Effects of coupled heat and mass transfers in adsorbent on the performance of a waste heat adsorption cooling unit

Abstract

This paper presents a numerical analysis of the performance of a waste heat adsorption cooling system associated with the coupled heat and mass transfer mechanisms in the adsorbent. A new three-dimensional non-equilibrium model is developed and used to investigate and optimize the simultaneous transport of heat and mass in the waste heat adsorber. In the model, a linear driving force equation is used to account for the mass transfer resistance within the pallets (internal resistance), while the Darcy's law is introduced to describe the adsorbate flows in the interparticle voids (external resistance). Using the model, the effects of the bed configurations such as the number of fins, the bed dimensions, the heat transfer coefficients, the permeability and the adsorption rate on the system performance are extensively investigated. it is found that the performance of the system can be seriously deteriorated by poorer mass transfers in the adsorbent if its permeability is smaller than a critical value. On the other hand, for systems with short cycle times, the internal mass transfer resistance can be a significant limiting factor as well.