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Advances in Catalyst Substrates, 2018

2018-04-03
Papers included in this collection cover the systems engineering experience required to achieve ultra-low emission levels on gasoline light-duty vehicles. Emission system component topics include the development of advanced three-way catalysts, the development of NOX control strategies for gasoline lean burn engines, the application of high cell density substrates to advanced emission systems, and the integration of these components into full vehicle emission systems.
Technical Paper

On the Influence of Manifold Geometry on Exhaust Noise

1999-05-17
1999-01-1650
The influence of manifold geometry on exhaust noise is studied. First, a linear description of the problem is presented, so that potential relevant factors may be identified. Then a full non-linear simulation is performed, for a simple geometry, in order to check, in more realistic conditions, the ideas obtained from the linear theory. The results indicate that, although some qualitative trends may be obtained from the linear analysis, the role of back-reaction of the manifold on the engine (a non-linear coupling effect) may be determinant.
Technical Paper

Effects of Load on Emissions and NOx Trap/Catalyst Efficiency for a Direct Injection Spark Ignition Engine

1999-05-03
1999-01-1528
A 1998 Toyota Corona passenger car with a direct injection spark ignition (DISI) engine was tested at constant engine speed (2000 rpm) over a range of loads. Engine-out and tailpipe emissions of gas phase species were measured each second. This allowed examination of the engine-out emissions for late and early injection. Regeneration of the lean NOx trap/catalyst was also examined, as was the efficiency of NOx reduction. NOx stored in the trap/catalyst is released at the leading edge of regenerations, such that the tailpipe NOx is higher than the engine-out NOx for a brief period. The efficiency of NOx reduction was <50% for the lowest loads examined. As the load increased, the efficiency of NOx reduction decreased to near 0% due to excessive catalyst temperatures. Loads sufficiently high to require a rich mixture produce high NOx reduction efficiencies, but in this case the NOx reduction occurs via the three-way catalysts on this vehicle.
Technical Paper

Interaction of Sulfur with Automotive Catalysts and the Impact on Vehicle Emissions-A Review

1999-05-03
1999-01-1543
The requirement to meet more stringent emission standards has focused attention on the effects of gasoline sulfur on automotive emissions. Numerous studies have shown that three-way catalyst performance is severely inhibited by sulfur. A literature review of laboratory studies on the interaction of sulfur with automotive catalyst components provides the basis for understanding impacts on catalyst activity under the variety of conditions encountered in vehicle operation. Under stoichiometric and rich conditions, SO2 formed during combustion is dissociatively adsorbed on platinum group metal surfaces to form strongly bound Sad. Sulfur inhibition results from both physical blockage and electronic effects of Sad, such that low coverage of Sad results in disproportionately higher levels of reaction site blockage. This is responsible for the nonlinear effects observed with increasing fuel sulfur level.
Technical Paper

Tailpipe Emissions Comparison Between Propane and Natural Gas Forklifts

2000-06-19
2000-01-1865
It is commonly stated that natural gas-fueled forklifts produce less emissions than propane-fueled forklifts. However, there is relatively little proof. This paper reports on a detailed comparative study at one plant in Edmonton, Canada where a fleet of forklift trucks is used for indoor material movement. (For convenience, the acronym NGV, ie. Natural Gas Vehicle is used to designate natural gas-fueled and LPG, ie. Liquified Petroleum Gas, is used to designate propane-fueled forklifts). Until recently the forklift trucks (of various ages) were LPG carburetted units with two-way catalytic converters. Prompted partially by worker health concerns, the forklifts were converted to fuel injected, closed-loop controlled NGV systems with three-way catalytic converters. The NGV-converted forklifts reduced emissions by 77% (NOX) and 76% (CO) when compared to just-tuned LPG forklifts.
Technical Paper

The Systematic Evaluation of Twelve LP Gas Fuels for Emissions and Fuel Consumption

