Effect of V-Ribs on the Performance of a Double-Pass Solar Air Heater: A Technical Study

The surface characteristics alteration, like the inclusion of grooves, ribs, baffles on the heat-absorbing plate, increases the dissipation of heat in a double-pass solar air heater (DPSAH). A numerical work analyzing the thermal and hydraulic effectiveness of a 3-D model of a DPSAH with a 10:1 aspect ratio and with V-shaped ribs arranged in spanwise direction on the absorber plate has been carried out, considering a constant heat flux of 880 W/m2. The investigation is carried out varying the Reynolds number, Re from 3,000 to 11,000, and pitch ratio, p/e from 2.85 to 5.71, and the normalized surface roughness, e/Dh from 0.221 to 0.442. The optimized blockage ratio, e/H, is fixed at 0.4. The rise in Re leads to an increase in the thermal enhancement factor and a decrease in the pressure loss of the system. At Re = 3,000, e/H = 0.4, p/e = 2.85, and e/Dh = 0.221 there is optimal convective heat conveyance with Nu = 141.28 and minimum pressure drop indicated with the friction factor, f = 0.27940.