Free convection condensation heat transfer of steam on horizontal square wire wrapped tubes

Abstract

New experimental data are reported for the condensation of steam on square wire wrapped on horizontal instrumented copper tube. 0.8mm square cross-section wires made of copper and brass and 1.0mm square cross-section wire made of copper with pitches of 2.0mm, 4.0mm and 6.0mm are used. For both 0.8mm and 1.0mm square cross-section wire wrapped tubes, best performing pitch was found to be 4.0mm i.e. 1.53 and 1.5 for 0.8mm and 1.0mm square wire wrapped tubes respectively. The effect of thermal conductivity was evident in case of 0.8mm (copper and brass) square wire wrapped tube at all pitches tested with significance at 2.0mm pitch. Compared to equivalent round cross-section wire wrapped tubes, 0.8mm square wire wrapped tubes showed lower heat transfer enhancement than 0.8mm diameter round wire wrapped tubes while heat transfer enhancement was higher for 1.0mm square wire wrapped tubes than 1.0mm diameter round wire wrapped tubes i.e. 13.4%, 7.1% and 3.7% higher enhancement than the round wire wrapped tubes at 2mm, 4mm and 6mm respectively.