Theoretical study on a frost-free household refrigerator-freezer

• A frost-free household refrigerator-freezer is proposed in this paper.
• Desiccant is applied to dehumidify the air before it enters evaporator.
• Condensation heat of the refrigerant is used to regenerate the desiccant.
• The proposed system can achieve high energy efficiency.

This study deals with a frost-free household refrigerator-freezer, in which frosting can be retarded by dehumidifying the air before it enters the evaporator of the refrigerator-freezer 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 household refrigerator-freezers), the proposed system can achieve high energy efficiency. Calculations show that the coefficient of performance of this system (COP) is within the range 1.5–2.5 at an ambient temperature of 15–35 °C. Moreover, it is found that the relative humidity of the refrigerator air (RHRA) and the temperature of freezer air (TFA) have a significant effect on COP: COP decreases by about 13% when RHRA varies from 0.4 to 0.8 and by 10% when TFA runs from −18 to −23 °C.