The electrostatic precipitator (ESP) is used all over the world to clean particles from contaminated industrial and domestical air. Recent observations and experiments however are disturbing. These indicate that, when capturing an oil mist or possibly droplets in general, phenomena occur that can cause the ESP to generate rather than remove (sub)micron particles. At spots where the electric field strength is high enough, collected droplets deform into a conical shape, the so-called Taylor cone. At the tip of this cone a jet is formed that breaks up in an enormous number of (sub)micron-sized droplets. In the ESP, this occurs at the charging corona wires and at sharp points on the collector plates. Because a part of the ESP energy is thus being used to spray droplets electrically, less energy can be utilized for ionization to charge incoming particles. Simultaneously, the active field strength between the collector plates decreases. These factors result in a substantial decrease in collection efficiency over the total size range. In addition to this overall decrease in efficiency, particles in the order of 1μm are generated from the tip of the developed Taylor cones. Most of these generated droplets will be trapped in the ESP, but droplets formed close to the exit of the plates, depending on the configuration of the ESP, will be discharged from the precipitator. Thus, for particles of this size, the ESP is a particle generator rather than a particle remover.
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