Performance study on the dehumidi fier of a packed bed liquid desiccant system

A liquid desiccant evaporation cooling air conditioning system is introduced in this paper, in which the dehumidier and regenerator play the most important role. For liquid-gas contact, packed towers with a low pressure drop provide good heat and mass transfer characteristics for compact designs. The experimental data have been obtained from a built prototype of a liquid desiccant system in a packed bed unit with a surface area per unit volume ratio of 125 m2/m3; the liquid desiccant being lithium chloride. The result showed that the mean mass transfer coecient of the packing dehumidier was 0.02 kg/m2s. Also, the absorber characteristic parameter, the packing size or Number of Transfer Units (NTU) and Air-to-desiccant Solution Mass ow Rate ratio (ASMR) are crucial parameters. These parameters, which aect humidity eectiveness and enthalpy eciency, are introduced and dened in this paper, and high eciency may be achieved if proper values of these variables are selected. In this study, enthalpy eciency from experimental results has been compared with analytical computation results based on optimum ASMR. From the analytical solution, an optimum mass ow rate ratio can be deduced for optimal design of both dehumidiers and regenerators. In this study, the behavior of the absorber has also been considered.