Abstract
The pool boiling CHFs were investigated to clarify the generalized phenomena of transition to film boiling at transient condition. The CHFs were measured on a 1.0 mm diameter platinum horizontal cylinder for exponential heat generation rates with various periods for saturated liquids at atmospheric pressure. The incipience of boiling processes was completely different depending on pre-pressurization. Also, the dependence on pre-pressurization in transient CHFs changed due to the wettability of boiling liquids. The trend of typical CHFs were clearly divided into the first, second, and third groups for long, short, and intermediate periods, respectively. Due to the effect of pre-pressurization, the boiling incipience mechanism was replaced from that by active cavities entraining vapor to that by the HSN in originally flooded cavities.
