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Technical Paper

1-D Dynamic Diesel Particulate Filter Model for Unsteady Pulsating Flow

A fast time-scale 1-D dynamic diesel particulate filter model capable of resolving the pressure pulsations due to individual cylinder firing events is presented. The purpose of this model is to investigate changes in the firing frequency component of the pulsating exhaust flow at different particulate loadings. Experimental validation data and simulation results clearly show that the magnitude and phase of the firing frequency components are directly correlated to the mass of particulate stored in a diesel particulate filter. This dynamic pressure signal information may prove particularly useful for monitoring particulate load during vehicle operation.
Technical Paper

1D Modeling of the Hydrodynamics and of the Regeneration Mechanism in Continuous Regenerating Traps

The present work focuses on the simulation of the hydrodynamics, transient filtration/loading and catalytic/NO2-assisted regeneration of Diesel after-treatment systems. A 1D unsteady model for compressible and reacting flows for the numerical simulation of the behavior of Diesel Oxidation Catalysts (DOCs) and Diesel Particulate Filters (DPFs) has been developed. The numerical model is able to keep track of the amount of soot in the flow; the increasing of back-pressure through the exhaust system (mainly due to the Diesel Particulate Filter) can be predicted by the calculation of the permeability variation of the porous wall, as the soot particles goes inside the DPF. A sub-model for the regeneration of the collected soot has been developed: the collected particulate is oxidized by the Oxygen (O2) and by the Nitrogen Dioxide (NO2).
Journal Article

3-Cylinder Turbocharged Gasoline Direct Injection: A High Value Solution for Low CO2 and NOx Emissions

Today turbo-diesel powertrains offering low fuel consumption and good low-end torque comprise a significant fraction of the light-duty vehicle market in Europe. Global CO₂ regulation and customer fuel prices are expected to continue providing pressure for powertrain fuel efficiency. However, regulated emissions for NO and particulate matter have the potential to further expand the incremental cost of diesel powertrain applications. Vehicle segments with the most cost sensitivity like compacts under 1400 kg weight look for alternatives to meet the CO₂ challenge but maintain an attractive customer offering. In this paper the concepts of downsizing and downspeeding gasoline engines are explored while meeting performance needs through increased BMEP to maintain good driveability and vehicle launch dynamics. A critical enabler for the solution is adoption of gasoline direct injection (GDi) fuel systems.
Technical Paper

3-D Catalytic Regeneration and Stress Modeling of Diesel Particulate Filters by ABAQUS FEM Software

The design of reliable DPF systems has proved a complex and demanding task that is increasingly being assisted by modeling. 1-D but also 2-D (axisymmetric) modeling has already been applied in design optimization case studies, with varying degrees of success. The introduction of advanced technology SiC and cordierite filters with modular structure and the need to accurately model transient temperature and stress fields in low space velocity scenarios, made necessary the shift to 3-D modeling. In this paper, 3-D modeling is carried out in an effective and reliable way, by interfacing a well-documented and validated 1-D model with the ABAQUS commercial FEM software. The new modeling methodology proves a powerful tool in the hands of the filter and diesel exhaust system design engineer.
Technical Paper

3-D Transient Elastic Thermal Stress Field during Diesel Particulate Filter Regeneration

A displacement based finite element model is developed to predict 3-D thermal stress induced by high temperature and temperature gradient during diesel particulate filter (DPF) regeneration. The temperature field predicted by 3-D conservation of energy is used as input. This finite element model is self-contained and independent of commercial package. It includes functions of meshing body, assembling global stiffness matrix and force vector, solving final equilibrium equations as well as post-processing. This model is validated by commercial software ANSYS and good agreement is observed. Typically, it is the peak temperature rather than temperature gradients that lead to maximum compressive thermal stress in DPF during regeneration. The maximum stress always appears at the channel corner located at the end of DPF. Parametric studies of DPF during loading and regeneration as well as the effect of particulate loading on thermal stress during regeneration are carried out.
Journal Article

3D Numerical Study of Pressure Loss Characteristics and Soot Leakage Through a Damaged DPF

