The diesel engine has long been the most energy efficient powerplant for transportation. Moreover, diesel engines emit extremely low levels of hydrocarbon and carbon monoxide that do not require after combustion treatment to comply with current and projected nitrogen oxides and particulate matter standards.
Traditionally, measures aimed at reducing one of these two exhaust species have led to increasing the other. This physical characteristics, which is known as NOx/PM trade-off, remains the subject of an intense research effort. Diesel engine has low specific fuel consumption and it also has a little CO and HC emission, while NOx and PM emission are very much, compared with exhaust emission standards.
However, the limit level is more and more strengthened yearly due to the importance of environmental protection. So, the optimal countermeasure for the reduction of NOx and PM emission below limit level is required.
In the meantime, many advances were achieved in diesel exhaust after combustion emission control devices technology.
Selective catalytic reduction(SCR), used in the past to reduce NOx from large industrial installations, is now being developed for heavy-duty on-highway diesel engines.
Diesel particulate filters(DPF) which are known for their ability in reducing PM have previously suffered from regeneration, reliability and durability problems.
PM can be removed by various filtering processes, but the filter is blocked relatively fast and needs to be regenerated. The SCR solution, however, gives problems with storage of the reducing agent. This is of both inconvenience and safety concern.
An alternative way to access the NOx and PM reduction problem is to use an plasma reactor. In plasma reactor, electricity supplied from the vehicle electrical power supply is used to reduce NOx and PM.
In this study, an experimental research has been conducted to reduce NOx and PM emission simultaneously from combustion flue gases by application corona discharge type electrostatic precipitator(ESP). The ESP was located on the exhaust line after silencer. The operating conditions as inlet parameters taken in this experiment were corona power input, gas velocity and mist concentration. It was found that the corona discharge type electrostatic precipitator could reduce diesel exhaust particles at moderatly efficiency but appeared to bring slight effect on NOx.