이산화탄소를 적용한 급탕 열펌프 시스템의 운전조건 변화에 따른 성능특성에 관한 실험적 연구 = Experimental study on the performance of a CO2 heat pump water heater system under various operating conditions

다국어 초록 (Multilingual Abstract)

In this study, a CO2 heat pump water heater system was built and the performance was measured in steady state under various operating conditions such as refrigerant charge amount, EEV opening, compressor frequency, water mass flow rate, and outdoor temperature. The optimum refrigerant charge amount was 1600 g. The CO2 system was optimized at each outdoor temperature. At outdoor temperatures of 25/21, 16/12, and 7/6℃, the optimum EEV openings were 16, 16, 16%, the compressor frequencies were 50, 50, 60 Hz, and water mass flow rate were 115, 105, 105 kg/h respectively. At these conditions, COPs were 2.92, 2.96, 2.75, and water heating temperatures were 71.9, 67.4, 66.8℃ respectively. At the outdoor temperature of 2/1℃, the outdoor heat exchanger was frosted and the COP and water heating temperature decreased with time.
Transient performance tests were also conducted to investigate major system effects associated with the interaction between the CO2 heat pump water heater and the water tank. In this study, the transient state means that the water inlet temperature varies with time. There were two scenarios to conduct transient performance tests. One was initial tank heating and the other was reheating the tank after normal water usage. In the transient condition, the instantaneous COP and heating capacity rapidly decreased as the inlet water temperature increased.

목차 (Table of Contents)

• Abstract i
• Contents iii
• List of Figures v
• List of Tables ix
• 제 1 장 서론 1
• 1.1 연구배경 1
• 1.2 연구동향 3
• 1.3 연구 목적 및 내용 7
• 제 2 장 실험장치 및 실험방법 9
• 2.1 실험장치의 구성 9
• 2.2 계측장치 구성 18
• 2.3 실험방법 및 실험조건 25
• 2.4 성능 계산 28
• 제 3 장 정상상태에서 급탕 시스템의 성능특성 29
• 3.1 냉매 충전량에 따른 시스템의 급탕 성능특성 29
• 3.2 EEV 개도 변화에 따른 시스템의 급탕 성능특성 35
• 3.3 압축기 주파수에 따른 시스텝의 급탕 성능특성 41
• 3.4 급수유량에 따른 시스텝의 급탕 성능특성 47
• 3.5 외기온도에 따른 시스텝의 급탕 성능특성 52
• 제 4 장 천이상태에서 급탕 시스템의 성능특성 63
• 4.1 초기 운전시 시스템의 급탕 성능특성 66
• 4.2 온수 사용 후 시스템 재가동시 시스템의 급탕 성능특성 72
• 제 5 장 결론 79
• 5.1 정상 상태에서의 이산화탄소 급탕 시스템 성능특성 79
• 5.2 천이 상태에서의 이산화탄소 급탕 시스템 성능특성 81
• 5.3 향후 계획 82
• 참고문헌 83