Simultaneous effects of electrostatic field and thermophoresis on inhalable particulate matter removal

Abstract

An inhalable particulate matter removal technique was developed based on the simultaneous effects of an electrostatic field and the thermophoretic force on the particulate matter. An experimental system was designed to measure the electrostatic and thermophoretic particulate matter removal efficiencies. An Electrical Low Pressure Impactor (ELPI) was used for on-line measurements of the particle concentration distribution in the experimental section. The experimental system was used to measure the separated and simultaneous effects of the electrostatic field, thermophoresis, water film on the inhalable particulate matter removal efficiency. The experimental results show that the inhalable particulate matter deposition efficiencies were quite low without the combined effects of the electrostatic field, thermophoresis and water film absorption. With increasing temperature difference between the gas and the cold wall with the addition of the water film, the combined effects of the electrostatic field and the thermophoretic force significantly improve the inhalable particulate matter deposition efficiencies, especially for particles smaller than 1 μm (sub-micron particles). Increased gas flow rates reduced the inhalable particulate matter removal efficiency. It provided guidance to design advanced wet ESPs, which could overcome the insufficient for traditional ESP theory by utilizing the simultaneous effects of the electrostatic field, thermophoresis and water film for removing inhalable particles.