Study of the flow characteristics and augmentation of heat performance in a horizontal tube with and without spring inserts

Abstract

In this project, heat transfer and thermal performance factor characteristics in a tube fitted with coil wire and twisted tape inserts, using air as working fluid are investigated experimentally. Enhancement forced convection heat transfer characteristics is studying for air Reynolds number range from 10.328×103 to 11.769×103 and 10.927×103 to 12.029×103 in the tube without and with coil wire inserts. Effects of various hydrostatics parameters on the heat transfer are considered in this work with heat flux are constant conditions of 600 W/m² and 800 W/m² with using the coil wire and twisted tapes with three ratios (y/w = 3, 4 and 5). The test section is a horizontal annular passage with outer diameter 10 cm. The results indicated that the enhancement of heat transfer coefficient factors in tube with coil wire inserts provide local heat transfer coefficient percentages of (5.1% to 7.8%) for heat fluxes (600) W/m² and (800) W/m² respectively. While tube with swirl inserts provide local heat transfer coefficient percentages of (3.6% to 6.1%) for heat fluxes (600) W/m² and (800) W/m² respectively. The obtained results show that mean Nusselt number and heat transfer coefficient in the tube with twisted tape and coil wire increase with decreasing twisted ratio (y/w). It is also observed that the percentage of heat transfer coefficient for the coil wire when compared with that of swirl inserts tube were ranged between (10.6%) to (16.5%) and (11.5%) to (17.3%) for the heat flux (600) W/m².