A new prediction equation of compressed liquid isochoric heat capacity for pure fluids and mixtures

Abstract

In this paper, a new prediction equation for compressed liquid isochoric heat capacity (cv) was developed based on the corresponding states principle (CSP). By knowing acentric factor (ω), critical parameters (Tc, pc and vc) and ideal gas isochoric heat capacity (cv,0), the new equation could predict cv for pure fluids and mixtures (including polar and nonpolar fluids) at 0.25 < Tr < 1 and 0.5 < pr < 10. The overall average absolute relative deviation (AARD) of the new equation for 25 pure fluids and 10 mixtures are 2.21% and 1.62%, respectively. A comparison was conducted between the new equation and other models (PR EoS, Helmholtz energy EoSs, generalized equation (GE) of Zhong et al. [1] and corresponding states equation (CSE) of Sheng et al. [2]). The new equation significantly improves the prediction performance for the heat capacity of important fluids, such as halogenated hydrocarbons, carbon dioxide, water and so on, compared with the existing models. Although the prediction performance of the new equation is slightly worse than that of the Helmholtz energy EoS, the new equation has a simpler form and more powerful prediction performance than the Helmholtz energy EoS for mixtures.