Evaluation of Portable Number Emission Systems for Heavy-Duty Applications under Steady State and Transient Vehicle Operation Conditions on a Chassis Dynamometer 2018-01-0348

The European Commission plans to introduce a (solid) particle number (PN) emission limit for type approval and in-service conformity (ISC) by the end of 2018 (Euro VI d) using PEMS (Portable Emission Measurement System) tests on heavy duty vehicles on the road. Performance, measurement accuracy and sensitivity of several on-board particle counters for heavy duty applications have not been tested yet in parallel on a chassis dyno with Euro VI vehicle (N3-class, 12.8 l). The PN PEMS examined were CPC (Condensation Particle Counter) and DC (Diffusion Charger) based. Evaluation was conducted at different ambient temperatures from −7 °C to 35 °C while running different test cycles: WHVC (World Harmonized Vehicle Cycle), steady state engine operation, active regeneration and ISC-tests. A particle number system following the current heavy duty regulation requirement and recommendations of the Particle Measurement Program (PMP) served as reference (PMP_TP). CPC based instruments showed stable and accurate measurement behavior with good correlations to PMP_TP (CPC#1: s = 1.08, R² = 0.99; CPC#2: s = 0.74, R² = 0.97), DC based instruments showed good correlation at high concentrations (>1x10¹¹ p/kWh) (DC#1: s = 1.15, R² = 0.96; DC#2: s = 1.05, R² = 0.91). No particular influence was seen from regeneration, high exhaust gas temperature, high exhaust flow, ambient temperature. T_amb = −7 °C affected one CPC instrument. Probably urea particles were counted by one DC based instrument because their size could be close to DC instruments cut-off size. The main conclusion of this study is that PN-PEMS are robust and testing is feasible for heavy duty applications.