فهرست نشریات علمی دسترسی آزاد ایران

Concentric tube heat exchangers play a vital role in optimizing thermal control across diverse industrial processes, yet their performance is heavily influenced by the inner tube's geometric configuration. This study investigates the thermohydraulic and exergy performance of four novel cross-sectional geometries: square (Case 1), hexagonal face (Case 2), curved triangle (Case 3), and curved star (Case 4), compared to a conventional circular tube (base model) at a Reynolds number of 20,000 using 3D CFD simulations (realizable k-ε model). Parameters such as the Nusselt number, U-value, pressure drop, efficiency, and exergy degradation are analyzed. The proposed geometries maintain identical inlet and outlet areas as the base model, ensuring material efficiency and practical manufacturability. Quantitative results demonstrate that Case 4 (curved star) achieves the highest performance, with a Nusselt number increase of 25% and exergy destruction reduced by 18% compared to the base model, driven by enhanced turbulence and secondary flows. Case 2 (hexagonal face) offers a balanced performance with a 15% Nusselt number improvement and a moderate pressure drop increase of 22%. Cases 1 and 3 yield enhancements of 10% and 12%, respectively. These observations underscore the capability of modified cross-sectional designs to enhance thermal performance in heat exchange equipment, presenting budget-friendly options for high-energy consumption industries such as electrical power and chemical synthesis.