Feasibility study on the extension of the Real Driving Emissions (RDE) procedure to Particle Number (PN) : experimental evaluation of portable emission measurement systems (PEMS) with diffusion chargers (DCs) to measure particle number (PN) concentration

The particle number method based on the Particle Measurement Programme (PMP) is part of the light duty legislation and starts to expand to other sectors as well. As a consequence systems for in service conformity and random driving emissions procedures will be necessary. These systems should be small and compact. The commercial systems at the moment are not ready for on-road use because the Particle Number Counters (PNCs) sensors (condensation particle counters, CPC) are sensitive to vibrations. For this reason a different concept has been suggested: Diffusion chargers (DC). The main target of this report was to evaluate theoretically and experimentally in the laboratory various PN-PEMS using diffusion chargers as PNCs as alternative technique to the PMP method for on-road measurements. It was shown theoretically that DCs introduce an extra 50% uncertainty due to a size dependency since the size is not known during a test; PMP systems should have <15% differences.. Then various protottype PN-PEMS were evaluated in the laboratory. It was shown experimentally that it is feasible to cover a size range of 35-90 nm (for polydisperse aerosol) with differences within -33% and +50% to the PMP system. Based on the experience gained during the evaluations a suitable calibration setup and procedure is recommended. In addition calibration specifications for the next generation of PN-PEMS is given.