Computational Fluid Dynamics Analysis of a Helical Coil Heat Exchanger with Varying Pitch

This study presents a Computational Fluid Dynamics (CFD) analysis to evaluate the effect of coil pitch on the thermal performance of a helical coil heat exchanger. The model features a helical tube carrying hot water and a surrounding shell with cold water. Simulations were conducted for three coil pitches—0.03 m, 0.05 m, and 0.07 m—under identical boundary conditions. Hot fluid entered the coil at 120 °C and 1.2 m/s, while cold fluid entered the shell at 25 °C and 0.6 m/s. Turbulence and energy models were applied to examine flow behavior and heat transfer. Results show that the smallest pitch (0.03 m) yields the highest Nusselt number and heat transfer coefficient, indicating enhanced thermal performance. This is due to stronger secondary flows and improved fluid mixing. Larger pitches resulted in lower turbulence and reduced heat transfer. The study highlights coil pitch as a key design parameter for optimizing compact heat exchangers in energy and process industries. Key Words: Helical Coil Heat Exchanger, Computational Fluid Dynamics (CFD), Coil Pitch, Heat Transfer Performance, Nusselt Number.