Comparison of several equations of state in evaluating compression factors and fugacities of real gases

Date

10-2005

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ernesto J Del Rosario

Abstract

Five established equations of state (E0Ss), namely the 13eattie-Bridgeman. Berthelot, Dieterici, Redlich-Kwong, and van der Waals equations, were compared based on their ability to accurately predict the compression factors and fugacity coefficients of thirteen substances (air, argon, carbon dioxide, carbon monoxide, ethylene, hydrogen, krypton, methane. neon, nitrogen. oxygen, water, and xenon). The relative deviation of each equation of state from tabulated empirical data was determined for each substance. The results indicate that it is possible for a two-parameter EOS to give hover deviations than a multiparameter equation. The Redlich-Kwong EOS was the most accurate at temperatures above the critical temperature and the Berthelot EOS was the best below the critical temperature. The fugacity coefficients from the equations of state essentially reproduce the trends shown by fugacity coefficients estimated from empirical data. The second virial coefficient was also studied in the belief that good agreement between the EOS-predicted and actual compression factors may be dependent on the agreement of the second virial coefficient. It is seen that the accuracy of an EOS does not necessarily follow from good agreement between actual and predicted second virial coefficients. All comparisons were made against the second virial coefficient based on the standard Laniard-Jones 6-12 potential. Two modifications of the Dieterici EOS, with the exponent of the temperature changed to either 3/2 or 2, were also tested. Both modifications gave relative deviations at least as loss as the established equations of state in the quadrant below the critical pressure and temperature, but were inaccurate in other quadrants. The Dieterici 2 modification showed a slight edge over the Dieterici 3/2 modification, giving the least deviation from empirical data among all EOSs compared. A Mathematica and user interface was written in order to facilitate the computations and graphs in the study.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2005 C4 M37

Document Type

Thesis

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