• Journal of Industrial Technology
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• v.36
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• pp.17-22
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• 2016

A circular pin fin (CPF) and a half circular pin fin (HCPF) are by using the one-dimensional analytic method. For these two fins, 90% of the maximum heat loss, Corresponding fin length for 90% of the maximum heat loss, fin effectiveness and fin efficiency are compared as functions of convection characteristic number and fin radius. Also, the ratio of heat loss from the HCPF to that from CPF listed with variation of fin length when the fin volumes are the same. One of the results shows that the efficiency of a CPF is larger than that of a HCPF while the effectiveness of a CPF is smaller than that of a HCPF when convection characteristic number, fin length and fin radius are the same.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.2 no.1
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• pp.27-30
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• 1978

Conditions for increasing heat transfer by increasing uniform circular fin length are investigated. When free end of the fin is not thermally insulated, correction fin length, which gives equal heat transfer from an insulated end fin, is given. Optimum design of a uniform circular fin based on the equivalent fin with insulated end is given.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.259-267
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• 1997

Average heat transfer coefficients and friction coefficients have been measured from staggered short pin-fin arrays to investigate the effect of fin shapes. Flow entering into the test section is a fully developed duct flow and the Reynolds number ranges from 5,000 to 25,000 based on fin diameter and average approaching velocity. The fin has three different shapes; uniform-diameter circular fin, two stepped-diameter circular fins. Average heat transfer rates change slightly with the fin shapes. However, friction loss(pressure loss) for the stepped-diameter fins is significantly less than that for the uniform-diameter fin. This results indicate that the stepped-diameter fin arrays in duct flow enhance heat transfer rates largely based on unit pumping power.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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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％.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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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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• v.14 no.1
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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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.

• Journal of computational fluids engineering
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• v.14 no.4
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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 $mr{\phi}$.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.925-934
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• 2003

An experimental study is performed to investigate the characteristics of near wake flow behind a circular cylinder with serrated fins using a constant temperature anemometer and flow visualization. Various vortex shedding modes are observed. Fin height and pitch are closely related to the vortex shedding frequency after a certain transient Reynolds number. The through velocity across the fins decreases with increasing fin height and decreasing fin pitch. Vortex shedding is affected strongly by the velocity distribution just on top of the finned tube. The weaker gradient of velocity distribution is shown as increasing the freestream velocity and the fin height, while decreasing the fin pitch. The weaker velocity gradient delays the entrainment flow and weakens its strength. As a result of this phenomenon, vortex shedding is decreased. The effective diameter is defined as a virtual circular cylinder diameter taking into account the volume of fins, while the hydraulic diameter is proposed to cover the effect of friction by the fin surfaces. The Strouhal number based upon the effective diameters seems to correlate well with that of a circular cylinder without fins. After a certain transient Reynolds number, the trend of the Strouhal number can be estimated by checking the ratio of effective diameter to inner diameter. The normalized velocity and turbulent intensity distributions with the hydraulic diameter exhibit the best correlation with the circular cylinder's data.