抄録
Electrical discharge process using corona is effective in reducing particulate matter (PM) and nitrogen oxides (NOx) of diesel engine exhaust. We experimentally evaluate the application of DC corona discharge reactor to reduce the PM and NOx from diesel exhaust. Particulate trapping in a corona reactor can be accomplished by electrostatic precipitation. The accumulated PM on a nichrome electrode of reactor can be regenerated by the controlled burning process. In a corona reactor, NO is oxidized to NO_2 and NO_2 reacts with H_2O contained in exhaust. NOx decreases as a result of HNO_3 formation in a reactor. HNO_3 is neutralized on the filter paper contained alkali. A corona reactor consists of cylindrically-shaped outer electrode made of stainless steel and central electrode made of rolled nichrome wire. Dimensions of prototype reactors are ID×length=φ27×160,φ54×320,a flow rate of 14l/min, resulted in space velocity of about 9200 and 1250/hr. In this study, the effects of corona voltage, current and the space velocity of reactor on the soot collection efficiency and the NOx removal efficiency are investigated. Also discussed is the particle size distribution of soot collected by a reactor. Experimental results show that 1) a corona discharge reactor is capable of reducing both diesel particulates and NOx simultaneously, 2) Nano-particles less than φ0.5μm can be removed by a corona process.
