The effect of Geometrical parameters on heat transfer coefficient in helical double tube exchangers

Helical coil heat exchangers are widely used in industrial applications ranging from cryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due to
their compact size and high heat transfer coefficient. In this kind of heat exchangers, flow
and heat transfer are complicated. This paper reports a numerical investigation of the influence of different parameters such as coil radius, coil pitch and diameter of tube on the characteristics of heat transfer in helical double tube heat exchangers using the well-known Fluent CFD software. Modeling of the study was implemented based on principles of heat transfer, fluid mechanics, and thermodynamics. By imposing boundary conditions and selecting of an appropriate grid, whereby the results are independent of meshing, the obtained results were compared and validated with existing experimental results in the open literature. The results indicate that heat transfer augments by increasing of the inner Dean number, inner tube diameter, curvature ratio, and by the reduction of the pitch of the heat exchanger coil.