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The combined exhaust gas aftertreatment systems (DPF+SCR) are the most efficient way and the best available technology (BAT) to radically reduce the critical Diesel emission components particles (PM&NP) and nitric oxides (NOx). SCR (selective catalytic reduction) is regarded as the most efficient deNOx-system, diesel particle filters are most efficient for soot abatement. Today, several suppliers offer combined systems for retrofitting of HD vehicles. Quality standards for those quite complex systems and especially for retrofit systems are needed to enable decisions of several authorities and to estimate the potentials of improvements of the air quality in highly populated agglomerations. The present paper informs about the VERTdePN *) quality test procedures, which were developed in an international network project with the same name 2007-2011 (VERT … Verification of Emission Reduction Technologies; dePN … decontamination, disposal of PM / NP and of NOx).

Analysis of non-legislated engine-emission components, with different exhaust-gas after-treatment techniques, is an important air quality objective. This paper reports the results for various nitrogen oxides, ammonia and differentiated hydrocarbons emitted at part load from a small 4-S SI engine. It was operated with gasoline, with CNG and with two different three-way catalytic converters. CNG produces less HC and less aromatics. But the HC conversion rate is insufficient. This is due to the lower exhaust gas temperatures, at part load with CNG, and due to the higher stability of light HCs. CNG affects the λ-regulation window, of the investigated system, such that the NOx conversion rate is lowered. In the rich domain of the λ-regulation window, the NO & NOx emissions after catalyst were lowest, while the NH₃ formation was most intense, and vice versa.

The selective catalytic reduction SCR is extensively used for NOx reduction of recent HD-vehicles. There are some manufacturers and some applications of SCR as retrofit systems (mostly for the low emission zones LEZ and in combination with a DPF). In charge of Swiss authorities AFHB investigated several SCR-systems, or (DPF+SCR)-systems on HD-vehicles and proposed a simplified quality test procedure of those systems. This procedure can especially be useful for the admission of retrofit systems but it can also be helpful for the quality check of OEM-systems. The project name was TeVeNOx - Testing of Vehicles with NOx reduction systems. In the present paper the test procedures will be described and some specific results will be discussed.

Limited and nonlimited emissions of scooters were analysed during several annual research programs of the Swiss Agency of Environment Forests and Landscape (SAEFL, BUWAL)*). Small scooters, which are very much used in the congested centers of several cities are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers. In the present work detailed investigations of particle emissions of different 2-stroke scooters with direct injection and with carburetor were performed. The nanoparticulate emissions with different lube oils and fuels were measured by means of SMPS, (CPC) and NanoMet *). Also the particle mass emission (PM) was measured with the same method as for Diesel engines. Extensive analyses of PM-residuum for PAH & SOF/INSOF, as well as for VOC were carried out in an international project network.

In the diesel sector the fatty acid methyl esters (FAME's) - in Europe mostly RME (rapeseed methyl ester) and in US mostly SME (soja oil methyl ester) - are used as a various share, % volume blends with the diesel fuel (B5, B7, B10, B20, Bxx). The present joint project focuses on RME being the most important representative of the biofuels of 1st generation in Europe. The influences of RME blend fuels on emissions and on lube oil deterioration are emphasized. Emissions were investigated on a modern engine with exhaust gas aftertreatment devices like SCR and (DPF+ SCR). Beside the legally limited exhaust emission components some non-legislated like NO₂, N₂O, NH₃ and nanoparticles were measured at stationary and dynamic engine operation.

In order to analyze the processes during the gas exchange in the engine, knowledge of pressure states in both inlet and outlet is required. This pressure measuring is known as “low pressure indication”. In the present work, three examples of controlling the quality of low pressure measurement are presented. An insight in the pressure waves in exhaust pipe, especially in the exhaust blow-off is given. It was shown that: a small inaccuracy of measurement, lower than 10 mbar can be attained, the asymmetric course of the exhaust pulse can clearly be verified, and a protection screen for a sensor exposed to the exhaust blow-off pressure wave can be a tool to optimize between longlife and accuracy. The most important statements are: both presented methods of low pressure indication - the direkt and the indirect yield the results with highest accuracy.

Advances in emission control technologies have demanded development of new ceramic chemistries and improved microstructures in catalytic substrates and especially in diesel particulate filters. High porosity filters are desirable, as they decrease engine backpressure and enable application of advanced catalysts including, but not limited to, multi-functional filters (MFF). A significant recent development has been in the use of ceramic fibers to create cross-linked microstructures in extruded honeycomb ceramics. This development allows high porosities to be attained while maintaining mechanical strength. However, according to the World Health Organization, certain classes of ceramic fibers are considered to have adverse health effects if released in air and inhaled.

