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다양한 운전조건에서 이젝터를 적용한 CO<sub>2</sub> 냉동기의 성능비교
강변,조홍현,Kang, Byun,Cho, Hong-Hyun 대한설비공학회 2011 설비공학 논문집 Vol.23 No.7
Recently, many researchers have analyzed the performance of the transcritical $CO_2$ refrigeration cycle in order to identify opportunities to improve the system energy efficiency. The reduction of the expansion process losses is one of the key issues to improve the efficiency of the transcritical $CO_2$ refrigeration cycle. In this study, the analytical study on the performance characteristics of $CO_2$ cycle with an ejector carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the system performance could be improved over 85% by using an ejector for various operating condition because of the reduction of compressor work. Moreover, the cooling capacity increased about 18% for variable outdoor condition. Therefore, the high performance of an ejector system could be maintained for wide operating conditions and system reliability could be improved compared to that of a basic system.
이젝터를 적용한 이산화탄소 냉동사이클의 내부열교환기 길이에 따른 성능 변화
강변(Byun Kang),조홍현(HongHyun Cho) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.2
Recently, many researchers have studied the performance of the transcritical CO2 refrigeration cycle in order to improve the system efficiency. In this study, the length of IHX in the CO2 ejector cycle was varied so as to evaluate the performance improvement. As a result, compressor work and cooling capacity was increased by 3% and 5% as the length of internal heat exchanger was changed from 3 m to 15 m. The best COP was appeared at internal heat exchanger length of 12 m, and it was 3.01. Besides, the length of internal heat exchanger has a big effect to pressure lift ratio and entrainment ratio in the ejector CO2 cycle and it may be changed with operating conditions and system specifications.
성능향상을 위해 이젝터를 적용한 CO₂ 냉동기의 성능비교
강변(Byun Kang),명치욱(Chiwook Myung),조홍현(Honghyun Cho) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
Refrigerating system using an ejector is proposed in order to increase performance and system reliability in a CO₂ cycle. In this study, the analytical study on the performance characteristics of CO₂cycle with an ejector carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the system performance improved by using an ejector for various operating condition because of the decrease compressor work. Besides, the high performance of an ejector system could be maintained for wide operating conditions compared to that of a basic system.
다양한 운전조건에서 이젝터를 적용한 CO₂ 냉동기의 성능비교
강변(Byun Kang),조홍현(Honghyun Cho) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.7
Recently, many researchers have analyzed the performance of the transcritical CO₂ refrigeration cycle in order to identify opportunities to improve the system energy efficiency. The reduction of the expansion process losses is one of the key issues to improve the efficiency of the transcritical CO₂ refrigeration cycle. In this study, the analytical study on the performance characteristics of CO₂ cycle with an ejector carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the system performance could be improved over 85% by using an ejector for various operating condition because of the reduction of compressor work. Moreover, the cooling capacity increased about 18% for variable outdoor condition. Therefore, the high performance of an ejector system could be maintained for wide operating conditions and system reliability could be improved compared to that of a basic system.
R744와 R22를 적용한 태양열 하이브리드 열펌프의 성능 시뮬레이션 비교 분석
강변(Kang, Byun),조홍현(Cho, Honghyun) 한국태양에너지학회 2013 한국태양에너지학회 논문집 Vol.33 No.2
Simulation study of a solar hybrid heat pump using R744 and R22 for residential applications was carried out according to heat pump operating temperature, outdoor temperature and solar radiation. As a result, when the heat pump operating temperature increases from 40℃ to 48℃, the COP of a R744 and R22 heat pump system decrease from 2.15 to 1.7 and from 3.09 to 2.69, respectively. Besides, as the outdoor temperature rises from 3℃ to 11℃, the COP of R744 and R22 heat pump system increase from 1.73 to 2.12 and from 2.73 to 3.02. When the solar radiation increases from 10 to 20 MJ/m², the collector operating time and collector efficiency of R744 heat pump increase 10.3 times and 50.7%, respectively. The performance of R744 solar hybird heat pump is more sensitive to operation condition compared to that of R22. Besides, the solar heating system is more effective to the R744 heat pump system.
다양한 이젝터 상관식을 적용한 이젝터 사이클의 성능 비교
강변(Byun Kang),김진현(Jinhyun Kim),조홍현(Honghyun Cho) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
Recently, many researchers have analyzed the performance of the transcritical CO₂ refrigeration cycle in order to identify opportunities to improve the system energy efficiency. In this study, the various correlations of ejector was applied to CO₂ cycle with an ejector and the COP, compressor work, cooling capacity, entrainment ratio, and pressure lift ratio was compared. As a result, the Yari eq. showed more higher COP, cooling capacity than that of Sarkar eq. and Groll eq. Moreover, Yari eq. presented a lower compressor work than that of other correlations.
봄철 태양열 하이브리드 이산화탄소 열펌프 성능에 대한 고찰
강변(Byun Kang),김진현(Jinyuun Kim),조홍현(Honghyun Cho) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
In this study, the performance of solar hybrid CO2 heat pump for rain day and fair day was analyzed by using experimental method during spring season. The system was consisted of concentric evacuated tube solar collector, heat medium tank, heat storage tank, heat pump, and so on. As a result, the compressor operating time for fair day and rain day was 12 and 17 hours, respectively. The collector operating time, ambient temperature and room temperature for rain day were smaller than for fair day.
내부열교환기를 적용에 따른 이산화탄소 이젝터 사이클의 성능고찰
강변(Byun Kang),조홍현(Honghyun Cho) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
Refrigerating system using an ejector with an internal heat exchanger is proposed in order to increase performance and system reliability in a CO₂ cycle. In the study, the analytical study on the performance characteristics of the ejector cycle with an internal heat exchanger carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the optimal IHX length of the ejector cycle for given operating condition was 12 m, and the maximum COP was 3.1. Besides, the system performance improved by using an internal heat exchanger for various operating condition.
열원의 온도변화에 따른 겨울철 태양열-지열 하이브리드 R22 열펌프의 성능에 관한 해석적 연구
강변(Byun Kang),조홍현(Honghyun Cho) 한국지열·수열에너지학회 2012 한국지열에너지학회논문집 Vol.8 No.4
The solar and geothermal energy have many advantage like low cost, non-toxic, and unlimited. But those have very low energy efficiency. In this study, the theoretical study of performance in a solar-geothermal hybrid heat pump with operating conditions has carried out. As a result, as the solar radiation increases from 1 MJ/㎡ to 20 MJ/㎡, the heat pump operating time decreases by 19.5% from 18 times to 14.5 times and the heat pump heat decreases by 23%. Besides, the heating COP increases by 21.4% when the evaporator inlet temperature increases from 11℃ to 19℃. By adapting the geothermal system into a solar hybrid R22 heat pump, the system performance and reliability increases significantly for variable operating conditions during winter season.