Numerical and experimental investigations of heat transfer inside a rectangular channel with a new tilt angle of baffles for solar air heater

Abstract

This work represents an experimental and numerical study of heat transfer by forced convection inside a channel containing the baffles of a solar collector. The study chose the shape of the baffles as an important factor to improve heat exchange, which has a rectangular shape and is transversal with air flowing at an angle of inclination ? = 90 degrees. The study was conducted at different mass flow rates and different times of the day, to find out the effect of these conditions on the convective heat transfer from the absorber plate to the air through the channel of the collector. The operating conditions taken from the experiment were entered as boundary conditions in CFD, for a comparative study between the heat transfer coefficient by convection of the measurement data, and the simulation data. It was found that the results of it in the numerical and experimental methods gave a good approach, also it can be concluded that this coefficient was affected by different parameters such as the mass flow rate, absorber temperature, and shape of the baffles. Through the results, it was confirmed that when the Reynolds number increases, it means an increase in velocity, which means that the air passing through the duct becomes cooler, therefore there is a difference in temperature between the passing air and the absorber plate, and this leads to an increase in heat transfer between the air and the absorber plate.