Number Measurements and Size Dependent Volatility Study of Diesel Exhaust Particles

An in-house developed volatility tandem differential mobility analyzer (v-TDMA) instrument in tandem mode has been used to study the exhaust particles of a heavy-duty Diesel engine equipped with a continuously regenerating trap (CRT) at two steady state conditions: medium speed / 100 % load and high speed idle. By use of the tandem mode of the v-TDMA instrument, particles in a narrow size range are led to the heater and the size dependent volatility can be studied. A rotating disc diluter was used to condition the sample. Temperatures between ambient temperature and 350 °C have been applied to study the volatility of the particles.

The current work indicates that particles generated at high load have the same size after heating as before being heated. At high speed idle, small fractions of material can be found as smaller sized particles after heating. The study is an attempt to obtain size dependent information about engine exhaust particles. The main contribution is in the size distributed information about particle volatility. The current work also shed some light on the complexities of size separated particle number measurements.