The effect of an electric field on behaviour of thermally induced bubble in liquid nitrogen

The effect of a dc uniform electric field on the behaviour of bubbles in liquid nitrogen such as their growth, deformation and departure frequency has been experimentally investigated. The experiment was performed using a stainless steel mesh-plate electrode. The experimental results show that (1) prolate spherical bubbles are formed in the direction of electric field and bubble deformation increases with increasing applied voltage, (2) the bubble departure frequency decreases and the departure volume increases with increasing electric field strength, (3) any effect of the electric field polarity is not obvious. For clarifying these phenomena, the electric field distribution around a bubble has been simulated using the finite element analysis (FEA) method and the electric force acting on bubble calculated numerically. In addition, the effect of changes to thermal bubble behaviour on boiling heat transfer is also discussed. Obtained results may lay a foundation for exploring the mechanism of electrohydrodynamic (EHD) enhancement of boiling heat transfer of liquid nitrogen.