An Investigation of the Benedict Equation of State as a Means of Correlating Volumetric Data for Light Hydrocarbons

Author: Brough, Harry Ward, Jr.

Year: 1950

Degree: Engineer's thesis

Advisor: Sage, Bruce H.

Committee Member: Unknown, Unknown

Option: Chemical Engineering

DOI: 10.7907/6n8t-1k91

Abstract

The problem of evaluating constants for the Benedict equation of state is discussed. It is concluded that a method must be found which is adaptable to high-speed digital computers and which is capable of precise analytical interpretation if the equation is to be made practical as a means of correlating data for mixtures of hydrocarbons.

A study has been made of the least squares criterion of best fit as a means of evaluating the Benedict constants from volumetric data alone. The necessary equations are presented and some analytical characteristics of the solution investigated. A procedure was developed for performing the calculations with commercial punched card equipment, and the results of two test calculations are presented. It is shown that a significantly better fit of volumetric data is possible that was obtained by Benedict. Computations are shown which indicate that the Benedict constants are determined by the experimentally observed behavior to four digits at most. Coefficients are presented for for an equation by means of which the least squares measure of the precision of fit may readily be calculated for any arbitrary values of the constant.

It is concluded that the method used is suitable for digital-computer treatment and, as applied to volumetric data, gives both an improved fit and the desired precise interpretation of the fit

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