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Technical Paper

“Trapless” Trap – A Catalytic Combustion System of Diesel Particulates Using Ceramic Foam

“Trapless” Trap, which makes possible the effective collecting of particulates in diesel exhaust gas and their simultaneous combustion has been developed by use of a ceramic foam in combination with catalysts containing copper salt. From a TEM photograph, it was observed that the particulate was rapidly oxidized by mobile copper ion, showing worm-eaten like spots. Screening of various base metal salts by TGA presented CUCl2-KCl-NH4VO3 and CuCl2-KCl-(NH4)6Mo7O24 as very active catalysts for diesel particulate oxidation. They had thermal stability up to 900°C when they were supported on titania. The results obtained by measuring the back pressure using 1.8L diesel engine suggest the above trap to be a self-cleaning trapless trap.
Technical Paper

“OPERAS” In Advanced Diesel Engines for Commercial and Military Applications

Advanced diesel engines developed for the commercial market need to be adapted to the military requirements by OPERAS (Optimizing the injection pressure P, the Exhaust gas recirculation E, injection events Retard and/or Advance and the swirl ratio S). The different after treatment devices, already used or expected to be applied to diesel engines, require feed gases of appropriate properties for their efficient operation. To produce these gases some OPERAS are needed to control the diesel combustion process. Since military vehicles do not need the after treatment devices, the OPERAS of the commercial engines should be modified to meet the military requirements for high power density, better fuel economy, reduction of parasitic losses caused by the cooled EGR system, and reduction of invisible black and white smoke in the field.
Technical Paper

“KATPROG” for the Determination of an Optimal Cost Effective Catalyst System

An two-dimensional axial symmetrical finite volume model will be introduced for the calculation of catalytic converters. It is able to predict transient temperatures and conversion rates in different converter systems according to the driving conditions. Input data are the mass-flow rate, the converter inlet temperature and the raw emissions. The performance of this model is demonstrated on an Indian motorcycle application. Cold start behavior and peak temperatures are investigated. This model has proven to be an effective tool for the preselection of an optimal cost effective catalyst system.
Technical Paper

“Investigation of High Achievable Pollutant Reduction on a “State of the Art” Indian 2 Wheelers - Technology Road Map to a Cleaner Air”

Affordable, efficient and durable catalytic converters for the two and three wheeler industry in developing countries are required to reduce vehicle emissions and to participate in a cleaner and healthier environment. As a contribution Continental Emitec started a comprehensive testing program with a state of the art 180 cc Bharat Stage (BS) III Indian motorcycle. The program consists of testing the state of the art of Metallic substrates with structured foils with various catalyst sizes and positions (original or close coupled). The publication presents a short literature survey and the results of the investigation with a big catalyst volume mounted in underfloor position as well as in close coupled position, gained over the World-wide harmonized Motorcycle Test Cycle, considering the two possible vehicle classifications of this motorcycle, Sub-Class 2.1 and Sub-Class 2.2.
Technical Paper

“Doing More with Less” - The Fuel Economy Benefits of Cooled EGR on a Direct Injected Spark Ignited Boosted Engine

Due to the rising costs of fuel and increasingly stringent regulations, auto makers are in need of technology to enable more fuel-efficient powertrain technologies to be introduced to the marketplace. Such powertrains must not sacrifice performance, safety or driver comfort. Today's engine and powertrain manufacturers must, therefore, do more with less by achieving acceptable vehicle performance while reducing fuel consumption. One effective method to achieve this is the extreme downsizing of current direct injection spark ignited (DISI) engines through the use of high levels of boosting and cooled exhaust gas recirculation (EGR). Key challenges to highly downsized gasoline engines are retarded combustion to prevent engine knocking and the necessity to operate at air/fuel ratios that are significantly richer than the stoichiometric ratio.
Technical Paper

“Catalytic Engine” NOx Reduction of Diesel Engines with New Concept Onboard Ammonia Synthesis System

