Enhancement of the Separate Sensible and Latent Cooling Air-Conditioning Systems

A separate sensible and latent cooling (SSLC) air-conditioning system integrated with a desiccant wheel (where the desiccant is regenerated with the heat from the condenser/gas cooler) provides potential energy savings as compared to a conventional air-conditioning system. The main design challenge is providing sufficient hot air flow rate to the desiccant wheel (DW) for its regeneration, which can easily result in an excessive discharge pressure of the vapor compression system as compared to the conventional system. This paper proposes the idea of applying divided condensers (or gas coolers) to the R410A (or CO2) SSLC system. To investigate the feasibility of this enhancement option, both the baseline and the SSLC air-conditioning systems were modeled. The models were optimized to achieve maximum COP while maintaining the required air regeneration temperature and cooling capacity. The simulation results show that the application of divided heat exchangers to the SSLC system provides sufficient hot air flow for regenerating the desiccant wheel at both a reduced high side pressure (from 10.4 MPa to 9.7 MPa for CO2, from 3.46 MPa to 3.45 MPa for R410A) and a reduced discharge temperature from the condenser (gas cooler) (4K lower for both refrigerants) of the vapor compression cycle. For the CO2 cycle, the simulation results show that the addition of a suction line heat exchanger further improves the performance by 7% on the basis of the SSLC system with divided gas coolers.