Comparative Energy and Exergy Analyses of Air Conditioning Systems Integrated with an Air Enthalpy Exchanger for Different Refrigerants

Abstract

Energy and exergy analyses were conducted for air conditioning (AC) systems with and without an enthalpy exchanger, based on four common refrigerants: R44A, R47C, R41A, and R51A. The investigated AC system had better performance, with cleaner operation, when integrated with an enthalpy exchanger, which lowered its energy demand. Key performance indicators assessed were COP, evaporator cooling load, compressor input power, exergy efficiency, exergy destruction rate, irreversibility ratio, fuel depletion ratio, and productivity lack. Although the improvement in COP when an enthalpy exchanger was used was shown to be small, cooling load and input power decreased significantly. Moreover, the exergy destruction rate was significantly reduced (by more than 55%) and consequently exergy efficiency was improved. The AC system operating on R47C had the highest exergy efficiency (33%). However, a system operating on R41A is recommended because it requires the lowest compressor input power to maintain a given temperature and thus provides the best performance (COP=5.7). On average, the compressor and the evaporator were found to have the highest irreversibility ratios: .26 and .37, respectively.