Contribution of Microlayer Evaporation to Bubble Growth in Pool Saturated Boiling of Water

Heat transfer and formation characteristics of the microlayer are investigated by the surface temperature measurement with a MEMS thermal sensor and the wall heat transfer evaluation using an experimental data. The temperature data clearly indicated transition of heat transfer phenomenon on the heated surface from microlayer formation via dry-out of the microlayer to rewetting of the dry-out region. Microlayer evaporation transferred extremely high heat flux over 1 MW/m² and was found to be the dominant heat transfer mechanism in the wall heat transfer during isolated bubble boiling of water. The contribution of microlayer evaporation to bubble growth was found to be 50% and not vary with wall superheat. Finally the spatial distribution of initial thickness of microlayer was calculated from the wall heat transfer.