PEMS Light-Duty Vehicles Application: Experiences in Downtown Milan

Portable Emissions Measurement Systems (PEMS) are becoming an important regulatory tool to monitor the in-use compliance of large sources like heavy-duty vehicles (HDV) or non-road mobile machinery (NRMM). Legislative research programmes in Europe, United States and Japan are introducing PEMS in the regulations. The application of PEMS to light-duty vehicles (LDVs) is not part of or driven by official legislative requirements. However, as the vehicle-engine operation points in the laboratory test cycles are limited, emissions and fuel consumption under real world driving conditions can differ significantly from those measured under controlled laboratory conditions. The present paper discusses the application of PEMS to real-world emission measurements of passenger cars, under the light of the existing instruments and test protocols already developed for heavy-duty vehicles. Data are reported for a measurement campaign carried out in downtown Milan. In the first phase, three light duty diesel vehicles, running on their duty cycles (most often in a urban and congested area), were equipped with smart data loggers to retrieve engine and vehicle activity parameters from the engine Electronic Control Unit (ECU) in order to monitor their driving conditions in the city of Milan. Data collected were used to identify “typical” operating patterns to be reproduced in the laboratory on the chassis dynamometer. The emissions results obtained on these ‘real-world’ cycles were compared to the ones obtained on the New European Driving Cycle (NEDC), to provide a first insight on the variability of emissions induced by the real-world conditions. In the second phase, a 2 litre Diesel vehicle was equipped with a commercial PEMS to measure exhaust emissions under real-world conditions. These results were compared to reference laboratory data under both a standard NEDC and a “typical” urban cycle using the Constant Volume Sampling (CVS) technique.