Abstract
An abnormal phenomenon which appears after critical heat flux and before minimum heat flux in pool boiling is introduced. We do not know why this phenomenon occurs only in a certain range of subcooling and is never observed for saturated liquid. Why a cycle of wet and dry occurs between minimum and critical heat fluxes appears during cooling is still unknown. An interesting phenomenon is observed during quenching with impinging jet cooling, which can be categorized into three different characteristics: the first one is homogeneous nucleation, second is repetition of wet and dry, during which surface is gradually cooled and then a well wetted condition by which the surface is rapidly cooled. A model is tentatively proposed to explain the mechanism of homogeneous nucleation.
