This paper presents a method for enhancing the efficiency of a solar air heater by applying artificial roughness to the absorber surface. The bottom side of the absorber plate is roughened by placing rectangular sectioned rib as turbulent promoters. The various arrangements of ribs with rectangular sections have been analyzed while altering Reynolds number from 4000 to 18000. The rectangular sectioned ribs' thermo hydraulic performance parameter (THPP) and energy efficiency with e/D= 0.015 (relative roughness height) and p/e=10 (relative roughness pitch) outperformed other configurations. The flow behavior and turbulent characteristics have been analyzed by velocity and turbulence kinetic energy contours. The exergetic efficiency of ribs having e/D=0.015 is higher than other ribs.

Numerical Study of Solar Air Heater Roughened With Rectangular Sectioned Ribs