Influence of nozzle profile on submerged pipe jet impingement heat transfer

Current work focuses on enhancing the performance of solar air heater by employing vertical submerged pipe jets featuring different profiles: circular, square, triangular, and rectangular. The study investigates parameters including jet diameter ratio $\left({d/{D_h}} \right)$d/Dh ranging from 0.044 to 0.11 and the jet spacing ratio ($Sj/{D_h}$Sj/Dh) varying from 0.108 at 0.433 while keeping the streamwise ($X/{D_h}$X/Dh) and spanwise $\left({Y/{D_h}} \right)$Y/Dh pitch ratio fixed at 0.867. The Reynolds number $\left({Re} \right)$Re ranges from 3,000 to 18,000. Initial results for all the profiles were obtained through CFD simulations, indicating that the circular pipe jet demonstrates superior heat transfer and thermo-hydraulic performance parameter (THPP). The experimental validation of circular profile pipe jet showed a maximum $THPP$THPP of 2.69 achieved at a $d/{D_h}$d/Dh of 0.066 and $Sj/{D_h}$Sj/Dh of 0.217, with a Reynolds number of 15,000.