Solar air heaters are extensively used for room heating and food drying purposes, to name a few. In this work, a double-pass solar air heater (DPSAH) has been numerically investigated using the finite volume provisions of ANSYS R16 to solve the continuity, momentum, energy, turbulent kinetic energy as well as dissipation rate equations. The convective and diffusion terms of transport equations are discretized using the 2^nd order upwind and central difference schemes in a staggered grid arrangement. The Reynolds number (Re), eccentricity (e/D), end-gap (L/D) as well as the thickness of the absorber plate (t/D) have been varied in the range 5,000−15,000, -0.39 to +1.85, 4.68−26.48 and 0.05−0.98, respectively. This numerical technology has also been validated with previous published research papers. We observed that Nu ̅̅̅̅̅̅increases both with the Re and negative eccentricity; whereas, it decreases with positive eccentricity. Also, the Nusselt number for a thin absorber plate is found to be more than a thick one. The end-gap of the plate has an insignificant effect on the heat transfer rate, irrespective of all considered Reynolds number.