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Trends towards lower vehicle fuel consumption and smaller environmental impact will increase the share of Diesel hybrids and Diesel Range Extended Vehicles (REV). Because of the Diesel engine presence and the ever tightening soot particle emissions, these vehicles will still require soot particle emissions control systems. Ceramic wall-flow monoliths are currently the key players in the Diesel Particulate Filter (DPF) market, offering certain advantages compared to other DPF technologies such as the metal based DPFs. The latter had, in the past, issues with respect to filtration efficiency, available filtration area and, sometimes, their manufacturing cost, the latter factor making them less attractive for most of the conventional Diesel engine powered vehicles. Nevertheless, metal substrate DPFs may find a better position in vehicles like Diesel hybrids and REVs in which high instant power consumption is readily offered enabling electrical filter regeneration.

Establishing a certain maintenance-free time period regarding modern diesel exhaust emission control systems is of major importance nowadays. One of the most serious problems Diesel Particulate Filter (DPF) manufacturers face concerning system's durability is the performance deterioration due to the filter aging because of the accumulation of the ash particles. The evaluation of the effect of the ash aging on the filter performance is a time and cost consuming task that slows down the process of manufacturing innovative filter structures and designs. In this work we present a methodology for producing filter samples aged by accumulating ash produced by the controlled pyrolysis of oil-fuel solutions. Such ash particles bear morphological (size) and compositional similarity to ash particles collected from engine aged DPFs. The ash particles obtained are compared to those from real engine operation.

The measurement of vehicle particle number emissions and, therefore, regulation, necessitates a rigorous sampling and conditioning technology able to deliver solid emitted particles with minimum particle losses. European legislation follows a solid particle number measurement method with cutoff size at 23 nm proposed by the Particle Measurement Programme (PMP). Accordingly, the raw exhaust is sampled with constant volume, subsequently passes through a volatile particle remover (VPR), and finally is measured with a particle counter. Lowering the 23 nm cutoff size with current VPR technologies introduces measurement uncertainties mainly due to the high particle losses and possible creation of artefacts. This study describes the development and evaluation of a sampling and conditioning particle system, the SCPS, specially designed for sub-23 nm solid particles measurement.

A computational lumped parameter model (MTU-Filter-Lumped) was developed to describe the performance of diesel particulate filters (DPFs) during loading and regeneration processes. The model was formulated combining three major sub-models: a filtration model, a pressure drop model, and a mass and an energy balance equation for the total filter volume. The first two sub-models have been widely validated in the literature, while the third sub-model is introduced and combined with the first two sub-models in the present study. The three sub-models combined can give a full description of diesel particulate filter behavior during loading and regeneration processes, which was the objective of the present work. The total combined lumped parameter model was calibrated using experimental data from the literature covering a range of experimental conditions, including different catalytic regeneration means and engine operating conditions.

Novel catalytic coatings with a variety of methods based on conventional and novel synthesis routes are developed for Diesel Particulate Filters (DPFs). The developed catalytic composition exhibits significant direct soot oxidation as evaluated by reacting mixtures of diesel soot and catalyst powders in a thermogravimetric analysis apparatus (TGA). The catalyst composition was further deposited on oxide and non-oxide porous filter structures that were evaluated on an engine bench with respect to their filtration efficiency, pressure drop behavior and direct soot oxidation activity under realistic conditions. The effect of the catalyst amount on the filtration efficiency of non-oxide filters was also investigated. Evaluation of the indirect soot oxidation was conducted on non-oxide catalytic filters coated with precious metal.

Asymmetric and Variable Cell (AVC) geometry Diesel Particulate Filters (DPF) occupy an increasing portion of the DPFs currently offered by various DPF manufacturers, aiming at providing higher filtration area in the same filter volume to meet demanding emission control applications for passenger cars but also for heavy duty vehicles. In the present work we present an approach for designing and optimizing such DPFs by providing a quantitative description of the flow and deposition of soot in these structures. Soot deposit growth dynamics in AVC DPFs is studied computationally, primary and secondary flows over the inlet channels cross-sectional perimeters are analyzed and their interactions are elucidated. The result is a rational description of the observed growth of soot deposits, as the flow readjusts to transport the soot particles along the path of least resistance (which is not necessarily the shortest geometric path between the inlet and outlet channel, i.e. the wall thickness).

Diesel Particulate Filters (DPFs) need to be periodically regenerated in order to achieve efficient and safe vehicle operation. Under typical diesel exhaust conditions, this invariably requires the raising of the exhaust gas temperature by active means, up to the point that particulate (soot) oxidation can be self-sustained in the filter. In the present work the development path of an advanced catalytic filter technology is presented. Full scale optimized Catalytic Diesel Particulate Filters (CDPFs) are tested in the exhaust of a light-duty modern diesel engine in line with a Diesel Oxidation Catalyst (DOC). The management of the DOC-CDPF emission control system is facilitated by a virtual soot sensor in order to ensure energy-efficient operation of the emission control system.

