تحلیل عددی اثر باد بر عملکرد کلکتور خورشیدی بدون پوشش نفوذپذیر

Considering problems associated with nonrenewable fuels such as pollution and high cost, efforts are being made to develop use of renewable energy sources like solar energy. Solar collectors could often be employed as important devices for thermal applications. Unglazed Transpired Collector (UTC) is a modern preheating and heating equipment used for ventilating air or drying crops. Heat transfer in the UTC is accomplished by passing air through holes of the unglazed collector. In this study, the effect of wind stream parallel to the collector surface on its performance is investigated using numerical techniques. The study is based on total energy balance where new equations are incorporated in order to consider the wind effect. 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.