Molecular dynamics simulation of ethanol electrohydrodynamic atomization: Microscopic mechanism of the operating parameter effects

Abstract

Electrohydrodynamic (EHD) atomization is a physical process, in which a liquid subjected to an external strong electric field and pumped through a capillary tube, disintegrates into monodisperse fine drops. In present work, EHD atomization behaviors under various operating parameters were numerically investigated using molecular dynamics (MD) methods. Good agreement was obtained between the MD simulations and the previous experimental work. The effects of electric potential, liquid flowrate, sodium chloride concentration and temperature on EHD atomization process were systematically examined, analyzed and discussed from the microscopic perspective. The results show that the jet length and the number of ethanol molecules ejected from capillary tube increased with an increase in electric Bond number. As the electric Bond number increases, the interaction between ethanol molecules decreases, and the hydrogen bond number reduces. As the Weber number increases, the jet length also increases, and the jet morphology may change from ‘plump’ to ‘sharp,’ and finally disrupts into liquid fragments. Sodium chloride plays an important role in the formation of atomization mode. With increasing ions concentration, a continuous jet can convert into dripping, which results from that the ions could destroy the stable structure of hydrogen bond among ethanol molecules. Furthermore, the ethanol clusters would gradually increase in size as the sodium chloride ion concentrations increasing. In addition, the movement of cations is inseparable from the breakup of the jet. The trend of individual atom motion in an ethanol molecule increases with an increase in temperature. This work provides a microscopic insight into EHD atomization and will be potentially useful for optimizing operating parameters and improving efficiency.