A study and comparison of complete kinetics, linear driving force approximation and equilibrium models in simulation of gas adsorption systems

Document Type : Research Article


Department of chemical engineering, faculty of oil, gas and petrochemical engineering, persian gulf university, Bushehr, Iran


In this study, the equilibrium, complete kinetics and linear driving force (LDF) approaches in numerical simulation of gas adsorption systems using the element-increment differential quadrature method were investigated. Where in the complete kinetics, all mechanisms such as, Knudsen diffusion, viscous flow, slip flow, molecular diffusion and surface diffusion are considered. In the LDF model, the mass transfer is described by a lumped overall mass transfer coefficient (OMTC) instead of all mass transfer resistances, and consequently computational demand is reduced. However, LDF approximation is greatly depend on average adsorbent particles radius and deviation from complete kinetics is increased by increase of adsorbent particles. In the equilibrium model, the adsorption kinetics are not taken into account and the concentration changes in the system have been determined base on equilibrium adsorption isotherm. The numerical results showed that with increasing radius of absorbent particles, the complete kinetics model will be more appropriate to describe the adsorption behavior. Also, OMTC is varied based on the temperature and pressure conditions. Whereas, it is increased by increase of temperature and it is more sensitive to change of temperature at low pressure. In addition, OMTC is not constant and goes through a minimum at an intermediate pressure.