Journal of Chemical and Engineering Data, Vol.52, No.1, 226-229, 2007
Method for estimating critical pressure
A new method is suggested to estimate the critical pressure of non-associative fluids. It is based on the extrapolation of the function fitted over the range of standard conditions up to the critical temperature. The approximate equation for the logarithm of pressure is based on the expansion of the Haggenmacher's formula for the difference between specific volumes of saturated liquid and vapor into series that consists of first and forth powers of the inverse reduced temperature. It has been shown that such a combination provides a clear minimum for the error of approximation. Calculation of the critical pressure for 109 substances of various classes (n-alkanes, halogensubstituted hydrocarbons, alkylbenzenes, etc.) has been evaluated with the proposed approximation. The results are in quite good agreement with the experimental data.