Thermal performance evaluation of U-shaped obstacles with rectangle perforation in solar air heater

Solar air heaters (SAHs) have emerged as a global solution of thermal energy harvesting and low environment impact. Today, solar heaters are the most widely used option due to high energy saving, stable heat generation and low cost. However, monitoring solar heater temperature is crucial in performance control by preventing overheating with durable operation conditions. In this paper, thermal monitoring performance of solar air heater with U-obstacles and Perforations is analyzed for different ranges of air velocities. The height of solid U-obstacles is varied (namely, 50, 100, and 150 mm) and arranged in segregated distribution. The analysis are modeled using ANSYS 19 software with assuming turbulent air flow and for Reynold number ranges from (5000-25000). The obstacles height increase enhances the thermal performance at the expense of pressure losses penalty. The Nusselt number increased by 70% compared to plain solar heater while the pressure drop increased 7 times compared to plain solar heater. Then, the rectangular Perforations with widths of 10, 30, 50, and 70 mm are applied for reducing the pressure drop and friction losses located in the middle of each U-obstacle. The pressure drop reduced compared to solid U-obstacle and the heat transfer performance is increased depending on obstacle height and perforation width scale. The pressure drop reduced by 30% in the case of SAH-U150-W30 and the heat transfer performance increased by 20% compared to solid U-obstacles solar heater. The criteria of thermal performance is conducted in this study to ensure the efficiency of thermal performance and pressure losses.