MING-CHANG LUHsu Y.-T.Li J.-X.Lu M.-C.2019-09-102019-09-10201813594311https://scholars.lib.ntu.edu.tw/handle/123456789/424511Continual increases in the functionality and miniaturization of electronic devices have resulted in a rapid increase in the power density of such devices. Thus, an efficient cooling technology is required to maximize heat dissipation and prevent electronic failure. Immersion cooling is a promising technique for the thermal management of high-power-density electronics. However, common working fluids in immersion cooling have high global warming potential, and the heat transfer performance of immersion cooling requires improvement to achieve efficient cooling of state-of-the-art high-power-density electronics. In this study, Novec 649, which has low global warming potential and a low boiling point, was applied as a working fluid for immersion cooling. A Si nanowire (SiNW) array, Si micropillar (SiMP) array, and Si nanowires on a Si micropillar (SiNW/MP) two-tier structure were employed to enhance boiling performance. The SiMP surface exhibited the highest critical heat flux (CHF) of 23.5 ¡Ó 1.3 W/cm2, whereas the SiNW surface exhibited the lowest CHF but a relatively high heat transfer coefficient (HTC). The SiNW/MP surface exhibited the highest HTC of 23611.7 ¡Ó 1586.2 W/m2 K and a relatively large CHF of 17.4 ¡Ó 1.2 W/cm2. Compared with a plain SiO2 surface, the CHF and HTC of the SiNW/MP two-tier structure could be enhanced by 30% and 455%, respectively. These results suggest that the SiNW/MP surface is effective for enhancing immersion cooling. ? 2017 Elsevier LtdBoiling heat transferCritical heat fluxHeat transfer coefficientImmersion coolingNovec 649Two-tier structurejournal article10.1016/j.applthermaleng.2017.12.0672-s2.0-85039149267https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039149267&doi=10.1016%2fj.applthermaleng.2017.12.067&partnerID=40&md5=48904962ef03eebfc39255369a1df6ff