The ISM Equation of State Applied to Refrigerants

In this work, we apply an equation of state based on statistical-mechanical perturbation theory to liquid refrigerants and their mixtures. Three temperaturedependent parameters are needed to use the equation of state: the second virial coefficient, B2(T), an effective van der Waals covolume, b ( T ) , and a scaling factor, A(T ) . The second virial coefficients are calculated from a correlation based on the heat of vaporization, THvap, and the liquid density at the freezing point, pfp. A ( T ) and b(T) can also be calculated from the second virial coefficient by a scaling rule. Based on the theory, these two temperature-dependent parameters depend only on the repulsive branch of the potential function, and therefore, by our procedure, can be found from THvap and pfp. The theory has considerable predictive power, since it permits the construction of the p-v-T surface from the heat of vaporization plus the triple-point density. The equation of state is tested for pure, two- and three-component liquid refrigerant mixtures