SINOPSIS

Control of humidity in air conditioning application plays a vital role in the energy requirement and indoor air quality. Desiccant dehumidification system is one of the energy efficient alternatives to conventional air conditioning system for humidity control. Direct contact and indirect contact dehumidifiers are the two major types of liquid desiccant dehumidifiers. Indirect contact dehumidifiers avoid desiccant carryover problem in the direct contact dehumidifiers whereas they have a higher heat and mass transfer resistance. Therefore, selecting a dehumidifier for the given application becomes crucial, and hence, the comparison between the dehumidifiers becomes essential for selecting a dehumidifier for high mass transfer or desiccant free air. In the present study, the performance of the direct contact and indirect contact dehumidifiers is compared with the same contact area under the effect of operating parameters for the hot and humid climatic conditions prevailing in Chennai. The operating parameters of air side are inlet temperature, mass flow rate and specific humidity, whereas those of the desiccant side are inlet temperature, mass flow rate and concentration. The mass transfer performances are compared in terms of moisture removal rate and latent effectiveness. The results show that the direct contact dehumidifiers have 40−75% higher mass transfer performance than the membrane dehumidifier with 2 to 10 times higher pressure drop on the air side as well as higher exergy destruction.