Partial nucleate boiling of pure fluid under constant wall temperature condition

Nucleate pool boiling experiments for pure R11 with a constant wall temperature condition were carried out. A microscale heater array was adopted for the quantitative analysis of heat flow rate behavior owing to bubble growth. And the images of bubble during the growth period were captured by the high speed CCD camera synchronized with heat flow rate measurement. The captured images of bubble show almost truncated sphere, whereas the image at the initial growth stage shows an ellipsoidal shape. At the initial stage, the ellipsoidal shape and small contact angle enable the heat supplied from the wall to be higher. The measured heat flow rate shows an abrupt increase. The volume change of the observed bubble requires more heat flow rate than the measured heat flow rate. The required heat is about twice as much as heat supplied from the wall. During the steady growth stage, bubble growth rate is small and it is controlled by the heat supplied from the wall. The contact diameter during the departure stage decreases faster than that during the steady growth stage and the heat flow rate from the wall decreases to the base value