Developing an active, high-heat-flux thermal management strategy for power electronics via jumping-droplet phase-change cooling

Hot spot cooling;Electronics hot spot cooling;Jumping-droplet condensation;Electric-field-enhanced jumping-droplet;High-heat-flux;High power density;Power electronics;Thermal management

Foulkes, Thomas Peter ; Pilawa-Podgurski ; Robert C. N. ; Miljkovic ; Nenad

关键词: Hot spot cooling;    Electronics hot spot cooling;    Jumping-droplet condensation;    Electric-field-enhanced jumping-droplet;    High-heat-flux;    High power density;    Power electronics;    Thermal management;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/97344/FOULKES-THESIS-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Mitigating heat generated by hot spots inside of power electronic devices is a formidable obstacle to further increases in power density. This work presents the first demonstration of active cooling for hot spots in compact electronics via electric-field-enhanced (EFE) jumping-droplet condensation. To test the viability of EFE condensation for electronic hot spot cooling, an experimental setup was developed to remove heat via droplet evaporation from single and multiple high-power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm).An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and an electrically floated circuit (directly to the transistor) or a guard ring (surrounding the transistor). Heat transfer measurements were performed in ambient air (22-25 degrees Celsius air temperature, 20-45% relative humidity) to determine the effect of gap spacing (1-5 mm) between the GaN transistor and superhydrophobic surface, strength of the electric field (50-250 V/cm), and the cooling performance at different applied heat flux conditions (demonstrated to 13 W/cm^2) along with power dissipation levels (approximately 1.57 W). EFE condensation was shown to enhance the heat transfer from the local hot spot by approximately 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases (NCGs) is discussed, promising local hot spot heat dissipation rates approaching 120 W/cm^2. This work not only demonstrates EFE-condensation-based electronics cooling for the first time, but also provides a framework for the development of active jumping-droplet-based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.