Ammonia is one of the most useful compounds that react with NOx selectively on a catalyst, such as V2O5-TiO2, under oxygen containing exhaust gas. However ammonia cannot be stored because of its toxicity for the small power generator in populated areas or for the diesel vehicles. A new concept for NOx reduction in diesel engine using ammonia is introduced. This system is constructed from the hydrogen generator by fuel reformer, the ammonia synthesizer, SCR catalyst for NOx reduction and the gas injection system of reformed gas into the cylinder. Experimental results show that, the SCR catalyst provides a very high rate of NOx reduction, reformed gas injection into cylinder is very effective for particulate reduction. WHEN CONSIDERING INTERNAL COMBUSTION ENGINES of the 1990's the question of how to harmonize the engine with the natural environments is one of the greatest problems. The internal combustion engine changes a substance into energy via its explosive combustion.
Journal Article

xD+1D Catalyst Simulation-A Numerical Study on the Impact of Pore Diffusion

This paper presents a numerical study on the impact of washcoat diffusion on the overall conversion performance of catalytic converters. A comprehensive transient 1D pore diffusion reaction model is embedded in state-of-the-art 1D and 3D catalytic converter models. The pore diffusion model is discussed with its model equations and the applied diffusive transport approaches are summarized. The diffusion reaction model is validated with the help of two available analytical solutions. The impact of basic washcoat characteristics such as pore diameters or thickness on overall conversion performance is investigated by selected 1D+1D calculations. This model is also used to highlight the impact of boundary layer transfer, pore diffusion and reaction on the overall converter conversion performance. The interaction of pore diffusion and flow non-uniformities is demonstrated by 3D+1D CFD simulations.
Technical Paper

and Repeatability of Transient Heat Release Analysis for Heavy Duty Diesel Engines

Reduced emissions, improved fuel economy, and improved performance are a priority for manufacturers of internal combustion engines. However, these three goals are normally interrelated and difficult to optimize simultaneously. Studying the experimental heat release provides a useful tool for combustion optimization. Heavy-duty diesel engines are inherently transient, even during steady state operation engine controls can vary due to exhaust gas recirculation (EGR) or aftertreatment requirements. This paper examines the heat release and the derived combustion characteristics during steady state and transient operation for a 1992 DDC series 60 engine and a 2004 Cummins ISM 370 engine. In-cylinder pressure was collected during repeat steady state SET and the heavy-duty transient FTP test cycles.
Technical Paper

Zone Length Optimization to Improve PGM Utility

“Zoning” a catalytic converter involves placing higher concentrations of platinum group metals (PGM) in the inlet portion of the substrate. This is done to optimize the cost-to-performance tradeoff by increasing the reaction rate at lower temperatures while minimizing PGM usage. A potentially useful application of catalyst zoning is to improve performance using a constant PGM mass. A study was performed to assess what the optimum ratio of front to rear palladium zone length is to achieve the highest performance in vehicle emission testing. Varying the zone ratio from 1:1 to 1:9 shows a clear hydrocarbon performance optimum at a 1:5.66 (15%/85%) split. This performance optimum shows as both a minimum in FTP75 non-methane organic gas (NMOG) emissions as well as a minimum in hydrocarbon, carbon monoxide, and nitrogen oxide light-off temperature. Overall, an improvement of 18%, or 11 mg/mi of combined NMOG+NOx emissions was obtained without using additional PGM.
Journal Article

Zero-Dimensional Modeling of Combustion and Heat Release Rate in DI Diesel Engines

Zero-dimensional heat release rate models have the advantage of being both easy to handle and computationally efficient. In addition, they are capable of predicting the effects of important engine parameters on the combustion process. In this study, a zero-dimensional combustion model based on physical and chemical sub-models for local processes like injection, spray formation, ignition and combustion is presented. In terms of injection simulation, the presented model accounts for a phenomenological nozzle flow model considering the nozzle passage inlet configuration and an approach for modeling the characteristics of the Diesel spray and consequently the mixing process. A formulation for modeling the effects of intake swirl flow pattern, squish flow and injection characteristics on the in-cylinder turbulent kinetic energy is presented and compared with the CFD simulation results.
Technical Paper

