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Fulfillment of SULEV standards without catalyst - this is a target engineers at IAV have been working on since the middle of the 1990s. The core of this development is an advanced steam engine with a high performance burner. This burner features extremely low raw pollutant emission. This paper describes new solutions that were found to solve the challenging tasks in the development of such an engine concept.

Selective Catalytic Reduction (SCR) with NH3 or urea is one of the most effective methods for removal of NOx in exhaust from HD diesel engines with potential for achieving more than 90% NOx-reduction measured in the European transient or a US HD FTP test cycle. The present paper describes the following two systems; One OEM UREA-SCR SILENCER, comprising a silencer with built-in catalyst. The system was tested on a Scania DC1205 320 kW diesel engine, which was calibrated for the Euro II emission standard. The test results showed that it is possible to reduce more than 85% of the NOx emission with an insignificant NH3 slip in the ETC transient test cycle. The pressure-drop of the system was measured at 80% of that of the engine's original silencer and the silencing performance was improved for low frequencies below 125 Hz. One RETROFIT UREA-SCR SYSTEM for HD engines, comprising a silencer with built-in catalyst, an electronic urea injection control system, urea injection and a urea tank.

As part of a California Selective Catalyst Reduction (SCR) system demonstration and evaluation project [13], the authors and their industrial partners have conducted engine dynamometer emissions tests of SCR systems. The transient Federal Test Procedure (FTP) cycle and 13 Mode European Stationary Cycle (ESC) were conducted using certification diesel fuel with 300-500 ppm of sulfur. This paper reviews the performance of the first system to meet the goal of attaining 1 g/bhp-hr NOx emissions in the transient FTP cycle on a 1999 DDC Series 60 engine that has an initial 4 g/bhp-hr level. This paper discusses key characteristics of a typical automotive SCR system and then presents the results and analysis of the engine dynamometer emission testing of a SCR system. The paper concludes with a discussion of the challenges involved in on-road operation of the system.

A catalytic deSoot-deNOx system, comprising Pt and Ce fuel additives, a Pt impregnated wall-flow monolith soot filter and a vanadia-type monolithic NH3 - SCR catalyst, was tested with a 2 cylinder DI diesel engine. The soot removal efficiency of the filter was 98-99% (mass), the balance temperature (stationary pressure drop) was 315 °C at an engine load of 55%. The NOx-emission at high loads is around 15% lower than those of engine running without fuel additives. The NOx conversion ranged from 40 to 73%, at a NH3/NOx ratio of 0.9, both measured at a GHSV of 52,000 l/l/h. The maximum NOx conversion was obtained at 400 °C. No deactivation was observed after 380 h time on stream.

The LEV II and EURO V legislation in 2007/2008 require a high conversion level for nitrogen oxides to meet the emission levels for diesel SUVs and trucks. Therefore, U.S. and European truck manufacturers are considering the introduction of urea SCR systems no later than model year 2005. The current SCR catalysts are based mainly on systems derived from stationary power plant applications. Therefore, improved washcoat based monolith catalysts were developed using standard types of formulations. These catalysts achieved high conversion levels similar to extruded systems in passenger car and truck test cycles. However, to meet further tightening of standards, a new class of catalysts was developed. These advanced type of catalytic coatings proved to be equivalent or even better than standard washcoat formulations. Results will be shown from ESC, MVEG and US-FTP 75 tests to illustrate the progress in catalyst design for urea SCR.

The aggressive reduction of future diesel engine NOx emission limits forces the heavy- and light-duty diesel engine manufacturers to develop means to comply with stringent legislation. As a result, different exhaust emission control technologies applicable to NOx have been the subject of many investigations. One of these systems is the NOx adsorber catalyst, which has shown high NOx conversion rates during previous investigations with acceptable fuel consumption penalties. In addition, the NOx adsorber catalyst does not require a secondary on-board reductant. However, the NOx adsorber catalyst also represents the most sulfur sensitive emissions control device currently under investigation for advanced NOx control. To remove the sulfur introduced into the system through the diesel fuel and stored on the catalyst sites during operation, specific regeneration strategies and boundary conditions were investigated and developed.

