Diesel particles filter

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

Under the EuroIV regulation (2005), the Diesel Particle Filter (DPF) emerged and is necessary for the heavily loaded applications. Renault plans to make a CSF offer for all the diesel product range. This system enables to treat nearly 100% of the particle matter (PM, soot). When loaded, the DPF requires a regeneration phase to bum the accumulated soot. This regeneration is mandatory to keep not only the engine performance and reliability, but also the DPF reliability itself. 

Overall, EGR and combustion/injection systems constitute the key factors to comply with the EuroIV standards (applied in January, 2005). The EuroIV step exhibits EuroIII NO and soot particles limits divided by 2. Besides, vehicle s weight is always increasing due to the introduction of new safety systems and equipment. Therefore, pollutants emissions increase and a supplementary effort to reach the normative threshold is to be made. To comply with this target, some evolutions have been introduced, as for example multi-injection or water-cooling of the EGR system. The NO,/particle compromise adjustment remains possible for most of the applications without any after-treatment system like the Diesel particle filter (DPF). 

DIESEL PARTICLE FILTER MANDATORY IN EUROV - ITS CONSTRAINTS... 

Diesel particle filters are a very efficient means of reducing PM mass emissions from diesel vehicles, but do not directly target NOx. However, most diesel particulate filter (DPF) systems contain catalytic materials which assist in the DPF regeneration (the combustion of PM accumulated on the filter to clean the DPF and prevent blockage). Such catalytic materials can have a similar impact to DOCs... 

Boger T, He S, Collins T A, Heibel A K, Beall D, Remy C (2011) A Next Generation Cordierite Diesel Particle Filter with Significantly Reduced Pressure Drop. SAE Int J. Engines 4(1) 902-912... 

Oxidative catalytic converters are used to reduce CO and HCs originating from imperfect combustion in engines. At certain temperatures, these converters may also oxidize NO to NO2. Original equipment manufacturer (OEM) particle filters (PFs) employ NO2 to oxidize trapped soot at lower temperatures. However, the excess NO2 may escape from the system as tailpipe emissions. NO2 is very toxic to humans, and it also has impacts on atmospheric ozone-forming chemistry. Alvaraz et al. have stated that the primary NO2 emissions of modern diesel cars are increasing [76]. 

The small particles are reported to be very harmful for human health [98]. To remove particulate emissions from diesel engines, diesel particulate filters (DPF) are used. Filter systems can be metallic and ceramic with a large number of parallel channels. In applications to passenger cars, only ceramic filters are used. The channels in the filter are alternatively open and closed. Consequently, the exhaust gas is forced to flow through the porous walls of the honeycomb structure. The solid particles are deposited in the pores. Depending on the porosity of the filter material, these filters can attain filtration efficiencies up to 97%. The soot deposits in the particulate filter induce a steady rise in flow resistance. For this reason, the particulate filter must be regenerated at certain intervals, which can be achieved in the passive or active process [46]. 

Vlachos, N., Housiada, P., Zarvalis, D., and Konstandopoulos, A. G., Transient filtration and pressure drop behavior of diesel particulate filters, in Particle Loading and Kinetics of Filtration in Fibrous Filters (M. J. Lehmann, and G. Kasper Eds.), pp. 13-26. University of Karlsruhe, Karlsruhe (2002). 

Three-way catalysts are used in gasoline cars to control the emissions of hydrocarbons, carbon monoxide and nitrogen oxides. Oxidation catalysts and diesel particulate filters, DPFs, are used in diesel vehicles to control the emissions of soot particles, hydrocarbons, carbon monoxide and nitrogen oxides. All of these after-treatment devices are sensitive to additive components of the lubricant. Three-way... 

A second compromise between the other specifications which will be set for fuels in 2005 and the increase in self-consumption has also to be found. Some of these specifications are effectively interdependent and this interdependence must be taken into account when selecting them. For instance, in the future why would it be necessary to keep the aromatics content below 35% in gasoline if the almost complete elimination of sulphur enables total elimination of harmful hydrocarbons discharged in exhaust gas (50) A similar question can be asked regarding the lowering of the T95 in diesel fuel which aims at limiting the formations of polyaromatics and soot in exhaust gas, when eventually diesel vehicles will be fitted with particle filters (50). 

