Prediction of High Pressure Vapor-Liquid Equilibria with a Mixing Rule Using the Asog Group Contribution Method

Abstract

In many of the studies previously reported, high pressure vapor-liquid equilibria have been calculated by applying equations of state. The method for calculating the vapor-liquid equilibria using two-parameter cubic equations of state is simple and widely applied in practice1–3. To predict high pressure vapor-liquid equilibria using two-parameter cubic equations of state, namely, P = f(v, T, a, b), it is necessary to know the mixture energy parameter, a, and mixture size parameter, b. Conventionally, parameters a and b for the mixture have been evaluated by the following mixing rules: $$a = \sum\limits_i {\sum\limits_j {x_i x_j a_{ij} } }$$ ((1)) $$a_{ij} = (1 - m_{ij} )(a_{ii} a_{jj} )^{0.5}$$ ((2)) $$b = \sum\limits_i {x_i b_i }$$ ((3)) The interaction coefficient, mij, in Eq. (2) must be determined with experimental vapor-liquid equilibrium data for each system and temperature studied. Vapor-liquid equilibria can then be calculated by using these mij and component parameters, aii, bi. In this study, the mixture energy parameter is determined by using aii, bi and the chemical formulas for the components.KeywordsHydrogen EthaneFugacity CoefficientCryogenic EngineerHydrogen MethaneInfinite PressureThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.