Comparative study on the liquid desiccant dehumidification performance of lithium chloride and potassium formate

Abstract

Liquid desiccant dehumidification is promising as it could be driven by renewable energy. In the present study, it newly investigated the dehumidification characteristics of KCOOH solution in an internally cooled dehumidifier. To select suitable concentration range, the vapor pressure of KCOOH solution with different solution concentration and temperature was measured with static method firstly. Then comparative experimental study was conducted to identify the dehumidification performance of KCOOH and LiCl solution under different solution and air flow rate, temperature and air humidity. Experimental results indicated that 70.3% KCOOH solution had almost the same vapor pressure as 35% LiCl solution. Under the same experimental conditions, the absolute moisture removal of 70.3% KCOOH solution was slightly higher than that of 35% LiCl solution as a result of the increased wetting area. It was found that the mass transfer coefficients of the two liquid desiccants were almost the same. An empirical correlation of Sh number was obtained to predict the mass transfer coefficient of KCOOH solution for dehumidification with a mean absolute relative deviation of 7.81%.