Simulation and analysis of heat transfer in counter-flow helical double-pipe heat exchangers using CFD

Heat exchangers play a vital role in industrial applications by facilitating efficient thermal energy exchange between two distinct fluid streams. These fluids are separated by a solid barrier, which prevents mixing, conserves energy and reduces operational costs. To enhance the efficiency of heat exchangers, wire inserts are often incorporated into the fluid paths. These inserts increase turbulence, improve fluid mixing, and boost heat transfer rates, making the system more effective. In this study, a counter-flow helical double-pipe heat exchanger was analyzed using Computational Fluid Dynamics (CFD) through the simulation software Ansys CFX. The simulations were conducted for cold fluid temperatures ranging from 12 degrees C to 22 degrees C and hot fluid temperatures between 32 degrees C and 52 degrees C, with Reynolds numbers varying from 5x103 to 45x103 to capture a broad spectrum of flow behaviors. The CFD model demonstrated excellent agreement with experimental results, achieving high correlation coefficients of 0.96 for the hot fluid and 0.95 for the cold fluid. This high level of accuracy validates the robustness of the model in predicting real-world heat transfer dynamics. The inclusion of wire inserts within the cold fluid flow path played a critical role in enhancing heat exchanger performance. By inducing turbulence, the wire inserts disrupted the thermal boundary layer, allowing for greater heat transfer between the hot and cold streams. This resulted in a substantial improvement in heat transfer rates, reaching a 25% increase under optimized conditions. This also led to an improved temperature difference between the fluid at the inlet and outlet, optimizing the thermal performance of the exchanger. Alternative materials such as aluminum or titanium could also be considered for wire inserts, potentially improving thermal efficiency at varying costs.