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정동호(D.H. JUNG),신승호(S.H. SHIN),남보우(B.W. Nam),김현주(H.J. KIM),이호생(H.S. LEE),문덕수(D.S. MOON) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
A mooring line for keeping the position of a floating wave energy conversion is designed with using a commercial software, Ores flex. Static analysis for one line is performed to decide the properties and pretension of a mooring line. With considering the ocean environmental condition and importance of a floating structure, the layout of multi-line is determined. The result of free decay of the designed mooring system estimates that the designed mooring system meets the resonance on the extreme ocean environment si condition. The initial design for mooring line is inevitably modified with adjustment of pretension. Adjustment of pretension with the change of length of mooring line results in the decrease of the ultimate tension on mooring line. The extreme value in tension of mooring line shows to be very sensitive to pretension of mooring line.
정동호(D.H. JUNG),신승호 (S.H. SHIN),남보우(B.W. Nam),김현주(H.J. KIM),이호생(H.S. LEE),문덕수(D.S. MOON) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
A mooring line for keeping the position of a floating wave energy conversion is designed with using a commercial software, Orcaflex. Static analysis for one line is performed to decide the properties and pretension of a mooring line. With considering the ocean environmental condition and importance of a floating structure, the layout of multi-line is determined. The result of free decay of the designed mooring system estimates that the designed mooring system meets the resonance on the extreme ocean environmental condition. The initial design for mooring line is inevitably modified with adjustment of pretension. Adjustment of pretension with the change of length of mooring line results in the decrease of the ultimate tension on mooring line. The extreme value in tension of mooring line shows to be very sensitive to pretension of mooring line.
R32/R152a 혼합작동유체를 적용한 해양온도차발전사이클 성능 특성
이호생(H. S. Lee),김현주(HJ. Kim),차상원(S. W. Cha),이승원(S. W. Lee) 한국해양환경·에너지학회 2013 한국해양환경·에너지학회 학술대회논문집 Vol.2013 No.11
우수한 열역학적 성질들로 인해 1930년대부터 사용하던 염화불화탄소(CFC) 및 수소화염화불화탄소(HCFC)가 오존층 붕괴의 주원으로 밝혀짐에 따라, 몬트리올의정서에 따라 기존에 사용하던 CFC, HCFC계열의 냉매들은 사용이 규제되고 이를 해결하기위한 대체냉매의 개발이 시급한 상황이다. 이를 해결하기 위한 방법으로는 신 냉매제작 또는 기존의 냉매를 혼합하여 사용하는 방법이 있다. 본 논문에서는 기존의 냉매를 혼합하여 해양온도차발전에 적용하였을 때에 그에 따른 사이클의 성능특성에 대해 연구를 하였다. 다양한 혼합작동유체 중 산업용 히트펌프에 연구 중인 R32/R152a를 해양온도차발전에 적용하였다. 사이클로는 기존의 밀폐형사이클, 암모니아/물 혼합물에 적용하고 있는 칼리나 사이클에 대해 시뮬레이션 해석을 수행하였다. 온열원의 온도는 26℃, 냉열원의 온도는 5℃를 적용하였다. R32를 적용한 밀폐사이클의 출력은 22kW, 사이클의 효율은 2.02%를 보였다. 혼합작동유체를 적용하였을 때에 R32/R152a(67%:33%)의 출력은 23.24kW, 사이클 효율은 2.26%로 기존의 단일 냉매보다 5.6%, 사이클효율은 11%상승함을 확인 하였다. 칼리나 사이클 또한 위와 같은 방법으로 연구를 수행하였다. It has been discovered that chlorofluorocarbon(CFC) and hydrochlorofluorocarbon(HCFC) which had been used since 1930 caused ozone layer depletion due to high thermodynamics characteristics. Series of CFC and HCFC refrigerants were regulated according to the Montreal Protocol. Therefore, development of an alternative refrigerant urgently needs to resolve ozone layer depletion. There are two ways to resolve the problem; Development of a new refrigerant and mixed refrigerants. In this paper, performance characteristics of cycles was studied when mixed existing refrigerants were used for ocean thermal energy conversion (OTEC). Among the various mixed refrigerants for industrial heat-pump, R32/R152a used in ocean thermal energy conversion system. For simulations, R32/R152a were used in existing closed cycle and Kalina cycle which is used only ammonia and water as mixed refrigerant. Temperature of the warm heat source was 26 celcius degree, temperature of the cold heat source was 5 celcius degree. In results of simulation, Gross power of the closed cycle on R32 was 22kW, and efficiency of the cycle was 2.02%. When the mixed refrigerant of R32/R152a, in the ratio of 67 to 33, gross power of the closed cycle was 23.24kW, and efficiency of the cycle was 2.26%. Gross power and cycle efficiency of R32/R152a increased by 5.6% and 11% than those of existing single refrigerant. Additionally, the same simulations were conducted in Kalina cycle with the same various composition ratio of mixed refrigerant.
