Thermo-hydraulic efficiency and correlation development of an indoor designed jet impingement solar thermal collector roughened with discrete multi-arc ribs

Abstract

The present work examines the combined influence of artificial roughness and jet impingement on the performance of solar air heater (SAH). The impingement jet SAH is roughened with discrete multi-arc-shaped ribs. The experiment is performed by varying the Reynolds number (Re) from 3000 to 19,000. The different roughness parameters of multi-arc ribs varied during experimentation are as follows; relative discrete distance (Dd/Lv) from 0.27 to 0.86, relative discrete width (gw/Hr) from 0.32 to 1.72, relative rib height (Hr/H) from 0.025 to 0.047, relative rib pitch (Pr/H) from 0.58 to 3.1, arc angle (αa) from 35° to 65°, the streamwise pitch ratio (X/Dh) from 0.47 to 1.72 and spanwise pitch ratio (Y/Dh) from 0.46 to 0.82. The Nusselt number (Nu) and friction factor (f) for roughened solar thermal collector are found to be 7.61 and 6.48 times higher than that of smooth channel. A thermal-hydraulic performance of 4.1 is obtained for the array of designed parameters. The correlations are also established for Nu and f using experimental data. So, utilizing roughness element along with jet impingement in SAH is found to have a substantial impact on its thermo-hydraulic performance (ηthp).