Effect of Dissociation-Recombination Processes in a Dielectric Dispersion Medium on the Coalescence and Non-Coalescence of Conducting Droplets Suspended in it

An electrical coalescence of conducting droplets is the basis for electrostatic oil cleaning, when tiny water droplets are removed from the dispersion (continuous) medium. However, most studies on the topic treat oil as a perfect dielectric or, at least, disregard dissociation-recombination charged layers near the water-oil interface without appropriate substantiation. The effect of finite (i.e., non-zero) electrical conductivity of oil and dissociation-recombination phenomena in it on the electrical coalescence processes is considered in the present investigation. Two important cases are examined, where oppositely charged ions have equal and different mobilities. In the first case, the threshold electric field strength value, the average electric field strength in the interelectrode space when coalescence of droplets is replaced with non-coalescence, shows a weak decrease compared to the case of dielectric oil. In the latter case, the collision between droplets becomes unlikely due to their translation motion in the same direction and the emergence of electrohydrodynamic jet in the opposite direction behind the droplets.