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Technical Paper

SCR for Passenger Car: the Ammonia-Storage Issue on a Fe-ZSM5 Catalyst

2009-06-15
2009-01-1929
A comprehensive experimental approach has been developed for a Fe-ZSM5 micro-porous catalyst, through a collaborative project between IFP, PSA Peugeot-Citroën and the French Environment and Energy Management Agency (ADEME). Tests have first been conducted on a synthetic gas bench and yielded estimated values for the amount of NH3 stored on a catalyst sample. These data have further been compared to those obtained from an engine test bench, in running conditions representative of the entire operating range of the engine. 15 operating points have been chosen, considering the air mass flow and the exhaust temperature, and tested with different NH3/NOx ratios. Steady-state as well as transient conditions have been studied, showing the influence of three main parameters on the reductant storage characteristics: exhaust temperature, NO2/NOx ratio, and air mass flow.
Technical Paper

Detailed Particulate Characterization from HCCI Combustion for Future DPF Development

2009-04-20
2009-01-1185
This paper presents the detailed characterization of particulate emissions from a NADI™ dual mode engine (HCCI at low load and conventional combustion at high load). Morphology, composition and chemical reactivity of the particulate matter generated on an engine running in HCCI mode have been specified and compared to the conventional mode reference. Results showed that HCCI combustion formed particles with a higher volatile organic fraction due to the relatively high level of HC generated by this kind of combustion. Advanced soot characterization emphasized that HCCI soot is oxidized at a slower reaction rate than conventional soot, but with a lower temperature. This last characteristic could partially compensate the poor continuous regeneration effect due to low NO2 emission levels observed in HCCI combustion. Microscopic observation and particle sizing did not show significant differences between HCCI and conventional soot.
Technical Paper

Generating Thermal Conditions to Regenerate a DPF: Impact of the Reductant on the Performances of Diesel Oxidation Catalysts

2009-04-20
2009-01-1085
The influence of the type of fuel and the feeding means to a DOC, in order to regenerate a DPF, was investigated. Diesel fuel in cylinder late post-injection was compared to the injection in the exhaust line, through an exhaust port injector, of diesel fuel, B10 (diesel fuel containing 10% of esters) and gasoline. Diesel fuel exhaust injection resulted in a deteriorated conversion efficiency, while the incorporation of esters to the diesel fuel was demonstrated to have no influence. Gasoline exhaust injection led to less HC slip than diesel fuels. Temperature dynamics resulting from injection steps showed taught that the shorter the hydrocarbons (within the tested fuels), the slower the response. These differences can be caught by simple models, leading to interesting opportunities for the model-based control of the DPF inlet temperature during active regenerations.
Journal Article

Analysis of Combustion Process in Cold Operation with a Low Compression Ratio Diesel Engine

2010-04-12
2010-01-1267
Future emissions standards for passenger cars require a reduction of NOx (nitrogen oxide) and CO₂ (carbon dioxide) emissions of diesel engines. One of the ways to reach this challenge while keeping other emissions under control (CO: carbon monoxide, HC: unburned hydrocarbons and particulates) is to reduce the volumetric compression ratio (CR). Nevertheless complications appear with this CR reduction, notably during very cold operation: start and idle. These complications justify intensifying the work in this area. Investigations were led on a real 4-cylinder diesel 13.7:1 CR engine, using complementary tools: experimental tests, in-cylinder visualizations and CFD (Computational Fluid Dynamics) calculations. In previous papers, the way the Main combustion takes place according to Pilot combustion behavior was highlighted. This paper, presents an in-depth study of mixture preparation and the subsequent combustion process.
Journal Article

Cold Start on Diesel Engines: Effect of Fuel Characteristics

2010-05-05
2010-01-1506
Faced with the need to reduce greenhouse gas emissions, diesel engines present the advantage of having low CO₂ emission levels compared to spark-ignited engines. Nevertheless, diesel engines still suffer from the fact that they emit pollutants and, particularly nitrogen oxides (NOx) and particulates (PM). One of the most promising ways to meet this challenge is to reduce the compression ratio (CR). However a current limitation in reducing the diesel CR is cold start requirements. In this context, the fuel characteristics such as the cetane number, which represents ignition, and volatility could impact cold start. That is why a matrix of 8 fuels was tested. The cetane number ranges from 47.3 to 70.9 and the volatility, represented by the temperature necessary to distillate 5% of the product (T5%), ranges from 173 to 198°C. The engine tests were carried out at -25°C, on a common rail 4-cylinder diesel engine.
Journal Article

