NUMERICAL INVESTIGATION OF HEAT TRANSFER AND FRICTION CHARACTERISTICS OF SOLAR AIR HEATER DUCT WITH INCLINED RIBS WITH A GAP IN STAGGERED ARRANGEMENT

THERMAL ENGINEERING

In this thesis, results of CFD analysis on heat transfer and friction in rectangular ducts with roughened with inclined ribs with a gap in staggeredarranged at an inclination with respect to the flow direction. The range of parameters for this study has been decided on the basis of practical considerations of the system and operating conditions of solar air heaters. The numerical investigation encompassed the Reynolds number(Re) range from 2000 to 16,000, relative width to height ratio (W/H) of 8.0, relative gap position (dt/W & dl/W) of 0.3 & 0.4, relative gap width (g/e) is varied of 0.5 to 2.5, relative roughness height (e/Dh) of 0.045, relative roughness pitch (P/e) of 8, angle of attack (a) of 40ᵒ. The effects of relative gap width on Nusselt number, friction factor and thermo-hydraulic performance Rib roughness on the underside of the top wall of a duct has been found to substantially enhance the heat transfer coefficient. Surface roughness disturbs the laminar sub-layer in the turbulent flow and promotes local wall turbulence that, in turn, increases the heat transfer from the surfaces. The augmentation in heat transfer accompanies a higher pressure drop penalty of the fluid flow. In this work the maximum value is found to be relative gap width 1.0 at a Reynolds number of 16000.

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.