Abstract
Expansion of a single coalesced bubble rapidly growing on a small film heater succeeding spontaneous nucleation is investigated experimentally under various heating conditions using two-stage heating pulse. The maximum volume and the volume expansion rate of the bubble are shown to increase with the increase in superheated energy stored in the liquid layer before the boiling incipience and to be well correlated with the superheated energy. The shape of the bubble at the maximum volume is also shown to be well correlated with the maximum volume. The obtained results suggest that the bubble size and growth rate can be actively controlled to the prescribed values by the preheating effect at the first pulse stage.
