Hotspot Cooling Performance of Two-Phase Confined Jet Impingement Cooling at the Stagnation Zone
Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems(2022)
摘要
Jet impingement can be particularly effective for removing high heat fluxes from local hotspots. Two-phase jet impingement cooling combines the advantages of both the nucleate boiling heat transfer with the single-phase sensible cooling. This study investigates two-phase confined jet impingement cooling of local, laser-generated hotspots in a 100 nm thick Hafnium (Hf) thin film on glass. The jet/nozzle diameter is ∼1.2 mm and the normal distance between the nozzle outlet and the heated surface is ∼3.2 mm. The jet coolants studied are FC 72, Novec 7200, and Ethanol with jet nozzle outlet Reynolds numbers ranging from 250 to 5000. The hotspot area is ∼0.06 mm 2 and the applied hotspot-to-jet heat fluxes range from 20 W/cm 2 to 350 W/cm 2 . This heat flux range facilitates studies of both the single-phase and two-phase heat transport mechanisms for heat fluxes up to critical heat flux (CHF). The temporal evolution of the temperature distribution of the laser-heated surface is measured using infrared (IR) thermometry. This study focuses on the stagnation point heat transfer - i.e., the jet potential core is co-aligned with the hotspot center. For ethanol, the CHF is ∼315 W/cm 2 at Re ∼1338 with a corresponding heat transfer coefficient of h ∼102 kW/m 2 K. For FC 72, the CHF is ∼94 W/cm 2 at Re∼ 5000 with• a corresponding h∼ 56 kW/m 2 .K. And for Novec 7200, the CHF is ∼108 W/cm 2 at Re∼ 4600 with a corresponding h ∼ 50 kW/m 2 •K.
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关键词
Hotspot Cooling,IR Thermography,Confined Jet Impingement
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