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Portable Emissions Measurement Systems (PEMS) represent a robust and accurate solution to study the in-use emissions of combustion engines and are becoming part of the emissions control regulations, as evidenced by the latest requirements introduced in the United States. Their application is ranging from large heavy duty engines to small light-duty vehicles and off-road mobile machinery. Currently, PEMS for gaseous exhaust measurements exhibit performances that are close to the ones of laboratory grade systems, but the development of portable PM instruments remain a complex challenge, as simultaneous progress take place in engine and after-treatment technologies. This paper presents the PM phase of the European PEMS program, aiming at checking the feasibility of PEMS to measure accurately particle mass at low PM levels.

The health threat from sub-100 nm particulates, emitted in significant numbers from gasoline vehicles, and anticipated changes in legislation to address this, have prompted investigation of techniques capable of trapping and oxidizing particulates from gasoline engines. Numerical studies have indicated that cooling to encourage particle capture by thermophoresis is less effective than use of electrostatic fields. A laboratory wire-cylinder electrostatic trap is under development, showing promising initial results. As an alternative trapping technique, the effectiveness of a cordierite wall-flow filter has been demonstrated, in simulation experiments and on a GDI-engined vehicle. Catalysts have been identified for particulate oxidation at typical exhaust temperatures, using water vapour and carbon dioxide as the oxygen source and retaining activity after short-term high-temperature aging.

Fuel consumption is already one of the parameters taken into account for the final ranking of some competitions organized by the Federation International de l'Automobile (FIA). Pollutant emissions, such as CO, HC and NOx, could also be taken into consideration in the near future. In occasion of a competition organized by the FIA in the framework of the “Alternative Energies Cup” championship, several vehicles were equipped for demonstration and scientific purpose with portable emission measurement systems (PEMS) in order to measure the gaseous emissions during the competition. The competition took place at the Autodromo Nazionale of Monza on the same track used for the Formula 1 Grand Prix as well. For this competition the track was divided into three sections simulating respectively the typical speeds and driving patterns on urban roads, on extra-urban roads and on motorways.

Portable Emissions Measurement Systems (PEMS) represent a robust and accurate solution to study the in-use emissions of combustion engines. The application of PEMS is now ranging from large engines to the smallest light-duty vehicles. The current commercially available PEMS exhibit measurement performances that are close to the ones of laboratory grade systems; when PEMS data are analysed with an adequate method, the test results allow a detailed insight into the on-road emissions performance of the vehicles with respect to their behaviour on the standard laboratory test cycles. The development of representative test cycles, which has become a typical approach in the last years, supposed to address special driving situations, now becomes less efficient because of the effort needed for their development and the poor representativeness of the results. In this light, PEMS testing offers an easy and efficient way to evaluate the vehicle emissions over a huge variety of conditions.