Numerical investigation on the effect of flat-tube heat exchanger geometrical structure on the performance of adsorption chiller

In the present study¡ for the first time¡ adsorbent bed of SWS-1L/water adsorption chiller with rectangular and trapezoidal finned flat-tube heat exchanger with has been simulated three dimensionally based on the distributed parameters model and finite volume method. Effects of some important parameters on the chiller performance such as bed averaged pressure¡ temperature and uptake variations with cycle time have been examined for better understanding of bed dynamic behavior. Also¡ a comparative study between two different configurations of adsorbent bed including rectangular and trapezoidal fins has been conducted based on identical adsorbent mass. For this purpose¡ bed temperature¡ uptake and pressure distributions as well as the vapor flow patterns at the end of heating cycle phases and also effects of fin height and spacing on the system performance have been studied. In this investigation at fixed bed length of 20mm¡ fin height and spacing variations have been examined in the range of 8-20mm and 3-12mm¡ respectively. Results indicated that the system performance with rectangular and trapezoidal adsorbent beds are almost similar except for those conditions which fin spacing is 3mm and fin height are 14¡ 20mm. For the mentioned dimensions¡ the specific cooling power (SCP) of rectangular beds are almost 5% and 17% (for fin heights of 14 and 20mm¡ respectively) better than those of trapezoidal beds. Maximum and minimum SCP of adsorption chiller with flat-tube heat exchanger were obtained about 882 and 163W/kg for the smallest and the largest bed geometry and operating conditions considered in this study.