Heat and mass transfer in packed bed liquid desiccant regenerators - An experimental investigation

Liquid desiccant cooling can provide control of temperature and humidity, w hile at the same time lowering the electrical energy requirement for air co nditioning: Since the largest energy requirement associated with desiccant cooling is low temperature heat for desiccant regeneration, the regeneratio n process greatly influences the overall system performance Therefore, the effects of variables such as air and desiccant flow rates, air temperature and humidity, desiccant temperature and concentration, and the area availab le for heat and mass transfer on the regeneration process are of great inte rest. Due to the complexity of the regeneration process, which involves sim ultaneous hear and mass transfer, theoretical modeling must be verified by experimental studies However, a limited number of experimental studies are reported in the literature. This palter presents results from a detailed ex perimental investigation of the heat and mass transfer between a liquid des iccant (triethylene glycol) and air in a packed bed regenerator using high liquid flow rates. To regenerate the desiccant, it is heated to temperature s readily obtainable from flat-plate solar collectors. A high performance p acking that combines good heat and mass transfer characteristics with low p ressure drop is used The rate of water evaporation, as well as the effectiv eness of the regeneration process if assessed based an the variables listed above. Good agreement is shown to exist between the experimental findings and predictions from finite difference modeling. In addition, the findings in the present study are compared to findings previously reported in the li terature. Also, the results presented here characterize the important varia bles that impact the system design.