Zero-Delay Light-Off - A New Cold-Start Concept with a Latent Heat Storage Integrated into a Catalyst Substrate

This study aims at a new concept for a fast catalyst light-off in combining a latent heat storage with a catalyst. The arrangement of a latent heat storage device into the exhaust system offers significant benefits for the catalyst light-off. Different arrangements have been examined. The first arrangement, called the sequential arrangement, comprises a latent heat storage device and a subsequent catalyst. This offers a significantly faster heat up of the catalyst compared to the standard arrangement. By that emissions during the cold start phase can be significantly reduced. The setup of the latent heat storage device is designed for a high heat transfer between storage material and the exhaust gas. A second integrated arrangement of a latent heat storage and a catalyst into one common substrate has also been set up and investigated. The main advantage of this arrangement is that the catalyst itself is kept on its operation temperature during the engine off time.
Technical Paper

Zero Dimensional Models for EGR Mass-Rate and EGR Unbalance Estimation in Diesel Engines

A precise estimation of the recirculated exhaust gas rate and oxygen concentration as well as a predictive evaluation of the possible EGR unbalance among cylinders are of paramount importance, especially if non-conventional combustion modes, which require high EGR flow-rates, are implemented. In the present paper, starting from the equation related to convergent nozzles, the EGR mass flow-rate is modeled considering the pressure and the temperature upstream of the EGR control valve, as well as the pressure downstream of it. The restricted flow-area at the valve-seat passage and the discharge coefficient are carefully assessed as functions of the valve lift. Other models were fitted using parameters describing the engine working conditions as inputs, following a semi-physical and a purely statistical approach. The resulting models are then applied to estimate EGR rates to both conventional and non-conventional combustion conditions.
Journal Article

X-Ray Radiography Measurements of the Thermal Energy in Spark Ignition Plasma at Variable Ambient Conditions

The sparking behavior in an internal combustion engine affects the fuel efficiency, engine-out emissions, and general drivability of a vehicle. As emissions regulations become progressively stringent, combustion strategies, including exhaust gas recirculation (EGR), lean-burn, and turbocharging are receiving increasing attention as models of higher efficiency advanced combustion engines with reduced emissions levels. Because these new strategies affect the working environment of the spark plug, ongoing research strives to understand the influence of external factors on the spark ignition process. Due to the short time and length scales involved and the harsh environment, experimental quantification of the deposited energy from the sparking event is difficult to obtain. In this paper, we present the results of x-ray radiography measurements of spark ignition plasma generated by a conventional spark plug.
Technical Paper

Worldwide Trends in Heavy-Duty Diesel Engine Exhaust Emission Legislation and Compliance Technologies

This paper reviews the trend in worldwide exhaust emission regulations for heavy-duty diesel engines and common key technologies that must be developed and applied in order to meet these regulations. The common key technologies are intake and exhaust system with turbocharger and intercooler, electronically controlled high-pressure fuel injection system, exhaust gas recirculation, and exhaust gas after-treatment devices. This paper also introduces test results of common key technologies, concepts for low-emission heavy-duty diesel engines, and the possibilities for meeting future exhaust emission legislation is described.
Technical Paper

Wire Mesh Mixer Optimization for DEF Deposit Prevention

Diesel engine NOx emissions requirements have become increasingly stringent over the past two decades. Engine manufacturers have shown through the use of EGR and SCR technology that these requirements can be met. However, the desires for improved fuel efficiency, lower overall cost, and potential legislation to reduce NOx levels further increase the demand for higher DEF dosing rates. To meet this demand, a new DEF mixing technology has been developed. This paper describes the development methods used to create a compact, in-pipe mixer which utilizes an optimized wire mesh along with swirling flow to permit high DEF dosing rates without deposit formation. Its excellent mixing characteristics allowed for high NOx reduction to be achieved. Utilization of this technology makes it possible to reduce regeneration frequency, reduce the overall size of the SCR system, possibly eliminate the EGR system, and improve fuel efficiency through combustion enhancements.
Technical Paper

Wide Band Oxygen Sensor Electronic Control Unit (LambdaTronic)

