Improvement of adsorption heat exchangers by the enhancement of contact points between adsorbent and surface

In this study, we are aiming at the improvement of heat exchangers for the adsorption heat pump. To achieve it, it is important to reduce thermal contact resistance between adsorbent and heat transfer surface. The thermal contact resistance can be reduced by increasing the contact points between adsorbents and heat transfer surface. To increase the contact points, four patterns of heat transfer surface geometry were examined. They are flat surface, V-shaped surface, oblong surface, and arc shaped surface, which have one, two, three and maximum contact points, respectively. The flat surface is the one used by the conventional heat exchanger, and the arc shaped surface is the ideal one. The heat conduction in the adsorbent (silica gel) bed was predicted by mathematical simulation. The structure of adsorbent bed was the hexagonal closest packing. For the fundamental analysis, a two dimensional model was developed, and steady-state simulation was performed. The results showed that V-shaped surface could increase heat flux by 10 %. In addition, the reduction of the thermal contact resistance was more effective on the thinner adsorbent layer than that on the thicker one.