Investigation of heat transfer performance of various internal fins in high heat flux applications

Abstract

This study introduces a novel optimization strategy for conjugate heat transfer under extreme heat flux conditions (5 MW/m2) by exploring longitudinally varying transverse fin geometries. A novel characteristic length (L<inf>c</inf>=4V<inf>fluid</inf>/A<inf>surface</inf>),(with units of length) is proposed to quantify fin-fluid interactions and guide design. Fifteen transverse fin configurations, five shapes (a–e) evaluated across three size variants (3 × 3 mm, 4 × 3 mm, and 5 × 3 mm), were simulated using ANSYS Fluent 2022 R2 to assess convective heat transfer coefficients, thermal resistance, pressure drop, and overall performance. Among these, shape “d_3 × 3” consistently exhibited the most favourable results, achieving up to 20 % surface temperature reduction compared to the baseline, driven by increased effective surface area and optimized flow distribution (elevated Nusselt number and heat transfer coefficient). These results significantly surpass conventional fin designs, which typically yield temperature reductions of only 10–15 % under similar operating conditions. Furthermore, this study highlights the importance of balancing geometric complexity with pressure drop penalties to maximize thermal efficiency. The findings provide actionable design guidelines for next-generation thermal management systems and offer a foundation for further enhancements through the incorporation of nanofluids, phase-change materials, or advanced manufacturing techniques such as topology optimization and additive manufacturing. © 2025 Elsevier B.V., All rights reserved.