압축기 발열을 이용한 냉장고 도어 히터에 루프 히트파이프의 적용에 관한 연구

Abstract

Nowadays the electric heater is used to prevent freezing in a freezer door. The heater is turned on to always be there, a lot of energy is consumed when the heater is in use for a long time. To solve this energy problem, We decided to use the heat of the compressor waste heat as a heat source of the heater and developed the door heater using Loop Heat Pipe(LHP) in order to reduce energy consumption at the freezer. LHP is operated by nucleate boiling in the evaporating section, and the boiling heat rate is transported to the condensing section by oscillation and circulation. And large amount of heat is transferred by the latent heat from evaporating section to condensing section. We conducted a comparison experiment between the traditional electric heater and the door heater using LHP. This experiment was conducted under next conditions : Material of LHP was copper, working fluid was R-134a, R-410a, R-600a, charging ratio was 35%, 40%, 45%, 50%. Experimental equipment consists of LHP, freezer, thermocouple, data logger and PC for data acquisition. In order to confirm the proper operation of the LHP, T-type thermocouples were attached to the surface of the heat pipe (eight point of condensing part, two points of adiabatic part, two points of evaporating part). And we confirmed about energy savings about power consumption comparison. As a results, the temperature of LHP was about 29.0℃ ~ 31℃ and electric heater was 10℃ ~ 16.1℃ respectively in steady state. This shows that the temperature of the electric heater is not constant. The temperature difference of LHP among each point was only 0.2℃. But the temperature difference of electric heater amon each point was 7.9℃. This means that the temperature distribution of the electric heater is not even. As a results of power consumption comparison, power consumption of the freezer applied LHP can save 12 percent than power consumption of the freezer applied traditional electric heater. From the above results, we confirm the possibility of the door heater using LHP.