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평면 충돌제트에서 노즐 깃이 단상 및 비등 열전달에 미치는 영향
신창환(Chang Hwan Shin),임성환(Seong Hwan Yim),우성제(Seong Je Wu),조형희(Hyung Hee Cho) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
The water jet impingement cooling is one of the techniques to remove heat from high heat flux equipments. We investigate the local heat transfer of the confined water impinging jet and the effect of nozzle collar to enhance the heat transfer in the free surface jet and submerged jet. Boiling is initiated from the furthest downstream and the wall temperature increase is reduced with developing boiling, forming the flat temperature distributions. The reduction in the nozzle-to-surface distance for H/W≤1 causes the significant increases and distribution changes in heat transfer. Developed boiling reduces the differences in heat transfer for various conditions. The nozzle collar is employed at the nozzle exit. The distances from heated surface to guide plate, H<SUB>c</SUB> are 0.25W, 0.5W and 1.0W. The liquid film thickness is reduced and the velocity of wall jet increase as decreased spacing of collar to heated surface. Heat transfer is enhanced for 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 compare with higher velocity condition. It is because the increased velocity by collar is de-accelerated at downstream.