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루버핀을 적용한 이산화탄소 마이크로채널 증발기의 서리성장에 따른 성능 해석
신은성(Eunsung Shin),조홍현(Honghyun Cho) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
The performance characteristics of a microchannel evaporator with louver fin are analyzed according to the frost growth. Under the fixed conditions of inlet air, the performance of a micochannel heat exchanger was analyzed with the variations of time and inlet quality. As a result, the frost thickness of fin and tube surface and the block ratio increase as operating time rises. Besides, the cooling capacity decreases by 23.7% when the time has passed 120 minutes.
서리성장에 따른 이산화탄소용 마이크로채널 증발기의 성능에 관한 해석적 연구
신은성(Eunsung Shin),조홍현(Honghyun Cho) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.10
The microchannel evaporator with louver fin using carbon dioxide are analyzed according to the frost growth. To predict the performance of microchannel evaporator with the frost growth under low temperature, the simulation condition of previous studies was applied. As a result, the frost thickness increases and its increasing rate is reduced when the operating time increases. Frost thickness increases gradually below the quality of 0.74, and then it decreases rapidly. In addition, the frost growth of present model under same surface temperature is very similar trends with Moallem’s test results. In case of low temperature application, the dimensionless frost thickness increases dramatically and it is about 0.86 after 10 minutes.
운전조건 변화에 따른 CO₂ 적용 마이크로채널 증발기의 최적화 연구
신은성(Eunsung Shin),김지호(Jiho Kim),홍명석(Myung-suk Hong),조홍현(Honghyun Cho) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
The purpose of this study is to determine the performance characteristics for the micro-channel evaporator with various operating conditions. The performance of four kind of HX models were analyzed and optimized with the variation of refrigerant inlet pressure, mass flow rate, air velocity, and outdoor temperature. As a result, the evaporator with 13 tubes showed the maximum capacity with variable operating conditions due to the increase of heat transfer area. In addition, the pressure drop of the evaporator with 13-tube increased significantly because the heat flux improved owing to the decrease of cross section area.
CO₂용 마이크로채널 가스쿨러의 운전조건 변화에 따른 성능특성에 관한 해석적 연구
신은성(Eunsung Shin),배경진(Kyungjin Bae),김병철(Byeongcheol Kim),조홍현(Honghyun Cho) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
The purpose of this study is to determine the performance characteristics for the micro-channel gascooler with various operating conditions. The performance of four kind of HX models were analyzed and optimized with the variation of refrigerant inlet temperature, air velocity, outdoor temperature. As a result, Model B showed the maximum capacity and high performance could be maintained for wide operating conditions. Beside, the micro-channel heat exchanger could be appled to CO₂ system appropriately because of a small pressure drop and high heat transfer rate.
압력조건 변화에 따른 이단압축 이산화탄소 사이클 성능 해석
신은성(Eunsung Shin),조홍현(Honghyun Cho) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
The simulation research on the performance of two-stage compression CO₂ cycle has carried out with the operating conditions. To analysis the performance characteristics and the variation of two-stage compression CO₂ cycle, the middle and discharge pressure was changed by using the variation of 1<SUP>st</SUP>- and 2<SUP>nd</SUP>-stage EEV opening. As a results, the COP decreased by 29.5% when the outdoor temperature rose from 30℃ to 40℃ for basic condition. In addition, the COP increased about 0.6% with the increase of 1<SUP>st</SUP>-stage EEV opening. The system had the maximum COP when the 2<SUP>nd</SUP>-stage EEV opening was 54% at the fixed 1<SUP>st</SUP>-stage EEV opening of 16%. In this study, the 2<SUP>nd</SUP>-stage EEV opening should be operated below 20% in order to protect the wet compression at compressor.
이산화탄소 열펌프 성능특성에 대한 수치 및 실험결과 비교
신은성(Eunsung Shin),조홍현(Honghyun Cho) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
The experimental and numerical study under the same conditions was carried out to analysis the performance characteristics of the CO₂ heat pump. Based on the proved simulation, the performance characteristics were investigated with variation of EEV opening and compressor frequency. As a results, the COP of the simulation was 0.54 higher than that of the experiment. In addition, the optimal EEV opening of simulation was by 26%. The COP was decreased by 8.2% when the compressor frequency rose from 30 ㎐ to 60 ㎐ at the optimal EEV opening.
배경진(Kyungjin Bae),신은성(Eunsung shin),홍명석(Myung-suk Hong),조홍현(Honghyun Cho) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
Since the operating pressure of CO₂ gascooler is so high compared with that of previous subcritical condenser, the optimization of gascooler is needed for improve heat exchanger performance. In this study, the performance characteristics of five kinds of heat exchangers were analyzed and compared with operating conditions. As a result, the 4-20 HX-tube shows the maximum gascooler capacity because the heat transfer is effective and pressure drop is small. Beside, the high performance of 4-20 HX-tube could be keep for wide operating condition.
운전조건 변화에 따른 이산화탄소 냉방시스템들의 성능 비교
배경진(Kyungjin Bae),신은성(Eunsung Shin),조홍현(Honghyun Cho) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
Since the cooling performance of a CO₂ cooling cycle is varied significantly with a variation of refrigerant charge amount and outdoor temperature, the reliability of CO₂ system is down. In this study, the performance characteristics of three kinds of CO₂ systems were measured and analyzed by varying refrigerant charge amount and outdoor temperature so as to study the characteristics of variation with cycle option. The applied system options are the single-stage compression(1C-1E) system, two-stage compression with 1-EEV(2C-1E) system, and two-stage compression with 2-EEV(2C-2E) system. The performances of two-stage compression with 2-EEV system were less sensitive than those of other systems and the system operated safely and steadily for wide charge amount. The performance of the two-stage compression with 1-EEV(2C-1E) system was the most sensitive to the charge amount, and that of the single-stage compression(1C-1E) system varied a lot with outdoor temperature.