شبيه سازي عددي تأثير ريب‌هاي ساده بر انتقال حرارت و افت فشار در كانال كلكتور هواي خورشيدي

Solar air heaters are among the simplest an‎d most cost-effective systems for utilizing solar energy an‎d are widely used in space heating, agricultural drying, an‎d certain industrial processes. However, the low heat transfer coefficient of air an‎d the formation of a thick thermal boundary layer over the absorber surface significantly limit their thermal efficiency. One effective method to enhance the thermal performance of solar air heaters is the use of artificial roughness on the inner surface of the air duct. Such roughness elements increase heat transfer by disturbing the flow an‎d enhancing local turbulence, but they may also lead to higher pressure losses an‎d pumping power. Therefore, a simultaneous eva‎luation of thermal an‎d hydraulic performance is essential. In this study, the thermal, hydraulic, an‎d thermo-hydraulic performance of a solar air heater equipped with artificial roughness is investigated using computational fluid dynamics (CFD). Two types of artificial rib geometries, namely rectangular ribs an‎d semi-circular ribs, are considered an‎d compared with a smooth duct. The simulations are performed using ANSYS Fluent under turbulent flow conditions, an‎d the effects of Reynolds number on temperature distribution, velocity field, Nusselt number, friction factor, an‎d pressure dro‎p are examined. The results indicate that the use of artificial ribs significantly enhances the Nusselt number compared to the smooth duct. Among the investigated geometries, the semi-circular rib exhibits superior thermal performance over the entire range of Reynolds numbers. The hydraulic analysis shows that the rectangular rib produces the highest pressure dro‎p, whereas the semi-circular rib results in lower flow resistance. eva‎luation of the thermo-hydraulic performance using the TPF index reveals that the semi-circular rib provides a better balance between heat transfer enhancement an‎d pressure dro‎p, making it a more suitable option for practical applications in solar air heaters.

مرضيه رضازاده

بهمن اسدي , ابوالحسن عسگر شمسي