Numerical investigation of thermal enhancement in a micro heat sink with fan-shaped reentrant cavities and internal ribs

• A new micro heat sink with fan-shaped reentrant cavities and internal ribs.
• Effects of relative rib height and Reynolds number on fluid flow and heat transfer.
• Empirical correlations of the apparent friction factor and average Nusselt number.
• The combined effect between reentrant cavities and ribs on thermal enhancement.

This paper numerically investigated the behavior of water through the micro heat sink with fan-shaped reentrant cavities and internal ribs (FRCR) with different relative rib height (e/Dh) for Reynolds number ranging from 150 to 600. This study is also to propose empirical correlations of apparent friction factor and average Nusselt numbers for FRCR, as a function of Reynolds number and relative rib height. The results show that Nusselt number for FRCR is 1.3–3 times more than the rectangular microchannel, although apparent friction factor is 6.5 times more, depending on the Reynolds number within its range. Thermal enhancement with moderate relative rib height is preferable, which will be attained 1.6 at e/Dh = 0.12, Re = 592. The comparison of present data with the open data are also shown that the combined effect of cavity and rib has better performance of heat transfer, and the effect of relative rib height is stronger than the individual effect of the arrangement or the size of reentrant cavity when Re > 300.