This study proposes the use of symmetrical ogive-shaped ribs on the walls of microchannel heat sinks (MCHS) to improve their thermal performance with minimal pressure drop. The ribs are arranged in three different configurations: ribs attached to all channel walls (MC-SAWR), ribs attached to side channel walls (MC-SSWR), and ribs attached to the bottom channel wall (MC-SBWR). Numerical investigations are conducted using the laminar conjugate heat transfer model to study the flow and heat transfer characteristics of the MCHS. The augmentation entropy generation number and thermal enhancement factor criterion are used to quantify the overall hydrothermal performance of the MCHS. The results show that the inclusion of symmetrical ogive-shaped ribs improves the Nusselt number of MCHS. The MC-SAWR configuration shows the highest Nusselt number improvement of 13–50% compared to the smooth MCHS over the Reynolds number range of 100–1000. Additionally, the MC-SAWR configuration shows a maximum reduction of 58% in the total entropy generation rate as it has the smallest augmentation entropy generation number value of 0.42. In terms of the thermal enhancement factor criterion, the MC-SSWR configuration shows the highest performance at Reynolds numbers below 400, but the MC-SAWR configuration outperformed the MC-SSWR configuration at Reynolds numbers above 400. Therefore, the MC-SAWR configuration is the best configuration that provides high cooling performance.

In this study, 3D numerical conjugate heat transfer modeling is used to investigate the thermal and hydraulic characteristics of the microchannel heat sink (MCHS) with different configurations of novel ogive shape ribs on channel walls. It was found that new proposed MCHS configurations with ogive ribs have a high Nusselt number as compared to the smooth MCHS because ogive ribs enhance the heat dissipation between channel walls and fluid by continuously interrupting the thermal boundary layer development. MCHS configuration with ogive ribs mounted on bottom wall improves the Nusselt number of smooth MCHS by 1.13–1.87 times, while MCHS with ogive ribs mounted on both side walls and MCHS with ogive ribs mounted on bottom channel wall improve Nusselt number by 1.12–1.70 and 1.08–1.59 times, respectively, at Re 100–1000. In terms of thermal enhancement factor criterion, the MCHS with ogive ribs on side walls shows superior performance at Re 100–300 and has the highest thermal enhancement factor. While MCHS with ogive ribs on bottom wall outperformed other configurations in terms of thermal enhancement factor at Reynold number > 300. A maximum thermal enhancement factor of 1.42 is reported for MCHS with bottom wall ribs ogive at Re = 1000.