THERMAL NON-EQUILIBRIUM MODELING OF COUPLED HEAT AND MASS TRANSFER IN BULK ADSORPTION SYSTEM OF POROUS MEDIA

摘要

According to the volume-averaging method, a two-dimensional thermal non-equilibrium mathematical model was developed to simulate the coupled heat and mass transfer in porous media with strong adsorption, in which local fluid and solid temperatures were dealt with separately. The temperature-dependent Langmuir isotherm was applied to describe the equilibrium characteristics of binary gas CO_2 adsorbed by zeolite 13X. The adsorption-generated heat was considered in the energy equation of the solid matrix. The coupling of two energy equations was made by considering the interfacial heat transfer term. The adsorption feature of a packed bed filled with porous adsorbent and the effects of bulk flow velocity, particle diameter, effective thermal conductivity of solids, and specific heat of adsorbent on product concentration were investigated numerically. The numerical simulation shows that the heat transfer characteristic has notable effects on the quantity of adsorption and the purity of the product. High adsorption efficiency can be achieved by improving the adsorbent physical properties and reducing the temperature span of the pressure swing adsorption process. Experimental data reported by other researchers validate the accuracy of the present model.