• 설비공학논문집
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• 제15권9호
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• pp.762-767
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• 2003

An experimental study was conducted to investigate the heat transfer characteristics of a circular finned-tube heat exchanger. The nineteen cases of configuration varying fin material, fin outer diameter and fin pitch were tested by means of the experiment and the numerical calculation. The measured heat transfer data for the circular finned-tube heat exchanger were provided. A transition of heat transfer was found in the case of low fin pitch. The thermal conductivity of fin affected on the pure heat transfer coefficient.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.109-115
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• 2002

Vortex generators are fabricated on the fin surface of a fin-tube heat exchanger to augment the convective heat transfer. In addition to horseshoe vortices formed naturally around the tube of the fin-tube heat exchanger, longitudinal vortices are artificially created on the fin surface by vortex generators. The purpose of this study is to investigate the local heat transfer phenomena in the fin-tube heat exchangers with and without vortex generators, and to evaluate the effect of vortices on the heat transfer enhancement. Naphthalene sublimation technique is employed to measure local mass transfer coefficients, then analogy equation between heat and mass transfer is used to calculate heat transfer coefficients. Experiments are performed for the model of fin -circular tube heat exchangers with and without vortex generators, and of fin-flat tube heat exchangers with and without vortex generators. Average heat transfer coefficients of finn-flat tube heat exchanger without vertex generator are much lower than those of fin-circular tube heat exchanger. On the other hand, fin-flat tube heat exchanger with vortex generators has much higher heat transfer value than conventional fin-circular tube heat exchanger At the same time, pressure losses for four types of heat exchanger is measured and compared.

• 설비공학논문집
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• 제9권4호
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• pp.454-461
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• 1997

Heat transfer and pressure drop for single phase flow of water in circular smooth and micro-fin tubes are measured. Copper tubes of 9.52 and 7mm outer diameter were used. The internal roughness in micro-fin tubes was formed by spiral grooves having $25^{\circ}$ helx angle, 0. 12mm fin height and 0.454mm pitch in 9.52mm tubes; $18^{\circ}$ helix angle, 0.15mm fin height and 0.322mm pitch in 7mm tubes. The measured friction factor and heat transfer coefficient are compared with relevant previous works, and the correlations for micro-fin tube are developed.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권1호
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• pp.14-18
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• 2006

This study was performed to investigate the heat transfer characteristics of the circular fin-tube heat exchanger. This paper contains the experimental data for the seven kinds of fin geometries. The correlation of Stasiulevicius agreed with the experimental data at high Reynolds number, however not well at low Reynolds number. The Nusselt number was well correlated with Graetz number, and showed a transition near Gz=10. An empirical correlation proposed in the present study agreed well with the experimental data.

• 설비공학논문집
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• 제16권6호
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• pp.584-588
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• 2004

This work was performed to investigate the heat transfer characteristics of the circular fin-tube heat exchanger. This paper contains the experimental data for the seven kinds of fin geometries. The correlation of Stasiulevicius agreed with the experimental data at high Reynolds number, however not well at low Reynolds number. The Nusselt number was well correlated with Graetz number, and showed a transition near Gz=10. An empirical correlation proposed in the present work agreed well with the experimental data.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권3호
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• pp.150-157
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• 2003

Local and overall heat transfer characteristics of fin-flat tube heat exchangers with and without vortex generators were investigated. Local heat transfer coefficients were measured with the heat exchanger model using naphthalene sublimation technique. In case of a fin-flat tube heat exchanger without vortex generators, only the horseshoe vortices formed around tubes augment the heat transfer. On the other hand, longitudinal vortices created artificially by vortex generators additionally enhance heat transfer in case of a fin-flat tube heat exchanger with vortex generators. Overall heat transfer coefficients were measured with the prototypes of the fin-flat tube heat exchanger with and without vortex generators in a wind tunnel and results were compared with those of a fin-circular tube heat exchanger with wavy fin. Friction losses for heat exchangers were also measured and compared. The fin-flat tube heat exchanger with vortex generators is found to be more effective than the fin-circular tube heat exchanger with wavy fin.

• 설비공학논문집
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• 제14권11호
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• pp.939-947
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• 2002

Local and overall heat transfer characteristics of fin-flat tube heat exchangers with and without vortex generators are investigated. Local heat transfer coefficients are measured with the heat exchanger model using naphthalene sublimation technique. In case of a fin-flat tube heat exchanger without vortex generators, only the horseshoe vortices formed around tubes augment the heat transfer. On the other hand, longitudinal vortices created artificially by vortex generators enhance heat transfer dramatically in case of a fin-flat tube heat exchanger with vortex generators. Overall heat transfer coefficients are measured with the prototype of the fin-flat tube heat exchanger with and without vortex generators in a wind tunnel and results are compared with those of a fin-circular tube heat exchanger with wavy fin. Friction losses for heat exchangers are also measured and compared. The fin-flat tube heat exchanger with vortex generators is found to be more effective than the fin-circular tube heat exchanger with wavy fin.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 춘계학술발표논문집
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• pp.75-78
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• 2003

These experiments is to determine design equations for heat transfer and for pressure drop in a new designed heat exchanger with the waved circular fin tube bundles under various experimental conditions. The results with waved circular fin tube bundles are compared with those with the flat circular fin tube bundles. Heat transfer coefficients in the waved circular fin tubes were enhanced to about 50％ in comparison with those in the flat circular fin tubes, This is expected to reduce the capacity of a heat exchanger up to 30％.

• 한국전산유체공학회지
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• 제14권4호
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• pp.7-12
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• 2009

The purpose of the present study is to investigate the convective heat transfer characteristics and the validity of fin efficiency of the circular finned-tube heat exchanger by using commercial CFD code. The heat transfer coefficient obtained by using the laminar model was 22% overestimated to the experimental data. The fin surface temperature compared with the experimental data measured by the liquid crystal method. The fin efficiency by the present numerical experiment, defined as normalized and averaged fin surface temperature, was greater than the theoretical fin efficiency and the difference is increased at high value of the factor $mr{\phi}$.

• 대한기계학회논문집B
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• 제34권5호
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• pp.515-522
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• 2010

본 연구의 목적은 무착상 조건에서 나선형 원형핀-튜브 열교환기의 형상변수에 따른 열전달특성을 고찰하고 평판 사각핀-튜브 열교환기와 열전달성능을 비교하는 것이다. 나선형 원형핀-튜브 열교환기는 Lfoot 길이 2.7 mm 에서 열전달계수가 최대로 나타났으며, 공기측 열전달계수는 튜브열수가 2 열에서 5 열로 증가하면서 평균 10% 감소하였고 핀피치가 5 mm 에서 10 mm 로 증가하면서 평균 17.5% 증가하였다. 모든 풍량조건에서 나선형 원형핀-튜브 열교환기의 튜브피치 30 mm 가 35 mm 보다 열전달량이 평균 5.1% 높게 나타났고 튜브두께 0.5 mm 가 0.7 mm 보다 열전달량이 평균 4.1% 높게 나타났다. 나선형 원형핀-튜브 열교환기의 열전달계수가 평판 사각핀-튜브 열교환기에 비하여 평균 24.3% 정도 높게 나타났다.