Novel compact bed design for adsorption cooling systems: Parametric numerical study

A new bed configuration consists of two layers of packed beads separated by vapor passage is simulated using transient three-dimensional local thermal non-equilibrium model (LTNE). Darcy-Brinkman equation is solved in both the porous layers and the vapor passage. Silica-gel/water is selected as a working pair. Heat and mass diffusion time are calculated from the scaling analysis of the governing equations. Results show that reducing particle diameter and adsorbent bed thickness while enhancing the bed thermal conductivity can lead to a dramatic improvement in specific cooling power (SCP). Also, the feeding vapor passage is needed for particle size smaller than 0.5 mm but it can be removed for bigger particles. Analysis of results indicates that the adsorption process is controlled by heat diffusion resistance when heat diffusion time to mass diffusion time ratio (tth/tm)~O(100) or more. While the adsorption is controlled by mass diffusion resistance when (tth/tm)~O(1) or less.