이호생(H.S Lee),차상원(S.W Cha),문덕수,오위영(O.W. Young),김현주(H.J Kim) 한국해양환경·에너지학회 2014 한국해양환경공학회 학술대회논문집 Vol.2014 No.11
극지방과 같은 극한지의 저온 해수열에너지를 이용한 복합해수플랜트 개념설계를 수행하였다. 복합해수플랜트는 해수난방시스템과 온도차발전플랜트로 구성된다. 즉, 저온 해수를 해수난방시스템의 증발기 열원으로 사용하여 난방열을 공급하고, 해수난방시스템에서 배출되는 해수를 온도차발전으로 공급하여 전기를 생산하게 된다. 온도차발전의 경우 배출 해수를 증발기 열원으로 이용하고, 극한지 대기를 응축기 열침으로 이용하게 된다. 해수난방시스템과 온도차발전플랜트를 연계하여 극한지에 적용 가능한 복합해수플랜트를 제안하기 위한 개념설계를 수행하였고, 플랜트 모듈 용량별 필요 해수, 난방 용량 및 생산 전력량에 대한 기초 해석을 수행하였다. 추후 극한지 지역별 해수 온도, 작동유체 및 사이클별 적용 가능한 복합해수플랜트에 대한 열설계도를 제시하고자 한다. Ocean Thermal Energy Conversion(OTEC) is a method that utilizes the natural temperature gradient that exists in tropical ocean between warm surface water and the deep sea water to generate electricity. When the temperature difference between surface seawater and deep seawater is over 20℃, the system can be run with much better efficiency. Researches for the cases of low temperature differences are also ongoing. In this paper, to perform an experiment on the 20kW OTEC, a closed OTEC cycle was designed and fabricated. R32 was used as the working fluid, and the temperature of the heat source and heat sink were 26℃ and 5℃ respectively. A semi-welded-type heat exchanger was used as the evaporator and condenser, and the OTEC cycle was designed for a gross power of 20kW. R32-OTEC was installed in Seawater Utilization Plant Research Center in Gosung-gun, Gangwon-do. In order to analyze performance of the R32-OTEC pilot plant, the simulation results were compared to the experiment results.
이호생(H. S. Lee),진병주(B. J. Jin),성광훈(K. H. Seong),윤정인(J. I. Yoon) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In this study, evaporation heat transfer experiments were performed in 12.7㎜ micro-fin tube using natural refrigerants. The test rig had a straight, horizontal test section and refrigerant was heated by water through an annulus surrounding test section. Evaporation heat transfer coefficient was increased with increasing quality, refrigerant mass flux. The local and average evaporation heat transfer coefficients in micro-fin tube were compared to those a bare tube. The local evaporation coefficients of R-22 and natural refrigerants for the micro-fin tube were 131% and 96~124% higher than bare tube. EF(enhancement factor) is defined as the ratio of the micro-fin tube heat transfer coefficient to that of a comparable bare tube at a similar mass flux, heat flux, pressure level, and inlet outlet quality. EF of R-22 and natural refrigerants are presented average 2.68 and 2.41 at the all refrigerant mass flux in the experiment range.
탄화수소계 냉매용 열펌프의 성능특성에 관한 실험적 연구
이호생(H.S.Lee),차동안(D.A.Cha),김재돌(J.D.Kim),한인근(I.G.Han),윤정인(J.I.Yoon) 한국마린엔지니어링학회 2003 한국마린엔지니어링학회 학술대회 논문집 Vol.2003 No.-
Performance of a heat pump using hydrocarbon refrigerants are experimentally investigated. The working fluids for this study are R-290(propane), R-600a(iso-butane) as a natural refrigerant and HCFCs refrigerant R-22. The experimental apparatus is a conventional vapor compression type heat pump system. The performance of each refrigerant are obtained under several compressor speeds and the change temperature levels of secondary heat transfer fluids. The compressor work increased as the evaporating temperature increased and were a little higher using hydrocarbon refrigerant than HCFCs refrigerant. The increasement of refrigeration capacity with hydrocarbon refrigerant were better than R-22 according to the evaporating temperature. And COP increased linearly as evaporating temperature increased and showed the highest value when R-600a(iso-butane) was used as a working fluid. Experimental results showed some hydrocarbon refrigerants had better characteristics than R-22, that is, the natural refrigerants can be used as substitute for R-22.<br/> <br/>