What is unique about helical heat exchangers is that the helical coil shape improves heat transfer and reduces fouling, making them perfect for high-viscosity or clogging applications. Unlike standard heat exchangers, the helical shape provides a larger surface area in less space, enabling thermal exchange in tight places. The form also creates a whirling flow pattern that enhances heat transfer and decreases pressure loss, improving its operating benefits. All of these unique features have led us toward simulating a helical heat exchanger via ANSYS Fluent. The study benefits from several reference papers including:

• 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 of Helical Heat Exchanger

Simulation Process

Prior to taking any step, we need to know that providing proper slices in the geometry will pave the way for generating a structured grid. The sections are depicted in the figure. Regarding the generation of hexagonal elements, 1302912 cells are produced using ANSYS meshing software. The copper wall between two tubes plays the role of an efficient conductor. Cold and hot water flows in opposite directions at 290K and 355K, respectively. A crucial parameter in the assessment of heat exchangers is Mean Temperature Difference which should be calculated via an expression.

Figure 2: Helical heat exchanger blocked for structured grid

Post-processing

The post-processing study of the CFD simulation of the helical heat exchanger shows important thermal performance characteristics. There is a steady change in temperature from 290K (cold inlet) to 355K (hot inlet), as shown by the temperature contours. The average temperature difference across the system is 49.63K. The picture makes it easy to see how the temperatures are spread out along the helical shape, with clear thermal differences visible along the coiled structure. The constant change in temperature across the spiral turns shows that the copper wall between the tubes effectively helps heat transfer, proving the thermal efficiency of the design.

Figure 3: Temperature changes during helical coil for inside pipe

The fluid dynamics study shows that the velocity changes a lot between the inlet and outlet conditions. For example, measurements show that the velocity goes up from 3.19 m/s at the inlet to 3.25 m/s at the outlet in the cold tube. The helical shape creates helpful secondary flows that improve heat transfer performance while keeping pressure losses within acceptable levels. This shows that the geometrical design is better than regular straight-tube exchanges.