Experimental Investigations Heat Transfer and Pressure Drop Characteristics of Flow Through Circular Tube Fitted With Drilled Cut-Conical Rings

Abstract

The heat transfer rate and pressure drop characteristics of turbulent flow of airthrough uniformly heated circular tube fitted with drilled cut conical rings withthree space ratios (X=5.4, 6.4, and 8.4) have been studied experimentally. The flowcharacteristics are governed by space ratio (the ratio of the distance between drilledconical ring and the inner diameter of tube), Reynolds number, and drilled conicalring diameter to inner diameter of tube. The goal of the present work is toinvestigate the effect of drilling of the cut conical ring turbulators (with constantring to tube diameter ratio) and space ratio on heat transfer, friction factor, andenhancement efficiency under ranging of Reynolds number from 5000 to 23500.Inaddition, correlation for Nusselt number, friction factor and performanceevaluation criteria to assess the real benefits in using the drilled-conical ringturbulator of the enhanced tube are determined. The results show that the processof drilling of the conical ring inside tube gives high rates of heat transfer more thanthat in the conical ring without drilling.