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팽창기를 적용한 이산화탄소 냉방시스템의 성능특성에 관한 해석적 연구
조홍현,백창현,류창기,김용찬 대한설비공학회 2007 설비공학 논문집 Vol.19 No.9
A CO2 cycle shows large throttling loss during the expansion process. The application of an expander into the CO2 cycle can reduce the throttling loss and then improve system performance. In this study, the performance of a transcritical CO2 cycle with an expander was analytically investigated in order to improve the cooling performance of the system. The expander was applied to the single-stage and two-stage compression cycles. The performance was analyzed with the variations of compressor frequency, outdoor temperature, and expander efficiency. The single-stage and two-stage compression cycles with the expander showed COP improvement of 25% and 32%, respectively, over the single-stage cycle with an EEV.
김현재(Kim, Hyun-Jae),김유찬(Kim, You-Chan),김현진(Kim, Hyun-Jin) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.11
A steam Rankine cycle was considered to recover waste heat from the exhaust gas of an automobile. Conceptual design of a swash plate type expander was practiced to convert steam heat to shaft power. With the steam pressure and temperature of 35 bar and 300?C at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 1.93 kW from the exhaust gas waste heat of 20 kW. The expander output increased linearly accordingly to the amount of exhaust gas waste heat in the range of from 10-40 kW, and the Rankine cycle efficiency was more or less constant at about 9.6% regardless of the waste heat amount.
김호영(Ho Young Kim),안종민(Jong Min Ahn),김현진(Hyun Jin Kim),조성욱(Sung Oug Cho) 대한설비공학회 2009 설비공학 논문집 Vol.21 No.1
Relatively low cycle performance of a conventional CO₂ system is partly due to significant increase in friction loss in the expansion process, since the pressure drop across the expansion device is considerably large compared to a conventional refrigeration cycle. To recover friction loss and increase refrigeration effect by providing isentropic expansion, a rotary vane type expander has been designed. Performance of the designed expander has been investigated by numerical simulation. With the pressure condition of 9 ㎫/4.5 ㎫ and inlet temperature of 35 ℃, volumetric, isentropic, and mechanical efficiencies of the expander are calculated to be 58.1%, 101.1%, and 78.8%, respectively, resulting in total expander efficiency of 46.3%. With this expander, COP of a CO₂ refrigeration cycle is estimated to be improved by about 14%.
김현재(Hyun Jae Kim),김현진(Hyun Jin Kim) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.5
For a steam Rankine cycle to recover waste heat from the exhaust gas of an internal combustion engine, a swash plate type of expander as a power conversion unit has been designed. Numerical simulation has been carried out to estimate the performance of the designed expander. With the steam pressure and temperature of 35 bar and 300℃ at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 2.67 kW from the exhaust gas waste heat of 25.2 kW. The expander output increased almost linearly with the amount of exhaust gas waste heat in the range of from 5~40 ㎾, and the expander and Rankine cycle efficiencies showed gradual decreases in the ranges of 72.2%~69.5% and 10.8%~10.4%, respectively.
김현재(Hyun Jae Kim),김성준(Sung Jun Kim),김유찬(You Chan Kim),김현진(Hyun Jin Kim) 한국유체기계학회 2009 유체기계 연구개발 발표회 논문집 Vol.2009 No.-
A steam expander has been studied for its usability as a power conversion device in a Rankine cycle, which can be used for on site power generation or waste heat recovery. Design of swash plate type expander has been practiced and its performance has been estimated. With the steam pressure and temperature of 35bar and 300℃ at the expander inlet, respectively, it was calculated that the expander produced the shaft power output of about 5㎾ from steam energy of 35㎾. Adiabatic and mechanical efficiencies of the designed expander were 86.5% and 96.7%, respectively. With the volumetric efficiency of 90%, the total efficiency of the expander was 75.3%.