔解焓、空位形成能、空位浓度以及纳米微粒相图的影响.该模型的预测结果和已有的实验数据一致.     

Thermodynamic Properties of High-Temperature Superconductors in the Pseudogap Regime

Experimental data extracted from thermodynamic measurements in underdoped high-temperature superconductors show significant deviations from the results predicted by the BCS theory. In these particular compounds, the anomalies observed in the superconducting phase are associated also to the presence of a pseudogap in their normal state. On the basis of a simple model, which treats the pseudogap phenomenologically, we performed a Ginzburg–Landau expansion to extract the main properties of the superconducting phase. Our results for the specific-heat-coefficient jump at the transition point, (T _c), coherence length, T(T), and penetration depth, (T), qualitatively recover the experimental data.     

制冷工质R22热力性质的一种快速算法

制冷工质热物性的计算是数值模拟技术非常重要的一个环节，开展这一工作的研究且有重要的价值。本文在结合Martin-Hou方程的基础上提出了制冷工质热力性质的一种快速算法，经实例验证，该算法具有精度高、适应范围广、稳定性好等特点，可供制冷工质热物性算法设计的初学者作参考。     

制冷系统仿真中的工质热力性质计算程序

制冷系统仿真中必然用到工质热力性质计算程序,本文针对制冷系统中常用到的9种工质进行了热力性质分析,利用VB6.0编写了其计算程序模块,并在实际的制冷仿真系统中得到了应用,最终通过动力实验平台的测试,证实计算程序是合理的.     

A Generalized Model for the Thermodynamic Properties of Mixtures

A mixture model explicit in Helmholtz energy has been developed which is capable of predicting thermodynamic properties of mixtures containing nitrogen, argon, oxygen, carbon dioxide, methane, ethane, propane, n-butane, i-butane, R-32, R-125, R-134a, and R-152a within the estimated accuracy of available experimental data. The Helmholtz energy of the mixture is the sum of the ideal gas contribution, the compressibility (or real gas) contribution, and the contribution from mixing. The contribution from mixing is given by a single generalized equation which is applied to all mixtures studied in this work. The independent variables are the density, temperature, and composition. The model may be used to calculate the thermodynamic properties of mixtures at various compositions including dew and bubble point properties and critical points. It incorporates accurate published equations of state for each pure fluid. The estimated accuracy of calculated properties is ±0.2% in density, ±0.1 % in the speed of sound at pressures below 10 MPa, ±0.5% in the speed of sound for pressures above 10 MPa, and ±1% in heat capacities. In the region from 250 to 350 K at pressures up to 30 MPa, calculated densities are within ±0.1 % for most gaseous phase mixtures. For binary mixtures where the critical point temperatures of the pure fluid constituents are within 100 K of each other, calculated bubble point pressures are generally accurate to within ±1 to 2%. For mixtures with critical points further apart, calculated bubble point pressures are generally accurate to within ±5 to 10%.     

制冷系统仿真中的工质热力性质计算程序

制冷系统仿真中必然用到工质热力性质计算程序,本文针对制冷系统中常用到的9种工质进行了热力性质分析,利用VB6.0编写了其计算程序模块,并在实际的制冷仿真系统中得到了应用,最终通过动力实验平台的测试,证实计算程序是合理的.     

Crossover SAFT Equation of State and Thermodynamic Properties of Propan-1-ol

In this work we have developed a new equation of state (EOS) for propan-1-ol on the basis of the crossover modification (CR) of the statistical-associating-fluid-theory (SAFT) EOS recently developed and applied to n-alkanes. The CR SAFT EOS reproduces the nonanalytical scaling laws in the asymptotic critical region and reduces to the analytical-classical SAFT EOS far away from the critical point. Unlike the previous crossover EOS, the new CR SAFT EOS is based on the parametric sine model for the universal crossover function and is able to represent analytically connected van der Waals loops in the metastable fluid region. The CR SAFT EOS contains 10 system-dependent parameters and allows an accurate representation of the thermodynamic properties of propan-1-ol over a wide range thermodynamic states including the asymptotic singular behavior in the nearest vicinity of the critical point. The EOS was tested against experimental isochoric and isobaric specific heats, speed of sound, PVT, and VLE data in and beyond the critical region. In the one-phase region, the CR SAFT equation represents the experimental values of pressure with an average absolute deviation (AAD) of less than 1% in the critical and supercritical regions and the liquid densities with an AAD of about 1%. A corresponding states principle is used for the extension of the new CR SAFT EOS for propan-1-ol to higher n-alkanols.     

A Fundamental Equation for Calculation of the Thermodynamic Properties of Ethanol

A formulation for the thermodynamic properties of ethanol (C₂H₅OH) in the liquid, vapor, and saturation states is presented. The formulation is valid for single-phase and saturation states from 250 to 650K at pressures up to 280MPa. The formulation includes a fundamental equation and ancillary functions for the estimation of saturation properties. The experimental data used to determine the fundamental equation include pressure-density-temperature, ideal gas heat capacity, speed of sound, and vapor pressure. Saturation values computed from the ancillary functions were used to ensure thermodynamic consistency at the vapor-liquid phase boundary. Comparisons between experimental data and values computed using the fundamental equation are given to verify the uncertainties in the calculated properties. The formulation presented may be used to compute densities to within ±0.2%, heat capacities to within ±3%, and speed of sound to within ±1%. Saturation values of the vapor pressure and saturation densities are represented to within ±0.5%, except near the critical point.     