Diesel Particulate Filters (DPF) are widely used to meet 2007 and beyond EPA Particulate Matter (PM) emissions requirements. During the soot loading process, soot is collected inside a porous wall and eventually forms a soot cake layer on the surface of the DPF inlet channel walls. A densely packaged soot layer and reduced pore size due to Particulate Matter (PM) deposition will reduce overall DPF wall permeability which results in increasing pressure drop across the DPF substrate. A regeneration process needs to be enacted to burn out all the soot collected inside the DPF. Soot mass is not always evenly distributed as the distribution is affected by the flow and temperature distribution at the DPF inlet. As a result, the heat release which is determined by the burn rate is locally dependent. High temperature gradients are often found inside DPF substrate as a result of these locally dependent burn rates.
Technical Paper

3D Simulation of Diesel Particulate Filter Regeneration with Supplementary Fuel Injection

To ensure reliable Diesel Particulate Filter (DPF) regeneration, even in critical situations such as slow city driving, a fuel vaporizer can be used to introduce additional hydrocarbons directly into the Diesel aftertreatment system. The fuel vaporizer provides significantly shorter reaction times than possible with engine measures alone and also helps minimize the extensive engine measures normally required to achieve the DPF ignition temperatures. As with other components, correctly optimizing complex aftertreatment systems requires not simply characterizing and optimizing an individual component, but also understanding the interaction between components and the behaviour of the system as a whole. The value of a system simulation lies in rapid turnaround times combined with the ability to address three-dimensional phenomena, since they often have a decisive impact on the system performance (e.g., the hydrocarbon distribution and its associated catalytic heat release).
Technical Paper

3D Simulation of Soot Loading and Regeneration of Diesel Particulate Filter Systems

A novel CFD simulation technique has been developed that unites realistic three-dimensional resolution of diesel particulate filter systems with computational efficiency. Three-dimensional resolution of the thermofluiddynamic behaviour during transient soot loading and regeneration is necessary for the optimization of the function, durability, weight and cost of DPF systems. Computational efficiency is required to allow its use as a standard development tool during all engineering phases and to allow the simulation of driving cycles. The detailed conclusions that can be drawn about soot distribution and thermal characteristics during the regeneration assist in ensuring the DPF function and avoiding DPF failures over the operational lifetime.
Technical Paper

A 1D Unsteady Thermo-Fluid Dynamic Approach for the Simulation of the Hydrodynamics of Diesel Particulate Filters

A new approach for the fluid-dynamic simulation of the Diesel Particulate Filters (DPF) has been developed. A mathematical model has been formulated as a system of nonlinear partial differential equations describing the conservation of mass, momentum and energy for unsteady, compressible and reacting flows, in order to predict the hydrodynamic characteristics of the DPF and to study the soot deposition mechanism. In particular, the mass conservation equations have been solved for each chemical component considered, and the advection of information concerning the chemical composition of the gas has been figured out for each computational mesh. A sub-model for the prediction of the soot cake formation has been developed and predictions of soot deposition profiles have been calculated for different loading conditions. The results of the simulations, namely the calculated pressure drop, have been compared with the experimental data.
Technical Paper

A 2-Dimensional Simulation Model for a Diesel Particulate Filter

The paper presents a 2-dimensional model for the calculation of the regeneration process in a wall flow diesel particulate filter. The model includes heat transfer by conduction and convection, a model for particle combustion based on diffusive burning of individual particles, and flow through the channels and across the filter walls. It was found that only the pressure drop across the walls need be considered for normal regeneration conditions. Comparisons between model predictions and experimental results for spatial dependent temperature time histories, and integrated degree of regeneration are used to validate the model. The validations were carried out for a series of severe regenerations, where there are large changes in flow and temperature throughout the process. Relative magnitudes of energy flows due to combustion, convection, and conduction are presented, as well as parametric studies of the effects of temperature, oxygen concentration and soot loading.
Technical Paper

A CFD Study to Optimize the Injection Strategy for Diesel Particulate Filter Regeneration

