Numerical simulation of roughened solar air heater on heat transfer augmentation and frictional flow characteristics in turbulent flow region

This paper works on the numerical simulation of heat transfer augmentation and frictional flow characteristics in roughened Solar Air Heaters by using two-Dimensional CFD for a different type of rib shapes arrangement. The numerical simulation was performed with the RNG k-ϵ turbulence model in ANSYS 15 software. Aluminum and the air were expressed as absorber plate material and working fluid in the present analysis, respectively. The 'second-order upwind' approach was used for the momentum and energy equations. To couple velocity-pressure, the SIMPLE algorithm was used. For all residuals, a low convergence criterion was preferred to accurately predict different parameters. An investigation was done for different Relative roughness pitches (p/e) values and Reynolds numbers (Re) ranging from 4000 to 16000 in turbulent flow areas. The result reveals that the rectangular rib with a triangular end provides the highest Nusselt number (Nu). The Nusselt number has been discovered to have a maximum value of 58.35 at Re 16000 for the rectangular rib with a triangular end. The heat transfer augmentation ratio or Nusselt number ratio is maximum in the case of a rectangular rib with a triangular end.