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Recently, it was reported that the atmospheric pollution levels of nitrogen dioxide (NO2) and particulate matter (PM) are not decreasing despite the introduction of stricter vehicle emission regulations. The difference between conditions of the test cycles defined by the vehicle emission regulations and the real driving can contribute to the differences between expected and actual pollution levels. This has led to the introduction of in-use vehicle emission monitoring and regulations by means of a portable emission measurement system (PEMS). An optimized on-board PM analyzer was developed in this study. The on-board PM analyzer is a combination of a partial flow dilution system (PFDS) particulate sampler and a diffusion charger sensor (DCS) for real-time PM signals. The measuring technology and basic performance of the analyzer will be explained. Acceleration of the vehicle can cause uncertainty of flow measurement in the PM sampler.

The Particle Measurement Programme (PMP) established under the United Nations Economic Commission for Europe has developed the solid particle number (PN) measurement methodology, which has relatively higher sensitivity than the particulate matter measurement protocol. The first PN emission regulation was introduced in 2011. The stationary PN measurement system (PMP system) has been applied in the chassis and the engine test cells. In recent years, real driving emissions (RDE) measurement is attracting attention. Portable emissions measurement systems for PN measurement (PN-PEMS) which can be installed on vehicles during RDE testing are available now. The European RDE regulation requires validation of PN-PEMS by comparing emission measurement results with a stationary PMP system on a chassis dynamometer prior to the on-road emissions testing. Measurement differences between the PN-PEMS and the PMP system has to be within the tolerance defined by the regulation.