Particle Measurement Programme (PMP): Particle Size and Number Emissions Before, During and After Regeneration Events of a Euro 4 DPF Equipped Light-Duty Diesel Vehicle.

Abstract

By early 2006, all major manufacturers of light-duty Diesel vehicles were marketing models equipped with Diesel particulate filters (DPFs). This paper focuses on Particulate Matter (PM) emissions by mass and number of a representative light-duty Diesel vehicle equipped with a DPF and employing a fuel-borne catalyst (FBC) to aid regeneration.

PM emissions and solid particle numbers according to the Particle Measurement Programme (PMP) proposals and regulated gaseous emissions were acquired throughout testing. According to the PMP recommendations, a particle number counter was employed downstream of an evaporation tube sampling from the CVS to measure solid particles. In addition, an Engine Exhaust Particle Sizer (EEPS) connected directly to the CVS was used to give real time number and size distributions, both volatile and nanoparticles. The effect of cold start (at 23 °C) is discussed, especially for particle number emissions. Low temperature start (-7 °C) gave increased gaseous emissions but resulted in small changes in PM and number concentration compared to the 23 °C tests.

The paper focuses on particle emissions changes in response to types of regenerations. Real time size distributions show nucleation mode evolution during regeneration events. When the vehicle speed changes during active DPF regenerations a second nucleation mode peak may appear due to changes in the oxidation process of the deposited material in the DPF. NEDC emissions of total solid and volatile particles during regenerating cycles are two orders of magnitude higher than those from non regenerating cycles. However, non-volatile particle emissions levels observed from regenerating cycles stay at the same order as non-regenerating cycles. Differences between emissions before and after regeneration are discussed for both PM mass and number. Based on NEDC emissions and two regeneration events during the 3000 km tests conducted, vehicle stabilization distances are proposed.