ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Nucleation Incipience on a Heated Surface: Effect of Pressure Oscillations
Abstract
Boiling is used as a heat transfer enhancement technique due to the high heat transfer coefficient which can be reached. However, the onset of boiling requires high wall temperatures. A technique to control the onset of nucleation is proposed. It consists in the dynamic deformation of a confinement wall which induces oscillations of the liquid pressure over time. This technique provides nucleation by simultaneous cavitation and boiling process. Experimental results demonstrate the efficiency of this technique: the temperature required for boiling incipience is greatly decreased. In addition, the physical mechanisms involved in this configuration differ from those predicted by existing theories of nucleation: some dynamic effects have a major effect on the nucleation. Theoretical studies are performed to identify the physics governing the evolution of an embryo trapped into a cavity assuming that the contact line can move or not. It is shown that dynamic contact angle effects can be a dynamic effect which promotes nucleation in such configuration.