• 설비공학논문집
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• 제17권1호
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• pp.62-70
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• 2005

In this study, the air-side heat transfer coefficients of several types of evaporators in the household freezer/refrigerators are investigated. The types considered in this work are: discrete flat plate fin-and-tube type(in-lined tube array), continuous flat plate fin-and-tube type(staggered tube array), and spine fin-and-tube type(in-lined tube array). The heat transfer correlations obtained from this study for each heat exchangers could expect heat transfer coefficients less than $5\%$ of errors. The result indicates that the air-side heat transfer performance of spine fin-and-tube type evaporator shows the highest value under dry conditions, but discrete flat plate fin-and-tube type evaporator shows the highest value among these three evaporators under frosting conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2390-2395
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• 2007

The present research was experimentally performed to analyze the effect of delta-wing vortex generators(DWVG) on the heat transfer of fin surface of the plate fin-oval tube. The local heat transfer coefficient of the fin surface for four kinds of DWVG's arrangement was measured by the naphthalene sublimation technique for Reynolds numbers ranging from 2000 to 3200. The results showed that the heat transfer of the plate fin-oval tube can be significantly enhanced by DWVG for relatively low Reynolds numbers.

• 설비공학논문집
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• 제11권3호
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• pp.292-300
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• 1999

Fin conduction not only enhances heat transfer to the ambient air but also increases tube-to-tube conduction. The latter is known to deteriorate the heat exchanger performance. Heat conduction between neighboring tubes thorough the fin is numerically investigated for accurate performance analysis of plate finned-tube heat exchangers. Governing equations for arbitrary plate fin are solved and the temperature distribution is obtained using the principle of superposition. Analysis is made using finite element method by changing the shapes of fin, the arrangements of tubes and the fin parameter mD. It is found that tube-to-tube conduction is significant when mD is small or the distance between neighboring tubes is small.

• 대한기계학회논문집B
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• 제35권3호
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• pp.269-278
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• 2011

본 연구에서는 구리 재질의 평판 핀과 나선형 핀-관 열교환기에 대하여 핀 피치와 열수의 변화에 따른 공기측 전열성능을 검토하였다. 두 형상 모두 핀 피치가 열전달계수에 미치는 영향은 미미하였다. 마찰인자는 핀 피치가 증가하면 증가하였다. 열수가 미치는 영향은 형상에 따라 다르게 나타났다. 평판 핀-관 열교환기의 경우 열전달계수는 열수가 증가할수록 감소하였다. 하지만 나선형 핀-관 열교환기의 열전달 계수는 열수가 증가하면서 그 값이 증가하는 경향을 보였다. 평판 핀-관 열교환기의 열전달계수는 나선형 핀-관 열교환기의 열전달계수보다 높게 나타났다. 하지만 열수가 증가하면 그 차이가 줄어들어 4열이 되면 거의 같았다. 한편 마찰인자는 평판 핀-관 열교환기에서 다소 높게 나타나고 열수의 영향은 크지 않았다. 본 실험 데이터를 기존 상관식의 예측치와 비교하였다.

• 설비공학논문집
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• 제17권10호
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• pp.930-937
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• 2005

The objective of this study is to investigate the heat transfer performance of flat plate finned-tube heat exchangers with large fin pitch. In this study, twenty-two heat exchangers were tested with a variation of fin pitch, number of tube row, and tube alignment. The heat transfer coefficient decreased with a reduction of the fin pitch and an increase of the number of tube row. The staggered tube alignment improved heat transfer performance more than $10\%$ compared to the inline tube alignment. A heat transfer correlation was developed from the measured data for flat plate finned-tubes with large fin pitch. The correlation yielded good predictions of the measured data with mean deviations of $3.6\%\;and\;6.4\%$ for the inline and staggered tube alignment, respectively.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.274-280
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• 2005

