Numerical investigation of convection heat transfer in solar air heater with semi-circular shape transverse rib

Abstract

Heat transfer devices have been employed in a wide range of industrial and home applications for heat conversion and recovery. Artificial roughness in the shape of repetitive ribs on a surface is a useful approach for improving heat transfer rates. The heat transfer and fluid flow properties of fully developed turbulent flow in a rectangular duct with repeated transverse semi-circular sectioned rib roughness on the absorber plate were investigated. A numerical solution has been done using fluent ANSYS 16 commercial software, and validation of result was carried out with Dittus–Boelter correlation. The numerical investigation of the thermal performance of a solar air heater was carried out at relative roughness pitch (between 7.14 and 17.86), Reynolds number (3800 and 18,000), heat flux (1000 W/m2), and constant relative roughness height (e/D = 0.042). For the analyzed range of parameters, it was found that the semi-circular transverse rib roughened duct with P/e = 10.71 and e/D = 0.042 provides the optimum thermo-hydraulic performance parameter. Within this optimum configuration, the maximum thermo-hydraulic performance parameter has been found to be 1.7328 at Reynolds number 15,000.

Keywords

• solar air heater
• Nusselt number
• friction factor
• semi-circular rib
• CFD