Diesel engines have been progressing a lot during recent years. Beside the driving pleasure due to high torque and the low fuel consumption, it is more and more important to reduce combustion noise and pollutant emissions such as smoke and NOx. The exhaust after-treatment systems, in particular Diesel Particulate Filter (DPF), have therefore become as a standard for Euro5 applications and for some of the heaviest vehicles for Euro4. The DPF requires periodic regenerations under high temperature conditions in order to burn out the soot cumulated inside. One of the simplest strategies consists of one or several late injections. Typically, retarding the main and adding an early post injection generate high exhaust temperature while a very late one with a suitable quantity provides hydrocarbons, which burn inside the Diesel Oxidation Catalyst (DOC), and ensures the required temperature upstream the DPF.
Technical Paper

A Comprehensive Study on DOC Selection for Euro 6 Compliant Heavy Commercial Vehicles

Euro 6 emission norms are getting implemented in India from April 2020 and it is being viewed as one of the greatest challenges ever faced by the Indian automotive industry. In order to achieve such stringent emission norms along with top performance for vehicle, a good strategy should be incorporated to control system out NOx emissions and soot regeneration. Extruded Vanadium catalyst is deployed for this passive regeneration system with DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter) and SCR (Selective Catalyst Reduction), where the amount of catalyst loading in DOC plays an apex role in deciding conversion efficiency of SCR and passive regeneration capabilities. This study mainly focuses on the impact of catalyst loading of DOC over SCR efficiency. NO2 to NOx ratio should be close to 0.5 for optimum conversion efficiency of SCR. Catalyst loading in DOC decides the amount of NO2 coming upstream to SCR.
Technical Paper

A Computational Model Describing the Performance of a Ceramic Diesel Particulate Trap in Steady-State Operation and Over a Transient Cycle

A model for calculating the trap pressure drop, various particulate properties, filtration characteristics and trap temperatures was developed during the steady-state and transient cycles using the theory originated by Opris and Johnson, 1998. This model was validated with the data obtained from the steady-state cycles run with an IBIDEN SiC diesel particulate filter. To evaluate the trap experimental filtration efficiency, raw exhaust samples were taken upstream and downstream of the trap. A trap scaling and equivalent comparison model was developed for comparing different traps at the same volume and same filtration area. Using the model, the trap pressure drop data obtained from different traps were compared equivalently at the same trap volume and same filtration area. The pressure drop performance of the IBIDEN SiC trap compared favorably to the previously tested NoTox SiC and the Cordierite traps.
Technical Paper

A Cost Effective Solution to Reduce Particulate Emissions

Growing concern over the health effects of airborne particles and a desire to reduce the associated cost has resulted in legislation, regulations and other measures, in the industrialised world to severely restrict particulate emissions from diesel-fuelled automotive transport. Developing countries are also introducing initiatives to try and reduce emissions, an example is the legislation in India to replace diesel engines with gas fuelled engines in some major conurbations. Such measures are expensive, both in terms of replacing the engines of the vehicles and of implementing the required infrastructure. There is still also debate over whether such measures reduce the number of ultra-fine particulates. A well-proven alternative is to fit diesel engines with Diesel Particulate Filters (DPFs), either as original equipment or as a retrofit system. Regenerating DPFs has in the past been an obstacle to their widespread application.
Technical Paper

A Diesel Engine Emission System Based on Brownian Diffusion a Separation

Diesel engine exhaust poses an ongoing threat to human health as well as to the environment. Automotive exhaust treatment systems have been developed over the years to reduce the large amount of diesel particulate matter (DPM) released to the atmosphere. Current systems can be categorized as selective catalytic reduction, catalytic converters, and diesel particulate filters. This study presents an emission system that focuses on the removal of exhaust particles using Brownian diffusion of DPM toward fog drops followed by cyclonic separation of DPM rich fog drops. The experimental system consisted of a 13.2 kW diesel engine, heat exchanger to cool the exhaust to saturation temperature, ultrasonic fogger, cyclone separator, and recovery of waste particulate. Representative emission tests have been performed at five different diesel engine speeds and corresponding crankshaft loads.
Technical Paper

