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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

SUBCOOLED FLOW BOILING WITH MICROBUBBLE EMISSION DEVELOPMENT FOR HIGH HEAT FLUX COOLING TECHNOLOGY IN POWER ELECTRONICS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.280
8 pages

Abstract

Passive-active cooling device is manufactured and tested for high heat flux cooling in power electronics. In the experiment, the heating surface with 100 mm in length and 10 mm in width is placed on the bottom of the main rectangular channel. The sub-channel is assembled overhead of the main channel and multi-needle nozzle with 1 mm in diameter are vertically fitted to the heating surface. Distilled water is used for boiling liquid and subcooled water in the sub-channel flows counter to the main channel flow. In lower heat flux region than 600 kW/m2, passive cooling mode is performed by oozing subcooled water of 40 K though the needle nozzles from sub-channel. Liquid velocity in the main channel is 0.05 m/s. With increasing thermal emission, main channel flow is increased and subcooled flow boiling without impinging jets is performed for cooling by microbubble emission boiling. The maximum cooling heat flux is about 3 MW/m2 at liquid subcooling of 40 K and liquid velocity of 0.5 m/s. Active cooling mode is performed in higher heat flux region than 3 MW/m2. The subcooled jets are strongly issued into the heating surface through the multi-nozzle from the sub-channel and accelerate microbubble emission boiling. The maximum heat flux obtained is about 6 MW/m2 at 40K of liquid subcooling, 0.5m/s of main-channel flow and 4 m/s of jet velocity. No coalesced bubbles are observed in the downstream section of heating surface in the active cooling mode and the pressure fluctuation is very low. The experimental results are effective for silent and high heat flux cooling technology in power electronics.