2000-06-19
2000-01-1867
The effects on bi-fuel car exhaust emissions, fuel consumption and acceleration performance of a range of LPG fuels has been determined. The LPGs tested included those representing natural gas condensate and oil refineries' products to include a spectrum of C3:C4 and paraffiinic:olefinic mixtures. The overall conclusions are that exhaust emissions from the gaseous fuels for the three-way catalyst equipped cars tested were lower than for gasoline. For all the LPGs, CO2 equivalent emissions are reduced by 7% to 10% or more compared with gasoline. The cars' acceleration performance indicates that there was no sacrifice in acceleration times to various speeds, with any gaseous fuel in these OEM developed cars.
Technical Paper

Ultra Low Emissions and High Performance Diesel Combustion with a Combination of High EGR, Three-Way Catalyst, and a Highly Oxygenated Fuel, Dimethoxy Methane (DMM)

2000-06-19
2000-01-1819
Ultra low emissions and high performance combustion was achieved with a combination of high EGR, a three-way catalyst, and a highly oxygenated liquid fuel, neat dimethoxy methane (DMM), in an ordinary DI diesel engine. The smokeless nature of neat DMM effectively allowed stoichiometric diesel combustion by controlling BMEP with EGR. NOx, THC, and CO emissions were reduced with a three-way catalyst. At lower BMEP with excess air, the EGR effectively reduced NOx. High-speed video in a bottom view type engine revealed that luminous flame decreased with increased fuel oxygen content and almost disappeared with DMM.
Technical Paper

Stratified Scavenging Applied to a Small Capacity Two-Stroke Scooter for the Reduction of Fuel Consumption and Emissions

1999-09-28
1999-01-3271
The advantages of high power to density ratio and low manufacturing costs of a two-stroke engine compared to a four-stroke unit make it currently the most widely used engine type for 50cc displacement 2-wheelers. This dominance is threatened by increasingly severe exhaust emissions legislation, forcing manufactures to develop their two-stroke engines to comply with the legislation. This paper describes a simple solution to reduce these harmful emissions in a cost effective manner, for a scooter application. The method of stratified scavenging is achieved by delivering the fuel into the rear transfer passage from a remote mechanical fuel metering device, operated by intake manifold pressure. Air only is delivered into the cylinder from the remaining transfer passages which are directed towards the rear transfer port, thus impeding the fuel from reaching the exhaust during the scavenging process.
Technical Paper

Three-Way Catalyst Technology for Off-Road Equipment Engines

1999-09-28
1999-01-3283
A project was conducted by Southwest Research Institute on behalf of the California Air Resources Board and the South Coast Air Quality Management District to demonstrate the technical feasibility of utilizing closed-loop three-way catalyst technology in off-road equipment applications. Five representative engines were selected, and baseline emission-tested using both gasoline and LPG. Emission reduction systems, employing three-way catalyst technology with electronic fuel control, were designed and installed on two of the engines. The engines were then installed in a fork lift and a pump system, and limited durability testing was performed. Results showed that low emission levels, easily meeting CARB's newly adopted large spark-ignited engine emission standards, could be achieved.
Technical Paper

Influence of Mixture Preparation on Combustion and Emissions Inside an SI Engine by Means of Visualization, PIV and IR Thermography During Cold Operating Conditions

1999-10-25
1999-01-3644
The focus of this work was to determine the influence of spray targeting on temperature distributions, combustion progress and unburned hydrocarbon (HC) emissions at cold operating conditions, and to show the capability of model and full engine tests adapted for different measurement techniques. A comprehensive study applying endoscopic visualization, infrared thermography, combustion and emission measurements was carried out in a 4-stroke 4-cylinder 16-valve production engine with intake port injection during different engine operating conditions including injection angle and timing. In addition 2D visualization and PIV measurements were performed in a back-to-back model test section with good optical access to the intake manifold and the combustion chamber. The measurements in both set ups were in good agreement and show that model tests could lead to useful findings for a real engine.
Technical Paper

