Optimization and performance of a small scale adsorption cooling system fully powered by solar energy for hot arid areas

Abstract

The aim of this study is to identify the optimal design parameters of a fully solar-powered adsorption cooling system for residential buildings located in hot arid areas. The proposed system consists of solar collectors, hot water tank, water–silica gel adsorption chiller of 8 kW cooling capacity, cold water tank, fan coil unit, and cooling tower. An optimization based on computer simulation has been conducted for achieving the aim of this study. The proposed system was applied to Assiut, Egypt as a case study. The optimization shows that the optimal design parameters of the proposed system are as follows: 58 m2 solar collecting area, 5.5 m3 hot water tank and 1 m3 cold water tank. The simulation of the proposed system with the optimal design parameters during the design day shows that the chilled water temperature leaving the chiller is between 17 and 18 °C with high cooling water temperature of 34.5 °C. This makes the system unable to achieve the indoor thermal design conditions. However, the system is able to meet the cooling demand in most days of the cooling season except for about 9.15% representing extreme hot days. The simulation also shows that during the design day, the proposed system achieves daily solar collecting efficiency of 56% and can produce chilling energy of 113.3 kWh with 7.35 kW energy rate and daily COP of 0.41. In addition, the cold water tank enables the system to extend the operation period for 110 min after switching off the chiller.