Improving a Power Series Approach for Heat of Vaporization Predicted By the SRK Equation

Equations of state like the Soave-Redlich-Kwong (SRK) equation are used to predict the thermodynamic properties of various substances. In previous research, a new adjusted temperature variable, η, was introduced to simplify calculations of equilibrium properties. The goal of this project was to continue using the adjusted temperature variable in both the SRK and Clapeyron equations to model heat of vaporization. An existing calculation algorithm for the Clapeyron equation in reduced temperature was modified to express a new variable, the adjusted heat of vaporization, as a power series in the adjusted temperature. Coefficients of the power series consisted of a constant, K₁, and a second term proportional to the acentric factor function of the SRK equation, K₂f(ω). The series using K₁ constants followed the predicted SRK heat of vaporization data to within the same multiplicative factor, which was used as an empirical adjustment. Constants up to the thirteenth series term were verified. Results matched the predicted SRK data to within 0.1 percent for all adjusted temperatures greater than 0.0418, and to within one percent for all adjusted temperatures greater than 0.0295. Work continues to replace the empirical correction with an exact calculation, to find higher order constants which converge to the SRK data, and to evaluate the constants K₂ for the terms proportional to the acentric factor function.