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http://dx.doi.org/10.3795/KSME-B.2005.29.7.878

The Effect of Nozzle Collar on Single Phase and Boiling Heat Transfer by Planar Impinging Jet  

Shin Chang Hwan (연세대학교 대학원 기계공학과)
Yim Seong Hwan (연세대학교 대학원 기계공학과)
Wu Seong Je (삼성전자 DA 사업부)
Cho Hyung Hee (연세대학교 기계공학과)
Publication Information
Transactions of the Korean Society of Mechanical Engineers B / v.29, no.7, 2005 , pp. 878-885 More about this Journal
Abstract
The water jet impingement cooling is one of the techniques to remove the heat from high heat flux equipments. Local heat transfer of the confined water impinging jet and the effect of nozzle collar to enhance the heat transfer are investigated in the fee surface jet and submerged jet. Boiling is initiated from the farthest downstream and increase of the wall temperature is reduced with developing boiling, forming the flat temperature distributions. The reduction in the nozzle-to-surface distance fur H/W$\le$1 causes significant increases and distribution changes of heat transfer. Developed boiling reduces the differences of heat transfer for various conditions. The nozzle collar is employed at the nozzle exit. The distances from heated surface to nozzle collar, Hc are 0.25W, 0.5W and 1.0W. The liquid film thickness is reduced and the velocity of wall jet increases as decreased spacing of collar to heated surface. Heat transfer is enhanced fur region from the stagnation to x/W$\~$8 in the free surface jet and to x/W$\~$5 in the submerged jet. For nucleate boiling region of further downstream, the heat transfer by the nozzle collar is decreased in submerged jet comparing with higher velocity condition. It is because the increased velocity by collar is de-accelerated downstream.
Keywords
Confined Jet; Convective Nucleate Boiling; Free Surface; Jet Impingement; Nozzle Collar; Planar Jet;
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  • Reference
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