Optimization of a Euro 5 Vehicle Powered by an Ethanol Based Diesel Fuel

2010-05-05
2010-01-1520
Diversifying energy resources and reducing greenhouse gas emissions are key priorities in the forthcoming years for the automotive industry. Currently, among the different solutions, sustainable biofuels are considered as one of the most attractive answer to these issues. This paper deals with the vehicle application of an innovative diesel fuel formulation using Ethanol to tackle these future challenges. The main goal is to better understand the impact of using biofuel blends on engine behavior, reliability and pollutants emissions. This alternative oxygenated fuel reduces dramatically particulate matter (PM) emissions; this paves the way to improve the NOx/PM/CO₂ trade-off. Another major interest is to avoid adding a particulate filter in the exhaust line and to avoid modifying powertrain and vehicle hardware and therefore to minimize the overall cost to fulfill upcoming emission regulations.
Technical Paper

Improving Emissions, Noise and Fuel Economy Trade-Off by using Multiple Injection Strategies in Diesel Low Temperature Combustion (LTC) Mode

2010-10-25
2010-01-2162
Latest emissions standards impose very low NOx and particle emissions that have led to new Diesel combustion operating conditions, such as low temperature combustion (LTC). The principle of LTC is based on enhancing air fuel mixing and reducing combustion temperature, reducing raw nitrogen oxides (NOx) and particle emissions. However, new difficulties have arisen. LTC is typically achieved through high dilution rates and low CR, resulting in increased auto-ignition delay that produces significant noise and deteriorates the combustion phasing. At the same time, lower combustion temperature and reduced oxygen concentration increases hydrocarbon (HC) and carbon oxide (CO) emissions, which can be problematic at low load. Therefore, if LTC is a promising solution to meet future emission regulations, it imposes a new emissions, fuel consumption and noise trade-off. For this, the injection strategy is the most direct mean of controlling the heat release profile and fuel air mixture.
Journal Article

Effects of Methane/Hydrogen Blends On Engine Operation: Experimental And Numerical Investigation of Different Combustion Modes

2010-10-25
2010-01-2165
The introduction of alternative fuels is crucial to limit greenhouse gases. CNG is regarded as one of the most promising clean fuels given its worldwide availability, its low price and its intrinsic properties (high knocking resistance, low carbon content...). One way to optimize dedicated natural gas engines is to improve the CNG slow burning velocity compared to gasoline fuel and allow lean burn combustion mode. Besides optimization of the combustion chamber design, hydrogen addition to CNG is a promising solution to boost the combustion thanks to its fast burning rate, its wide flammability limits and its low quenching gap. This paper presents an investigation of different methane/hydrogen blends between 0% and 40 vol. % hydrogen ratio for three different combustion modes: stoichiometric, lean-burn and stoichiometric with EGR.
Technical Paper

Turbine Efficiency Estimation for Fault Detection Application

2010-04-12
2010-01-0568
In nowadays diesel engine, the turbocharger system plays a very important role in the engine functioning and any loss of the turbine efficiency can lead to driveability problems and the increment of emissions. In this paper, a VGT turbocharger fault detection system is proposed. The method is based on a physical model of the turbocharger and includes an estimation of the turbine efficiency by a nonlinear adaptive observer. A sensitivity analysis is provided in order to evaluate the impact of different sensors fault, (drift and bias), used to feed the observer, on the estimation of turbine efficiency error. By the means of this analysis a robust variable threshold is provided in order to reduce false detection alarm. Simulation results, based on co-simulation professional platform (AMEsim© and Simulink©), are provided to validate the strategy.
Journal Article

Study of Air Entrainment of Multi-hole Diesel Injection by Particle Image Velocimetry - Effect of Neighboring Jets Interaction and Transient Behavior After End of Injection.

2010-04-12
2010-01-0342
The air entrainment of multi-hole diesel injection is investigated by high speed Particle Image Velocimetry (PIV) using a multi-hole common rail injector with an injection pressure of 100 MPa. The sprays are observed in a high pressure, high temperature cell that reproduces the thermodynamic conditions which exist in the combustion chamber of a diesel engine during injection. Typical ambient temperature of 800K and ambient density of 25 kg/m3 are chosen. The air entrainment is studied with the PIV technique, giving access to the velocity fields in the surrounding air and/or in the interior of two neighboring jets. High acquisition rate of 5000 Hz, corresponding to 200 μs between two consecutive image pairs is obtained by a high-speed camera coupled with a high-speed Nd:YLF laser. The effect of neighboring jets interaction is studied by comparing four injectors with different numbers of holes (4, 6, 8 and 12) with similar static mass flow rate per hole.
Technical Paper

