Jet impingement can be particularly effective for removing high heat fluxes from local hotspots. Two-phase jet impingement cooling combines the advantage of both the nucleate boiling heat transfer with the single-phase sensible cooling. This study investigates two-phase submerged jet impingement cooling of local hotspots generated by a diode laser 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. Novec 7100 is used as the coolant and the Reynolds numbers at the jet nozzle outlet range from 250 to 5000. The hotspot area is ∼ 0.06 mm2 and the applied hotspot-to-jet heat flux ranges from 20 W/cm2 to 220 W/cm2. 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 also investigates the nucleate boiling regime as a function of the distance between the hotspot center and the jet stagnation point. For example, when the hotspot center and the jet are co-aligned (x/D = 0), the CHF is found to be ∼ 177 W/cm2 at Re ∼ 5000 with a corresponding heat transfer coefficient of ∼58 kW/m2.K. While the CHF is ∼ 130 W/cm2 at Re ∼ 5000 with a jet-to-hotspot offset of x/D ≈ 4.2.
Hotspot Cooling Performance of Two-Phase Confined Jet Impingement Cooling at the Stagnation
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 mm2 and the
applied hotspot-to-jet heat fluxes range from 20 W/cm2 to
350 W/cm2. 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/cm2 at Re ∼ 1338 with a
corresponding heat transfer coefficient of h ∼ 102 kW/m2·K.
For FC 72, the CHF is ∼94 W/cm2 at Re ∼ 5000 with a
corresponding h ∼ 56 kW/m2·K. And for Novec 7200, the
CHF is ∼108 W/cm2 at Re ∼ 4600 with a corresponding
h ∼ 50 kW/m2·K.
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- Award ID(s):
- 1653396
- NSF-PAR ID:
- 10341130
- Date Published:
- Journal Name:
- 2022 21st IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (iTherm)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
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