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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

HEAT TRANSFER AND PRESSURE DROP CHARACTERISTICS IN THE TRANSITIONAL FLOW REGIME OF TWISTED TAPE INSERT IN A CIRCULAR TUBE WITH RE-ENTRANT INLET

Get access (open in a dialog) DOI: 10.1615/IHTC16.her.023213
pages 4567-4574

Аннотация

The article presents experimental results of heat transfer in terms of Colburn j-factor and pressure drop in terms of friction factor characteristics in a smooth circular copper tube with a re-entrant inlet section and a twisted tape insert with twist ratio of 5. Water was circulated as test fluid in the tube and the experiments were conducted at a heat flux of 3 kW/m2 over the range of Reynolds numbers of 653 to 10 553 and Prandtl numbers of 3.23 to 6.5. Two sets of experiments were conducted. Firstly, in a smooth tube for the purpose of validation with literature and secondly in the smooth tube with twisted tape insert. These covered the laminar, transitional and turbulent flow regimes, with the specific aim of identifying the transitional flow regime in the tube with the twisted tape insert. The transitional flow regime in the tube with twisted tape insert was identified by using linear line method when the Colburn j-factor and friction factor, as well as their ratio, were plotted on a log-log scale as a function of Reynolds number. The results showed that the transitional flow regime in the tube with twisted tape insert started and ended at the Reynolds numbers of 918 and 1 310 respectively. The smooth tube results showed that the transitional flow regime started and ended at the Reynolds numbers of 2 541 and 2 795 respectively. The transitional flow regime occurred earlier in the tube with twisted tape insert compared with the smooth tube.