Design of micro-nano structures for counter flow diverging microchannel heat sink with extraordinarily high energy efficiency

In the current digital society, more energy-saving and reliable cooling systems are urgently needed for the flourishing electronic industry demanding a very high heat dissipation rate. Through the channel-to-channel heat transfer, a counter flow diverging microchannel heat sink has demonstrated to be a high performance cooling design in our previous studies. This work further integrates such an innovative design with surface modification of microscale cavities with optimal mouth diameter from the nucleation theory and nanoscale coating structures. The results of the present study demonstrate a significant enhancement on boiling heat transfer performance with the corresponding pumping power very close to that of the single-phase flow. Through highly efficient nucleate boiling from well-designed cavities with liquid replenished from the excellent wicking effect of nano-structure and stable two-phase flow, this study achieves a 4.8 kW effective heat dissipation rate on a 3 cm × 4 cm cooling area without sign of reaching the critical heat flux. Remarkably, an unprecedented coefficient of performance, defined as the heat dissipation rate to the pumping power, over 150,000, an order of magnitude higher than that reported in the literature, is accomplished.