Conductivity Effects on the Thermal Performance of Plate-Fin Heat Sinks

Abstract The forced convection heat transfer characteristics of plate-fin heat sinks are numerically investigated to evaluate the explicit influence of substrate material selection on thermal performance. Locking the physical geometry into a uniform heating profile (Lh/L = 1.0,Lc/L = 0.5), a high-fidelity 3D Conjugate Heat Transfer (CHT) CFD framework is developed to resolve the simultaneous coupling between solid conduction and fluid convection. A structured Hexcore mesh is utilized to capture complex solid-fluid boundary layer interactions across multiple volumetric flow rates (Q = 0.2 to 0.8 m3/min). The numerical results demonstrate that utilizing high-conductivity materials significantly suppresses downstream thermal accumulation, lowering peak operating temperatures compared to low condutivity materials like titanium or stainless steel, for example. Furthermore, the 3D model identifies a critical transition threshold where expanding the airflow rate yields diminishing returns as the system shifts from a convection-limited domain to a conduction-bound regime dictated entirely by the material’s bulk thermal conductivity (k). These findings establish vital thermodynamic selection criteria for the material and structural optimization of advanced high-power electronic cooling configurations.