Design and energy analysis of a solar desiccant evaporative cooling system with built-in daily energy storage

Abstract

Heat storage with thermochemical (TC) materials is a promising technology for solar energy storage. In this paper, a solar-driven desiccant evaporative cooling (DEC) system for air-conditioning is proposed, which converts solar heat energy into cooling with built-in daily storage. The system utilises thermochemical heat storage along with the DEC technology in a unique way. Magnesium Chloride (MgCl2·6H2O) has been used, which serves as both a desiccant and a thermochemical heat storage medium. The system has been designed for the subtropical climate of Lahore, Pakistan, for a bedroom with 8 h of cooling requirements during the night. MATLAB has been employed for modelling the system. The simulation results show that 57 kg of magnesium chloride is sufficient to meet 98.8% of cooling demand for the entire month of July at an elevated cooling requirement. It was found that the cooling output of the system increased with increasing heat exchanger effectiveness. The heat exchangers’ effectiveness was increased from 0.7 to 0.8, with the solar fraction increased from 70.4% to 82.44%. The cooled air supplied to the building meets the fresh air requirements for proper ventilation.