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ISSN Print: 1064-2285
ISSN Online: 2162-6561
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Flow Diverter Optimum Angle to Enhance Free Convection Heat Transfer from a Vertical Array of Isothermal Tubes
ABSTRACT
Effect of a flow diverter inclination angle on free-convection heat transfer from a vertical array of five isothermal horizontal tubes has been investigated experimentally using a Mach-Zehnder interferometer. Four fiberglass flow diverters with the width of a 3-cylinder diameter are placed parallel and midway between the tubes at an inclination angle of 30°, 45°, and 60°. The tubes vertical spacing (centre-to-centre) is kept constant to a 3-cylinder diameter. The experiments are carried out for various Rayleigh numbers based on the cylinder diameter in the range of 103 to 2.5 × 103 . Also the flow diverters of a 45° inclination angle which are made of copper are used in the experiments to study the effect of diverters' thermal conductivity on heat transfer from the array. Up to a maximum of 30% increase in heat transfer from the array is observed with a fiberglass flow diverter at an angle of 45°. Also a 10% decrease in the Nusselt number is occurred for the copper diverters with respect to fiberglass ones. The enhancement in heat transfer decreases as the flow diverter angle deviates from 45° for all Rayleigh numbers.