Thermo‐Hydraulic Performance Enhancement of Microchannel Heat Sinks: A Review of Passive Techniques and Emerging AI/ML Approaches

The rapid advancement of modern electronics resulted in intensified thermal management challenges, and positioned microchannel heat sinks (MCHSs) as a promising technology to dissipate high heat fluxes in next generation electronics. This review critically examines recent developments in passive thermo‐hydraulic enhancement of MCHSs, with emphasis on three major approaches: channel geometry modification, internal flow modifying structures, and working fluid enhancement. The reviewed studies are synthesized according to their underlying heat transfer mechanisms, including secondary flow generation, boundary layer redevelopment, vortex‐induced mixing, wake interaction, recirculation, and increased effective heat transfer area. Particular emphasis is placed on the balance between heat transfer enhancement and hydraulic losses, as an increase in Nusselt number alone does not necessarily indicate better thermo‐hydraulic performance. The review considers integrated and hybrid enhancement configurations, as the combined use of different flow disturbing elements provided improved heat transfer with properly designed interaction. Excessive flow blockage resulted in a pressure drop penalty and reduces the overall benefit. Nanofluids and hybrid nanofluids are also discussed, considering their potential to enhance thermal performance as well as practical concerns such as stability, increased viscosity, particle sedimentation, and higher pumping requirements. In addition, emerging AI/ML approaches are reviewed across performance prediction, deep learning, physics‐informed modelling, surrogate‐assisted optimization, reinforcement learning, and CFD–ML frameworks. The analysis indicates that AI/ML can accelerate design exploration and optimization within defined parameter domains, but limitations associated with dataset quality, extrapolation, uncertainty, and independent validation remain. Finally, key research gaps involving experimental validation, manufacturability, multi‐parameter optimization, transient thermal behavior, uncertainty quantification, and intelligent thermal control are identified. The review provides an integrated perspective for developing high performance and practically viable MCHSs for next‐generation electronics cooling.