Thermodynamic Properties of Methanol in the Critical and Supercritical Regions

The isochoric heat capacity of pure methanol in the temperature range from 482 to 533 K, at near-critical densities between 274.87 and 331.59 kg· m⁻³, has been measured by using a high-temperature and high-pressure nearly constant volume adiabatic calorimeter. The measurements were performed in the single- and two-phase regions including along the coexistence curve. Uncertainties of the isochoric heat capacity measurements are estimated to be within 2%. The single- and two-phase isochoric heat capacities, temperatures, and densities at saturation were extracted from experimental data for each measured isochore. The critical temperature (T_c = 512.78±0.02K) and the critical density (ρ_c = 277.49±2 kg · m⁻³) for pure methanol were derived from the isochoric heat-capacity measurements by using the well-established method of quasi-static thermograms. The results of the C_VVT measurements together with recent new experimental PVT data for pure methanol were used to develop a thermodynamically self-consistent Helmholtz free-energy parametric crossover model, CREOS97-04. The accuracy of the crossover model was confirmed by a comprehensive comparison with available experimental data for pure methanol and values calculated with various multiparameter equations of state and correlations. In the critical and supercritical regions at 0.98T_c≤ T ≤ 1.5T_c and in the density range 0.35ρ_c ≤ ρ leq 1.65 ρ_c, CREOS97-04 represents all available experimental thermodynamic data for pure methanol to within their experimental uncertainties.     

采用无容器凝固技术研究过冷熔体热物理性质

深过冷是获得特殊性能亚稳材料的一种非常重要的手段,采用无容器凝固技术可以在较低的冷却速度下实现并保持较长时间熔体的深过冷,使过冷熔体热物理性质参数的测量成为可能.介绍了电磁悬浮、助熔剂处理等几种常用的无容器凝固技术,阐述了它们在测量过冷熔体比热容等热物理性质方面的应用,同时综述了过冷状态下熔体比热容等热物理性质的研究现状,并展望了今后的发展趋势.     

稠油热采注汽管网的组织和性能

通过金相检验、硬度测试和拉伸试验研究了温度对稠油热采注汽管网组织的影响及组织与力学性能之间的相互关系。结果表明:管道内边缘处的珠光体含量明显少于内部,碳含量下降;珠光体球化和高温脱碳是碳含量下降的两大原因,组织的变化导致其硬度和抗压抗拉性能下降,使管网的安全性降低。     

A New Model for Predicting Ternary Thermodynamic Properties of Solution Phase and Its Application

A new geometric asymmetric model for predicting the thermodynamic properties of ternary systemfrom three sub-binaries is presented in this paper.Its analytical expression with good calculating ac-curacy is most simple in all asymmetric models.The new model was applied to predict the enthalpiesof mixing of the Bi-Ga-Sn.Au-Ag-Sn and NaCl-KCl-CaCl_2 ternary systems which were in goodagreements with experimental data.Based on thermodynamic principles,the importance of thechoice of asymmetric component is also discussed.The error analysis indicates that in the case ofjudging the asymmetric component in ternary system according to the thermodynamic criterion thedeviation is minimum.It is of great significance to improve the calculating accuracy for predictingthermodynamic properties of ternary solution phase from the sub-binary ones.     

常用制冷工质热力性质计算数据库的开发

建立了包括湿空气、R22、R21、R12、Rll、R134a、NH3、H2O的热力性质计算数据库系统，其中热力性质计算包括温度、压力、密度、比焓、比熵、比容、汽化潜热。对R11、R12、R21、NH3、R134a的热力性质计算公式进行了修正，计算结果与文献中的数据进行比较，结果显示：数据库中除R134a和湿空气外，其他丁质的计算误差均小于0．8％，此外R22的热力性质计算程序已在制冷循环仿真模型中得到应用。     

Thermodynamic Properties for R-404A

An 18-coefficient modified Benedict–Webb–Rubin equation of state has been developed for R-404A, a ternary mixture of 44% by mass of pentafluoroethane (R-125), 52% by mass of 1,1,1-trifluoroethane (R-143a), and 4% by mass of 1,1,1,2-tetrafluoroethane (R-134a). Correlations of bubble point pressures, dew point pressures, saturated liquid densities, and saturated vapor densities are also presented. This equation of state has been developed based on the reported experimental data of PVT properties, saturation properties, and isochoric heat capacities by using least-squares fitting. These correlations are valid in the temperature range from 250 K to the critical temperature. This equation of state is valid at pressures up to 19 MPa, densities to 1300 kg·m^–3, and temperatures from 250 to 400 K. The thermodynamic properties except for the saturation pressures are calculated from this equation of state.     

Thermodynamic and transport properties of some alternative ozone-safe refrigerants for industrial refrigeration equipment: Study in Belarus and Ukraine

The study of several hydrofluorocarbons (HFC) and fluorocarbons (FC) and their binary mixtures that have no ozone-depleting ability is being carried Out in the framework of Belarus National Program. The fluids include HFCs R134a. R152a, R135, and R32, and FC R218. The following properties are being investigated: ( I ) phase equilibrium parameters including the boiling and condensing curve and critical point, thermophysical properties at these parameters, and heat of evaporation: (2) isobaric and isochoric heat capacity, ethalpy, and entropy in the gas and liquid state: (3) speed of sound, thermal conductivity. viscosity, and density in the gas and liquid state: (4) dielectric properties and surface tension: (5) behavior of combined construction materials inside the refrigerant medium: and (6) solubility in compressor oils and other technological characteristics. The series of results obtained by authors during the period 1990–1993 is presented.Invited paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado. U.S.A.