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냉방주체 운전모드에서 동시냉난방 열펌프 성능향상에 관한 실험적 연구
정현준(Hyun Joon Chung),주영주(Youngju Joo),강훈(Hoon Kang),김용찬(Yongchan Kim),최종민(Jongmin Choi) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.5
The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the improved wall insulation. Hence, a multi-heat pump is required to cover heating and cooling simultaneously for each indoor unit. In this study, the operating characteristics and performance of a simultaneous heating and cooling heat pump in the cooling-main operating mode were investigated experimentally. The system adopted a variable speed compressor using R410A with four indoor units and one outdoor unit. In the cooling-main mode, the heating capacity decreased due to reduction of flow rate to the indoor unit under heating mode operation. The EEV opening was adjusted to increase flow rate to the indoor unit under heating mode operation. The total capacity and COP in the cooling-main mode increased by 20.5% and 29.2%, respectively, compared with those in the cooling-only mode.
정현준(Hyun Joon Chung),김용찬(Yongchan Kim) 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.6
Freezing, refrigerating, cooling and heating loads occurs at the same time in the supermarket, convenient store, etc. An all-in-one heat pump were proposed to handle these loads efficiently. The performance characteristics of the all-in-one heat pump were numerically investigated and compared with those of the multi heat pump and dual heat pump. The cooling mode COP of the all-in-one heat pump using R404c was 133.6% and 33.4% higher than those of the multi and dual heat pump, respectively. The cooling mode COP of the all-in-one heat pump using R410a was 146.0% and 40.5% higher than those of the multi and dual heat pump, respectively. The heating mode COP of the all-in-one heat pump using R404c was 63.7% and 6.5% higher than those of the multi and dual heat pump, respectively. The heating mode COP of the all-in-one heat pump using R410a was 67.9% and 9.2% higher than those of the multi and dual heat pump, respectively.
판형 열교환기에서 에틸렐글리콜 수용액의 열전달 및 압력강하 특성에 관한 실험적 연구
정현준(Hyun Joon Chung),강훈(Hoon Kang),김용찬(Yongchan Kim),이광진(Kwangjin Lee),이동균(Dongkyun Lee),이원희(Wonhee Lee),신완순(Wan-Soon Shine) 대한설비공학회 2018 설비공학 논문집 Vol.30 No.8
Having desirable thermal characteristics, such as a low freezing point, a high boiling point, better stability over a wide range of temperatures, and good thermophysical properties, ethylene-glycol water is a very popular antifreeze and heat-transfer fluid in numerous commercial and industrial applications. In this study, the heat-transfer and pressure-drop characteristics of a brazed-plate heat exchanger were investigated experimentally using ethylene-glycol water and R410a as the two fluids in a plate heat exchanger. The heat-transfer rate and pressure drop of the ethylene-glycol water were measured by changing inlet temperature, volumetric flow rate, and composition. The inlet temperature, volumetric flow rate, and composition were varied from 12.0 to 30.0℃, 4.9 to 26.8 lpm, and 30 to 55 percent, respectively. In addition, correlations were proposed to predict the heat-transfer coefficient and friction factor.