Computational study of heat transfer enhancement in double pipe heat exchanger using helical fins

In this numerical analysis, the enhancement of heat transfer in a double pipe heat exchanger using helical fins has been numerically examined. The inner pipe carries hot water, while the annular section contains cold water with Reynolds Numbers ranging from 2500 to 9500. A wavy fin with a rectangular cross-section and varying fin pitches of 25, 50, 75, and 100mm has been subjected to numerical scrutiny to assess its impact on overall heat transfer coefficient, friction factor, pressure drop, effectiveness, efficiency, pumping power, and Thermo-hydraulic performance index in the double-pipe heat exchanger. These findings are compared with those obtained from the plain pipe. It is evident that helical fins outperform the plain double pipe heat exchanger by inducing turbulence effects in the flow field. For a fixed Reynolds Number of 2500, the Nusselt number is 11.84 percentage higher with a fin pitch of 25mm compared to 50mm. Similarly, for pitches of 75mm, 100mm, and the plain pipe, the respective increases in Nusselt number are 18.58, 24.19, and 35.52 percentage respectively. Parametric investigations indicate that as fin pitch decreases, turbulent intensity rises, leading to improved heat transfer performance. The highest Thermo Hydraulic Performance Index, recorded at 2.36, is observed for the 25mm pitch at Reynolds number of 2500. This value is 30Percentage higher than that achieved with a 100mm pitch fin.