Bubble Dynamics in Boiling Under High Heat Flux Pulse Heating

A new theoretical model of bubble behavior in boiling under high heat flux pulse is presented. The essence of the model is nucleation in the superheated liquid followed by instantaneous formation of a vapor film, rapid bubble growth due to the pressure impulse, and cavitation bubble collapse. To check the model, boiling of methanol under 5 ~ 50 MW m⁻² heat flux pulse using a small thin film heater has been experimentally investigated. When the heat flux was relatively low (< 20 MW m⁻²), a bubble grew in a hemispherical shape. When the heat flux was extremely high (> 20 MW m⁻²), many small bubbles nucleated and combined into a vapor film. The bubble behavior in the latter case is explained well by the model.