Design of a cooling duct for solar cells on a solar powered unmanned aerial vehicle to improve performance

Solar Powered Unmanned Aerial Vehicles (SPUAV) have numerous applications and can be considered as environmentally friendly since they use only the sun’s energy for propulsion. It is known that the efficiency of solar cells decreases with temperature, especially in hotter climates and it is important to have proper thermal management in place in order to ensure optimal solar cell performance. Therefore, a concept was proposed which integrates a cooling duct inside the airfoil to provide convective cooling for the backside of solar cells. A MATLAB® code was first developed to model, size and provide optimum duct dimensions. Computational Fluid Dynamics (CFD) was also used to investigate the lift and drag characteristics of the modified airfoil. Heat transfer analysis on the solar array using CFD was performed to obtain solar cell temperatures of the baseline and modified design. The study investigated the lift and drag coefficients at different Reynold’s numbers, the angle of attacks at cruising conditions and solar cell temperatures at different altitudes. Results obtained from the cruising conditions showed that the maximum temperature drop was 4°C. This was with a duct height of 2 mm and Reynold’s number of 206,000 at an altitude of 1 km.