• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2116-2124
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• 2003

An experimental study providing additional knowledge of quasi-conical symmetry in swept shock wave/turbulent boundary-layer interactions is described. When a turbulent boundary layer on the flat plate is subjected to interact with a swept planar shock wave, the interaction flowfield far from fin leading edge has a nature of conical symmetry, which topological features of the interaction flow appear to emanate from a virtual conical origin. Surface streakline patterns obtained from the kerosene-lampblack tracings have been utilized to obtain representative surface features of the flow, including the location of the virtual conical origin. The scaling law for the sharp-fin interactions suggested by previous investigators has been reexamined for different freestream Mach numbers. It is noticed that the scaling law reasonably agrees with the present experimental data, however, that the law is not appropriate to estimate the location of the virtual conical origin. Further knowledge of the correlation for the virtual conical origin has thus been proposed.

• 설비공학논문집
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• 제2권2호
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• pp.99-104
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• 1990

A Study has been conducted experimentally on heat transfer characteristics of louvered fin heat exchangers with various louvered positions in air. The experimental results are as follows; 1. Mean heat transfer coefficient is increased with increasing air velocity and decreasing temperature difference. The maximum value of heat transfer coefficient shows at 10㎜ backward louvered fins. 2. Pressure drop is increased with increasing air velocity and apparently depended on the louvered positions at V>10m/sec. 3. $\bar{h}/{\Delta}P$ is decreased with increasing air velocity and its maximum value shows at 10mm forward louvered fins and its minimum value shows at plate fins.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.804-807
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• 2002

In general, the reinforcement of a structure is performed with cylinders. In this study, it is attempted to analyze the circular reinforcement with fins. And the maximum stress and deflection is investigated fur the circular reinforcement between two plates. The shape of models are : one which has only circular reinforcements of different diameters and one which has circular reinforcements with fins and one which has fin of same length and circular cylinders of different diameters. And in each model, there are two kinds; one is with upper and lower plates and the other with none. The results shows that the maximum stress is less in the model of circular reinforcement with fins than that in the model without fins. And the maximum stress of a model without upper and lower plate is less than that of a model with plates.

• 에너지공학
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• 제9권3호
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• pp.212-220
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• 2000

히트파이프 히트싱크의 라디에이터를 통과하는 공기 유동에 대한 열전달 및 유동 압력 강하를 구하기 위한 연구를 수행하였다. 이 라디에이터는 평판 휜-관 구조이며, 평판휜에 4개의 히트파이프가 유동 방향으로 정격 배열 되어있다. 입구 공기 속도 2.5~4m/s에 대해 열전달 성능실험과 수치해석을 수행하였다. 각 히트파이프의 단위 길이당 열속이 583.3W/m, 입구 공기 속도가 3m/s일때 총합 대류 열전달계수값은 약 32W/$m^2$K, 압력 강하는 8mmAq이었다. 전체속도범위에서 실험결과와 수치 해석 결과 사이에는 약 5%의 미만의 일치를 보였다.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.500-509
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• 2015

This paper presents the single objective design optimization of plate-fin heat sink equipped with fan cooling system using Genetic Algorithm. The proper heat sink and fan model are selected based on the previous studies. And the thermal resistance of heat sinks and fan efficiency during operation are calculated according to specific design parameters. The objective function is combination of thermal resistance and fan efficiency which have been taken to measure the performance of the heat sink. And Decision making procedure is suggested considering life time of semiconductor and Fan Operating cost. And also Analytical Model used for optimization is validated by Fluent, Ansys 13.0 and this model give a quite reasonable and reliable design.

• 한국CDE학회지
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• 제21권2호
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• pp.39-49
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• 2015

This paper presents the single objective design optimization of plate-fin heat sink equipped with fan cooling system using Genetic Algorithm. The proper heat sink and fan model are selected based on the previous studies. And the thermal resistance of heat sinks and fan efficiency during operation are calculated according to specific design parameters. The objective function is combination of thermal resistance and fan efficiency which have been taken to measure the performance of the heat sink. And Decision making procedure is suggested considering life time of semiconductor and Fan Operating cost. And also Analytical Model used for optimization is validated by Fluent, Ansys 13.0 and this model give a quite reasonable and reliable design.

