A mathematical treatment based on an interaction model has yielded an expression capable of establishing the critical temperatures of multicomponent aliphatic hydrocarbon mixtures. This model postulates an infinite-series expansion for the difference between the actual critical temperature and its corresponding pseudocritical value. For methane-free aliphatic hydrocarbon mixtures, this infinite series has been truncated beyond the third-order interactions. Explicit relationships are given for the second-order interaction coefficients Aij and Bij as a function of the binary-system parameter τij and the third-order interaction coefficient βijk as a function of χijk, the ternary-system parameter.
This interaction model has been applied to one hundred-sixteen different compositions of binary, ternary, quaternary, and quinary aliphatic hydrocarbon systems to produce an overall average deviation of 0.35%. Owing to the different interaction behavior of methane, systems containing methane have not been included in this study.