Experimental study of a membrane-based liquid desiccant dehumidifier based on internal air temperature variation

Abstract

A membrane-based liquid desiccant dehumidifier with the separated air stream and liquid desiccant channels has the ability to solve its working fluid carryover problem in the traditional direct contact system. The sensible, latent, total effectiveness and air moisture removal rate are adopted for the dehumidifier performance evaluation in this paper, and the dehumidifier main operating parameters are investigated experimentally to identify their influences and internal air temperature variations, including inlet air relative humidity (RH), inlet solution concentration and temperature, heat capacity rate ratio (Cr*) and number of heat transfer units (NTU). It is found that both the inlet air RH and solution temperature have the negative influences on the dehumidifier effectiveness, while the desiccant solution concentration has little positive influence; the air moisture removal rate rises sharply with the inlet air RH and solution concentration. The highest sensible, latent and total effectiveness achieved in this study are 0.823, 0.802 and 0.810 respectively when both Cr* and NTU are equal to 12. However the operating condition with NTU = 8 and Cr* = 6 is recommended with the corresponding sensible, latent and total effectiveness of 0.758, 0.71 and 0.728 respectively.