Boiling hysteresis of impinging circular submerged jets with highly wetting liquids

An experimental study was carried out to characterize the boiling hysteresis of impinging circular submerged jets with highly wetting liquids. The effects of noncondensable gases and surface aging on boiling curves were considered. The present study focused on the effects of jet parameters (jet exit velocity, radial distance from the stagnation point and nozzle diameter) and fluid subcooling on incipient boiling superheat and superheat excursion, as well as the physical mechanism of boiling hysteresis. Results show that the incipient boiling superheat decreases only with fluid subcooling regardless of jet parameters, and that the superheat excursion increases with nozzle diameter and radial distance from the stagnation point and decreasing jet exit velocity and fluid subcooling. Boiling hysteresis occurs due to deactivation of vapor embryos within larger cavities. Three anomalous phenomena at boiling inception are recorded and discussed in terms of irregular activation of vapor embryos. (C) 2003 Elsevier Inc. All rights reserved.