Thermal performance analysis of apex-up discrete arc ribs solar air heater-an experimental study

Abstract

The most efficient way to enhance the heat transfer performance of the Solar Air Heater (Sol-AHs) duct is by providing an artificial roughened plate. The present study compared the Thermo-hydraulic performance of a novel apex-up discrete arc rib absorber plate Solar Air Heaters (Sol-AHs) with existing best downstream flow ribs geometries. Furthermore, the parameters air flow angle of attack (α) of 30°, 45° and 60° and Reynolds number of 3000–14000 are examined by considering relative gap width (g/e) as 4, rib height to hydraulic diameter (e/Dh) as 0.045, a ratio of rib pitch to rib element diameter as 10, number of gaps as three. The results show that the new apex-up discrete arc rib absorber plates have superior thermal performance than the existing best apex-down ribs geometries. Maximum augmentation in Nu achieves an α of 30° that is 2.92 times the smooth plate. Thermo-hydraulic performance (THPP) is observed to be optimum at Re of 10000 and α of 30°. Correlation for heat transfer and roughness function obtained for varying air flow angle of attack.