A Feasibility Study of Using Solar Liquid-Desiccant Air Conditioner in Queensland, Australia

A feasibility study of using solar liquid-desiccant air conditioner (LDAC) developed in Queensland has been undertaken. The system uses high effectiveness cross-flow polymer plate heat exchanger (PPHE), as the absorber unit. Outside air is dehumidified by strong liquid desiccant and indirectly cooled within the PPHE. The warm dry air is, subsequently, cooled and humidified through a direct evaporative cooler and supplied to the conditioned space. The weak desiccant solution from the absorber unit is concentrated in a scavenger air regenerator using hot water from flat plate solar collectors. The prototype of the absorber unit of the liquid-desiccant system has been tested under the summer conditions of Brisbane, using lithium chloride as the absorbent solution. The results of the experiments indicate that they are in good agreement with a previously developed model for the absorber unit. The tests further reveal that the unit has a satisfactory performance in controlling the air temperature and relative humidity when installed on a commercial site of $120m2$ area in Brisbane. A commercialization strategy has been proposed in this study for a solar operated LDAC in Queensland and compared with the conventional direct expansion (DX) system. Based on the computer modeling results obtained from the system simulation for a building in Cairns, North Queensland, the operating costs of the LDAC are significantly lower than its conventional DX counterpart. This study further reveals that using the solar operated LDAC with a storage system will result in considerable savings in operating costs when compared with the equivalent gas-fired system. A simple payback of five years was determined for the solar components in this study.