Experimental Investigation of Heat Transfer and Pressure Drop Performance of a Circular Tube with Coiled Wire Inserts

Abstract

This paper evaluates the thermo-hydraulic performance of a coiled wire passive insert for internal turbulent flow through a circular copper tube test section in an in-tube exchanger. Experiments were carried out using water as the working fluid with Reynolds number ranging from 8000 to 32000. The experimental setup was validated for Nusselt number and friction factor with well-established equations for plain tubes. The average Nusselt number ratios (Nua/Nup) and the friction factor ratios (fa/fp) for the augmented tube case over the plain tube case are reported to range from 1.55 to 1.38 and from 1.513 to 1.583, respectively. The average performance ratios considering equal pumping power criteria are also reported and found in the range of 0.846 to 0.921. The study concludes that coiled wire inserts are suitable for heat transfer augmentation applications where pumping power is of minor concern.