Investigation of two-stage type electrostatic precipitator reentrainment phenomena under diesel flue gases

One electrostatic precipitator (ESP) application is cleaning the air and increasing the visibility index in highway tunnels. The main particles found in highway tunnels are made of carbon. ESP collection efficiency of a certain particle diameter is often negative when the ESP collects carbon particles of low resistance. This means that the number of particles downstream is greater than that of the number of particles upstream of the ESP. Generally, this phenomenon is explained by the reentrainment of particles. In this work, experiments were performed to investigate the cause of the ESP negative particle collection efficiency. Experimental results show that the ESP negative particle collection efficiency is caused by a reentrainment of particles during ESP operation. The effect of gas flow velocity on the ESP collection efficiency was also investigated to clear the cause of reentrainment phenomena. The result shows that the reentrainment may depend on gas flow velocity, because the ESP collection efficiency for the larger particles increases with increasing gas flow velocity.