• 설비공학논문집
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• 제13권11호
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• pp.1134-1140
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• 2001

In the present study, heat transfer characteristics of oil flow over offset strip fins were predicted by the numerical methods. Oil flow in the plate-fin passage was idealized by 2 dimension. Power law scheme and SIMPLE algorithm were used for convective diffusion formulation and pressure term respectively. Governing equations were discretized by control volume formulation. The flow patterns and heat transfer were predicted in details. The convective heat transfer coefficients were affected by separation bubbles which appeared at the wake region of offset strip fins.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.211-216
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• 1999

One of the problems in a refrigerator operation is the frost formation on a cold surface of the evaporator. The frost layer is formed by the sublimation of water vapor when the surface temperature is below the freezing point. This frost layer is usually porous and formed on the cold surface of the evaporator. The frost layer on the surface of a evaporator will make side effect such as thermal resistance. However, these important factors have not been used in determining the defrosting period. In this report, a prediction taking into account the change of the fin efficiency due to the growth of the frost layer.

• 대한설비공학회지:설비저널
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• 제38권12호
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• pp.51-60
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• 2009

본 연구에서는 착상 조건 하에서 열교환기 휜의 열전도를 고려하여 휜 표면에서의 착상 거동을 예측하기 위하여 수학적 모델을 제시한다. 이 때, 공기측은 착상 현상에 대한 3차원 유동 변화의 영향을 고려한다. 서리층 두께에 대한 해석 결과는 실험 결과를 최대 10% 오차 내에서 잘 예측한다. 유동에 수직한 방향(z-dir.)의 서리층 두께 성장은 휜의 열전도에 의해 휜 바탕 근처에서 활발하고, 휜 끝으로 갈수록 지수함수적으로 둔화된다. 휜의 열전도를 고려한 경우에 비해 휜의 표면온도가 일정한 조건에서 서리층 두께는 최대 2배, 열전달량은 평군 10% 정도 과대 예측한다. 따라서, 열교환기 휜에서의 착상 거동을 정확하게 예측하기 위해 착상 모델 해석 시 휜의 열전도를 고려해야 한다. 휜의 열전도 고려 유무에 따른 착상 거동의 차이를 보완하기 위해 열전달량에 대한 등가온도를 산출하며, 이를 근거로 무차원 등가 온도 상관식을 도출한다.

• 자원리싸이클링
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• 제24권2호
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• pp.3-12
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• 2015

본 연구에서는 급수예열기 및 공기예열기 등의 열교환장치의 구조 및 재질에 따른 열회수율 및 파울링 발생량 특성에 대해 조사하였다. 열교환기는 석탄화력발전소에서 일반적으로 구성된 급수예열기와 공기예열기를 대상으로 하였고, 소형소각로를 제작하여 모사실험을 수행하였다. 24시간동안 미분탄을 연소하면서 파울링 발생 및 열회수율의 변화를 관찰하였는데, 급수예열기의 구조에 따른 파울링 발생량은 핀(FIN) 튜브형 > 튜브 연결형 > 파이프형 > 자동세정형의 순서로 발생량이 많았으며, 그에 따른 열회수율은 핀튜브형 > 자동세정형 > 파이프형 > 튜브연결형 순으로 높게 나타났다. 공기예열기의 경우에는 구조에 따라 핀(FIN)튜브형 > 핀(FIN)판형 > 파이프형 > 테프론 파이프형 > 세라믹 파이프형 순으로 파울링 발생량이 많았으며, 열회수율도 같은 순서로 높게 나타났다. 재질의 내구성, 내산성, 내열성 등을 고려하여 세라믹이나 테플론 코팅을 할 경우에는 파울링량을 감소시킬 수는 있으나, 열회수율이 낮게 나타나 비효율적이었다.