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Characteristics of Heat Transfer in the Channel with Twisted Tape

Ahn, Soo-Whan (School of Mechanical & Aerospace Engineering, Institute of Marine Industry, Gyeongsang National University)
Kang, Ho-Keun (School of Mechanical & Aerospace Engineering, Institute of Marine Industry, Gyeongsang National University)

Publication Information

International Journal of Air-Conditioning and Refrigeration / v.15, no.3, 2007 , pp. 122-128 More about this Journal

Abstract

Heat transfer distributions and friction factors in square channels (3.0 ${\times}$ 3.0 cm) with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. The rib height-to-channel hydraulic diameter ratio, $e/D_h$ , is kept at 0.067 and test section length-to-hydraulic diameter ratio, $L/D_h$ is 30. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. The twisted tape is 0.1 mm thick carbon steel sheet with diameter of 2.8 cm, length of 90 cm, and 2.5 turns. Two heating conditions are investigated for test channels with twisted tape inserts and rib turbulators: (1) electric heat uniformly applied to four side walls of the square duct, and (2) electric heat uniformly applied to two opposite ribbed walls of the square channel. Results show that the twisted tape with interrupted ribs provides a higher overall heat transfer performance over the twisted tape with no ribs.

Keywords

Rough square duct; Twisted tape; Nusselt number; Friction factor;

Citations & Related Records

Reference

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