Electrohydrodynamic enhancement of evaporation from NaCl solutions

Abstract

Evaporation from and nucleation of saline solutions exposed to high fluxes of bipolar air ions produced by single corona electrodes were studied with a beta-ray gauge. NaCl solutions of various concentrations evaporated 3.5 to 3.9 times faster when exposed simultaneously to 0.94 × 10 12 positive and 1.83 × 10 12 negative ions cm −2s −1 than freely evaporating control solutions. Evaporation enhancement occurred at a steady-state temperature that was well below the corresponding wet bulb temperature. The nucleation sites in a solution were observed to be preferentially located below the overhead emitting electrodes; whereas the sites appeared to be spatially random for control solutions. The solutions exposed to the electrohydrodynamic forces nucleated earlier than the control. Electric wind is primarily attributed to the evaporation rate enhancement and the accelerated nucleation at preferred sites in the solutions.