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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).

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.

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.

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).

The main components of vehicle diesel engine emissions are nitrogen oxides and particulates. The emissions concept adopted for pressure-wave supercharging with controlled EGR and particulate trap, focuses on both components. In conjunction with electronic EGR-control the spontaneous response of the supercharger achieves minimum deviations from optimum air excess values, even during transients. In the US city cycle an NOx reduction to 35 % of the reference emission, without sacrificing fuel economy was established. Featuring a particulate trap arranged between engine and supercharger this system increases the regeneration probability and as a result of the improved supercharsinp, efficiency achieves satisfactory transient behavior, Catalytic coating of the rotor constitutes an additional means of reducing emissions.

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.

The fatty acid methyl esters (FAME's) - in Europe mostly RME (Rapeseed methyl ester) - are used in several countries as alternative biogene Diesel fuels in various blending ratios with fossil fuels (Bxx). Questions often arise about the influences of these biocomponents on the modern exhaust aftertreatment systems and especially on the regeneration of Diesel particle filters (DPF). In the present work different regeneration procedures of DPF systems were investigated with biofuels B0, B20 & B100. The tested regeneration procedures were: passive regenerations: DOC + CSF; CSF alone, active regenerations: standstill burner; fuel injections & DOC. During each regeneration on-line measurements of regulated and unregulated emission components (nanoparticles & FTIR) were conducted. It can be stated that the increased portion of RME in fuel provokes longer time periods to charge the filter with soot.

An independent periodical technical inspection (PTI)*) of vehicles is proposed in the last time as a better prevention against increased emissions of the fleet. Several projects focused on the Diesel vehicles (HD & LD) and on the functionality of the exhaust aftertreatment systems as a key element for lowering emissions of a vehicle or machine. The present paper summarizes the results obtained on 3 modern passenger cars Euro 6b (with EGR, DOC, DPF & SCR) during load jumps, representing the heat-up or cool-down behaviour of the exhaust system. The portable devices for PTI were tested together with the stationary measuring systems of the engine laboratory. In the second part of the report, the present knowledge and proposals of supplementary test procedures (like IUC or PTI) were shortly described.

The Comprex is the first pressure wave machine to reach series maturity. The direct contact between the media exhaust gas and combustion air permits a transfer of energy at high efficiency. Because of its basic characteristics, the pressure wave machine is especially well suited for the supercharging of passenger car diesel engines. It exhibits a spontaneous response and achieves high supercharging rates over a wide operation range, thereby contributing to an improvement in fuel economy. For the purpose of reducing emissions, it offers a simple means of providing EGR, thermal conditioning of the charge air, catalytic aftertreatment of the exhaust gas in the cell wheel and a compact particulate trap arrangement.

An active oxidation catalyst is an efficient measure to reduce not only gaseous components (CO, HC), but also particle emissions (mostly oil condensates) of a small 2-stroke engine with lost oil lubrication. Since the 2- and 3-wheelers with 2-stroke propulsion are still a very serious source of air pollution worldwide in many urban areas, it is important to have a look on some consequences of an improperly working catalyst. The present paper shows some results of user-oriented aging of catalyst on the vehicle and results of limited emissions and unlimited (nano)particles during the catalysts screening tests. The works are a part of an international scooter network project, which was performed (2004 to 2007) in the Laboratories for IC-Engines & Exhaust Emission Control of the University of Applied Sciences, Biel, Switzerland with main support of the Swiss Federal Office of Environment (BAFU), Swiss Petrol Union (EV) and Swiss Lubes (VSS).

Limited and non-regulated emissions of scooters were analysed during several annual research programs of the Swiss Federal Office of Environment (BAFU) *). 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 carburettor were performed. The nanoparticulate emissions 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 SOF/INSOF, PAH and toxicity equivalence (TEQ), were carried out in an international project network. Particle mass emission (PM) of 2-S Scooters consists mostly of SOF.