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대면적 마이크로채널 히트 싱크 내의 비등 유동의 밀도파 진동수 예측을 위한 이론적 접근
이승현(Seunghyun Lee),박재민(Jaemin Park),정해인(Haein Jung) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The mechanistic model using theoretical model is suggested to predict the frequency of density wave oscillations (DWO) and intermittent dry-out in large length to diameter micro-channel heat sinks. Repeated generation and disappearance of liquid slugs by the bubble expansion and vapor back flow is the main idea of the present model. The initial location of the bubble is determined by the onset of the nucleate boiling and bubble expansion rate is determined by the control volume analysis. After the bubble established at the inlet plenum that is generated by the vapor back flow pushes liquid slugs back into the channel, liquid slug enters the channel again by the pressure difference between the inlet plenum and channel. The velocity of the surged liquid is determined by the mass and momentum conservation. In the results, the MAE of predicted frequency is 14.76% and increases as the heat flux and mass flux increases. The predicted frequency shows the same trends with experimental results but the calculated value is over-predicted for all cases. The intermittent dry-out location is predicted by predicted steady-state liquid film thickness of the annular flow and oscillating frequency. The experimental local heat transfer coefficient decreases after passing dry-out location obtained by predicted frequency of DWO.