Performance of a Liquid Desiccant Solar Air Conditioner - An Experimental and Theoretical Approach

Application of liquid desiccant in air dehumidification /cooling appears promising in hot and humid locations of Iran, such as the Persian Gulf region, due to high availability of solar energy in summer. Dehumidification and indirect evaporative cooling of outside air are both achieved through a cross flow polymer plate heat exchanger, using lithium chloride solution as the desiccant. The dilute solution from the dehumidification process is concentrated in a scavenger air regenerator using hot water from flat plate solar collectors. Carryover of the desiccant particles has been avoided by using eliminators, such as demister or filter. Alternative methods in preventing the carryover are the application of a porous contact media that is flooded with solution or the use of indirect cooling, in which the supply air does not contact the desiccant. The latter could also be used to produce potable water from the atmospheric air in remote areas. In this paper the experimental results obtained from testing the prototype of a liquid desiccant absorber unit has been presented and compared with a previously developed model for the cross flow polymer plate heat exchanger. The comparison reveals that good agreement exists between the experiments and model predictions. The inaccuracies are well within the measuring errors of the temperature, humidity and the air and solution flow rates. The above tests further reveal that the unit has a satisfactory performance in controlling the air temperature and humidity of a commercial site of 200m2 area in Bandar Abbas. A commercialization strategy has been proposed in this study for a solar operated liquid desiccant air conditioner and compared with conventional vapour compression system. Based on the computer modelling results obtained from the system simulation for a building in Bandar Abbas, the operating costs of a liquid desiccant air conditioner is significantly lower than its conventional DX counterpart. This study further reveals that, for higher gas prices, using the solar operated liquid desiccant air conditioner with a storage system will result in considerable savings in operating costs when compared with the equivalent gas-fired liquid desiccant system. A simple payback of five years was determined for the solar components of the liquid desiccant system in this study.

کلیدواژه ها:

Liquid desiccant ، dehumidification ، plate heat exchanger ، solar regeneration