Impact of Multi-Stage Liquid Desiccant Dehumidification in a Desiccant and Evaporative Cooling-Assisted Air Conditioning System

Abstract

The purpose of this study is to investigate the energy conservation of multi-stage liquid desiccant system operation in a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS). To enhance the dehumidification performance, a cascade liquid desiccant approach is applied in the conventional LD-IDECOAS (CLDIDECOAS). The CLD-IDECOAS consists of a cascade liquid desiccant (CLD) unit along with direct and indirect evaporative coolers. The process air is dehumidified twice with the CLD to improve the cooling capacity of the evaporative coolers. Both conventional and proposed systems were integrated with water-side free cooling, by using the cooling tower to cool the desiccant solution. To evaluate the energy performance, both systems were simulated to serve an office space, and the results of the simulation were analyzed. The program TRNSYS 17 was used to estimate the thermal load of the model office space and cooling tower performances, whereas the energy consumption of both proposed systems were predicted using a commercial equation solver software, EES. The results showed that the CLD-IDECOAS consumed similar primary energy, but had lower thermal COP (TCOP) than the base case, due to more energy being used in the pumps and cooling tower.