The increasing need for controlled diesel engine emissions and the strict regulations in the abatement of diesel exhaust products lead to an ever increasing use of Diesel Particulate Filters (DPFs) in OEM applications. The periodic regeneration of DPFs (oxidation of soot particles) demands temperatures that rarely appear during engine operation. It is therefore necessary to employ direct or indirect catalytic measures. In the present work, the development and synthesis via aerosol-based routes, of nanostructured base metal oxides for direct soot oxidation, along with their characterization and their evaluation in engine exhaust is described. The synthesized powders were characterized with respect to their phase composition and morphology. XRD, SEM and TEM analysis have shown the nanostructured character of the powders, while Raman spectroscopy was employed for the preliminary characterization of the materials surface chemistry.

Catalysts that have been extensively investigated for direct soot oxidation in Catalyzed Diesel Particulate Filters (CDPFs) are very often based on mixed oxides of ceria with zirconia, materials known to assist soot oxidation by providing oxygen to the soot through an oxidation-reduction catalytic cycle. Besides the catalyst composition that significantly affects soot oxidation, other parameters such as morphological characteristics of the catalyst largely determined by the synthesis technique followed, as well as the reagents used in the synthesis may also contribute to the activity of the catalysts. In the present work, two ceria-zirconia catalyst samples with different zirconia content were subjected to different milling protocols with the aim to shift the catalyst particle size distribution to lower values. The produced catalysts were then evaluated with respect to their soot oxidation activity following established protocols from previous works.

In the present work we derive analytical solutions for the problem of convection, diffusion and chemical reaction in wall-flow monoliths. The advantage of having analytical instead of numerical treatments is clear as the analytical solutions not only can be exploited to bring full scale simulations of diesel particulate filters to the real time domain, but also they enable efficient implementations on computationally limited engine control units (ECUs) for on-board management and control of emission control systems. The presentation describes the mathematical problem formulation, the governing dimensionless parameters and the corresponding assumptions. Then the analytical solution is derived and several asymptotic (for limiting values of the parameters) and approximating solutions are developed, corresponding to different physical situations. Reactant distributions in the filter are presented and discussed for several values of the parameters.

To ensure overall optimisation of heavy duty engine performance (with the respect of NOx&PM future European and US emissions standards), the use of a high efficiency NOx after-treatment system such as a NOx trap appears to be necessary. But running in rich conditions, even for a short time, leads to a large increase of particulate emissions so that a particulate filter is required. A first investigation with a NOx-trap only has been carried out to evaluate and optimise the storage, destorage and reduction phases from the NOx conversion efficiency and fuel penalty trade-off. The equivalence ratio level, the fuel penalty and the temperature level of the NOx-trap have been shown as a key parameter. Respective DPF and LNA locations have been studied. The configuration with the NOx-trap upstream provides the best NOx / fuel penalty trade-off since it allows NOx slip reduction and does not disturb the rich pulses.

ELEVATE (European Low Emission V4 Automotive Two-stroke Engine) was a research project part funded by the European Commission to design and develop a compact and efficient gasoline two-stroke automotive engine. Five partners were involved in the project, IFP (Institut Français Du Pétrole) who were the project leaders, Lotus, Opcon (Autorotor and SEM), Politecnico di Milano and Queen's University Belfast. The general project targets were to achieve Euro 3 emissions compliance without DeNOx catalisation, and a power output of 120 kW at 5000 rev/min with maximum torque of 250 Nm at 2000 rev/min. Specific targets were a 15% reduction in fuel consumption compared to its four-stroke counterpart and a size and weight advantage over the four-stroke diesel with significant reduction in particulate and NOx emissions. This paper describes the design philosophy of the engine as well as the application of the various partner technologies used.

Diesel Particulate Filter (DPF) material design based on a traditional design of experiments approach can be very time consuming and costly, due to the high number of tests and prototype material samples required. This provides an opportunity for the application of simulation tools at the microscopic scale, which are recently seeing increasing use in DPF material studies. The current work describes a framework for such micro-scale simulations based on high fidelity digital representations of the porous materials of interest, on the rationale that the performance of the latter materials depends strongly on the coupling of different physicochemical phenomena occurring at the microscopic scale where material morphology is important.

