Evolution of a vapor cavity during explosive boiling on a film microheater: Experiment and numerical simulation

Abstract

Dynamics of formation, growth, and collapse of a vapor cavity during explosive boiling of liquids on film heaters under the action of pulsed heat fluxes q = 10 8 -10 9 W/m 2 is studied theoretically and experimentally. The description of the vapor-cavity formation process is based on the concept of a homogeneous mechanism of nucleation taking into account the influence of already formed and growing bubbles. Evolution of vapor structures is numerically simulated by solving the equations of dynamics of a compressible liquid with allowance for heat transfer, evaporation, and condensation. A comparison of experimental and numerical data shows that the model proposed offers an adequate description of the main features of explosive boiling of liquids on film heaters, including the effect of conditions of the thermal action and liquid properties on the duration of cavity evolution and on the cavity size.

Explosive micro-bubble actuator

“…This is comparable to the heights between 10μm to 70μm found from images in [71]. Varlamov et al [50] show images of a bubble with a height of 40μm for bubble nucleation in ethanol under similar conditions. Asai et al [56] found a bubble height between 70μm and 100μm for boiling in methanol.…”

“…In spite of the extensive research on bubble nucleation and growth in the past there are still a lot of questions on this subject and numbers of papers were written relatively recently on the subject [45,46,47,48,49,50,51]. In each paper a small part of the process is investigated and described, extending the theory somewhat further.…”

“…Lin et al [61] were the first to use a heater made of polysilicon and because the development of MEMS technology the effect of a heater with a irregular shape could be measured. Further investigations on the growth and the collapse of bubbles created due to pulse heating by a micrometer sized heater are described in following papers [62,63,64,65,66,23,67,50].…”

“…The time between the moment of nucleation and the first collapse decreases from 20μs at low power to 13μs at relatively high power. The time between the first collapse and the second collapse decreases from 16μs to 9μs for applied powers between 0.49W [50]. In this paper only the first collapse was considered and a bubble rebound was only briefly mentioned.…”

Effect of Dissolved Gases on the Evolution of a Vapor Cavity Formed During Explosive Evaporation

“…The thermodynamic and kinetic aspects of explosive evaporation of liquids, including the mechanism of boiling incipience, dynamics of vapor cavity evolution, effects of microbubble oscillations and multiple repeated boiling, and pressure and power generation, have been analyzed by many research groups [1,[4][5][6][19][20][21][22][23][24][25][26]. The effect of dissolved gases on boiling incipience temperature, bubble growth, and subsequent evolution of the vapor cavity is of particular importance.…”