A Diesel Particulate Filter System Using Assisted Regeneration for Mechanical Handling Equipment

A cooperative R&D program involving Engine Control Systems Ltd. (ECS) and Consolidated Freightways, Inc. (C-F) has resulted in a diesel emissions control system for small to medium sized mechanical handling equipment. This paper outlines the design specifics of the system with an emphasis on the manner in which forktrucks can relatively easily be retrofitted. Both laboratory and in-field test results are outlined. The particulate filter system uses electric power to induce regeneration when backpressure rises to unacceptable levels.
Technical Paper

A Diesel Particulate Regeneration System Using a Copper Fuel Additive

An earlier study (SAE Paper 920364) documented the ability of a Copper-based fuel additive to initiate regeneration of a particulate trap without external heat sources. Work performed with Southeastern Pennsylvania Transit Authority on diesel particulate filter systems for a 6V-92TA mechanical engine has been expanded to include 6V-92TA electronic, MAN and Caterpillar engines as well as an increased number of 6V-92TA mechanical engines. Both cordierite wall flow and fibre filter systems are currently being evaluated for performance and durability in field service. This paper outlines performance of the system which uses a copper-based fuel additive to induce regeneration along with emission reductions and health effects data. Additional data on compatibility of the copper fuel additive with typical commercial diesel fuels and lubricants is also presented.
Technical Paper

A Diesel Passenger Car Euro V Compliant System for India

With the implementation of Euro V emissions legislation in 2010, the vast majority of light-duty diesel vehicles now employ a diesel particulate filter. The expansion of the Diesel Euro V standard outside Europe is inhibited in part by the low availability of ≺50 ppm sulfur fuel. Having said this, countries such as India and China have ≺50 ppm sulfur fuel available in many urban centers today, with the geographical area covered growing each year. Whilst it is well known that diesel DPF applications require ≺50 ppm sulfur fuel for optimum long-term operation, the ability of the system to withstand periodic "high" sulfur events would be a useful enabler for the early implementation of Euro V legislation to these markets. In this paper, the authors set out to assess the capability of the DOC and cDPF exhaust gas aftertreatment system to cope with periodic high sulfur fuel events.
Technical Paper

A Durable and Efficient Cu Zeolite based SCR Catalyst for Cold Start and High Temperature DeNOx Applications

Typical diesel engine-out emissions consist of hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM) & oxides of nitrogen (NOx). The HC and CO emissions are oxidized by a diesel oxidation catalyst (DOC), placed upstream, closer to the exhaust manifold. The DOC is often followed by a diesel particulate filter (DPF), which entraps and combusts PM. The NOx is often controlled by a selective catalytic reduction (SCR) catalyst. An SCR catalyst commonly uses NH3 to reduce the NOx to N2. Vanadium-based SCR catalysts have been widely used for many years. More recently, Cu-Zeolite based SCR (CuZ-SCR) is gaining much attention primarily due to the potential environmental hazards of vanadium and a wider temperature window of effective operation. The SCR reaction is facilitated by the presence of NO2 at lower exhaust gas temperatures by means of the so-called “fast” reaction. However, this is only advantageous up to about 300°C.
Technical Paper

A Feasibility Demonstration of a Sensing Control Unit for Measurement of Large Capacitance for Particulate Matter Sensor

On-board diagnostics (OBD) of diesel vehicles require various sensors to detect system malfunctions. The Particulate Matter (PM) sensor is one of OBD devices which gather information which could be critical in determining a crack in the diesel particulate filters (DPFs). The PM sensor detects PM which penetrates cracked DPFs and converts the amount of PM into electrical values. The PM sensor control unit (SCU) receives those analog signals and converts them to digital values through hardware and software solutions. A capacitive sensing method would be a stable solution because it detects not raw analog signals but electrical charges or a time constant going through the capacitive load. Therefore, amount of PM would be converted reasonable value of capacitance even though there is a little amount of PM.