Prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin equation of state

Abstract

The prediction of vapor‐liquid equilibria with the Benedict‐Webb‐Rubin (BWR) equation of state has been restudied. It was found that the suitability of the equation of state to represent fully the behavior of the constituents is the main factor which affects the accuracy of the prediction. To improve the representation of the pure component data by means of equation of state it is necessary to modify the present form of the BWR equation of state. A tentative form of modification of the BWR equation of state has been chosen. Although the modified equation is still subject to further evaluation and refinement, satisfactory results have been obtained for the prediction of four binary systems containing nitrogen and carbon dioxide (nitrogen‐methane. methane‐carbon dioxide, propane‐carbon dioxide, and n‐butane‐carbon dioxide).The method of nonlinear estimation has been used to fit the coefficients in the equation of state to either vapor‐pressure data or P‐V‐T data.