Comparison between the exhaust particles mass determined by the European regulatory gravimetric method and the mass estimated by ELPI

2005-05-11
2005-01-2147
Electrical Low Pressure Impactor (ELPI) is often employed to measure the particle number and size distribution of internal combustion engines exhaust gas. If appropriate values of particle density are available, the particle mass can be estimated by this method. Exhaust particles of three Euro3 passenger cars (one gasoline operating under stoichiometric conditions, one Diesel and one Diesel equipped with Diesel Particulate Filter) are measured using the current European regulations (gravimetric method on the are New European Driving Cycle) and estimated by ELPI particle number and size distribution. Different values for particle density are used to estimate the particle mass using all ELPI stages or only some of them. The results show that the particle mass estimated by ELPI is well correlated with the mass determined by filters for PM emissions higher than 0.025 g/km. This correlation is not very good at lower emissions.
Technical Paper

Development of an Improved Gravimetric Method for the Mass Measurement of Diesel Exhaust Gas Particles

2005-05-11
2005-01-2145
The Particulate Measurement Programme (PMP) works on the identification of a method to replace or complete the existing particle mass (PM) measurement method. The French PMP subgroup, composed by IFP, PSA Peugeot-Citroën, Renault and UTAC, proposes an improved gravimetric method for the measurement of emitted particles, and conducted an inter-laboratory test to evaluate its performances. The technical programme is based on tests carried out on a Euro3 Diesel passenger car (PC), tested on the New European Driving Cycle (NEDC). To achieve low particulate matter (PM) emissions, the EGR is disconnected and a paraffinic fuel is used. The regulated pollutants are also measured. It is shown that the multiple filter weighing and a 0.1 μg balance instead of a 1 μg one are not necessary, as the first weighing and the 1 μg balance performances are satisfactory for type-approval purposes.
Technical Paper

Performances and Durability of DPF (Diesel Particulate Filter) Tested on a Fleet of Peugeot 607 Taxis: Final results

2004-03-08
2004-01-0073
In order to asses the durability of DPF, a study has been performed in order to study the evolution of several taxis (Peugeot 607) and the performance of this after-treatment systems over 80,000 km mileage in hard urban driving conditions, which corresponds to the recommended mileage before the first DPF maintenance (this periodicity is applied on the first generation of DPF technology launched in 2000). More specifically, the following evaluations are being performed at regular intervals (around 20 000 km): Regulated gaseous pollutant emissions on NEDC cycle (New European Driving Cycle) Particulate emissions, by mass measurement on NEDC but also by particle number and size measurement with SMPS (Scanning Mobility Particle Sizer) technique on NEDC and on unconventional steady-state running points.
Technical Paper

On the origin of Unburned Hydrocarbon Emissions in a Wall Guided, Low NOx Diesel Combustion System

2007-07-23
2007-01-1836
The formation mechanisms of unburned hydrocarbons (HC) in low NOx, homogeneous type Diesel combustion have been investigated in both standard and optical access single cylinder engines operating under low load (2 and 4 bar IMEP) conditions. In the standard (i.e. non-optical) engine, parameters such as injection timing, intake temperature and global equivalence ratio were varied in order to analyse the role of bulk quenching on HC emissions formation. Laser-induced fluorescence (LIF) imaging of in-cylinder unburned HC within the bulk gases was performed on the optical-access engine. Furthermore, studies were performed in order to ascertain whether the piston top-land crevice volume contributes significantly to engine-out HC emissions. Finally, the role of piston-top fuel films and their impact on HC emissions was studied. This was investigated on the all-metal engine using two fuels of different volatilities.
Technical Paper

A Study of Combustion Structure and Implications on Post-Oxidation Under Homogeneous and Stratified Operation in a DISI Engine

2006-04-03
2006-01-1262
An experimental investigation into the structure and flame propagation characteristics of stratified and homogeneous combustion has been performed in an optically-accessible, direct-injection spark ignition (DISI) engine using OH planar laser-induced fluorescence (PLIF) imaging. Homogeneous and stratified operation was achieved by employing either early or late injection timing strategies during the intake or compression stroke respectively. Planar LIF OH images obtained revealed that for stratified operation, the 3D structure of the combustion zone is highly inhomogeneous and is predominantly due to high fuel concentration gradients which are formed as a result of local fuel mixture stratification. The images reveal a combustion structure which suggests that the flame propagation pathway is ultimately determined by the presence of these local fuel mixture inhomogeneities.
Technical Paper

