Numerical comparison between relaxation and nonlinear equilibrium models. Application to chemical engineering

A model to take into account the finite exchange kinetic for the equilibriu m between phases in the chromatography experiment is studied. The resulting hyperbolic system with a nonlinear relaxation term is then formally treate d with a Chapman-Enskog type expansion. A first order correction to the cla ssical quasilinear hyperbolic model is derived which. consists of a nonline ar diffusion term. Numerical schemes for both models - relaxed and paraboli c - are then rested and compared for different initial and boundary values. A range of validity for the first order approximation is obtained through numerical simulations where its computational performance indicates that it should be advantageously used. (C) 2000 Elsevier Science B.V. All rights r eserved.