Particle collection characteristics of a prototype electrostatic precipitator (ESP) for a differential TEOM system

A differential tapered element oscillating microbalance (TEOM) system that includes an electrostatic precipitator (ESP) that is alternately switched on and off has been developed to improve the measurement of airborne particulate matter mass. Preliminary results showed that it has the potential to overcome the difficulties inherent in PM mass measurement and holds the promise of the measurement of PM mass as it exists in ambient air at ambient temperature. A critical aspect of this device is that the ESP totally removes particles from the air stream. In this study a prototype ESP developed by Rupprecht and Patashnick (R&P) Co., Inc. was evaluated for particulate removal efficiency. Laboratory tests were conducted to determine the removal efficiencies for different-sized particles by generating ultrafine (< 0.1 mu m) and fine (>0.1 mum) particles. The ultrafine particles were generated using a 5% solution of sodium chloride, while the fine particles were generated with the different sizes (0.5 mum and 1 mum) of polystyrene latex particles. The discrete size intervals of generated ultrafine particles were obtained from an electrical differential mobility analyzer (DMA). The transmitted ultrafine and fine particles passing through the ESP were then detected using a condensation particle counter (CPC) and a LAS-X, respectively. The overall particle collection efficiency of the ESP was calculated from the differential particle collection efficiencies and the specific particle size distributions of the test aerosols. The results showed that the collection efficiencies of the ESP were essentially constant over the range of corona current levels tested, indicating that those were not strong functions of the applied potential if the field strength was sufficiently high.