Heat transfer augmentation in microchannel heat sink using secondary flows: A review

This paper provides an extensive overview of heat transfer augmentation through various techniques using microchannel heat sink (MCHS). Continuous miniaturization of electronic devices due to multifunction, high heat flux over the unit area, and lower package volume has compelled researchers to find advanced and sophisticated heat removal technologies. This review paper (with more than 300 references) covers the recent developments in the area of different cooling technologies in general and MCHS in particular. The focus has been paid to the research articles since 2010 because of the enormous volume of papers published in this area in the last 10 years. Following a brief introduction to the rise of micro-scale devices, as well as conventional cooling technologies and applications, the review first classifies flow channels, as well as the various microchannel fabrication techniques used over the years. The next section provides different methods adopted for heat transfer enhancement that are broadly categorized under active and passive techniques, with the focus on passive devices. The final section provides heat transfer enhancement in MCHS by geometrical modifications. When flow inside a straight channel becomes regular and the boundary layer grows, heat transfer performance deteriorates. So, extensive studies have been conducted on channels that inherently provide boundary layer interruption, secondary flows, and chaotic advection that promote heat transfer without modest change in pumping power. Special emphasis has been given to the fractal shaped MCHS due to its inherent property of reducing temperature non-uniformity with an insignificant drop in pressure. Additionally, comments and perspectives to highlight the notable contributions are presented.