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스윙펌프를 내장한 가변속 스크롤 압축기의 오일공급시스템에 관한 CFD 시뮬레이션
조홍현,김용찬,유병길 대한설비공학회 2003 설비공학 논문집 Vol.15 No.1
An analytical study was carried out to investigate the performance of an oil pumping system of a variable speed compressor using a commercial CFD program. The simulations for the oil supplying system with the oil and air mixture were performed by varying compressor speed from 40 Hz to 90 Hz. Comparing the predicted with the measured data on the modified scroll compressor validated the simulation model. The predicted results were consistent with the test data with a maximum deviation of 12.8%. The oil flow rate significantly increased with a rise of compressor speed due to a higher oil flow rate from the swing pump and a greater centrifugal force on oil gallery.
냉매충전량이 초임계 이산화탄소 사이클의 냉방성능에 미치는 영향에 대한 연구
조홍현,류창기,김용찬,심윤희 대한설비공학회 2005 설비공학 논문집 Vol.17 No.5
The cooling performance of a transcritical CO2 cycle varies significantly with a variation of refrigerant charge amount. In this study, the performance of the CO2 system was measured and analyzed by varying refrigerant charge amount at a standard test condition. Besides, the losses of the major components in the CO2 system were estimated by evaluating entropy generation with refrigerant charge amount. The losses in the expansion device and the gascooler show the major portion of the total loss. For undercharging conditions, the expansion loss dominates the overall system performance, while the gascooler loss increases significantly with an increase of refrigerant charge amount.
이산화탄소를 적용한 주거용 냉난방 겸용 열펌프 시스템의 시뮬레이션
조홍현,이무연,김용찬 대한설비공학회 2003 설비공학 논문집 Vol.15 No.12
The performance of a residential heating and cooling system with CO2 is predicted by using a cycle simulation model. The simulations are conducted by varying design parameters and operating conditions. The efficiency of the transcritical cycle can be improved by utilizing the advantages in heat transfer characteristics of CO2 and developing microchannel indoor and outdoor heat exchangers. For the designed system of this study, the predicted COP of the heat pump system is approximately 3.5 in the heating mode and 3.0 in the cooling mode. The predicted optimal discharge pressure for the heat pump system is approximately 11 MPa in the heating mode and 9 MPa in the cooling mode.