CFD analysis of fluid flow and heat transfer in solar air heater having sinusoidal roughness

Abstract

CFD analysis of fluid flow and heat transfer in solar air heater (SAH) having sinusoidal (sine square function) rib roughness provided underneath the absorber plate facing towards the fluid flow inside the SAH duct has been carried out in the range of parameters, i.e., roughness pitch (P) 10 mm-18 mm, roughness height (e) 0.7 mm-1.2 mm and Reynolds number (Re) 4,000-15,000. In order to find the optimal thermohydraulic performance (THP), a parameter indicating the maximum heat transfer at the cost of minimum pumping power is required. The fine and uniform mesh has been used to resolve the viscous sublayer. Vortex (circulation) formed near the wall creates local turbulence and acts as a heat exchanger between the hot absorber surface and the main flow. The optimal value of THP (ɳ) has been found to be 2.03 which has been compared with other roughness models (triangular and rectangular) and found to be the maximum among the three models.