New approximations to the virial equation of state for fluids

✍ Scribed by R. Reijnhart

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 514 KB
• Volume: 83
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/0378-4371(75)90019-9

✦ Synopsis

A simple equation of state for square-well (SW) molecules has been derived by approximating the radial distribution function in the virial equation by a corresponding function for hard spheres. If optimum parameters for the SW potential are chosen, experimental P-V-T data for methane, ethane, nitrogen and (liquid) octane can be quite satisfactorily described by the equation, except near the critical point.

A similar equation of state has been derived for Kihara potentials by dividing the virial equation into repulsive and attractive parts and describing the former in terms of hard spheres.

As far as the description of methane data is concerned, the Kihara and SW equations prove to perform equally well, even though the Kihara potential might represent real pair interaction more accurately. However, the SW equation is to be preferred because of its simplicity.