• 한국추진공학회지
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• 제23권3호
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• pp.35-43
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• 2019

본 연구에서는 핀-휜이 있는 유로에 위치와 유동 입사각이 다른 가이드 베인을 부착하여 전열 성능 및 압력 강하 특성 변화를 분석하였다. 레이놀즈수가 1400일 때 가이드 베인의 위치와 입사각에 따른 전열 성능과 유동 특성을 수치해석으로 확인하였고, 핀-휜 만 있는 해석 결과와 비교하였다. 수치해석을 수행한 결과, Case 1의 입사각 $0^{\circ}$일 경우에 전열 성능이 최대가 되고 핀-휜 만 있는 유로에 비해 약 5% 향상되었다. Case 2의 입사각 $10^{\circ}$일 경우에 압력 손실이 최소가 되고 약 1.9% 감소하였다.

• 한국추진공학회지
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• 제23권4호
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• pp.28-34
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• 2019

본 연구에서는 터빈 냉각에 널리 사용되는 핀-휜 배열에 대한 연구를 진행하였다. 본 연구에서 원형 튜브 전방에 익형 와류발생기가 위치하며, 익형 단면 형상은 NACA-9410을 사용하였다. 본 논문에서는 와류 발생기가 있는 핀-휜 배열 유동의 전열 성능과 유동 특성을 수직인 방향으로 변화시키며 기존의 핀-휜 유동과 비교하였다. 레이놀즈수 영역은 6000, 10000 그리고 15000 세 가지를 계산하였다. 전산 해석은 상용 프로그램인 ANSYS v18.0 CFX, 난류 모델은 $k-{\omega}$ SST를 사용하였다. 결과적으로 전열 성능은 최대 5.8% 증가하였고 압력 손실은 1% 미만으로 증가하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1461-1466
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• 2003

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The characteristics of the frost formation on staggered fin array are somewhat different from those of in-line array. The frost layer at the first fin of the in-line array grows rapidly, compared to second fin, whereas the difference of the frost layer growth between the fins of the staggered array is small. For fin pitch below 10 mm, the frost layer growth of second fin in the staggered array is affected by that of first fin. The frost layer growth and heat transfer of single fin deteriorate with decreasing fin pitch regardless of fin array, however, the thermal performance of a heat exchanger, considering increase of heat surface area, becomes better.

• 설비공학논문집
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• 제15권9호
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• pp.711-717
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• 2003

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The frost behaviors of the staggered fin array are somewhat different from those of in-line array. The frost layer formed on the first fin of the in-line array grows rapidly, compared to second fin, whereas the difference of the frost layer growth between the fins of the staggered array is small. For fin pitch below 10 m, the frost layer growth of second fin in the staggered array is affected by that of first fin. The thickness of the frost layer and heat transfer of single fin are reduced with decreasing fin pitch regardless of fin array. However, the thermal performance of a heat exchanger is enhanced due to the increase of heat transfer surface area.

• Journal of Advanced Marine Engineering and Technology
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• 제40권9호
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• pp.786-790
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• 2016

본 연구는 자연대류상의 할로우 하이브리드 휜 히트싱크 (HHFHS) 의 열성능에 대한 방향 영향의 전산연구결과에 대해 논한다. HHFHS 는 휜 베이스 근처에 천공을 포함하는 중공 핀 휜과 판 휜의 결합형 휜들의 배열로 구성된다. HHFHS의 베이스면적기반, 질량기반 열성능에 대한 방향영향이 0 ~ 180도의 방향각에 대해서 수치적으로 연구되었고, 유사구조의 핀 휜 히트싱크 (PFHS) 와 비교되었다. PFHS 와 달리 HHFHS 의 열저항은 직립상태에서 45도까지 변화가 미미하며, 이후 증가하여 90도에서 최대이며, 이후로는 180도까지 감소함을 보인다. 이러한 열저항 특성의 차이는 HHFHS의 중공 휜의 내부유동에 의한 열펌핑 효과의 영향으로 사료된다. 다양한 방향각에도 HHFHS 의 질량기반 열저항은 약 30% 정도 PFHS 보다 작음을 보여주는데 이 결과는 자연대류 상의 전자장치에 대한 HHFHS 의 경량열관리 적용 가능성을 보여준다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2055-2060
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• 2007

Microfin arrays with fin heights of 100 ${\mu}$m and 200 ${\mu}$m and six different spacings from 30 ${\mu}m$to 360 ${\mu}m$ are fabricated using the DRIE process. Natural convective heat transfer around the microfin arrays on both vertical and horizontal surfaces is experimentally examined. It turns out that the orientation effect of microfin arrays is negligible compared with macrofin arrays. The obtained heat transfer coefficients are compared with the existing heat transfer correlation for the macrofin arrays. It is concluded that the existing macrocorrelation is no longer valid for the microfin arrays. Relevant empirical correlations for microfin arrays on the vertical and horizontal surfaces are presented based on the present experimental data.

• 설비공학논문집
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• 제17권11호
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• pp.974-980
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• 2005

The optimization of design factors on the frosting performance of a fin-tube heat exchanger is carried out using Taguchi method. The fin spacings of the heat exchanger are selected as design factors. Optimum values of the design factors under operating conditions of a household refrigerator/freezer are proposed. The average heat transfer rate and operating time of the optimum models, compared to those of a reference model, are increased at most by $6.5\%$ and $12.9\%$, respectively.

• 설비공학논문집
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• 제17권11호
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• pp.965-973
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• 2005

This paper proposes a mathematical model for predicting the frosting performance on a fin-tube heat exchanger. The model consists of empirical correlations of average heat transfer coefficients for the plate and tube surfaces and a diffusion equation inside the frost layer. The numerical results are compared with experimental data for the frost thickness, the frosting rate and the heat transfer rate to validate the proposed model. The results are in good agreement with the experimental data, and show that this model can be applied to predict frosting performance of common fin-tube heat exchanger.

• 한국전산유체공학회지
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• 제15권2호
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• pp.1-6
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• 2010

The purpose of the present study is to investigate the flow resistance and the heat transfer characteristics of oval fin-tube heat exchanger. Six kinds of oval fin having the same fin area and different diameter ratio tested numerically. Test data for the heat transfer, pressure drop and fin temperature were shown and discussed. The pressure drop and heat transfer increased for increasing the oval fin diameter ratio(diameter of span-wise direction to diameter of longitudinal diameter) up to 50% and 45% respectively.

• 설비공학논문집
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• 제10권4호
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• pp.423-430
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• 1998

Single phase heat transfer coefficients were measured for turbulent water flow in a micro-fin tube by using Wilson plot technique. An experiment for counterflow heat exchange between the micro-fin tube and its outer annulus passage was performed. The annulus side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a micro-fin tube were obtained by Wilson plot technique. Nusselt numbers based on the real heat transfer area and the nominal area were about 35% and 50% larger than those for smooth tube respectively Also, single-phase heat transfer correlations based on real heat transfer area and nominal area have been proposed for a micro-fin tube.