Performance analysis of a novel augmented desalination and cooling system using modified vapor compression refrigeration integrated with humidification-dehumidification desalination

Abstract

Waste heat rejection to ambient from air conditioning systems is one of the major causes of urban heat island effect. Increased urbanization and living standards leads to increased water demand. In this work, a new design of vapor compression refrigeration system integrated with humidification-dehumidification desalination is proposed without changing the actual size of vapor compression refrigeration system. The present system consists of a compressor, an evaporative condenser, an expansion device, an evaporator and a suction fan. Water to be desalinated is sprayed over the evaporative condenser. The evaporative condenser and the evaporator are also acting as humidifier and dehumidifier of humidification-dehumidification desalination. In order to recover waste heat rejected to ambient, cooling of evaporative condenser using indoor air and subsequent condensation of hot humid air in evaporator is proposed in this work. The proposed system performance such as desalination yield, cooling output, coefficient of performance, gained output ratio, energy utilization factor are analysed for various ambient temperature and relative humidity. The maximum desalination yield and cooling output are 7.35 LPH and 1.89 kW respectively. The highest system coefficient of performance, gained output ratio and energy utilization factor are 2.16, 6.11 and 8.27 respectively at ambient temperature of 20 °C and 30% RH. The annual average desalination and cooling output are 25.884 m3/year and 4.26 MWh/year respectively. The exergy efficiency of the proposed system is 39.34%. The unit cost of desalination is estimated to be $0.0096/L.