Performance of solar adsorption cooling system with internal finned vacuum tube bed

Abstract

Aiming to improve the performance of the solar adsorption cooling system using the silica gel-water as the working pair, a series of fin-enhanced vacuum tube bed have been developed and tested experimentally. The characteristics of the system were analyzed as the fin number changed between zero to eight in the bed. It is revealed that longer time was needed for the preheating and desorption of the bed in a cycle because of the increase of the heat capacity of finned tube bed. Nevertheless, the fast heat transfer of the finned tube has resulted in a significant reduction of the pre-cooling time of the bed, which usually took the biggest part in the whole cycle time originally. The comprehensive result was the cycle time of the solar adsorption cooling system diminished, and the general performance of the system was improved. As evaluated under the criterion of the specific cooling power (SCP), it is found that the SCP 2 of the finned system, which is defined by the cycle time, increased 37.4%–80.7% in comparison to the situation of the smooth tube bed. On the other hand, analyzing the coefficient of performance (COP) of the system has revealed that not always the more the internal fins, the better the performance result. The experimental results told us that the COP of the system reached the optimum as the fin number was equal to four. Over enhanced tube bed caused the performance of the adsorption cooling system to deteriorate.