LINEAR DRIVING-FORCE APPROXIMATION FOR ISOTHERMAL NON-ISOBARIC DIFFUSION CONVECTION WITH BINARY LANGMUIR ADSORPTION/

This paper presents several reduced models for the intraparticle diffu sion/convection mechanisms in spherical homoporous particles under iso thermal conditions. These semiempirical linear driving force approxima tions were developed for the cyclic steady state that is attained when a cyclic concentration and/or total pressure perturbation is imposed at the particle surface. The models are applicable to linear systems o r those obeying bicomponent Langmuir isotherms. The linear driving for ce approximations have two or three parameters for each component and are presented for the following cases: Knudsen diffusion, molecular di ffusion, molecular plus Knudsen diffusion in series, viscous flow, and also for both diffusion mechanisms in series, in parallel with the co nvective flow, as in the dusty gas model. Comparison between the resul ts obtained with these approximations and with the complete models sho ws that on average the relative quadratic error is approximate to 10% for non-smooth and 5% for smoother perturbations.