A modification of the BWR equation of state is proposed, which is a simplif
ied form of a previously proposed one. It applies to systems formed by hydr
ocarbons and related compounds, with particular attention to the critical c
onditions. The range of treatable compounds was extended to a value 0.9 of
the acentric factor, corresponding to C-20 hydrocarbons. The critical compr
essibility factor Z(c) was made independent of the acentric factor, for a m
ore accurate prediction of pure-component properties (the previous equation
did not give the same improvement). Mixing rules require one binary intera
ction constant for each component pair. Zero binary constants can be used f
or methane-alkane and alkane-alkane pairs. Examples of applications to pure
hydrocarbons and their mixtures are given. (C) 1999 Elsevier Science B.V.
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