Experimental–Numerical Investigation of Natural Convection from a Plate Fin Heat Sink with Correlation Assessment

This study investigates the thermal performance of a passive vertical aluminum heat sink with plate fins through combined experimental measurements and numerical simulations. Using a custom-made experimental apparatus which used water as the heat source, heat transfer rate was determined, and heat transfer coefficient was compared against established empirical correlations, demonstrating good agreement. A 3D steady-state mathematical model was developed to capture the conjugate heat transfer problem of conduction and natural convection, with buoyancy-driven airflow modeled with the incompressible ideal gas law. The problem was solved numerically using the finite volume method through ANSYS Fluent 18.2 solver and validated against experimental data and analytical correlations, exhibiting good agreement throughout. Parametric analysis followed, investigating the influence of various base (50, 65, 80 °C) and ambient (19, 24, 29 °C) temperatures, resulting in base-to-ambient temperature differences from 21 to 61 °C. Increasing this temperature difference led to a significant increase in heat transfer rate, while heat transfer coefficient increased and overall thermal resistance decreased moderately. Additionally, a Nusselt–Rayleigh (Nu–Ra) number correlation, consistent with ranges reported in the literature, was derived, providing the scaling to predict the thermal performance of similar natural convection-governed heat sinks. The validated computational methodology, combined with obtained experimental and numerical results, presents a foundation for future studies focused on more complex heat sink geometries and physics.