Advanced Platinum-Rhodium Exhaust Catalysts - An Economic Alternative To Palladium-Rhodium

2000-01-15
2000-01-1418
Three-way catalysts based on the use of palladium have proved highly effective at meeting the most stringent emissions legislation around the world. This has led to a rapid increase in the amount of palladium used in autocatalyst applications which has contributed to an increase in the palladium price. This has prompted a renewed interest in the use of platinum in advanced three-way catalyst (TWC) formulations. This paper compares the performance of advanced platinum-rhodium and palladium-rhodium technology on an engine test-bed. This showed the new platinum-rhodium catalyst to have equal or better performance at similar precious metal cost. Tests on selected vehicles confirmed future emissions standards can be achieved using the platinum-based catalysts.
Technical Paper

A Study on the Effects of Sulfur in Gasoline on Exhaust Emissions

2000-06-19
2000-01-1878
Exhaust emissions of nitrogen oxide (NOx), total hydrocarbons (THC) and carbon mono-oxide (CO) in terms of sulfur concentration were mainly investigated according to the Japanese 10.15 mode driving schedule. Tested vehicles had direct injection engines with nitrogen oxide (NOx) selective reduction catalyst or NOx storage reduction catalyst as well as stoichiometric combustion engines with three-way catalyst. Direct continuous measurement of NOx, THC and CO was also conducted. Exhaust Emissions were measured using He injection and mass spectrometry. The air fuel ratio (AFR) and driving conditions that would promote sulfur removal were found to be important factors in reducing NOx further, for recent gasoline-fueled vehicles with emerging technologies using low sulfur fuels under 100 ppm.
Technical Paper

The Effects of Driveability on Emissions in European Gasoline Vehicles

2000-06-19
2000-01-1884
Fuel volatility and vehicle characteristics have long been recognised as important parameters influencing the exhaust emissions and the driveability of gasoline vehicles. Limits on volatility are specified in a number of world-wide / national fuel specifications and, in addition, many Oil Companies monitor driveability performance to ensure customer satisfaction. However, the relationship between driveability and exhaust emissions is relatively little explored. A study was carried out to simultaneously measure driveability and exhaust emissions in a fleet of 10 European gasoline vehicles. The vehicles were all equipped with three-way catalysts and single or multi-point fuel injection. The test procedure and driving cycle used were based on the European Cold Weather Driveability test method.
Technical Paper

Optimization of Natural Gas Combustion in Spark-Ignited Engines Through Manipulation of Intake-Flow Configuration

2000-06-19
2000-01-1948
An investigation was performed to try to quantify the relative importance of large-scale mixing and turbulence in a multi-valve spark-ignited automotive engine converted to use natural gas fuel. The role of mixing was examined by comparing single-point versus multi-point combustion performance at several operating conditions. The fuel-air mixture passed through a static mixer prior to entering the intake manifold in the single point case. This configuration was assumed to produce a well-mixed charge entering the combustion chamber. The fuel was delivered just upstream of the intake port in the multi-point configuration. The charge was assumed to be stratified in this case. The results showed a significant degradation in combustion stability and maximum power but little difference in ignition delay and fully-developed burn duration using multi-point injection. The relative role of turbulence was examined by altering the intake-flow configuration to create three levels of inlet swirl.
Technical Paper

The Effect of Aging Temperature on Catalyst Performance of Pt/Rh and Pd/Rh TWCs

2000-06-19
2000-01-1954
With the ever-increasing stringency of emissions regulations, automotive three-way catalysts (TWCs) require much faster light-off performance and higher warmed-up activity than before. Most automotive manufacturers are considering the adoption of close-coupled catalyst systems as a means of dealing with cold start emissions and need the catalyst to have improved thermal durability. In this paper, a new Pd/Rh is reported to be suitable for high temperature application. Due to the recent increasing Pd metal cost, a Pt/Rh with equivalent or better TWC performance needs be developed to balance the PGM usage. A current Pt/Rh catalyst seems to possess comparable TWC performance to the new Pd/Rh catalyst when the catalysts are aged at 900°C. However, aging at a temperature higher than 900°C significantly deactivated the activity of the Pt/Rh catalyst to a point that is much worse than the Pd/Rh catalyst.
Technical Paper

