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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.

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.

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.

Portable Emissions Measurement Systems (PEMS) are becoming part of the emissions control regulations, as evidenced by the latest requirements introduced in the United States regulations for on-highway and non-road machinery. The European Union is currently following the same route to check the in-use behaviour of heavy-duty diesel vehicles. The current research programmes tend to demonstrate that both the instrumentation and the test methods are mature for gaseous emissions. For PM emissions, the development of portable PM instruments and their test protocols remain a complex challenge, as simultaneous progress take place in the engine after-treatment technologies and the official homologation procedures (the PMP programme in particular). The present paper discusses the current research strategy proposed in the EU for the development of an on-board PM test protocol. Case studies from the EU-PEMS project are presented.

Tightening of automotive particulate matter (PM) emission regulations, driven by health concerns over ultrafine (< 100 nm) and nano-sized (< 50 nm) particles, has focused attention on measurement of particle size and number at the tailpipes of diesel engines. This study presents an investigation of PM emissions by number from a Light-Duty Diesel Engine running on low sulphur fuel using different after-treatment systems. PM measurements by number and size were conducted over both transient and steady-state engine conditions using a standard CVS dilution tunnel. A Scanning Mobility Particle Sizer (SMPS), Electrical Low Pressure Impactor (ELPI), Differential Mobility Spectrometer (DMS) and an Engine Exhaust Particle Sizer (EEPS) were used for PM measurements. The performance of each particle size measurement instrument was assessed, and a comparison provided at similar experimental conditions.

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.

Motivated by the possibility of future emission regulations based on particle number as well as mass, after-treatment of ultrafine particles by a cordierite wallflow filter has been investigated. In a laboratory simulation, synthetic carbon particles of known size and concentration in air were captured with number-based efficiency exceeding 70% in the 20–100 nm size range. Effects of temperature, up to 400°C, filter loading time and ambient-temperature sample dilution have been quantified. Steady-speed and European drive cycle results for the same filter fitted to a passenger car with gasoline direct-injection engine have shown promising reductions in emissions, except at the highest speed of the cycle.

A counter–flow propane/air diffusion flame (ϕ= 1.79) is used for a fundamental analysis of the effects of oxygenated additives on soot precursor formation. Experiments are conducted at atmospheric pressure using Gas Chromatography for gas sample analysis. The oxygenated additives dimethyl carbonate (DMC) and ethanol are added to the fuel keeping the total volumetric fuel flow rate constant. Results show 10 vol% DMC significantly reduces acetylene, benzene, and other flame pyrolysis products. Ethanol (10 vol%) shows, instead, more modest reductions. Peak acetylene and benzene levels decrease as the additive dosage increases for both DMC and ethanol. The additive's effect on the adiabatic flame temperature and the fuel stream carbon content does not correlate significantly with acetylene levels. However, there does appear to be a linear relationship between acetylene concentrations and both the additive's oxygen and C–C bond content.