EXPERIMENTAL AND THEORETICAL INVESTIGATION OF CRITICAL HEAT FLUX INCLUDING EHD ENHANCEMENT

摘要

An experimental system has been developed to investigate the effect of EHD on the critical heat flux (CHF) in pool boiling on a horizontal wall. With increasing electric field strength, significant and nonlinear enhancement of the heat transfer in the nucleate boiling regime and of CHF has been observed. The preliminary measurements are consistent with published models for the effect of an electric field on the hydrodynamic mechanism for CHF at low fields but the models do not explain a nonlinear increase in heat transfer coefficient and CHF at high field strength. Progress has been made towards the development of a theoretical model for CHF based on the dynamics of individual bubbles. The model combines sub-models for a thin liquid microlayer and dynamic contact angle at the base of a bubble and a macro-region surrounding the dome of the bubble. Some preliminary results for the approximate matching of both models are presented, showing the evolution of the "dry-spot" and the shape of the bubble up to detachment with and without the electric field.