The relative contribution of two wheelers to local atmosphere pollution is increasing more and more due to ultra low emissions regulation applied to other vehicle as cars. In 1999, the first European emissions regulations for 50cc mopeds and scooters appeared (Euro I) and will also become more and more severe by the time. Euro II (2002) level will correspond to the next step. IFP has developed a simplified Direct Injection technology, named SCIP™, derived from the well known IAPAC® technology without the need of additional camshaft. This technology has been integrated with the MC500 Engine Management System developed by SAGEM for the growing 2-wheelers application. The final simple and cheap product is therefore well adapted to small displacement 2-stroke engines as 50cc engine for 2-wheelers application. This paper presents the development of a 50 cc scooter engine using SCIP™ technology and the calibration of the MC500 System to achieve Euro II regulation.

In this paper, a methodology is presented to study the influence of thermal aging on catalytic DPF performance using small scale coated filter samples and side-stream reactor technology. Different mixed oxide catalytic coating families are examined under realistic engine exhaust conditions and under fresh and thermally aged state. This methodology involves the determination of filter physical (flow resistance under clean and soot loaded conditions and filtration efficiency) and chemical properties (reactivity of catalytic coating towards direct soot oxidation). Thermal aging led to sintering of catalytic nanoparticles and to changes in the structure of the catalytic layer affecting negatively the filter wall permeability, the clean filtration efficiency and the pressure drop behavior during soot loading. It also affected negatively the catalytic soot oxidation activity of the catalyzed samples.

The paper deals with experimental activity concerning ATAC, which, in two-stroke gasoline engines, helps solving the crucial problem of combustion instability at light loads. ATAC consists of employing the energy of residual gas to prime an efficient combustion. The research is aimed to give further insight into ATAC mechanism both by visualisation of the combustion process and by examination of the influence which relevant parameters like air-fuel ratio, engine speed, compression ratio, scavenging passage design have on ATAC operation. Several results have been acquired and collected hitherto. A part of them are shown and discussed in this paper.

In the present work a practice for conducting experiments and analyzing the fundamental descriptors of Diesel Particulate Filter (DPF) flow resistance behavior is described. The recommended practice addresses each of the following areas: definition of flow resistance descriptors, filter geometrical characteristics, experimental setup and data analysis methods. The sources of errors in each area are identified and a sensitivity analysis is performed. Finally, the recommended practice is applied to several filter materials and configurations tested in the laboratory to determine objectively a set of flow resistance descriptors (namely the filter wall permeability, inlet/outlet loss coefficient) and their error bars. It is expected that application of the recommended practice for the determination of the flow resistance descriptors of DPFs will lead to better quality control procedures and meaningful comparisons of experimental data collected at different laboratories.

The IAPAC® Direct fuel Injection (DI) system, developed by IFP, has already well proven its capability to reduce pollutants emissions and fuel consumption of 2-stroke engines for both 2-wheeler and marine outboard application. This crankcase Compressed Air Assisted Fuel Injection process allowing the introduction of the fuel separately from the scavenging air, minimizes the fuel short-circuiting and has shown its potential on various prototype demonstrators. This paper presents the development and pre-industrialization work performed to apply this concept to an SELVA Marine 2-cylinder 50 HP outboard 2-stroke engine. A standard carbureted engine has been converted to a IAPAC® prototype engine by mainly modifying the cylinder head. Then, this prototype engine has been calibrated, tested and optimized on the dyno test bench to comply with future emissions regulation while keeping similar power output than the reference carbureted engine.

Diesel urban buses and refuse trucks are part of the particulate emissions sources that affect city air quality. In order to reduce particulate pollutant emissions, a development program has been carried out based on a Euro 4 engine with a DPF technology. Currently, for Euro 4 compliance, SCR is the favoured technology. To avoid a completely new development, the Exoclean™ DPF system was located after the SCR. Catalyst. The severe operating conditions and the location of the DPF necessitated the development of an active system based on the association of a DPF and a Fuel-Borne Catalyst. A Renault Trucks MD9 engine was used. This work was funded by ADEME (French Agency for Environment and Energy Management). Due to severe stop and go duty cycles and the interest to fit the DPF downstream of the SCR, this study shows the benefit of using an active DPF with an FBC to ensure full regeneration even at low temperatures.

Compliance with future emission standards for diesel powered vehicles is likely to require the deployment of emission control devices, such as particulate filters and DeNOx converters. Diesel emission control is merging with powertrain management and requires deep knowledge of emission control component behavior to perform effective system level integration and optimization. The present paper focuses on challenges associated with a critical component of diesel emission control systems, namely the diesel particulate filter (DPF), and provides a fundamental description of the transient filtration/loading, catalytic/NO2-assisted regeneration and ash-induced aging behavior of DPF's.