Studies on solid desiccant based hybrid air-conditioning systems

Desiccant based air-conditioning systems offer a promising alternative to conventional air-conditioning systems using vapour compression refrigeration especially under conditions involving high latent loads. The desiccant can be used either in a stand-alone system or coupled judiciously with a vapour compression system to achieve high performance over a wide range of operating conditions. In this paper, the results of a detailed study of solid desiccant-based hybrid air-conditioning systems are presented. The literature review revealed that various authors differ in their evaluation of the efficacy of these systems. This seems to be due to different methods of modelling of dehumidifier and differences in the operating conditions of the cycles employed. Accordingly, the performance of four hybrid cycles (which include a new proposed cycle) for typical hot-dry and hot-humid weather conditions has been evaluated using a detailed procedure for the analysis of rotary dehumidifier, the most commonly employed industrial dehumidifier, based on the analogy method of Maclaine-Cross and Banks [I.L. Maclaine-Cross, P.J. Banks, Coupled heat and mass transfer in regenerators — predictions using an analogy with heat transfer, Int. J. of Heat and Mass Transfer 15 (1972) 1225–1241]. Effect of room sensible heat factor, ventilation mixing ratio, and regeneration temperature has also been studied. The results show that solid desiccant-based hybrid air-conditioning systems can give substantial energy savings as compared to conventional vapour compression refrigeration based air-conditioning systems in most commonly encountered situations.