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김현주(H.J.Kim),이호생(H.S.Lee),차상원(S.W.Cha),홍사영(S.Y.Hong),남보우(B.W.Nam),권용주(Y.J.Kwon) 한국해양환경·에너지학회 2014 한국해양환경공학회 학술대회논문집 Vol.2014 No.5
해수온도차발전은 해양심층수와 표층해수의 온도차 에너지를 기계에너지로 변환시켜 전력을 생산하는 방법이다. 적도해역에는 연중 온도차가 20℃ 이상으로 안정적이므로 베이스 로드를 감당할 수 있을 뿐 아니라 가용량이 풍부하여 유용한 해양에너지로서 실용화 가능성이 큰 신재생에너지이다. 20kW 파일럿 플랜트의 설계, 제작 및 운전을 바탕으로 1MW OTEC plant를 설계 중이며, 적도해역의 설치 및 운전 개념에 따른 최적화 평가를 실시하고자 한다. 이를 위해, 작동유체 R32를 이용하는 1MW급 폐쇄순환식 해수온도차발전 싸이클 해석모델을 정립하고, 적도해역에서의 표층해수를 기준으로 수심에 따라 취수 가능한 심층수와의 온도차가 24, 22, 20℃를 대상으로 해수온도차발전 플랜트의 발전특성을 해석하였다. 그 결과, 온도차에 따라 발전효율은 2.75%, 2.28%, 1.8%로 산출되었다. 여기서, 해수온도차발전플랜트를 바아지 선박에 탑재하고, 4점 계류시스템으로 바아지의 위치 유지를 하는 것으로 하였다. 여기서, 샌드위치형 FRP 파이프로 구성된 라이저를 길이 1,000m, 800m 및 500m로 바아지 하단에 설치하여 심층수를 취수함으로써 온도차 24~20℃를 확보하는 경우를 비교하고자 한 것이었다. 샌드위치형 FRP로 제작되는 라이저는 비중이 물보다 가벼워서 하단에 중량체를 매달아서 취수간 형상을 유지하여야 하며, 라이저의 응답해석 결과로부터 라이저 전체의 수중 중량이 FRP관 수중중량의 50~75%인 경우가 적절할 것으로 나타났다. Ocean thermal energy conversion(OTEC) is to produce electricity by changing thermal energy from deep ocean water and surface ocean water to mechanical energy. In the coastal area near the equator, temperature gap between deep seawater and surface seawater is over 20℃ all year long, which is good enough to cover the base load. Addition to that, the amount of resource is abundant to be used as ocean energy for commercialization. Based on the design, installation, and operation of 20kW pilot plant, 1MW OTEC plant design is ongoing, and optimization assessment of its installation and operation in the coastal region near the equator is being planned. For the assessment, analysis models of 1MW closed-cycle OTEC cycle using R32 as working fluid was set up. Also, it was analyzed that OTEC plant performance characteristics for the ocean area near the equator where the temperature gap between deep ocean and the surface was 24℃, 22℃, and 20℃ respectively. As a result, the generation efficiency was 2.75%, 2.28%, and 1.8% respectively according to the temperature gap. In assumption, the OTEC plant was on a barge, and the barge was moored by four points for the analysis. It was to compare the cases with different temperature gap of 24℃, 22℃, and 20℃ using deep ocean water from sandwich type of FRP intake risers in depth of 1,000m, 800m, and 500m installed at the bottom of the barge. It was discovered that the sandwich type of FRP risers have to be installed with weight at the bottom since its specific gravity was lighter than water. It was found to be proper to have FRP risers’ underwater weight take account for 50~75% of the total risers’ underwater weight from riser response analysis.
하이퍼루프 차량의 압축기 입구 유로 형상에 따른 유동 해석
홍상원(S.W. Hong),강형민(H.M. Kang),권혁빈(H.B. Kwon) 한국전산유체공학회 2022 한국전산유체공학회지 Vol.27 No.1
In this study, the flow analysis in the compressor inlet flow path at the front of the hyperloop vehicle driving inside the subvacuum tube was performed using CFD(computational fluid dynamics). It was verified that the pressure imbalance between the inlet cross section and inside the flow path and the pressure decrease inside the flow path of the CFD results using the original shape of the vehicle. Therefore, flow analysis was performed by changing the length of the lower side of the inner inclined surface of the inlet nose shape by 2 times and 4 times. As a result, the pressure decrease at the inlet cross section was delayed, and the pressure inside the flow path was maintained at a higher level than the original slope of the inlet nose shape. Finally, it could be confirmed that the lower gradient of the inner inclined surface of the inlet nose shape, the better pressure results of flow in the compressor inlet flow path in this study.
이중반전 팬 선풍기의 하우징 형상에 따른 유동 특성 분석
서영재(Y.J. Seo),홍일성(I.S. Hong),권상원(S.W. Kwon) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.1
The objective of this study is investigate the flow performance analysis with various housings of an electric fan with counter-rotating fan. The housing of an electric fan serves as a guide for flow and has the effect of increasing flow straightness. Because of this advantage, the counter-rotating fan is designed to be used for ventilation purposes. The housing shape was modeled by selecting the radius of curvature as parameter. In this paper, the internal and external flow characteristics and performance of the counter-rotating fan were analyzed through CFD results according to the radius of curvature of the housing.
튜브 내부 압력에 따른 압축기 장착 하이퍼루프 차량의 공력 해석
강형민(H.M. Kang),홍상원(S.W. Hong),권혁빈(H.B. Kwon) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.1
The aerodynamic characteristics of Hyperloop train with air compressor were assessed according to the pressure inside the tube (P<SUB>tube</SUB>). The computation processes were as follows; at first, three dimensional steady state flow computations were performed without the operation of the compressor. From the results and the compressor performance analysis module, the mass flow rate at the inlet of compressor was obtained and itself was applied again to boundary condition. Then, the three dimensional flow simulation and calculation of mass flow rate were performed iteratively until the mass flow rate at the inlet of compressor converged. The overall processes were executed with changing the P<SUB>tube</SUB>; the P<SUB>tube</SUB> was set as 100, 300, 500, 1,000, 5,000 and 10,000 Pa. By these parametric studies, it was confirmed that the aerodynamic drag of the train increased as P<SUB>tube</SUB> increased because of the increase of air density. However, the drag did not linearly increase according to the Ptube because the drag coefficient (CD) decreased because Re of the Hyperloop train increased. These results can be used as the basic data for selecting proper P<SUB>tube</SUB> and designing the appropriate tube system.