A comparative numerical evaluation of the cooling performance in microchannel heat sinks for low and high Reynolds number laminar flows.

The aim of this research is to use numerical simulations combined with analytical approximations to investigate the cooling performance of low and high Reynolds Number (Re) laminar flow conditions in microchannel heat sinks (MCHSs). A comparative analysis is performed for Re in the ranges of 10 to 800, on a single-phase flow in a rectangular channel with a given aspect ratio categorized into two cases of low and high Re laminar flows. The two cases were conducted with constant thermophysical properties and further evaluated with a temperature-dependent viscosity condition. Subsequently this study further investigates the impact on performance by the addition of hydrophobic nanostructures within the walls of MCHSs inducing slip flow; essentially evaluating how boundary conditions such as slip affect heat exchange for a given pressure drop. The numerical results will be compared with analytical results based on boundary layer theory. The findings indicate that the model's heat transfer predictions are improved by accounting for variable viscosity. The results also show that heat transfer is significantly affected by wall slip as it decreases the thickness of the boundary layers further enhancing the performance. The outcomes of this study are expected to provide useful and valuable insights for MCHSs and contribute to the design progression of advanced cooling technologies