Urea-SCR system consisted of combined deNOx catalysts with wide range of temperature window, injector, sensor and injection controller. Synthetic gas activity test and NOx conversion efficiency test on the engine bench were carried out to evaluate and improve the performance of this system. To better suit the application of the urea-SCR system without engine modification, temperature of catalyst and engine RPM were used as input data to control amounts of urea aqueous solution that reacts with NOx. We concentrated on designing types of deNOx catalysts and controlling amounts of urea solution under different driving conditions to achieve higher NOx reduction and wider temperature window. Designed urea-SCR system showed substantial NOx reduction performance and relatively wide temperature window under different driving conditions.

One of the most attractive features of hybrid vehicles powered by SI-engines with three way catalysts is the potential of reaching extremely low emissions. In conventional drive trains, limitations in the air/fuel control result in lambda excursions during transients. These deviations from the ideal lambda result in increased emissions. In a hybrid vehicle, rapid load and speed changes of the SI-engine could be limited to an acceptable level as the battery acts as a power buffer. However, the efficiency of charging and discharging the battery is rather low, which means that excessive power buffering will increase the fuel consumption of the vehicle. Thus it is of great importance to know what degree of speed and load changes the air/fuel control system could cope with without an increase in emissions.

For years, secondary air injection Systems have been used to reduce hydrocarbon exhaust emissions for a short period after engine cold start. In the beginning, passive secondary air systems were used, with the airflow driven by the pressure pulsations in the exhaust system. Since 1990, for most applications, active secondary air systems (i. e., systems where air is injected into the hot exhaust gases by a pump) have been employed. Secondary air injection into the hot exhaust gases is realized by a d-c motor driven turbine pump, i. e. a secondary air pump, and a control valve. Numerous factors, including raw engine emissions during cold start and warm up, driveability requirements and the need to adapt to different emissions legislation, dictate the use of secondary air injection systems. The development of other exhaust aftertreatment systems, e. g., close-coupled or heated catalysts as well as packaging and cost factors will influence the market penetration of secondary air systems.

A breakthrough catalyst technology utilizing new mixed metal oxides in conjunction with Platinum Group Metals has been developed. Stable synergies are designed into the catalyst washcoat that enable high performance and durability to be achieved at low Platinum Group Metal usage. Extensive vehicle data is reported on catalysts aged using a variety of high-temperature accelerated aging cycles. Vehicle performance at the LEV, ULEV and LEV-II levels is discussed in the context of unique calibration-catalyst interactions. Conclusions concerning further areas of improvement and future applications are also reviewed.

The University of Texas 2000 Ethanol Vehicle Challenge team remains focused on cold start, cold drivability, fuel economy, and emissions reduction for our 2000 Ethanol Vehicle Challenge entry. We used the stock PCM for all control functions except control of an innovative cold-start system our team designed. The primary modifications for improved emissions control involved ceramic coating of the exhaust manifolds, use of close-coupled ethanol-specific catalysts, use of a moddified version of the California Emissions Calibrated PCM, and our cold-start system that eliminates the need to overfuel the engine at the beginning of the FTP. Additionally, we eliminated EGR at high load to improve power density. Major modifications, such as increasing the compression ratio or pressure boosting, were eliminated from consideration due to cost, complexity, reliability, or emissions penalties.

A two-stage combustion is one of the Mitsubishi GDI™ technologies for a quick catalyst warm-up on a cold-start. However, when the combustion is continued for a long time, an increase in the fuel consumption is a considerable problem. To solve the problem, a stratified slight-lean combustion is newly introduced for utilization of catalysis. The stratified mixture with slightly lean overall air-fuel ratio is prepared by the late stage injection during the compression stroke. By optimizing an interval between the injection and the spark timing, the combustion simultaneously supplies substantial CO and surplus O2 to a catalyst while avoiding the soot generation and the fouling of a spark plug. The CO oxidation on the catalyst is utilized to reduce the cold-start emissions. Immediately after the cold-start, the catalyst is preheated for the minimum time to start the CO oxidation by using the two-stage combustion. Following that, the stratified slight-lean combustion is performed.

Strict legislation standards for automotive emission limits (e.g. ULEV, SULEV), which target for HC conversion rates beyond 99 %, impose the necessity to dramatically shorten catalyst Light-Off time and increase catalytic efficiency through improved catalytic converter heat-up. Especially, in early design stages, modeling thermal energy management is crucial to predict wether emissions standards can be met. The CAE method (Computer Aided Engineering) presented in this study gives the flexibility composing the frontal exhaust system from modular numerical models, which describe heat transfer in single exhaust components, as e.g. takedown-pipes, flexible coupling element (FCE), flanges and conversion characteristics in catalytic converter. Each module upstream of the converter internally couples the energy equations of 1Dgas to 1D/2D-solid-structure, including heat transfer mechanism as radiation, natural and forced convection.

