Abstract
For the purpose of clarifying the mechanism of CHF for saturated and subcooled pool boiling, boiling behaviors close to a heating surface were investigated with micro-sensors. Dryout process of the heating surface appearing near the CHF was measured with a high accurate conductance probe. The wall void fraction increased rapidly just when the CHF occurs, suggesting that the CHF is triggered by dryout of the liquid-rich layer formed beneath the vapor masses. Also, temperature beneath the vapor masses was measured with a micro-thermocouple to examine an effect of subcooling on the liquid-vapor structure close to the heating surface. It was found that the effective subcooling of the liquid adjacent to the heating surface remains within a considerably lower value than the subcooling of bulk liquid.
