Energy balance in a solar chimney

Abstract

Solar chimneys are devices developed to generate electric power. With a few adaptations, they can be used to dry agricultutral products. It was built a prototype of a solar chimney in the Energetic Alternative Laboratory of the Mechanical Department of UFMG. To built the cover, a thermodiffuser plastic film and a greenhouse film were used. It was performed a balance of the solar radiation incident on the device and inside the device. The balances of solar radiation and energy developed through measurements of solar radiation, temperature, velocity and humidity are presented. The thermodiffuser plastic film showed greater durability and greater mechanical resistance compared with the greenhouse film, despite of its lower longwave transmittance (which reduced the thermal losses from the solar collector). Results indicate that the most significant thermal losses ocurred by conduction through the ground and by the thermal radiation emitted from the ground and transmitted trough the film. Keywords: Energy balance; Experimental Analysis; Solar Chimney.