DETR/SMMT/CONCAWE Particle Research Programme: Sampling and Measurement Experiences 2000-01-2850
This paper describes the observed effects of parameters such as tunnel dilution ratio, test procedures and measurement methods on particle emissions. Attention is drawn to the transient behavior of nanoparticles within real legislated cycle conditions using conventional dilution systems. The aim of the paper is to communicate the limitations of widely used measurement equipment to enable a more confident interpretation of the particle size data.
The paper describes the information obtained during the DETR/CONCAWE/SMMT Particle Research Programme with regard to the sampling and measurement of particles emitted from light duty vehicles and heavy duty engines. Light duty vehicles were tested on gasoline, diesel and LPG, while heavy duty engines were tested on both diesel and compressed gaseous fuels. Two Scanning Mobility Particle Sizer (SMPS) instruments were employed in order to cover a measurement range from a lower limit of ∼7nm up to ∼710nm. Particle mass measurements were undertaken with a Micro Orifice Uniform Deposit Impactor (MOUDI) covering a size range from <56nm to >10μm. Regulated Particulate matter measurements were also taken.
The two SMPS systems performed well independently, with size distributions showing statistical similarity when used under the same operating configurations. However different set-ups proved to give conflicting size distribution data. Particle size distributions from nominally identical idle conditions proved to be highly dependent on the preconditioning of the engine and dilution system. Excellent repeatability was observed during both steady state and transient cycles, both in the nanoparticle and accumulation mode regions, with mode to mode and cycle transitions proving the major influence on particle production.