The progressing exhaust gas legislation for on- and off-road vehicles includes gradually the nanoparticle count limits. The invisible nanoparticles from different emission sources penetrate like a gas into the living organisms and may cause several health hazards. The present paper shows some results of a modern chain saw with & without oxidation catalyst, with Alkylate fuel and with different lube oils. The measurements focused specially on particulate emissions. Particulates were analysed by means of gravimetry (PM) and granulometry SMPS (PN). In this way the reduction potentials with application of the best materials (fuel, lube oil, ox-cat.) were indicated. It has been shown that the particle mass (PM) and the particle numbers (PN), which both consisting almost exclusively of unburned lube-oil, can attain quite high values, but can be influenced by the lube oil quality and can be considerably reduced with an oxidation catalyst.

NO₂ is much more toxic than NO. The average proportion of NO₂ in exhaust gases of vehicles increases significantly due to the use of oxidation catalysts and catalytic coatings in the exhaust gas systems during the last decades combined with generalization of using low sulfur fuels. Diesel oxidation catalysts (DOC) and Pt-containing DPF coatings are widely used to support the regeneration of particle filters, being a source of strongly increased production of NO₂. The present work shows some examples and summarizes the experiences in this matter performed at the Laboratories for IC-Engines & Exhaust Emissions Control (AFHB) of the University of Applied Sciences Biel-Bienne, Switzerland, during some research activities on engine dynamometers in the years 2010-2012.

Concern for engine particle emission led to EC regulations of the number of solid particles emitted by LDV and HDV. However, all conventional piston-driven combustion engines emit metal oxide particles of which only little is known. The main sources are abrasion between piston ring and cylinder, abrasion of bearing, cams and valves, catalyst coatings, metal-organic lubrication oil additives, and fuel additives. While abrasion usually generates particles in the μm range, high concentrations of nanosize metal oxide particles are also observed, probably resulting from nucleation processes during combustion. In general, metal oxides, especially from transition metals, have high surface reactivity and can therefore be very toxic, especially nanosize particles, which evidently provide a high specific bioactive surface and are suspected to penetrate into the organism. Hence, these particles must be scrutinized for quantity, size distribution and composition.

All internal combustion piston engines emit solid nanoparticles. Some are soot particles resulting from incomplete combustion of fuels, or lube oil. Some particles are metal compounds, most probably metal oxides. A major source of metal compound particles is engine abrasion. The lube oil transports these abraded particles into the combustion zone. There they are partially vaporized and ultrafine oxide particles formed through nucleation [1]. Other sources are the metallic additives to the lube oil, metallic additives in the fuel, and debris from the catalytic coatings in the exhaust-gas emission control devices. The formation process results in extremely fine particles, typically smaller than 50 nm. Thus they intrude through the alveolar membranes directly into the human organism. The consequent health risk necessitates a careful investigation of these emissions and effective curtailment.

Diesel exhaust gas aftertreatment systems, which include the selective catalytic reduction (SCR)*) for reduction of NOx are necessary to fulfil the latest legal requirements and are extensively used in the heavy duty (HD) sector. The present paper informs about some results obtained with SCR and with SDPF (a DPF with SCR-coating) on a medium duty research engine Iveco F1C. Beside the limited gaseous emission components NH3, NO2 and N2O were measured. The analysis of nanoparticle emissions was performed with SMPS and CPC. The integration of functions of filtration and NOx-reduction in one element of exhaust aftertreatment system offers several advantages and is widely investigated and considered as a market solution.

Nanoparticle emissions of two 2-stroke scooters were investigated along the exhaust and the CVS (Constant Volume Sampling) systems. Two configurations were tested: regular full-flow dilution configuration (denoted as “closed”) and also a modified sampling configuration (denoted as “open”). The scooters represent two distinct modern technologies. One scooter had direct injection TSDI*) (Two-Stroke Direct Injection). The other had a carburettor. Depending on the technology, the scooters produce different kind of aerosols (state-of-oxidation and SOF content). Moreover, the scooters were operated with and without oxidation catalyst. The tests were performed at two constant vehicular speeds (20 km/h and 40 km/h). The measuring procedures are those established during the previous research of the Swiss Scooter Network. The nanoparticulate emissions were measured using SMPS (Scanning Mobility Particle Sizer) and DC (Diffusion Charging) sensors.

