In this study, defrost efficiency and its effects on system performance in a top mount domestic freezer have been investigated. A dual evaporator system, where two separate evaporators are connected either serially or in parallel, is used to discuss advantages and disadvantages of defrosting methods. Evaporators are located in each individual freezer and fresh food compartment. Since the fresh food evaporator's inlet air temperature is normally higher than 5ºC, it seems like a good idea to use this warm air for defrosting. The term "air defrosting"is used for this process, which is simply circulating the fresh food compartment air through the evaporator while the compressor is in the off position. In order to see the effects ofair defrosting, three possible cases are investigated experimentally. These methods are 1) heater defrost on both evaporators, 2) heater on freezer evaporator and air defrosting on fresh food evaporator, 3) heater on freezer evaporator and a combination of heater and air defrosting on fresh food evaporator. The separate and combined defrosting of the evaporators is also studied. Defrost efficiency and effects of defrostingin refrigerator energy consumption are measured. In the experiments, the effect of door opening is also included.

Units: SI