Particle Emission Measurements from L-Category Vehicles

In 2011 a particle number (PN) limit was introduced in the European Union's vehicle exhaust legislation for diesel passenger cars. The PN method requires measurement of solid particles (i.e. those that do not evaporate at 350 °C) with diameters above 23 nm. In 2013 the same approach was introduced for heavy duty engines and in 2014 for gasoline direct injection vehicles. This decision was based on a long evaluation that concluded that there is no significant sub-23 nm fraction for these technologies. In this paper we examine the suitability of the current PN method for L-category vehicles (two- or three-wheel vehicles and quadri-cycles). Emission levels of 5 mopeds, 9 motorcycles, 2 tricycles (one of them diesel) and 1 quad are presented. Special attention is given to sub-23 nm emission levels. The investigation was conducted with PN legislation compliant systems with particle counters measuring above 23 nm and 10 nm. In addition other approaches using catalytic strippers and counters from 3 nm or particle sizers were used to confirm the nature of the particles. The results showed that there is a significant portion of solid particles not counted with the current PN method. On the other hand, the high amount of volatile material can lead to artifacts below 23 nm, and thus great care has to be taken when measuring the PN of this category.