A Helical Heat Exchanger is a highly efficient device for transferring heat between two fluids. What makes it unique is its coiled, spiral shape. Unlike a straight tube, this helical design packs a very large heat transfer surface area into a very small, compact volume. This makes it a perfect solution for engineering applications where space is limited. Furthermore, the curved path forces the fluid to move in a swirling pattern. This secondary flow motion dramatically improves the rate of heat transfer and also helps to reduce the buildup of fouling on the tube walls, which is a common problem in standard heat exchangers. These distinct advantages have made the Heat Exchanger CFD simulation a critical tool for engineers to study and optimize these devices. This project is guided by key research papers in the field, including those by Abu-Hamdeh, N. H., et al. [1] and Kuvadiya, M. N., et al. [2].

• Reference [1]: Abu-Hamdeh, Nidal H., et al. “A detailed hydrothermal investigation of a helical micro double-tube heat exchanger for a wide range of helix pitch length.” Case Studies in Thermal Engineering 28 (2021): 101413.
• Reference [2]: Kuvadiya, Manish N., et al. “Parametric analysis of tube in tube helical coil heat exchanger at constant wall temperature.” International Journal of Engineering Research & Technology 1.10 (2015): 279-285.

Figure 1: Schematic diagram of the double-tube Helical Heat Exchanger used in the CFD simulation.

Simulation Process: Modeling the Helical Heat Exchanger CFD with ANSYS Fluent

To begin our Helical Heat Exchanger Fluent simulation, we first had to create a high-quality mesh. Because of the complex curves of the spiral, the geometry was carefully divided into sections, or “blocks,” as shown in Figure 2. This extra step allowed us to generate a fully structured grid with 1,302,912 hexagonal cells using ANSYS Meshing. A structured grid is the best choice for this type of problem because it provides the highest accuracy.

Figure 2: Helical heat exchanger blocked for structured grid

Post-processing: CFD Analysis of Thermal Performance in the Helical Heat Exchanger Fluent Simulation

The results of the simulation tell a clear story of how the helical geometry creates superior thermal performance. As the fluids travel along their spiral paths in opposite directions, the velocity of the cold water fluid actually increases slightly, from 3.19 m/s at the inlet to 3.25 m/s at the outlet. This is more than just fluid motion; this is the beginning of the heat transfer engine. The curved path forces the fluid into a secondary swirling motion, often called Dean vortices. This constant churning action aggressively disrupts the thermal boundary layers at the tube walls, ensuring that more of the fluid comes into contact with the hot surface and enhancing the convective heat transfer.

This enhanced mixing is visualized perfectly in the temperature contours in Figure 3. We can see a smooth and continuous exchange of thermal energy along the entire length of the coil. The hot water (initially red) gradually cools down, while the cold water (initially blue) steadily heats up. The copper wall between them acts as a perfect bridge for this energy transfer. The most significant achievement of this Helical Heat Exchanger CFD simulation is quantifying the mean temperature difference across the system as 49.63 K. This large temperature difference is direct proof of the design’s high efficiency. It confirms that the secondary flows generated by the helical shape are not a minor effect—they are the primary mechanism that makes this compact heat exchanger so effective.

Figure 3: Temperature contours along the coil, showing the effective heat transfer in the Helical Heat Exchanger Fluent simulation.