Thermodynamic Optimization of Microfluidic Heat-sinks via Entropy Generation Minimization (EGM) Approach

Modern electronic devices, especially flexible, compact, and high-power systems are pushing the limits of traditional thermal management solutions. As power densities continue to rise, microchannel heat sinks (MCHS) have become essential for maintaining device reliability, performance stability, and safe operating temperatures. However, conventional two-dimensional channel design often struggles to dissipate heat uniformly, leading to localized hotspots and increased thermodynamic losses. Three-dimensional (3D) microchannel architectures have recently gained attention for their ability to enhance heat spreading and improve coolant-surface interaction, yet their second-law performance across different operating conditions remains underexplored. This work presents a comprehensive computational study aimed at optimizing 3D microchannel heat sink performance using entropy generation as the primary assessment metric. A detailed computational fluid dynamic (CFD) simulation is carried out to evaluate their irreversibilities within coil-shaped, rectangular, and triangular microchannel geometries. Entropy generation and the Bejan number are computed to quantify the combined effect of heat transfer and fluid friction irreversibilities, offering a deeper thermodynamic perspective beyond conventional thermal resistance or Nusselt number analysis. In this study, the Reynolds number range between 1-50 was used to conduct the simulation. This study identifies the optimised microchannel for improved performance. The coil-shaped microchannel demonstrates strong potential for minimizing entropy generation. The insights from this study provide design guidelines for developing 3D microchannel designs, enabling effective thermal management solutions for contemporary electronic systems.