Search Results

Further efforts to reduce the air pollution from traffic are undertaken worldwide and the filtration of exhaust gas will also be increasingly applied on gasoline cars (GPF1 … gasoline particle filter). In the present paper, some results of investigations of nanoparticles from four MPI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, two variants of GPF were investigated on a high-emitting modern vehicle, including analytics of PAH and attempts of soot loading in road application. The modern MPI vehicles can emit a considerable amount of PN, which in some cases attains the level of Diesel exhaust gas without DPF and can pass over the actual European limit value for GDI (6.0 x 1011 #/km). The GPF-technology offers in this respect further poten-tials to reduce the PN-emissions of traffic.

In the present paper some results of investigations of nanoparticles from five DI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, five variants of “vehicle - GPF” were investigated. These results originate from the project GasOMeP (Gasoline Organic & Metal Particulates), which focused on metal-nanoparticles (including sub 20nm) from gasoline cars with different engine technologies. The PN-emission level of the investigated GDI cars in WLTC without GPF is in the same range of magnitude very near to the actual limit value of 6.0 × 1012 #/km. With the GPF’s with better filtration quality, it is possible to lower the emissions below the future limit value of 6.0 × 1011 #/km. There is no visible nuclei mode and the ultrafine particle concentrations below 10mm are insignificant. Some of the vehicles show at constant speed operation a periodical fluctuation of the NP-emissions, as an effect of the electronic control.

As a result of increased use of catalytic exhaust aftertreatment systems of vehicles and the low-sulfur Diesel fuels there is an increasing share of nitrogen dioxide NO2 in the ambient air of several cities. This is in spite of lowering the summary nitric oxides NOx emissions from vehicles. NO2 is much more toxic than nitrogen monoxide NO and it will be specially considered in the next legal testing procedures. There are doubts about the accuracy of analyzing the reactive substances from diluted gas and this project has the objective to show how NO2 is changing as it travels down through the exhaust- and the CVS systems. For legal measurements of NO2 a WLTP-DTP subgroup (Worldwide Light Duty Test Procedures - Diesel Test Procedures) proposed different combinations of NOx-analyzers and analysis of NO and NOx. Some of these set-ups were tested in this work.

The invisible nanoparticles (NP)*) from combustion processes penetrate easily into the human body through the respiratory and olfactory pathways and carry numerous harmful health effects potentials. NP count concentrations are limited in EU for Diesel passenger cars since 2013 and for gasoline cars with direct injection (GDI) since 2014. The limit for GDI was temporary extended to 6 × 1012 #/km, (regulation No. 459/2012/EU). Nuclei of metals as well as organics are suspected to significantly contribute especially to the ultrafine particle size fractions, and thus to the particle number concentration. In the project GasOMeP (Gasoline Organic & Metal Particulates) metal-nanoparticles (including sub 20nm) from gasoline cars are investigated for different engine technologies. In the present paper some results of investigations of nanoparticles from four gasoline cars - an older one with MPI and three newer with DI - are represented.

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.

The use of alternative fuels and among them the biofuels of 1st generation - fatty acid methyl esters FAME's and pure plants oils - for propulsion of IC engines is an important objective in several countries in order to save the fossil fuels and to limit the CO₂ production. The properties of bio-fuels and bio-blend-fuels can vary and this has an impact on the operation and emissions of diesel engines and on the modern exhaust aftertreatment systems. The present paper represents the most important results obtained with RME at AFHB, EMPA and EC-JRC. Most of the activities were performed in the network project BioExDi (Biofuels, Exhaust Systems Diesel) in collaboration between industry and research institutes.

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, and - 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.

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.

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 Swiss 1998 Ordinance on Air Pollution Control (OAPC) mandates curtailment of carcinogenic Diesel particle emissions at construction sites [4]. In addition particle traps are compulsory at underground workplaces [3]. In compliance, more than 6,000 Diesel engines were retrofitted with different particle trap systems. Many traps surpassed 99% filtration efficiency, from the beginning, and secondary emissions were mostly prevented. However, trap failure due to mechanical and thermal damage was initially rather high at about 10%. By Y-2000 the failure rate was halved to about 6%. Thanks to focussed improvements, the Y-2003 statistics show yearly failures of “only” about 2%. The Swiss target is to retrofit 15,000 construction machines with traps, fully compliant with environmental directives, having 5,000 operating hours durability and failure rates below 1%. Construction machines have much higher PM-emission factors than trucks, and are operated more intensely than tractors.

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.

From a comparison of different methods of supercharging it becomes evident that the pressure-wave-supercharger is a highly efficient device of improving fuel economy of automobiles without loss of performance. Tests on a chassis-dynamometer and computer simulations show that it is possible to save up to 25 % of fuel and at the same time to reduce the emissions of exhaust gases considerably by “Down-Sizing” and “Down-Speeding”.