Electrostatic precipitator is one of the technologies to reduce PM emissions from marine diesel engines. However, when electrostatic precipitators are applied to the exhaust gas treatment of diesel engines, their discharge characteristics have not been clarified. In this study, the effects of ambient gas conditions on the discharge characteristics of electrostatic precipitators have been investigated to develop an electrostatic-cyclone type precipitator. A high-pressure chamber with a discharge electrode and a collection plate placed inside was manufactured and used in the experiment. The ambient temperature and pressure could be adjusted within the range of room temperature and 300 deg C and the range of 0.1 and 0.5 MPa (abs.), respectively. The experimental results show that the discharge current of the saw-type electrode used here changes depending on the atmospheric temperature and pressure and is basically determined by the gas density of the atmosphere. Furthermore, the discharge characteristics in the exhaust gas of a 2-Stroke marine diesel engine was examined. The results show that the discharge characteristics in the exhaust gas are different from those in the atmosphere.
