NUMERICAL ANALYSIS OF SAH DUCT USING STAGGERED INCLINED RIBS WITH A GAP IN STAGGERED ARRANGEMENT

Mechanical 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 staggered arranged 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 is to (dt/W & dl/W) of 0.3 & 0.3, relative gap width (g/e) is 1.0, relative roughness height (e/Dh) of 0.045, relative roughness pitch (P/e) is to varied of 6 to 9, angle of attack (a) of 45ᵒ. The effects of relative roughness pitch (P/e) 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 roughness pitch (P/e) is 8.0 at a Reynolds number of 16000.

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