Diesel engines are widely used as power sources because of their high efficiency, high durability and low cost of operation. However, diesel engines contribute a significant fraction of nitrogen oxide (NOx) and particulate matter (PM) emissions, which have become the focus in diesel emission control technology.
Particulate matters (PM) are made of very small solid carbon cores, absorbed with organic materials derived from fuel (SOF) and engine lubricating oil, and sulfate particulates (sulfuric acid water). Some of the absorbed hydrocarbons are highly poisonous. Because of their small size (<10microns) and chemical composition, many countries published stringent standard for the PM emission.