Enhancement of Heat Transfer in Solar Air Heater

An investigation is done in relation to heat transfer enhancement in solar air heaters with circular V-shaped down ribs. Ribs were attached to the absorber plate having an angle of attack (α= 60 ⁰). The ratio of rib height to hydraulic diameter (e/D) was 0.047 while the range of rib pitch-to-height ratio was (P/e = 4 8 and 16) mm for three different sheets with the Reynolds number ranging from (Re = 1825-7759). The roughened wall of the duct is heated by direct sunlight while the remaining three walls are insulated. The concept of a V-shaped rib was developed to capitalise on this span-wise variation of heat transfer for inclined ribs. The V-shaped rib reduced the span-wise variation of heat transfer and increased average heat transfer.