Experimental analysis of single loop solar heat collector with jet impingement over indented dimples

Abstract

Abstract An experimental examination was conducted to consider the impact of convective heat transfer and airflow characteristics through an impingement jet solar heat collector (SHC) with indented dimple roughness geometry on the absorber plate. The experimental results included the arc angle (αd) from 30° to 75°, the relative indented roughness pitch (p/Dh) from 0.269 to 0.810, the relative indented roughness height (e/Dh) from 0.016 to 0.0267. The comprehensive performance of SHC was adequately assessed by fluctuating the Reynolds number (Re) from 3000 to 21000. The Nusselt number (Nuct) increases with the increase in Re, as predicted. It is observed that the value of Nuct is a vigorous function of αd. However, the values of Nuct for the indented dimples on the absorber plate are significantly higher than the values for the smooth absorber plate. The maximum value of the combined friction factor (ffct) takes place at an e/Dh of 0.0267, while the minimum value is at 0.016. The experimental outcomes confirm that the maximum thermohydraulic performance (ηct) enhancement value of 2.15 was obtained at αd\xa0=\xa060°, p/Dh\xa0=\xa00.269, and e/Dh\xa0=\xa00.0267 compared to conventional SHC. These experimental values were used to generate the correlations for the Nuct and friction factor ffct as a function of the indented dimpled roughness parameters.