As emission regulations continue to become more stringent, new design approaches need to be considered as implementation solutions. Wide band, or linear, oxygen sensors provide emission control benefits that can help meet these requirements. Due to the complexity of these oxygen sensors, a control ASIC is required. However, integrating a control ASIC into an existing electronic control unit (ECU) design can be problematic. The Bosch Wide Band Oxygen Sensor ECU (LambdaTronic) is a design proposal that provides a stand-alone solution to this issue. It is an ECU that provides oxygen sensor (LSU) control and diagnostics and communicates the information to the vehicle engine ECU via a standard automotive bus. LambdaTronic is currently being designed and developed for production release in the automotive market. When LambdaTronic is combined with one or more wide band LSU sensors, the system can be considered a “smart” oxygen sensor.
Technical Paper

Why Some Passenger Car Motor Oils Are No Longer Suitable for Motorcycles: Gear Pitting Issues

The new American Petroleum Institute (API) categories for passenger car motor oils have focused on improving fuel economy and reducing emissions. This has resulted in more fuel efficient oils being developed by lowering the viscometrics and by adding friction modifiers. The emissions reductions have resulted from lowering the percent phosphorus (%P) in the engine oils because phosphorus has been found to poison the catalyst in the catalytic converter. When friction modifiers were introduced, researchers from four Japanese motorcycle manufacturers published the results of their studies (SAE 961217) which indicated that low friction oil can cause too much slippage in starter motor clutches, one-way limited slip clutches, and wet multi-plate clutches. In that same study they reported that engine manufacturers use 10W-30 grade oil to develop new engine technology, and gear pitting was observed with oils of viscosity grades lower than 10W-30 in all four manufacturers' motorcycle engines.
Journal Article

Why Cu- and Fe-Zeolite SCR Catalysts Behave Differently At Low Temperatures

Cu- and Fe-zeolite SCR catalysts emerged in recent years as the primary candidates for meeting the increasingly stringent lean exhaust emission regulations, due to their outstanding activity and durability characteristics. It is commonly known that Cu-zeolite catalysts possess superior activity to Fe-zeolites, in particular at low temperatures and sub-optimal NO₂/NOx ratios. In this work, we elucidate some underlying mechanistic differences between these two classes of catalysts, first based on their NO oxidation abilities, and then based on the relative properties of the two types of exchanged metal sites. Finally, by using the ammonia coverage-dependent NOx performance, we illustrate that state-of-the-art Fe-zeolites can perform better under certain transient conditions than in steady-state.
Technical Paper

White Smoke Emissions Under Cold Starting of Diesel Engines

More stringent regulations have been enforced over the past few years on diesel exhaust emissions. White smoke emission, a characteristic of diesel engines during cold starting, needs to be controlled in order to meet these regulations. This study investigates the sources and constituents of white smoke. The effects of fuel properties, design and operating parameters on the formation and emissions of white smoke are discussed. A new technique is developed to measure the real time gaseous hydrocarbons (HC) as well as the solid and liquid particulates. Experiments were conducted on a single cylinder direct injection diesel engine in a cold room. The gaseous HC emissions are measured using a high frequency response flame ionization detector. The liquid and solid particulates are collected on a paper filter placed upstream of the sampling line of the FID and their masses are determined.
Technical Paper

Where Are All Those Gadgets Going?

With the passage of the federal Clean Air Act, the automotive industry has a clear assignment to reduce automobile emissions drastically by 1975. The control devices presently available have already reduced hydrocarbons 83%, carbon monoxide 70%, and nitrogen oxides 33%. By 1975, these figures must be 98%, 97%, and 90%, respectively. This paper discusses the devices that have been developed to accomplish the reductions to date, and concludes that in the future the crankcase controls will require little change, that the evaporative controls will require some additional improvement but will not change substantially, and that engine modifications do not have much chance of meeting the 1975 standards without a great deal of supplementation. The author feels two methods are available which may be able to reach the 1975 standards: use of manifold reactors and use of catalysts. However, both present problems of materials and thermodynamics, due to high exhaust temperatures.