This paper presents a numerical analysis of a novel and efficient solar air heater (SAH) designed with an integrated impingement‐return configuration to enhance thermal performance. The system consists of nine blackened copper tubes where incoming air first passes through the lower half of each tube. At the far end, the flow reverses direction in a 180° turn and returns through the upper half of the tube, which is exposed within an air layer enclosed between the glass cover and the absorber plate. The extended portion of the absorber plate into the tubes is strategically shortened before the tube’s end to facilitate the flow reversal. The finite element method (FEM) was employed to solve the governing continuity and momentum equations for turbulent forced convection inside the tubes, coupled with the equations for natural convection in the air gap and heat conduction in all solid components. The results demonstrate that the proposed design leads to a very low‐pressure loss, but effectively leverages conjugate heat transfer to achieve high thermal efficiency, which is about two times more than conventional plane solar collectors. For the test case with 0.01 kg/s air mass flow rate, numerical findings reveal a low pressure drop of 1 Pa, and the maximum absorber plate temperature was maintained below 80°C, even at the highest solar irradiation of 1000 W/m 2 . This contrasts sharply with the conventional SAH, where the absorber temperature exceeded 140°C, leading to substantial heat loss.
S. A. Gandjalikhan Nassab (Thu,) studied this question.