ROLE OF BUBBLE COALESCENCE IN CAUSING OSV IN SUBCOOLED FLOW BOILING

抄録

Despite available correlations that can indicate the conditions for the point of onset of significant void (POSV) with reasonably high accuracy, the mechanism to cause OSV is still not understood sufficiently. The bubble coalescence-based mechanistic model proposed by Okawa (2021) yields a good agreement with the Saha-Zuber empirical correlation on the prediction of subcooling conditions at OSV. Therefore, experiments were carried out to investigate the possible role of bubble coalescence in OSV for subcooled flow boiling. The high-speed camera (HSC) was used to observe the bubble dynamics before and during the OSV occurrence. In contrast, a gamma densitometer and a void probe are used to measure the global and local void fraction at POSV.