Energy Performance and Applicability Comparison of Two Different Types of Liquid Desiccant Assisted Evaporative Cooling Systems

Abstract

A desiccant enhanced evaporative (DEVap) cooling system has been introduced recently using at least vapor compression technology. The main components of the DEVap cooling system are a DEVap unit, a regenerator, a cooling coil and a reheating coil. This system is based on variable air volume system to deal with space load and it requires specific outdoor air intake strategies according to the outdoor air condition. The DEVap unit cools and dehumidifies the process air to control the room condition and cooling coil conducts extra cooling when the humidity ratio of the air is extremely high. A liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) which uses non vapor compression technology consists of a liquid desiccant, an indirect and a direct evaporative cooler and a sensible heat exchanger. The purpose of this research is to compare energy performance of the DEVap cooling system and applicability with those of the LDIDECOAS system by simulation in cooling season. The operating energy consumption will be estimated using TRNSYS 17 integrated with commercial equation solver (EES). In terms of fan energy consumption, LD-IDECOAS consumed 19% more energy because of pressure drop caused from each component compared with the VAV system. The DEVap cooling system consumed 46% more fan energy according to increased pressure drop and additional fans. For the regeneration of solution, the LDIDECOAS required 4 times more natural gas because it introduces 100% outdoor air in cooling season compared with the DEVap cooling system. As a results, the DEVap cooling system saved 84% and the LD-IDECOAS saved 71% of primary energy compared with the conventional VAV system.