Heat Transfer and Pressure Drop in Tape-Generated Swirl Flow of Single-Phase Water

Abstract

This paper summarizes the results of an investigation of the heat-transfer and pressure drop characteristics of single-phase water in tape-generated swirl flow. Extensive data are reported for electrically heated or water-cooled tubular test sections with tight fitting, full length tapes with twist ratios from 2.5 to 9.2. A method was developed for predicting the heat-transfer coefficient for swirl flow based upon the premise that the observed improvement is due primarily to: (a) the increased flow path created by the tape, (b) the increased circulation created with heating due to the large centrifugal force, and (c) the tape fin effect. The experimental results of this and previous swirl flow investigations are in good agreement with the prediction method. Correlations are also presented for adiabatic and diabatic friction factors. Heat-transfer and friction data are combined in a constant pumping power comparison for swirl and straight flow, which indicates that improvements of 20 percent can readily be obtained with swirl flow.