CFD based thermal efficiency of square shape protruded roughened absorber plate for solar air heater

In present paper, CFD technique is used to investigate the thermal efficiency of square shape protruded roughened absorber plate used in solar air heater. A 3-D CFD model of solar air heater with sixteen geometrical arrangements of roughness is analyzed under varying Reynolds number from 4000 to 20000 by using RNG k-epsilon method under transient conditions. The dimensionless geometrical parameters (P/e and e/D) having values vary from 38.8 to 61.1 and 0.016 to 0.036, respectively. The simulated results from the present study is further used to calculate the thermal efficiency of actual solar air heater with the help of computer program. Maximum enhancement in the value of performance parameters like, thermal efficiency, Nusselt number and friction factor are at minimum value of geometrical parameters (P/e) of 38.8 and at higher e/D value of 0.036. Design plot has been also proposed in order to design square shape protruded roughened solar air heater.