Experimental Comparative Study on Lithium Chloride and Calcium Chloride Desiccants

Abstract

Desiccants liquid or solid can be used in conjunction with solar energy to provide a viable alternative to traditional air-conditioning technique. In order to select the best desiccant for using in the liquid desiccant cooling system an experimental comparative study has been carried out on dehumidification/ regeneration process using CaCl2 and LiCl under the same operating conditions. The effect of air velocity and relative humidity on these processes has been analyzed. It is found that these two desiccants are able to attract moisture from the air and can be regenerated at low temperature 40°C. LiCl and CaCl2 are able to undergo successive cycles during many days by obtaining nearly their concentration. The concentration gap between the regeneration phases is very small within an average of 0.003% for CaCl2 and 0.042% for LiCl. The amount of water absorbed is nearly equal to the amount of water desorbed, in equilibrium condition, for a complete cycle. The comparison shows that, in the dehumidification process, the mass transfer potential of LiCl solution is better than that of CaCl2 solution in the same desiccant mass. On the other hand, in the regeneration process, CaCl2 solution shows better mass transfer potential compared with LiCl solution. For using in (LDCS), CaCl2 is very cheap while has the poorest absorption ability, but the ability of LiCl to dehumidify is far better. Also, it is found that a higher Reynolds number gives a higher potential of mass transfer.