Hope College Department of Physics and Engineering Research Experiences for Undergraduates Summer 2005 Project Summary

The purpose of this study was to test and improve a method to represent vapor pressure of any substance from zero to the critical temperature. An existing vapor pressure function, derived as a limiting expression from the Soave-Redlich-Kwong (SRK) equation at zero temperature, was tested by comparing it to exact vapor pressure predictions of the SRK equation. Results fell within an order of magnitude regardless of temperature or acentric factor. Various improvements were then applied. These included empirical determination of additional correction terms and a more detailed derivation of the exact low temperature limit reducing the order of magnitude error. The improvements were applied to SRK and a second equation, Peng-Robinson (PR), with the goal of estimating vapor pressure within 0.1 percent of the exact values from each equation. With SRK, the best method was this accurate for reduced temperatures between 0.58 and 1.00, and with PR, for reduced temperatures between 0.78 and 1.00.

Publications and Presentations:
Kowalsky, C.A., Lanser, J.L., Walsh, E.J., Wadelton, K., and Misovich, M.J., "Applying a Low Temperature Limit of a Cubic Equation of State to Model Pure Component Phase Equilibrium", AlChE Ann.Mtg. CD-ROM Proc. (2008)

Kowalsky, C.A., Lanser, J.L., Walsh, E.J., Wadelton, K., and Misovich, M.J., "Applying a Low Temperature Limit of a Cubic Equation of State to Model Pure Component Phase Equilibrium", Thirteenth Annual Michigan Space Grant Consortium Conference, Univeristy of Michigan, Ann Arbor, MI (2008)

Results from this work have been presented at the AIChE Annual Meeting for 2005

Misovich, M.J., K.F. Blohm, A.J. DeDoes, M.D. Goetz, E.J. Walsh, and K. Wadelton. "Explicit Phase Equilibrium Calculations from Cubic Equations of State". AIChE Annual Meeting CD-ROM Proc. New York, NY: AIChE. 2005. http://aiche.confex.com/aiche/2005/techprogram/MEETING.HTM