The objective of this study Is to investigate the heat transfer performance of plate discrete fin-and-tube heat exchangers with large fin pitch. In this study, twenty-two heat exchangers were tested with a variation of fin pitch, number of tube row, longitudinal tube pitch and fin alignment. Discrete fin type exchangers improved heat transfer performance more than 10% compared to tile continuous fin type heat exchangers. The air-side heat transfer coefficient decreased with a reduction of the fin pitch and an increase of the number of tube row, The staggered fin alignment improved heat transfer performance more than 6% compared to the inline fin alignment. The effect of longitudinal tube pitch was insignificant on the j-factor and experiments found opposite effects on the j-factor with respect to fin alignment. Heat transfer correlations were developed from the measured data for flat plate discrete fin-and-tube heat exchangers with large fin pitch. The correlations yielded good predictions of the measured data with mean deviations of 1,4% and 0.3% for tire inline and staggered tube alignment, respectively.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.648-656
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• 2004

In this study, a highly efficient shell-and-tube heat exchanger with plate fins is considered to improve thermal performance of the conventional shell-and-tube heat exchanger. This type of shell-and-tube heat exchanger with plate fins of various shape is simulated three-dimensionally using a commercial thermal-fluid analysis code. CFX4.4. The effect of the shape of the plate fin on heat transfer characteristics is also investigated by the simulation. Plate fins of four different shapes. plane, plane-slit. wave. and wave-slit fins, are considered. The flow fields, pressure drop and heat transfer characteristics in the heat exchanger are calculated. It is proved that the shell-and-tube heat exchanger with plate fins is superior to the conventional shell-and-tube heat exchanger without plate fins in terms of heat transfer. The shape of the plate fin is important in the performance of a heat exchanger such as heat transfer and pressure drop.

• 대한기계학회논문집B
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• 제37권3호
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• pp.205-212
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• 2013

본 연구는 평판 핀-튜브 증발기와 나선형 핀-튜브 증발기를 적용한 가정용 냉장고의 성능특성 비교를 통하여 기존에 사용하고 있는 핀-튜브 증발기를 나선형 핀-튜브 증발기로 대체할 수 있는 가능성을 고찰하는데 그 목적이 있다. 실험은 2단 15열의 평판 핀-튜브 증발기와 2단 15열에서 2단 11열까지 열 수를 단계적으로 감소시킨 3종류의 나선형 핀-튜브 증발기를 실제 냉장고에 적용하여 수행하였다. 핀-튜브 증발기의 열 수가 감소할수록 냉동시스템의 최적 냉매 충전량은 감소하였으며, 2단 13열과 2단 11열의 나선형 핀-튜브 증발기를 장착한 냉장고의 소비전력은 기존 2단 15열의 평판 핀-튜브 증발기를 적용한 냉장고 대비 각각 1.5%와 2.8% 감소하였다. 또한 내착상 실험결과 나선형 핀-튜브 증발기가 기존 평판 핀-튜브 증발기와 비교하여 같은 착상조건에서 3~7% 향상된 냉각능력을 보였다. 냉각속도 실험에서는 모든 증발기는 동등수준의 성능을 나타내었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2023-2028
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• 2008

In present study, the flow field near the fin surface of plate fin - oval tube heat exchanger with delta wing vortex generator was numerically analyzed. As results, the well developed vortex behind delta wing was observed. These vortex can improve heat transfer fin surface behind delta wing vortex generators.

• 설비공학논문집
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• 제12권5호
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• pp.494-501
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• 2000

Effectiveness of a 3-pass plate finned-tube heat exchanger is calculated using heat exchangelet method by changing the shape of fin and the arrangement of tubes. The alternative refrigerant R134a is taken in this study. Conduction between neighboring tubes along the fin is taken into account in addition to convection between the fin and the surrounding air. Governing equations are obtained by using energy balance in a small control volume containing a tube and fins. They are numerically solved following the tube. Effect of tube-to-tube conduction is investigated in single-phase and two-phase flows with various fin shapes and arrangements of tubes. Improvement of effectiveness by fin perforation is studied too. The results shows that perforating fins, increasing the number of tubes, and increasing the distance between neighboring tubes at the same fin area enhance the effectiveness.