Development of Highly Premixed Combustion Diesel Model: From Simulation to Control Design

2006-04-03
2006-01-1072
In the context of increasingly stringent pollution norms, reduced engine emissions are a great challenge for compressed ignition engines. After-treatment solutions are expensive and very complex to implement, while the NOx/PM trade-off is difficult to optimise for conventional Diesel engines. Therefore, in-cylinder pollutant production limitation by the HPC combustion mode (Highly Premixed Combustion) - including Homogeneous Charge Compression Ignition (HCCI) - represents one of the most promising ways for new generation of CI engine. For this combustion technology, control based on torque estimation is crucial: the objectives are to accurately control the cylinder-individual fuel injected mass and to adapt the fuel injection parameters to the in-cylinder conditions (fresh air and burned gas masses and temperature).
Technical Paper

Study of the Correlation Between Mixing and Auto-Ignition Processes in High Pressure Diesel Jets

2007-04-16
2007-01-0650
A tracer laser-induced fluorescence (LIF) technique for the visualisation of fuel distribution in the presence of oxygen was developed and then used sequentially with high speed chemiluminescence imaging to study the correlation between the mixing and auto-ignition processes of high pressure Diesel jets. A single hole common rail Diesel injector allowing high injection pressures up to 150MPa was used. The reacting fuel spray was observed in a high pressure, high temperature cell that reproduces the thermodynamic conditions which exist in the combustion chamber of a Diesel engine during injection. Both free jet and flat wall impinging jet configurations were studied. Several tracers were first considered with the objective of developing a tracer-LIF technique in the presence of oxygen. 5-nonanone was selected for its higher fluorescence efficiency.
Technical Paper

AMT Control for a Mild-Hybrid Urban Vehicle with a Downsized Turbo-Charged CNG Engine

2007-04-16
2007-01-0286
Compressed natural gas (CNG) is considered as one of the most promising alternative fuels for transportation due to its ability to reduce greenhouse gas emissions (CO2, in particular) and its abundance. An earlier study from IFP has shown that CNG has a considerable potential when used as a fuel for a dedicated downsized turbo-charged SI engine on a small urban vehicle. To take further advantage of CNG assets, this approach can be profitably extended by adding a small secondary (electrical) power source to the CNG engine, thus hybridizing the powertrain. This is precisely the focus of the new IFP project, VEHGAN, which aims to develop a mild-hybrid CNG prototype vehicle based on a MCC smart car equipped with a reversible starter-alternator and ultra-capacitors (Valeo Starter Alternator Reversible System, StARS).
Technical Paper

Ethanol as a Diesel Base Fuel: Managing the Flash Point Issue - Consequences on Engine Behavior

2009-06-15
2009-01-1807
Facing more and more stringent regulations, new solutions are developed to decrease pollutant emissions. One of them have shown promising and relevant results. It consists of the use of ethanol as a blending component for diesel fuel Nevertheless, the addition of ethanol to Diesel fuel affects some key properties such as the flash point. Consequently, Diesel blends containing ethanol become highly flammable at a temperature around ambient temperature. This study proposes to improve the formulation of ethanol based diesel fuel in order to avoid flash point drawbacks. First, a focus on physical and chemical properties is done for ethanol based diesel fuels with and without flash point improvement. Second, blends are tested on a passenger car diesel engine, under a wide operating range conditions from low load low speed up to maximum power. The main advantage of the ethanol based fuels generate low smoke level, that allows using higher EGR rate, thus leading to an important NOx decrease.
Technical Paper

Towards CO and HC Aftertreatment Devices for the Next Generation of Diesel Engines

2008-06-23
2008-01-1543
The reduction of NOx emissions required by the future Euro 6 standards leads engine manufacturers to develop Diesel Homogeneous Charge Compression Ignition (HCCI) combustion processes. Because this concept allows reducing both NOx and particulates simultaneously, it appears as a promising way to meet the next environmental challenges. Unfortunately, HCCI combustion often increases CO and HC emissions. Conventional oxidation catalyst technologies, currently used for Euro 4 vehicles, may not be able to convert these emissions because of the saturation of active catalytic sites. As a result, such increased CO and HC emissions have to be reduced under standard levels using innovative catalysts or emergent technologies. The work reported in this paper has been conducted within the framework of the PAGODE project (PSA, IFP, Chalmers University, APTL, CRF, Johnson Matthey and Supelec) and financed by the European Commission.
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