Generation of hydrogen bubble in biodiesel—Influence of non-uniform electric field

Abstract With regard to improving the blending performance of biodiesel with hydrogen, it is important to generate smaller hydrogen bubbles in biodiesel at low energy consumption. In this context, a strong non-uniform direct current (DC) electric field has been created between a needle-ring electrode configuration, which is used to study the effect of EHD on hydrogen bubble behaviors in biodiesel considering the various gas flow rates and applied voltages. The special geometry of gas cones similar to the Taylor cone in liquid droplets under an electric field is demonstrated. The hydrogen bubble features—which are characterized by the bubble heights, frequencies, velocities, bubble sizes, and shapes—show that the bubble geometry and dynamic characteristics in the electric field are performed in manners different from those reported in the literature. It is found that the hydrodynamic behavior of the bubbles is also modified by the EHD effect. The distributions of bubble size in different cases follow the Gaussian distribution. Small bubbles are more likely to be associated with high separation velocities. Further, the diversity of bubble shapes at the separation is demonstrated, and two regimes of impact mechanism based on the surface tension and electric forces are revealed.