Abstract
The increased public awareness of the adverse health effects of particle emissions from combustion sources, especially road and non-road traffic, has triggered numerous research and regulatory projects. Across most programmes, a tendency can be observed to focus on particle surface or number count of non-volatile particles rather than gravimetric particle mass measurement.
In terms of instrumentation, the desired focus on solid particles is achieved by careful conditioning of the exhaust gas sample. After extraction from the CVS tunnel, the sample is diluted and subsequently heated to evaporate the volatile particle fraction. A secondary diluter cools the sample to avoid damage to the particle counting system which measures the particle number concentration using the principle of a condensation particle counter.
Advantages of the method are its high correlation with health effects in the population, and its increased sensitivity, which is several orders of magnitude better than that of gravimetric PM measurement. Within the framework of the Particulate Measurement Programme (GRPEPMP) the method has been shown to be very reliable and robust, and to be more reproducible than gravimetric PM when particle concentrations are low.
Apart from type approval for vehicles and engines, this new measurement technology is used for the characterisation of Diesel particle traps and even in non-emission applications in ambient air or occupational exposure measurements. New instrument designs will allow mobile and even portable measurement. Extension of their scope of application to inspection and maintenance of large vehicle fleets is within close reach.
Keywords:particle, emission, non-volatile, measurement, PMP