Lattice Boltzmann methods for simulation of micro and macrotransport in a packed bed of porous adsorbents under non-isothermal condition

3D simulation of velocity and concentration profiles was carried out for a packed bed of porous adsorbents under non-isothermal conditions using lattice Boltzmann methods. The model developed in this study incorporates microlevel mass transport within the pores of the solid adsorbent particles and macrolevel transport in the bed voids between the particles. In addition, temperature profiles within the packed bed are calculated taking into account temporal rise in the temperature due to the exothermic heat of adsorption. Inherent multi-scaling capability of lattice Boltzmann technique permits simultaneous ascertaining of the magnitude of concentration profiles within the spherical particles due to the Knudsen diffusivity and that in the bulk gas phase due to combined convective and molecular diffusivity effects. The results in this study have significance, since most of the traditional numerical methods are based on 1D or 2D approximations, including averaging of intra-particle concentration gradients by linear driving force approximations or assuming parabolic concentration profiles within the particles. The model predicted breakthrough curves in this study are validated with the experimental data obtained by tomography technique for porous zeolite particles packed in a tubular adsorber.