Numerical analysis of wind effect on performance of Unglazed Transpired Solar Collecto

Based on problems due to use of nonrenewable fuels such as pollution and high cost، efforts are being made to develop use of renewable energies like solar energy. Unglazed Transpired Solar Collectors (UTC) are new industrial achievements for preheating and heating of ventilation air or crop drying. Heat transfer in the UTC is accomplished with passing air through holes of the collector. In this study، the effect of wind stream parallel to the collector surface on its performance is investigated numerically. The study is based on total energy balance and in order to consider the wind effects new equations are incorporated. The results show that increasing the wind velocity may decrease or increase the collector efficiency depending on the incoming air approach velocity. This is due to opposite effects of wind and radiation heat losses with convection heat transfer from collector surface to inlet air. Moreover، the heat exchange effectiveness increases with increasing the wind velocity for any approach velocity.