Performance of heat transfer and pressure drop in a spirally indented tube |
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Authors: | Sang Chun Lee Sang Chul Nam Tae Gon Ban |
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Affiliation: | (1) School of Mechanical Engineering, Yeangnam Univ., 214-1, Daedong, 712-749 Gyungsan, Korea;(2) Graduate School, Yeungnam Univ., 214-1, Daedong, 712-749 Gyungsan, Korea |
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Abstract: | In an effort to develop a heat transfer enhancement technique for low temperature applications such as utilization of LNG
cold energy, an experiment was carried out to evaluate the heat transfer and the pressure drop performance for a spirally
indented tube using ethylene-glycol and water solutions and pure water under horizontal single-phase conditions. The test
tube diameter was 14.86 mm and the tube length was 5.38 m. Heat transfer coefficients and friction factors for both inner
and outer surfaces of the test tube were calculated from measurements of temperatures, flowrates and pressure drops. Correlations
of heat transfer coefficients in the spirally indented tube, which were applicable for laminar and turbulent regimes were
proposed for inner, and outer surfaces. The correlations showed that heat transfer coefficients for the spirally indented
tube were much higher than those for smooth tubes, increased by more than 8 times depending upon the Reynolds number. The
correlations were compared with other correlations for various types of surface roughness. The effect of the Prandtl number
on the heat transfer characteristics was discussed. The critical Reynolds number from the laminar flow to the turbulent flow
inside the spirally indented tube was found to be around Re=1,000. |
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Keywords: | Spirally Indented Tube Heat Transfer Coefficient Double-Pipe Heat Exchanger Friction Factor |
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