Molecular, pressure, and thermal diffusion in nonideal multicomponent mixtures

Journal Article · Mon May 01 04:00:00 EDT 2000 · AIChE Journal (American Institute of Chemical Engineers)

DOI:https://doi.org/10.1002/aic.690460503· OSTI ID:20080304

Ghorayeb, K; Firoozabadi, A

A formalism based on powerful concepts of the thermodynamics of irreversible processes is derived for calculating multicomponent diffusion flux both at the critical point and away from the critical point. The derivations are based on the entropy balance expression combined with the phenomenological equations and Onsager reciprocal relations. The formalism results in a clear expression of the thermal contribution in the diffusion flux for nonideal multicomponent mixtures. The diffusion flux analysis at the critical point showed that, unlike isothermal and isobaric conditions where molecular diffusion flux is zero, molecular diffusion flux is finite and nonzero at the critical point. The thermal contribution in the diffusion flux is also finite at the critical point in multicomponent mixtures. At nonisothermal conditions, as well as nonisothermal and nonisobaric conditions, the composition gradient reaches infinity at the critical point; therefore, the mol fraction plot vs. spatial coordinates has an inflection point.

• Research Organization: Reservoir Engineering Research Inst., Palo Alto, CA (US)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: FG22-96BC14850
• OSTI ID: 20080304
• Journal Information: AIChE Journal (American Institute of Chemical Engineers), Journal Name: AIChE Journal (American Institute of Chemical Engineers) Journal Issue: 5 Vol. 46; ISSN AICEAC; ISSN 0001-1541
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
DIFFUSION
HYDROCARBONS
RESERVOIR ENGINEERING
THERMODYNAMICS