热物理学一直是物理学的非常重要的分支。随着1869年临界点的发现,显示出了理想气体模型的局限。为解释这一重要物理现象,理论物理学家van der Waals于1873年提出了vander Waals模型,这标志了平均场理论的首次引入。然而,随着实验技术的提高,发现了平均场理论给出的临界指数与实验结果相矛盾。随后引入了与实验一致的普适性与标度假定这两个突破了平均场理论框架的物理概念。这导致了理论物理学家Wilson于1972年提出了临界重整化群理论。目前,基于临界重整化群理论用简单普适的物理数学方法跨接描述流体的经典热力规律与奇异性物理规律,已为国际热物理界所关注。作者在读博士学位期间。
A new general vapor pressure equation based upon the theory of the corresponding statesprinciples is developed in this paper. The equation presented here has a simple and generalform, and has a comparable accuracy for prediction of the vapor pressure of fluids. Only thecritical temperature, critical pressure, acentric factor w and polar factor x are required forprediction. Satisfactory results are available for various kinds of substances such as simplefluids, quantum fluids, hydrogen-bond fluids, non- polar fluids, polar fluids, refrigerents andassociated fluids etc..
Thermodynamic properties of difluoromethane (HFC-32) are expressed in a 35-termcrossover equation of state. This equation of state is effective at pressures up to 35MPa,densities up to 1450 kg.m-3, and temperatures from 150 K to 480 K, respectively. Equations for Helmholtz energy, Gibbs energy, internal energy, enthalpy, entropy, isochoric heatcapacity, isobaric heat capacity, speed of sound, and second virial coefficient of HFC-32 arepresented. Independent equations are also included for vapor pressure and saturated liquiddensity as function of temperature.
A new crossover equation of state in the dimensionless Helmholtz free energy for the thermodynamic properties of 1, 1,1 ) 2-tetrafluoroethane (R 134a ) has been developed that incorporates singular thermodynamic behavior near the critical point with regular thermodynamic behavior far from the critical point. The equation of state is capable of representing all the thermodynamic properties of R134a including press ure-density-temperature properties, the isochoric and isobaric heat capacities, and the sound velocity in the entire region,at temperatures from the triple point to 453K, pressures up to 70MPa and densities from zero to three times and a half the critical density. The results have been compared with experimental thermodynamic-property data in the entire region and with other equations of state near the critical point.
