Influence of Duty Ratio on Collection Efficiency in a Rectangular AC Energized Electrostatic Precipitator
A. Zukeran1, H. Kawakami2, K. Yasumoto2, Y. Ehara3, and T. Yamamoto3
1Department of Electronic and Electrical Engineering, Kanagawa Institute of Technology, Japan
2Fuji Electric Co., Ltd., Japan
3Department of Electrical and Electronic Engineering, Tokyo City University, Japan
Abstract— Collection of low resistive particulate matter (PM) emitted from automobile and marine diesel engines or diesel generators have been known to be difficult by conventional electrostatic precipitators (ESPs). A two-stage ESP using the charging zone by a DC field, followed by the collection zone by a low-frequency AC field including the rectangular waveforms in the range of approximately 1 Hz, has been installed for the collection of diesel particles in road tunnels, while conventional ESPs utilize DC high voltage. In this paper, the influence of duty ratio on collection efficiency in a rectangular AC energized ESP is investigated. The ESP consists of the pre-charger and the collector. The pre-charger consists of wire electrodes and grounded plate electrodes. A negative DC voltage of 10.5 kV is applied. The collector has a parallel-plates configuration and the spacing between the adjacent plates is 9 mm. Rectangular AC high voltages are applied to the collector. The rectangular AC waveform is 7.8 kV in voltage, with a cycle of 1 s including 0.05—0.5 s of positive high voltage time. The negative DC high voltage is also applied to the collector. The gas flow velocity is 9 m/s. The particle concentrations on the upstream and downstream sides of ESP are measured by particle counters (RION, KC-01D), and collection efficiencies are calculated. The result has demonstrated that the effect of suppressing the particle re-entrainment is not influenced by the duty ratio of the rectangular AC high voltage.
Keywords— Electrostatic precipitator, collection efficiency, re-entrainment, diesel exhaust particle