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Transient heat fluxes in cutting-edge computing systems, electromagnetic switches, and diode-pumped lasers can exceed 50 MW/m2, which is nearly the heat flux radiated by the Sun. To manage extreme thermal loads, the State-of-the-Art is to boil and evaporate liquid coolants on micro- and nano-structured heat sinks. This work demonstrates the application of laser-scanning fluorescence thermography to identify the spatiotemporal limits of local, transient hot-spot cooling with impinging pulsed micro-jets and sprays. The laser-scanning fluorescence thermography measurements are based on the fluorescence of PS microspheres and quantum-dot thin-films deposited on FTO-glass heater substrates. The fluorescence-based thermometers are subsequently coated with either Hafnium (Hf) or Titanium (Ti) metal thin-films, serving as both protective coatings and the heater surfaces at near critical heat flux conditions. This work also discusses the fabrication procedure of the fluorescence heater/thermometers with micro-mesh heater surfaces and the corresponding pulsed-jet-boiling data via IR thermography.
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Fabrication and Testing of Flexible Pulsating Heat Pipes
The demand for flexible microelectronics has increased significantly within the last decade. This study investigates the cooling performance of flexible pulsating heat pipes (PHPs) made from acrylic with a bend radius of ≈300 mm. The fabricated devices support two-phase, pulsating fluid flow inside the rectangular microchannels. Both water and ethanol are used as coolants, where local hot spots are generated by cobalt-alloy foil heaters inside the flexible PHPs. The PHP's dissipate the heat generated to the environment via copper condensers with controlled setpoint temperatures. Based on a heater surface area of ≈1.5 cm 2 and a condenser setpoint temperature of 25°C, the maximum heat flux observed for sustained and repeatable cooling with water and ethanol was 8 W /cm 2 . These heat fluxes correlate well with other PHP studies with similar heater power loads, channel geometries, and coolants.
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- Award ID(s):
- 1653396
- PAR ID:
- 10433043
- Date Published:
- Journal Name:
- 2023 22nd IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)
- Page Range / eLocation ID:
- 1 to 7
- Format(s):
- Medium: X
- 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/ITherm55368.2023.10177672
