Comparative Assessment of Two Different Sampling Systems for Particle Emission Type-Approval Measurements

The Particle Measurement Programme (PMP), initiated from different Member States, aims at developing a method and sampling recommendations for a particle number-based emission standard, to support future emission regulation in Europe. In this paper we applied two different commercially available dilution systems (an FPS from Dekati Ltd and an MD19-2E from Matter Engineering AG) to record the particle emissions of a Euro II and a Euro III diesel passenger car. The latter was also fitted with a diesel particle filter (DPF) to simulate future emission levels. At their present development stage, both dilution systems failed to totally comply with all requirements of the PMP protocol. The main problems appeared to be the lack of accurate determination of the dilution ratio and the inability to reach the desired dilution temperature. However, they were able to eliminate nucleation mode particles and the results demonstrated that particle number concentration measurement is equally repeatable to the gravimetric method for the Euro III vehicle and even more so for the DPF one. Over the type-approval cycle, the Euro III vehicle was found to consistently emit below 10¹⁴ km^-1 particles without a DPF and 10¹¹ km^-1 particles with the DPF. The exact level could only be determined with external dilution ratio determination. These results suggest that it is possible to repeatably measure the particle number emissions but some additional refinements are still needed to today's technical solutions to meet the demanding requirements of type-approval measurements.