Effects of rib geometry on hydrothermal performance of composite secondary micro-channels

This study investigates the effect of secondary channels and micro-ribs on improving heat transfer and fluid flow performance in micro-channel heat sinks numerically. The parameters analyzed include the bottom wall temperature of the substrate, pressure drop across the micro-channel, and the dimensionless performance indicators Nu/Nu 0 and f/f 0 , along with hydro-thermal flow structures across various Re in the range of 100–500. The hydrothermal performance of five different ribbed composite micro-channels is examined based on the performance indicator value ( PIV ), thermal resistance, and the 2nd law of thermodynamics at different Reynolds numbers. The findings indicate that the secondary channel alone has a negligible effect on enhancing the heat and flow characteristics. However, the introduction of micro-ribs on the side walls has a favorable impact on hydrodynamics and thermal performance, as it produces a throttling effect and enhances the heat transfer area. Among all the configurations, the wall heat flux temperature ( T b ) decreases with increasing flow velocity due to the increment in flow rate. The MC-RD3 configuration exhibits the best thermal and fluid flow characteristics among the studied cases, achieving enhancements of 179.66 %, 425.77 %, and 60.67 % in Nu/Nu 0 , f/f 0 , and PIV , respectively, compared to MC-OSC at Re = 508.