Theoretical study on a frost-free refrigerated display cabinet

•A frost-free refrigerated display cabinet system is proposed.•Frosting can be retarded by dehumidifying the air of the evaporator via a desiccant.•The COP of the proposed system is 3.1. This study deals with a frost-free refrigerated display cabinet, in which frosting can be retarded by dehumidifying the air before it enters the evaporator of the display cabinet via a desiccant-coated heat exchanger. Because the desiccant can be regenerated via the condensation heat of the refrigerant (which is exhausted into ambient air in conventional refrigerated display cabinets), the proposed system can achieve high energy efficiency. Calculation shows that the coefficient of performance (COP) of this system is 3.1 and the daily electricity consumption of the compressor is 10.5 kWh when the temperature (TRA) and relative humidity (RHRA) of the return air entering the evaporator are 12 °C and 0.6, respectively. Furthermore, it is found that TRA and RHRA significantly affect the COP: COP increases by about 115% when TRA varies from 8 to 14 °C, and increases by 35% when RHRA varies from 0.5 to 0.8.