The Impacts of Engine Operating Conditions and Fuel Compositions on the Formation of Combustion Chamber Deposits

2000-06-19
2000-01-2025
This study is a continuing effort toward the goal of understanding deposit formation process in a combustion chamber by probing the impacts of engine operating conditions and fuel compositions on the formation of combustion chamber deposits. To facilitate the study, four retrievable deposit sampling probes were used. The engine operating parameters investigated include coolant temperature, spark advance, manifold air pressure (engine load), and fuel-air ratio. As a continuum of previous studies, toluene was used as the base fuel. In addition, CCD-forming tendencies of isooctane and other aromatics with higher boiling points were investigated. Coolant temperature, fuel-air ratio, and boiling point of the fuel have significant impacts on both the amount and the morphology of deposits formed in a combustion chamber. In contrast, spark advance has little impact on either deposit weight or deposit morphology. Manifold pressure has an intermediate impact on CCD.
Technical Paper

A Stochastic Model of the Fuel Injection of the SI Engine

2000-03-06
2000-01-1088
The paper is devoted to the issues of the non-stationary, stochastic analysis of the fuel injection. The aim of the experiment was to obtain data about SI engine operating parameters during operation. The object randomness in sequentially injected combustion engines are investigated. A numerical procedure is designed for the intake manifold mixture preparation to compensate the mixture variations. There are some direct consequences of inherent non-linearities in the basic dynamics of mixture preparation. Compensating for the mixture dynamics (fuel path, air path consisting of intake manifold and wall-wetting dynamics and the oxygen sensor dynamics) performs well only if the statistical properties of the stochastic processes are sufficiently matched. Since this a priori knowledge is hardly accessible in the present case, the authors implemented an experimental procedure.
Technical Paper

Comprehensive Charge-cooler Model for Simulating Gas Dynamics in Engine Manifolds

2000-03-06
2000-01-1264
Charge-coolers have a significant effect on the performance of turbocharged internal combustion engines. For a comprehensive simulation of internal combustion engines fitted with such devices it is important to model the whole of the manifold system. A wave-action model of a charge-cooler boundary is proposed, together with a methodology for predicting the heat transfer coefficient of the device. This approach enables the instantaneous effectiveness of the charge-cooler to be predicted as a function of the mass flow rate through the device.
Technical Paper

On the Validity of Mean Value Engine Models During Transient Operation

2000-03-06
2000-01-1261
Because there are no production-type sensors which are able to measure the flow directly at the intake port, it is becoming common practice to use models of varying complexity to infer the port air mass flow from other measurements. Given the tight requirements of modern air/fuel ratio (AFR) control strategies, the accuracy of these models needs to be better than ever, during steady-state of course (though λ feedback strategies are by design very robust), but mainly during transient operation. This paper describes why conventional models might be inaccurate during engine transients.
Technical Paper

A Nonlinear Wall-Wetting Model for the Complete Operating Region of a Sequential Fuel Injected SI Engine

2000-03-06
2000-01-1260
The wall-wetting dynamics represent a very important subsystem of the air/fuel path of an SI engine. The precise feedforward control of the air/fuel ratio requires a valid model of the wall-wetting dynamics over the whole operating region of the engine. A global wall-wetting model has been developed for a production SPFI gasoline engine. This model is capable of describing the wall-wetting dynamics not only in a fixed operating point, but also for radical changes of the operating point. Its structure specifically allows for model-based compensator design and on-line parameter identification. Earlier, related publications discussed linear model structures. Those models described the dynamics around a fixed operating point only. This paper shows how one global model for the whole operating range can be constructed from a linear model and its parameter range.
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