This paper presents the results of a comprehensive study of heat transfer and pressure drop for the laminar flow of water in circular tubes with twisted-tape inserts. Three different twist ratios and tape thicknesses were considered. Experiments were performed for two different tube diameters with Reynolds numbers ranging from 500 to 2200 under constant-wall-temperature boundary condition. The fully developed Nusselt number and friction factor were found to be influenced by the twist ratio and the tape thickness-to-diameter ratio. The Nusselt number increases with a decreasing twist ratio, increasing tape thickness, and increasing Reynolds number; whereas the friction factor increases with an increasing twist ratio and tape thickness. Correlations for the Nusselt number and friction factor are developed for a tube with inserted-tape inserts. The present correlations consider the effects of the tape thickness-to-diameter ratio and the twist ratio on the Nusselt number and friction factor. The thermal-hydraulic performance ratio decreases with an increasing Reynolds number and twist ratio, whereas the tape thickness has a slight effect on the thermal performance ratio.
Heat Transfer Enhancement for Laminar Flow in Circular Tubes with Twisted-Tape Inserts
Journal of Thermophysics and Heat Transfer ; 29 , 4 ; 805-811
2015-10-01
Article (Journal)
Electronic Resource
English
Subcooled Water Flow Boiling Heat Transfer in a Short SUS304-Tube With Twisted-Tape Insert
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