Numerical investigations of fluid flow and heat transfer characteristics in solar air collector with curved perforated baffles

Abstract

AbstractIn this article, an improved double‐pass solar air heater with multiple curved perforated baffles is proposed; the solar air heater can enhance the heat transfer between air and heat absorber plate sufficiently by using a perforated baffles. At the same time, to reduce the flow resistance of air, a curved shape was created on the baffles. This research is aimed at evaluating a novel solar air heater design in terms of its thermal efficiency and temperature distributions within the solar air heater in forced convection. This investigation is performed based on numerical simulations in two‐dimensional, steady, incompressible Navier‐Stokes and energy equations utilizing CFDRC software with the shear stress transport turbulence model. The main factors including the hole diameter, baffle inclination angle, and air mass flow rate were evaluated. The effects of these factors on the thermal efficiency of solar air heater and the temperature and pressure difference between the inlet and outlet were analyzed. The results obtained for the different cases show that the maximum thermal efficiency of the air heater is about 77% at air mass flow rate = 0.03 kg/s, hole diameter = 3 mm, and baffle angle = 7°. However, the work section pressure drop across this new solar air heater is varied between about 15.05 and 1.7 N/m2. These numerical results are important for the application of this improved solar air heater and show that the curved perforated baffles in the air channel is a crucial factor for improving of collector performance.