Influence of impingement jet designs on solar air collector performance

The present work shows the impact of jet shapes and absorber plate spacing on the performance of heat transfer and pressure drop in solar air collectors experimentally. Absorber wall temperature, outlet temperature, useful heat gain, Nusselt number, friction factor, and thermal-hydraulic performance (THP) are the parameters under investigation. The experiment is conducted at heat fluxes of 900 W/m2 and 1000 W/m2, and Reynolds numbers ranging from 3000 to 19000. The results indicate that, in comparison to the Nusselt numbers for square and triangular jets, the Nusselt number for the circular jet is greater by 11.64% and 18.94%, respectively. The average useful heat gain of the circular jet is 6.45% higher than that of the square jet and 15.19% higher than that of the triangular jet. The maximum useful heat gain is provided by lower absorber plate spacing values. When the ratio of absorber plate spacing to jet diameter is 3.3, the THP for circular and triangular jets is 0.96 and 1.04, respectively. As a function of the geometrical and flow characteristics, the jet's Nusselt number and friction factor correlations are proposed, which forecast the current experimental findings.