Two-Stage Air-Dehumidification System for the Tropics - Assessment of Conceptual System Configurations

摘要

Under tropical climate conditions, conventional air-conditioning systems consume a considerable amount ofrnelectricity in order to get rid of the high latent load (humidity) of the ambient air. This is due to the appliedrnsimultaneous dehumidification and cooling processes. Therefore, an idea of a separate handling of the latentrnand the sensible loads is investigated by applying series connected heat powered dehumidification andrnelectricity powered cooling systems. A two-stage dehumidification system including a membrane-based heatrnand mass exchanger and an Evaporatively COoled Sorptive dehumidification system (ECOS system) isrnproposed to dehumidify the ambient air; the sensible load (cooling of dehumidified air) is handled by anrnefficient conventional cooling process operating at relatively high evaporation temperatures (14-20℃).rnThe aim of this study is to evaluate different conceptual system configurations and to find optimized systemsrnfor tropical climate conditions (air humidity and temperature are in the order of 20 g/kg_(air) and 32℃,rnrespectively) by means of simulation calculations. The dehumidification capacity, the total specific removedrnenthalpy and the thermal coefficient of performance (COP) of the system are used as criteria for anrnassessment of the proposed concepts. The dehumidification system is mathematically modelled in MATLABrnand linked with TRNSYS-17.1. Experimental data are used to validate the components models. Design andrnperformance data of simulated air-dehumidification systems that are based on the concepts are presented.rnResults of the performance assessment show that using additional ambient air flow for the evaporativerncooling process in the ECOS system can improve the dehumidification performance of the system and canrnreduce the cooling load of the cooling system significantly.