• 설비공학논문집
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• 제15권11호
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• pp.957-963
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• 2003

The present work was conducted to investigate the air-side thermal-hydraulic performance of the brazing fin-tube heat exchanger. Pressure drop and heat transfer coefficient for a plain and a louvered fin configuration were compared numerically and experimentally. It was found that the heat transfer characteristics for the plain fin were similar to the developing flow in the rectangular channel. The louver fin showed about twice better heat transfer coefficient than the plain fin. Previous empirical correlations presented by Davenport, Sunden and Svantesson, Sahnoun and Webb, Chang and Wang, Achaichia and Cowell, and Kang were compared with the present experimental data.

• 설비공학논문집
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• 제27권5호
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• pp.254-262
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• 2015

Heat transfer rate can be increased by increasing the heat transfer area. In this study, wide louver fin-and-tube heat exchangers with $P_t/P_l=1.03$ were tested and compared with louver fin-and-tube heat exchanger with $P_t/P_l=0.6$. Results show that heat transfer capacities of wide louver samples are larger (9.8% at one row, 13.6% at two row and 4.1% at three row) than those of conventional louver samples. Considering the area ratio of 1.78, the increase of heat transfer capacity is rather small, possibly due to the smaller heat transfer coefficient and fin efficiency of the wide louver sample. The j factor of the louver fin was 67% larger at one row, 42% larger at two row and 52% larger at three row. The f factor of the louver fin was 81% larger at one row, 63% larger at two row and 60% larger at three row. The effect of fin pitch on j and f factors are not pronounced and the j factor decreased as the number of tube row increased.

• 설비공학논문집
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• 제17권6호
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• pp.529-535
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• 2005

This study experimentally examines the air-side performance of spiral finned tube heat exchangers. The effects of fin spacing, fin height, and tube alignment were investigated. Reduction of fin spacing decreased the Colburn j factor. However, the effect of fin height on the Colburn j factor was negligible. An increase of tube row decreased the Nusselt number for both staggered and in-line tube alignments. However, the decrease of the Nusselt number for the in-line tube alignment was much more significant than that of the staggered tube alignment. The average Nusselt number of the staggered tube alignment was larger than that of the in-line tube alignment by $10\%$ when the Reynolds number ranged from 300 to 1700. An empirical correlation of the Nusselt number was developed by using geometric parameters of heat exchanger and correction factors. The correction factor considered the effects of tube alignment and number of tube rows on the heat transfer. The proposed correlation yielded a mean deviation of $4\%$ from the present 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.

• 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.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.402-407
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• 2008

This study is performed to investigate heat transfer characteristics for thermal performance of fin-and-tube sensible heat exchangers under the low air flowrate according to fin geometry combination and coolant flowrate control. Fins and tubes of samples were separated between front row and rear row. Experiment results are plotted heat transfer rate of each row, heat transfer coefficient and sensible heat ratio against water flowrate control of each row. It is observed that thermal performance can be enhanced by fin geometry combination and water flowrate control of each row under the low air flowrate.

• 한국표면공학회지
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• 제49권5호
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• pp.439-446
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• 2016

In 2015, a fin tube (Cu-Ni 70/30 alloy) of package type heat exchanger for navy vessel was perforated through the wall which led to refrigerant leakage. This failure occurred after only one year since its installation. In this study, cause of the failure was determined based on available documents, metallographic studies and computational fluid dynamics simulation conducted on this fin tube. The results showed that dimensional gap between inserted plastic tube and inside wall of fin tube is the cause of the swirling turbulent stream of sea water. As a result of combination of swirling turbulence and continuing collision of hard solid particles in sea water, erosion corrosion has begun at the end of inserted plastic tube area. Crevice corrosion followed later in the crevice between the outer wall of plastic tube and inner wall of fin tube. It was found that other remaining tubes also showed the same corrosion phenomena. Thorough inspection and prompt replacement will have to be accomplished for the fin tubes of the same model heat exchanger.

• 설비공학논문집
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• 제25권5호
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• pp.279-288
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• 2013

Heat transfer and pressure drop characteristics of fin-and-tube heat exchangers having sine wave fins and oval tubes were investigated. Oval tubes having an aspect ratio of 0.6 were made, by deforming 12.7 mm round tubes. Twelve samples, having different fin pitch and tube row, were tested. The effect of fin pitch on the j and f factors was negligible. The effect of the tube row on the j factor, however, was different from that of common fin-and-tube heat exchangers having plain fins and round tubes. The highest j factor was obtained for a two-row configuration, while the lowest one was obtained for a one-row configuration. A possible reason was attributed to the flow mixing characteristics of the sine wave channel of the present geometry. Comparison with a plain fin-and-tube heat exchanger having 15.88 mm O. D. round tube reveals that the present oval fin-and-tube heat exchanger shows generally superior thermal performance, except for the one-row configuration.

• 설비공학논문집
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• 제18권6호
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• pp.477-485
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• 2006

A study on frost prevention of fin-tube heat exchanger is experimently performed by spreading antifreezing solution on heat exchanger surface. It is desirable that the antifreezing solution spreads completely on the surface forming thin liquid film to prevent frost nucleation and crystal growth and to reduce the thermal resistance across the liquid film. A small amount of antifreezing solution falls in drops on heat exchanger surface using two types of supplying devices, and a porous layer coating technique is adopted to enhance the wettedness of antifreezing solution on the surface. It is observed that the antifreezing solution liquid film prevents fin-tube heat exchanger from frosting, and heat transfer performance does not degrade through the frosting tests. The concentration of supplied antifreezing solution can be determined by heat transfer analysis of the first row of heat exchanger to avoid antifreezing solution freezing due to dilution by moisture absorption.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1067-1072
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• 2009

In vapor compression systems which use refrigerant as a working fluid, the oil is commonly used for compressor lubrication. Since the presence of lubrication oil can change the characteristics properties of refrigerant, the oil affects the heat transfer performance of heat exchanger to a large extent. In this paper, we focus on the effect of PVE oil experimentally on heat transfer performance of the fin-tube heat exchangers which use R410A as a refrigerant. To evaluate the heat transfer performance, the refrigerant to air type test facility chamber has been used. Fin-tube heat exchanger with grooved has been tested while according to the oil mass fraction variation from nearly zero to 1.7 wt%. It was found that the low level of oil mass fraction has an obvious effect on heat transfer performance, while the high level seems no significant influence. The influence of the oil mass fraction to heat transfer performance, however, is different between evaporation and condensation.