Assessing the Impact of Integrating Triangular Grooves on the Performance of a Double Pass Solar Air Heater

An extensive literature survey on a double pass solar air heater (DPSAH) contributed to the idea that the inclusion of fins, grooves, ribs, etc. on the absorber plate increased their performance. So, a numerical study for the enhancement of thermal and hydraulic performance of a DPSAH has been done. Equilateral triangular-shaped grooves of 15 mm length were placed at 50 mm from each other. The length, breadth and height of the solar air heater are 1014 mm, 350 mm and 72 mm respectively with a relative height ratio, i.e. e/H value of 0.4. A constant and continuous heat flux of 880 W/m2 was supplied on the roughened absorber plate. The entire computational work was carried out using ANSYS 23.0 software and the RNG k − ε turbulence model was used for the simulation. By performing the grid test, 2 mm grid size was considered for further analysis. And with the Reynolds number (Re) ranging between 3000–15,000 different values of the Nusselt number (Nu) and friction factor (f) were obtained. The Nu and f of the DPSAH with triangular grooved absorber plate is compared with that of a flat absorber plate to obtain the thermo-hydraulic performance parameter (THPP). The maximum THPP obtained is 3.29 at Re 3000 which is higher than the contemporary models.