POOL BOILING OF A NONAZEOTROPIC BINARY MIXTURE UNDER MICROGRAVITY

Pool boiling experiments with non-azeotropic water-ethanol mixtures we re conducted under 10-second microgravity conditions available from a drop shaft facility with a 490 m free fall. Comparing with the terrest rial condition, the boiling heat transfer was enhanced under micrograv ity. The observation from the back side of a transparent glass plate h eater suggests that the enhancement could be ascribed to the Marangoni flow induced by an ethanol concentration gradient due to preferential evaporation of ethanol along the surface of enlarged vapor bubbles de tached from, but still kept close to, the heater surface under microgr avity.