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Abstract 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.
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Novel Subcooled Boiling Chamber With Submerged Condensation for High Heat Flux Removal for Data Center Application
Electronic components, especially the CPUs/GPUs used in data centers are concentrated heat-generating sources. Their large Thermal Design Power (TDP), small die area and confined packaging make their thermal management a unique challenge. While conventional single-phase cooling methods fail to dissipate such large amounts of heat efficiently, recently developed two-phase cooling systems also lack the holistic approach of combining efficient boiling and condensation mechanisms. It is hypothesized that subcooled boiling with submerged condensation and reduced saturation pressure will result in high-heat flux dissipation while maintaining low surface temperatures. The novel boiling chamber presented in this work is demonstrated in a compact configuration that fits in a 1U/2U server rack by combining submerged condensation with subcooled pool boiling. The boiling chamber is filled with 13% and 40% fill ratio of water and Novec-7000 and experimentally investigated on a thermal test vehicle. Results show that the boiling chamber dissipates about 400 W of heat with a surface temperature of less than 80 °C using Novec-7000 working fluid. When tested with water, the device dissipated more than 750 W of heat (heat flux ≈ 67 W/cm2) with a surface temperature of less than 90 °C. Though the surface temperature rose to 120°C, further testing shows the device to dissipate more than 1 kW from a 34.5 × 32 mm2 plain copper chip. High-speed images identify submerged condensation and small diameters of vapor bubbles. Further enhancements can be achieved by implementing enhanced boiling and condensation surfaces. Lastly, a guide to design considerations and future work is provided to unlock the greater performance potential of the novel boiling chamber.
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- Award ID(s):
- 2022614
- PAR ID:
- 10583619
- Publisher / Repository:
- IEEE
- Date Published:
- ISSN:
- 1936-3958
- ISBN:
- 979-8-3503-6433-0
- Page Range / eLocation ID:
- 1 to 10
- Format(s):
- Medium: X
- Location:
- Aurora, CO, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ITherm55375.2024.10709501