This paper follows on from a previous publication [1] and describes the continued development of a generic Integrated Powertrain (IPT) model. Simulation tools have been used for many years in engine and vehicle development programmes, to predict fuel consumption and emissions over various drive cycles. The concept phase of these programmes typically considers the overall layout and sizing of the components, with the detailed control strategies developed later. Today, the increased integration of vehicle sub-systems requires a high degree of overall control early in the programme, firstly, to allow the sub-systems to function, and secondly, to apply a similar quality of system control to each hardware iteration. To address this issue, a control hierarchy has been applied comprising of a supervisor controller and multiple local controllers.

This paper describes some recent advances of the research work concerning the 1D fluid dynamic modeling of unsteady reacting flows in s.i. engine pipe-systems, including pre-catalysts and main catalysts. The numerical model GASDYN developed in previous work has been further enhanced to enable the simulation of the catalyst. The main chemical reactions occurring in the wash-coat have been accounted in the model, considering the mass transfer between gas and solid phase. The oxidation of CO, C3H6, C3H8, H2 and reduction of NO, the steam-reforming reactions of C3H6, C3H8, the water-gas shift reaction of CO have been considered. Moreover, an oxygen-storage sub-model has been introduced, to account for the behavior of Cerium oxides. A detailed thermal model of the converter takes into account the heat released by the exothermic reactions as a source term in the heat transfer equations. The influence of the insulating mat is accounted.

The task of matching engine, control system and catalytic converter has become very complex as the automotive industry strives to meet stringent demands for pollution abatement. To address the need for a robust, accurate modeling tool we have created a microkinetics-based simulation program that describes the reactions taking place on the surface of a catalytic converter. This chemically detailed approach permits the construction of faithful simulations of both steady state and transient performance of the catalyst using a combination of experimental measurements, literature data and quantum chemical calculations. The model can be coupled to existing simulations of the engine and control elements, notably those based on GT-Power.

In order to match catalyst OBDII conditions the common procedure is oven aging with air, which is not suitable for complete converter systems due to mantle corrosion. The goal was, therefore, to find an alternative procedure to ensure a defined catalyst aging that would match 1,75 times the emission standard and is also good for SULEV. The new procedure currently being developed allows the aging of metal and ceramic catalysts as well as complete catalyst systems. The paper will present the aging process, emission data of fresh and aged catalysts and the feedback to the test car OBDII system.

An analytical model for estimating shear and bending stresses during canning of cordierite ceramic catalyst supports is presented. These stresses arise when the radial pressure distribution is nonuniform due, primarily, to variations in gap bulk density (GBD ) of intumescent mat around the perimeter of the substrate. Variations in GBD can occur during canning, regardless of the canning technique, due to anisotropic can stiffness or component tolerances or mat overlap. The model helps relate shear and bending stresses to substrate size and orientation, elastic modulii, cell size and wall porosity. If these stresses approach the corresponding strength of substrate, a shear crack may develop during or after the canning process depending on the magnitude of stress. A special test fixture was developed to measure the shear strength of ceramic catalyst supports, with different cell sizes, before and after the application of washcoat.

Mass transfer limitations from the bulk gas phase to the surface of the catalyst as well as mass transfer limitations within the washcoat itself have important effects on conversion in washcoated monolith catalysts. These factors depend upon the shape of the channel as well as the loading of washcoat material. This paper outlines a method to describe the washcoat distribution profile for different channel shapes and washcoat loadings. This allows for prediction of effectiveness factors and bulk mass transfer coefficients as a function of cell geometry and washcoat loading for the oxidation of propane. It was found that differences in the diffusion limitations within the washcoat control conversion in the catalyst more than differences in bulk mass transfer rates when comparing different cell shapes. The results show that optimum washcoat loadings exist for the geometry of each cell, and that these optimum loadings are a function of catalyst temperature.

The influence of physical parameters of the catalyst's substrate such as thermal mass, hydraulic diameter and geometric surface area on catalyst's efficiency is well known as published in numerous works. This paper will show interactions of these parameters and will provide a guideline on how to design the optimum system for a specific application, taking into account system's back pressure and system costs. Based on engine test bench results that show the influence of the physical parameters, the results for the optimized design regarding emission tests and maximum conversion rate at higher loads will be demonstrated.