Numerical modelling of flow and coupled mass and heat transfer in an adsorption process

In this paper, a detailed three dimensional mathematical formulation and a simplified one dimensional model for the numerical simulation of the flow and coupled heat and mass transport in a gas channel coated with adsorbing material are presented. In the three dimensional model, the velocity distribution of the gas flow is obtained by solving the momentum equation. The coupled heat and mass transport phenomena are locally described in both the gas channel and the adsorbent layer, and the concomitant adsorbate adsorption and desorption processes are taken into account. In the one dimensional model, the gas flow is assumed as a plug flow, and the heat and mass transfer across the solid-fluid interface is estimated by empirical transfer coefficients. A comparative study between the detailed three dimensional model and a simplified one dimensional model is carried out. Both model predictions are compared with experimental data available from literature. The heat and adsorbate concentration gradients observed in both radial and circumferential directions indicate that the detailed three dimensional model is desired. The time-dependent variations of temperature and heat flux distributions at the interface between the gas channel and the adsorbent layer justify the use of the more detailed three dimensional model. Three dimensional modelling is essential to obtain accurate predictions for cases where the solid side transport resistances are dominating.