Numerical and Computational Fluid Dynamics (CFD) Analysis of Heat Transfer in Twisted Helical Coiled Heat Exchangers

Abstract

Heat exchangers are critical components in various engineering systems, including nuclear reactors, air conditioning units, refrigeration systems, power plants, heat recovery systems, the food industry, and chemical processing. Among the many designs available, helical coil heat exchangers are particularly effective due to their compact structure and superior heat transfer capabilities. They are perfect for use in chemical reactors and other heat systems because of their capacity to give a big surface area in a small amount of space.

This study focuses on the analysis of helically coiled heat exchangers using a range of correlations sourced from existing literature under different operating conditions. The most common configuration consists of multiple helically coiled tubes stacked within a cylindrical shell. Manifolds attached to the ends of the inner tubes serve as fluid inlets and outlets, while cooling fluid can also circulate through the outer shell, which is similarly equipped with inlet and outlet manifolds. The tube bundle, arranged in layers, is enclosed within a helical casing.

The curved geometry of helical coils introduces complex fluid dynamics that offer significant advantages over straight tube designs, particularly in terms of heat transfer coefficient enhancement, mass transfer efficiency, and improved area-to-volume ratios. Convective heat transfer between the working fluid and the heat exchanger surface remains a central focus of thermal engineering research.

In this project, the effect of counter-flow configuration on overall heat transfer performance is examined. Simulations were conducted using ANSYS 13.0 to analyze temperature distributions, velocity vectors, local Nusselt numbers, and total heat transfer rates along the tube walls. Copper was selected as the tube material due to its high thermal conductivity, and water was used as the working fluid in both the inner tube and outer casing.