Investigation of a Storage Type Solar-Driven Solid Desiccant Cooling System

Abstract

Solar-driven solid desiccant assisted evaporative cooling could be an effective alternative to conventional vapour compression cooling systems due to its lower operating costs and lower environmental impact. This technology has been widely investigated for continuous operation through the use of desiccant wheels. However, the investigation of such technology for storing solar radiation in the form of coolth energy is missing in the literature. In that regard, primary objective of the present study is to investigate a fixed bed solar driven desiccant assisted evaporative cooling system, that uses vermiculite-calcium chloride composite sorbent, to be utilized as a coolth storage in hot-humid climate. To achieve this aim, a prototype unit was designed, developed and tested under real climatic conditions of North Cyprus. According to the results, over six hours of charging period, at regeneration temperature between 51 – 62 °C and air mass flow rate of 0.03 kg/s, average moisture desorption rate of 3.9 g/min was obtained. On the other hand, over four hours of discharging at air inlet temperature of 32 – 35 °C and mass flow rate of 0.06 kg/s, vermiculite-calcium chloride / wood chips couple provided average air temperature drop and cooling capacity of of 8.4 °C and 0.49 kW respectively. Hygrothermal efficiency of the system is also found 0.65. Additionally, the average wet-bulb effectiveness and average dew-point effectiveness were obtained as 121.6%, and 90.2% respectively. Furthermore average total and thermal coefficient of performance of 0.35 and 0.6 were achieved over the three consecutive cycles. These results suggest that the proposed system could be a potential technology for storing solar energy to be used in air conditioning applications in buildings.