Bubble dynamics and pressure oscillation in highly subcooled water jet array impingement boiling under periodical heat flux

Jet array impingement boiling is promising to be used in the applications of large-area high-heat-flux cooling. In this study, the bubble dynamics and pressure oscillations of a one-dimensional confined jet array impingement boiling of highly subcooled water on smooth silicon wafer surface under periodical heat fluxes are investigated experimentally. It is found nucleate boiling mainly occurs nearby wall jet collision (WJC) zones and the initial bubble nucleation starts after a certain period of time in each heating cycle, which is insensitive to heating frequency under the present experimental conditions but related to the positions of WJC zones due to the crossflow effect. The initial bubbles have relatively larger size and will departure from heating surface or not, while the offspring bubbles have relatively smaller size and will not departure from heating wall but collapse on the heating wall. The collapsing of the above two kinds of normal-sized bubble will generate microbubbles (i.e., Microbubble emission boiling, MEB) and the number of microbubbles in jet chamber increases during the heating period. The periodical bubble growth and collapse causes high frequency pressure oscillation, with its frequencies being related to the bubble nucleation rates. The peak oscillation frequency shows somewhat increasing trend with the increasing of heating frequency.

Automated summary

In the study of jet array impingement boiling, it was found that nucleate boiling mainly occurs nearby wall jet collision zones, and initially formed bubbles have relatively larger size while offspring bubbles have relatively smaller size and will collapse on the heating wall. The periodical bubble growth and collapse causes high frequency pressure oscillation, with frequencies related to bubble nucleation rates and showing a somewhat increasing trend with the heating frequency.