The control technology that is applied to the vehicle itself also has consequences to the ultimate emission and formation of UFP. Diesel particulate traps are now commonly used to control the mass emissions of PM. There are new classes of continuously regenerating diesel particulate filters that allow for PM emissions to be controlled. One of the consequences of this technology is an increased formation of small particles (<10 nm) due to the absence of elemental carbon downstream of the trap. 

The method commonly used for preparation of diesel particle extracts employs a Soxhlet extaction apparatus with dichloromethane as the extracting solvent. This procedure has been found optimal for extraction of the mutagenic components adsorbed to the particulate (4). Most of our studies have been conducted with an extract prepared from particulate collected by electrostatic precipitation, which allowed the collection of a moderate amount of material in a short period of time (5). Extracts were also prepared from diesel particulate collected by two other methods. These extracts and the methods of particle collection are described in Table 1. The baghouse filter apparatus was used to obtain a large quantity of particulate required for a skin-painting carcinogenesis assay (6). This method involves collecting the particulate from hot undiluted... 

Markets have also been more strongly generated by the legislator, for example, in the form of regulations within the framework of environment protection, if you think of catalyst support for power stations and the motor car or of the development of particle filters for diesel engines (Fig. 50). 

Diesel particulate filters (DPFs) (see Figure 19.1) are used to remove soot particles from the exhaust stream [1-4]. These filters usually consist of wall-flow monoliths, that is, honeycomb-like structures with 50% of the channels plugged at the gas entry side and the remaining channek plugged at the exit The gas stream enters into the filter through the open channels and is forced to pass through the porous walls where the soot particles get stuck. 

Two chemical processes have been selected by automotive makers lean NO e trap (LNT) [11] or NO c storage reduction (NSR) and selective catalytic reduction by ammonia (SCR-NH3) [12]. For LNT process, the cost is very expensive, because a large amount of noble metal is required. It is why the second possibility (SCR-NH3) has paid attention and has been developed first on trucks and bus. The result is positive in terms of efficiency and decrease of pollutants, but the required location remains a major problem especially when the technology must be applied to a particular vehicle. In order to improve the process, a new concept has been proposed and involves bringing together two technologies into one. In this chapter, we will describe the integration of the SCR-NH3 catalyst in the structure of the particles filters for application in diesel posttreatment. 

The second method used to reduce exliaust emissions incorporates postcombustion devices in the form of soot and/or ceramic catalytic converters. Some catalysts currently employ zeolite-based hydrocarbon-trapping materials acting as molecular sieves that can adsorb hydrocarbons at low temperatures and release them at high temperatures, when the catalyst operates with higher efficiency. Advances have been made in soot reduction through adoption of soot filters that chemically convert CO and unburned hydrocarbons into harmless CO, and water vapor, while trapping carbon particles in their ceramic honeycomb walls. Both soot filters and diesel catalysts remove more than 80 percent of carbon particulates from the exliatist, and reduce by more than 90 percent emissions of CO and hydrocarbons. 

One of principal problems in larger urban centers is the presence of particulate material in the atmosphere due to the emission of diesel engine[l]. One of the most dangerous components of diesel exhaust is particulate, which consists of agglomerates of small carbon particles with a number of different hydrocarbons and sulfates adsorbed on their surfece. A potential way to face the related enviromnental problem is that of filtering the particulate and burning it out in catalyzed traps before any emission of diesel exhausts in the environment. 

These are the nonbumable components, typically metals and metalloids, found in fuel. Depending upon size, these particles can contribute to fuel system wear and filter and nozzle plugging. Sodium, potassium, lead, and vanadium can cause corrosion of certain high-temperature alloys such as those found on diesel engine valves and gas turbine blades. 

By using improved fuel injection and engine control techniques, the concentration of soot particles in the exhaust gas was reduced (less gray filter paper), but the number of soot particles was increased and their average size was reduced, which made the diesel engine emissions even more harmful. So, everyone was back to square one - and the unfavored end-of-pipe technology for the reduction of diesel soot emissions came back to life again ... 

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