Improvement in Natural Convection Cooling Performance of a Heatsink by Replacing the Upper Section of Cylindrical Pin Fins with a Spring Structure

Natural convection-based cooling technology has attracted considerable attention as a promising approach for achieving both lightweight characteristics and efficient thermal management in electronic devices and energy systems. In this study, a novel heatsink in which the upper portions of conventional cylindrical pin fins were replaced with spring structures was proposed, and its thermal performance in naturally convective flow conditions was evaluated through numerical and experimental analyses. The wire diameter, height, and pitch of the spring were selected as design variables, and optimization was carried out employing the Response Surface Methodology (RSM) based on numerical results. The findings revealed that the spring height was the dominant parameter affecting thermal resistance. Under the optimal conditions of a diameter of 1.25 mm, height of 10 mm, and pitch of 2.2 mm, the difference between the RSM prediction and numerical result was only 0.72%, confirming the accuracy of the model. Compared with the reference heatsink composed only of cylindrical pin fins, the optimized cylindrical-spring pin fin heatsink reduced thermal resistance by 10.4% while decreasing mass by 5.7%. Flow field analysis revealed that the spring structure promoted fluid mixing and accelerated upward flow through the interaction between the internal core flow and external side flow, facilitating natural convection heat transfer enhancement. The experimental and numerical outcomes agreed with a discrepancy of less than 5.14%, while the maximum experimental uncertainty was evaluated as 5.83%. The proposed cylindrical-spring pin fin heatsink is anticipated to offer a promising design strategy for simultaneously improving cooling performance and reducing weight.