Experimental study on a new finned tube defrosting heater for household frost-free refrigerators

Abstract

For frost-free refrigerators, the tubular metal sheathed type defrosting heater installed at the downstream of the evaporator is usually stainless steel circular tube defrosting heater (CTDH). During the defrosting process, a large part of the heat leaks into the cabinets of the refrigerator, causing the cabinet temperature to rise. This paper proposes a finned tube defrosting heater (FTDH) by using an aluminum alloy finned square tube as the metal sleeve of the defrosting heater. The external surface area of the defrosting heater is greatly increased due to the existence of the fins, thus strengthening the natural convection between the air and the defrosting heater and shortening the defrosting duration. The defrosting performance (defrosting duration, temperature rise, energy consumption) between FTDH and CTDH are compared experimentally. Results show that the whole defrosting cycle duration is shortened by 12%, while the freezer cabinets (FCs) temperature rise is reduced by 2.1 °C and the maximum FC temperature is reduced by 2.4 °C. In addition, the shorter defrosting operation cycle and the lower FC maximum temperature result in a 10.4% reduction in energy consumption of the whole defrosting cycle. In conclusion, FTDH is promising in refrigerators for reducing the FC temperature rise, shortening the duration and decreasing energy consumption during the defrosting cycle.