Performance analysis of roughened triangular solar air heater for preheating applications

This research investigates the comparative performance of solar air heater utilizing equilateral triangle ducts integrated with various rib configurations, such as inclined wire ribs, square ribs, broken inclined ribs and chamfered rectangular ribs on the absorber surface. Over a range of operating conditions, including Reynolds numbers up to 35,000, with consideration for roughness pitch to height ratio (e/Dh) values between 4 and 16, and rib inclination angles spanning from 30 to 75 degrees. The results consistently demonstrate the chamfered rectangular rib’s superior performance, achieving maximum effective and exergy efficiencies of 80.14 and 3.46%, respectively. Remarkably, the chamfered rectangular rib maintains its advantage between Reynolds numbers of 2300 and 13,300, making it the top choice for improving solar air heater efficiency in various applications, while at higher Reynolds numbers, the inclined rib emerges as the most efficient option.