CFD Analysis of Heat Transfer Enhancement Using Spring Turbulator as Insert in Corrugated Pipe Heat Exchanger

Abstract

The paper employs Computational Fluid Dynamics (CFD) tools to analyze the augmentation in heat transfer in counterflow Double Pipe Heat Exchanger (DPHE) with arrangements and inserts like corrugation on the inner pipe, helical spring insert in inner pipe and combination of both. ANSYS FLUENT-15.0 was used in the investigation to predict the effects of the arrangements on overall heat transfer coefficient, heat gain, friction factor and pressure drop. Mass flow rate of water was taken such that the Reynolds number ranged from 10,000 to 15,000. The variation in the friction factor and Nusselt number was plotted and analyzed against the Reynolds number. The results showed that there was a considerable increase in heat transfer rate when an obstacle and/or modified surface (like corrugation) was inserted on the flow path; however, this increase was at the cost of pressure drop. 7% increase in Nusselt number was achieved by incorporating the corrugation on the pipe with only 23% increase in the friction factor, while this increase in Nusselt number was 4.5% and 8% in the case of tube with spring insert and combination of corrugation and spring both, respectively, accompanied by an increase of 374% and 386% in the friction, which cost a lot of pumping power.

Keywords: Double Pipe Heat Exchanger (DPHE), Helical coil spring insert, Corrugation, Heat transfer enhancement, Friction factor, Turbulent flow