Influence of Dilution Ratio on PM Emission Data

To clarify the proper dilution ratio, new dilution system was designed. The sampling line that was heated by flexible heater was inserted to dilution tunnel horizontally. And the tip of the line was designed as double pipe so that exhaust gas may not be cooled by dilution air. The examinations were carried out to change the dilution ratio was set from 4 to 30 by using old and new dilution systems. Results obtained from the examinations are as follows. (1) Measured PM decrease when a dilution ratio is enlarged. (2) The decrease ratio become about 1/4 by using the new system. (3) The most suitable value of the dilution ratio is around 5.