Exhaust emissions measurements of a small 2-S Scooter Peugeot TSDI*), 50cc with different particle filters have been performed in this present work according to the measuring procedures, which were established in the previous research in the Swiss Scooter Network, [1, 2, 3, 4, 5, 6, 7, 8, 9]. The investigated particle filtration materials were supplied from different manufacturers as samples without specifications and they were applied by the research laboratory in a special muffler able to be taken apart. The investigated scooter represented a modern (2002) 2-stroke technology with direct injection, with oxidation catalyst and with injection of the lube oil to the intake air. Since there is a special concern about the particle emissions of the small engines, the particle mass and nanoparticle measurements were systematically carried out. The nanoparticulate emissions were measured by means of SMPS (CPC) and NanoMet*).

Ultrafine particles, in particular solid sub-100 nm particles pose high risks to human health due to their high lung deposition efficiency, translocation to all organs including the brain and their harmful chemical composition; due to dense traffic, the population in urban environments is exposed to high concentrations of those toxic air contaminants, despite these facts, they are still widely neglected. Therefore, the EU-Commission set up a program for clean and competitive solutions for different problem areas which are regarded to be hotspots of such particles. HORIZON AeroSolfd is an EU project, co-funded by Switzerland that will deliver affordable, adaptable, and sustainable retrofit solutions to reduce exhaust tailpipe emissions from petrol engines, brake emissions and pollution in semi-closed environments.

Different Diesel Particle Filters (DPF)*) were tested on a 2-Stroke Detroit-Diesel bus engine 6V 92 TA. The investigations focused on soot burden and regeneration of the DPF with special filter materials. Also examined was promoting the regeneration by: throttling, additive (FBC), oxidation catalytic converter upstream of DPF and the catalytic coating of the filter material. The metrics were the particulate matter emission, its composition and the nanoparticles. The most important results are: The average SOF content in the engine exhaust particulate matter is 77.6 % and the majority of it is emitted as bigger droplets The wire-mesh filter catalyst (WFC) - a novel emission reduction technology -substantially curtails the SOF and PM. WFC traps and oxidizes the oil droplets and produces a “dry” soot. This can be very advantageous for the DPF downstream of WFC. (WFC can be also very interesting for 2-S gasoline engines).

1 Small off-road 2-stroke SI-engines have very high pollutant emissions. The Swiss environmental protection agency (BUWAL) investigates the state of the technology and emissions with the scope to show the potential of improvements by means of the best available technology (BAT) and to motivate the consumers to use the more sophisticated equipment and cleaner fuels to protect their health and the environment. In the present work emission measurements of chainsaws were performed with a special concern of particulate emissions. Particulates were analysed by means of: gravimetry, SMPS, NanoMet and differential analysis of filter residue. The varied conditions were: A/F-ratio, lube-oil content and the fuel quality. It has been shown, that the particulate mass and the nanoparticle numbers, which both consisting almost exclusively of unburned lube-oil, attain very high values. They are strongly influenced by the mixture tuning and by the lube-oil content.

During the VERT *) testing of different DPF systems it was remarked, that the oxidation catalyst converts sometimes a big part of NO to NO2, producing on the one hand a more toxic composition of the exhaust gases and causing on the other hand measuring artefacts, which tend to underestimate of NO2 and NOx by the cold NOx - measurement. The present work summarizes the experiences in this matter elaborated at the Laboratories for IC-Engines & Exhaust Emissions Control (AFHB) of the University of Applied Sciences Biel-Bienne, Switzerland, during several VERT activities and didactic projects on engine and chassis dynamometers in the years 2000-2006.

The most efficient way and the best available technology (BAT) to radically reduce the critical diesel emission components particles (PM&NP) and nitric oxides (NOx) are combined exhaust gas aftertreatment systems (DPF+SCR). SCR (selective catalytic reduction) is regarded as the most efficient deNOx-system, diesel particle filters are most efficient for soot abatement. Today, several suppliers offer combined systems for retrofitting of HD vehicles. The presented results are part of the work in the international network project VERT *) dePN (de-activation, de-contamination, disposal of particles and NOx), which has the objectives to establish test procedures and quality standards and to introduce the SCR-, or combined DPF+SCR-systems in the VERT verification procedure.

During the first decade of diesel particle filter development and deployment in cars, trucks, buses and underground sites, DPF regeneration methods were engineered that were compatible with the then prevalent high sulfur content in the fuel ≻ 2000 ppm. The mainly used methods were burners, electrical heaters, replaceable filters and non-precious metal fuel additives. Low sulfur diesel fuel became only available from 1996 in Sweden, 1998 in Switzerland, and after 2000 everywhere in Europe. Thus, the deployment of precious metal catalytic converters was feasible both as original equipment and retrofitting of in-use engines. The so-called CRT particle filters using PGM-catalysis for providing NO₂ for low temperature regeneration became very successful wherever ULSD was available.