Collection efficiency of ultrafine particles by an electrostatic precipitator under DC and pulse operating modes

High particle collection efficiency in terms of particle weight volume mg/m/sup 3/ is well achieved by a conventional electrostatic precipitator (ESP). However, the collection efficiencies in terms of number density for the ultrafine (particle size between 0.01 to 0.1 /spl mu/m) or submicron particles by a conventional ESP are still relatively low. Therefore, it is necessary to improve the collection efficiency for ultrafine particles. In this work, attempts have been made to improve the ultrafine particle collection efficiency using the short pulse energizations. The present version of ESP consists of three sets of wire plate type electrodes. For ESP under DC operation modes, experimental results show that the collection efficiency for DC applied voltage decreases with increasing dust loading when particle density is larger than 2.5/spl times/10/sup 10/ part/m/sup 3/. For ESP under pulse operating modes, the particle collection efficiency increases with increasing pulse peak voltage until 25 kV then decreases with increasing pulse peak voltage. The ultrafine particle collection efficiency based on particle density by DC energizations is much higher compared with pulse energizations without DC bias may be due to the reentrainments of ultrafine particles.