Ultrahigh CHF prediction for subcooled flow boiling based on homogenous nucleation mechanism

Liu, W.; Nariai, Hideki*

Homogeneous nucleation, although being discounted as a mechanism for vapor formation for water in most conditions, is found being possible to occur under some extreme conditions in subcooled flow boiling. In this paper, firstly, the existence of the homogeneous nucleation governed condition is indicated. Followed, a criterion is developed to judge a given working condition is the conventional one or the homogeneous nucleation governed one. With the criterion, subcooled flow boiling data are categorized and typical homogeneous nucleation governed datasets are listed. CHF triggering mechanism for the homogeneous nucleation governed condition is proposed and verified. Parametric trends of the CHF, in terms of mass flux, pressure, inlet subcooling, channel diameter and the ratio of heated length to diameter are also studied.