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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

HIGH HEAT FLUX COOLING OF LARGE AREAS BY IMPROVED LIQUID SUPPLY FOR FLOW BOLING IN NARROW CHANNELS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.320
12 pages

Sinopsis

Most of heat transfer researches concerning the development of electronic devices are conducted for the cooling of small semiconductor chips, while there is a limited number of challenging investigation for the cooling of a large area at extremely high heat flux larger than 2×105W/m2. An innovative cooling technology is needed for the cooling of a large semiconductors referred to as power electronics which are widely introduced in the power conversion process, for example, in power plants and various factories and in power controllers for hybrid automobiles. The use of new SiC power electronics operated at moderate temperatures reduces markedly the power conversion loss compared to the use of conventional Si semiconductors, which contributes to the energy conservation and, in turn, to the improvement of global environment.
A narrow channel between parallel plates is one of ideal structures for the application of boiling phenomena for the cooling of such large semiconductors. To realize the cooling of large areas at extremely high heat flux under the conditions of a minimum gap size and a minimum flow rate of liquid supplied, a new structure of heated channel is devised, where liquid is additionally supplied from the auxiliary unheated channel in the transverse direction perpendicular to the bulk flow in the main heated channel. Despite of a long heated length of 150mm, a CHF value of 2.2×106W/m2 is obtained for a gap size 5mm at low inlet velocity 0.2m/s for water with subcooling of 15K under near atmospheric pressure. The value is larger by around 1.5 times than that without enhanced liquid supply. The increment of CHF is more pronounced to become 2.5 times for the lowest inlet velocity of 0.065m/s tested in this study. Even at a small gap size of 2mm, critical heat flux of 1.0×106W/m2 is obtained at low inlet velocity of 0.065m/s. Heat transfer coefficients as much as 1.0×105W/m2K are realized for s=5mm at heat flux near CHF by the evaporation of thin liquid film in the devised narrow channel structure.