Development of a Laminar Flow Desiccant Bed for Solar Air Conditioning Application

摘要

Mass transfer in silica gel beds of different configurations is reviewed in connection with use in the Solar-Desiccant-Evaporative Cooling System. A laminar flow, coated-sheet concept is proposed since it ensures a low pressure drop and minimal solid side mass transfer resistance. A preliminary bed design gives 1/3 the pressure drop of a previous packed particle bed design and a large reduction in volume and silica gel inventory. The construction of a packing module and test rig is described, and test results reported for a particle size of 0.12 mm (60 to 200 mesh) with a passage width of about 1.5 mm. In order to compare theory and experiment, an existing code, NUMINT, which solves the partial differential equations governing heat and mass transfer in silica gel beds, was revised to include the effects of substrate heat capacity, and non-adiabatic operation. Comparisons between theory and experiment were found to be generally satisfactory, though it was found that specification of the bed initial water content for adsorption tests presented some difficulties. The effect of solid side mass transfer resistance was found to be small, which suggests that an optimum design may incorporate a larger particle size. Topics for further work are suggested. (ERA citation 09:028179)