Bubble-driven heater dynamics in saturated pool boiling

Exploring energy within boiling system is becoming an effective way to enhance heat transfer nowadays. Novel bubble-driven heater has great potential to achieve it. However, heater dynamics in this technique are crucial but unclear in previous studies. Here, boiling on a movable suspended heater with the same density of liquid was simulated to investigate heater dynamics and corresponding mechanisms in detail. Smaller departure diameter and higher frequency were found on movable heater. Periodical up-down motion was observed and the upward movement only occurred at high heat fluxes. Up-down motion contributed to small dry spot diameter and rapid cold liquid supply. The mechanism of different motion over entire bubble cycle was investigated for the first time. Heater moved downwards due to evaporation momentum force (Fe) and add mass force (Fa) during the initial bubble growth stage with expanding triple line, moved upwards due to surface tension force (Fs) during bubble growth period with nearly constant triple line, and it moved downwards again due to Fa when bubble departed. Fa and Fe which impeded bubble departure before were found benefit departure by induced movable heater. Heater manipulation mechanism was found and our study would benefit the design of smart and automatic heater.