Search Results

A proposal for sub-23 nm Solid Particle Number (SPN) measurement method was developed by the Particle Measurement Programme (PMP) group, based on the current SPN measurement method. In the proposal, a Particle Number Counter (PNC) having (65 ± 15)% counting efficiency at 10 nm and >90% at 15 nm (PNC10) replaces the current regulation PNC efficiency of 50±12% at 23 nm and >90% at 41 nm. Additionally, a catalytically active evaporation tube (CS) is required for sub-23 nm measurement method instead of the non-reactive evaporation tube (ET) of the current regulation. Here experimental work carried out at the JRC to address the issues of sub-23 nm SPN-measurement method is presented. The PNC10 was shown to be less dependent on the particle material than the PNC23, thus soot-like particles are still allowed for PNC-calibration. The high charging probability of soot-like particles was shown to have a low effect on PNC calibration uncertainties.

The effect of SCR on nanoparticle emissions has been a subject for some recent diesel particle emission related studies. In this study, the effect of after-treatment (DOC and SCR) on particle emissions was studied with a heavy-duty off-road diesel engine (emission level stage 3b with an SCR). A special “transient cold test cycle” (TCTC) was designed to describe the SCR system operation at low exhaust gas temperatures. The particle instrumentation made it possible to measure on-line the particle number concentration, particle size distribution and chemical composition of particles. The largest particle number concentrations were measured after the exhaust manifold. The exhaust after-treatment was observed to reduce the total particle number concentration by 82.5% with the DOC and 95.7% with the DOC+SCR.