Simulation of Thermo-Hydraulic Performance of Solar Air Heater with Longitudinal Baffles

Abstract

This research offers a 3D analysis of a solar air heater’s performance using Computational Fluid Dynamics (CFD) and COMSOL Multiphysics software. The air heater design is multi-pass and therefore, the air will remain in the heater longer, thus increasing the transfer of heat from the surface to the air. Fluid flow and heat transfer governing equations were solved via the finite element method with time-dependent boundary conditions using actual measured solar radiation and ambient temperature data. The results of the simulation showed that there is a clear indication of the diurnal thermal response of the heater; the surface temperature rose from the morning to midday, peaked during the times of maximum solar radiation, and then fell from midday to night. The air outlet temperature was always higher than the air inlet temperature over the entire operating time frame, thus demonstrating heat was transferred to the working fluid. Additionally, heat gain increased greatly during times of high solar radiation and the range of heat transfer coefficients remained tight, indicating stable convective performance. Overall, the simulations confirm that the incorporation of longitudinal baffles provides improved thermo-hydraulic behaviour and thermal effectiveness in usually outdoor conditions of a solar air heater.