Browse Topic: Catalytic converters

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Optimization of Catalytic Converter Design to Improve Under-Hood Thermal Management2019-01-12634/2/2019
The Catalytic Converter along with the inlet pipe and heat shields are part of the exhaust system that emits powerful heat to the surrounding components. With increasing need for tight under-hood spaces it is very critical to manage the heat emitted by the exhausts that may significantly increase temperature of surrounding components. In this paper a design methodology for catalytic converter has been applied which optimizes the design of the catalytic converter to reduce the surface temperature. The exhaust surface temperature is simulated as a function of time to account for transient effects. The simulation also considers various duty cycles such as road load, city traffic and grade driving conditions. To control the heat output of the exhaust system to the surrounding components different materials and properties of catalytic converter have been considered to reduce radiative heat transfer. The most influential design factors for the catalytic converter which affect the surface temperature of the exhaust system have been identified with this process. The paper summarizes the optimization steps necessary to meet the optimal functional goals for the vehicle as mentioned above. Taguchi's Design for Six Sigma (DFSS) methods have been employed to conduct this analysis in a robust way.
El-Sharkawy, Alaa, Arora, Dipan, Huxford, Michael W.
Water Injection Benefits in a 3-Cylinder Downsized SI-Engine2019-01-00341/15/2019
With progressing electrification of automotive powertrains and demands to meet increasingly stringent emission regulations, a combination of an electric motor and downsized turbocharged spark-ignited engine has been recognized as a viable solution. The SI engine must be optimized, and preferentially downsized, to reduce tailpipe CO2 and other emissions. However, drives to increase BMEP (Brake Mean Effective Pressure) and compression ratio/thermal efficiency increase propensities of knocking (auto-ignition of residual unburnt charge before the propagating flame reaches it) in downsized engines. Currently, knock is mitigated by retarding the ignition timing, but this has several limitations. Another option identified in the last decade (following trials of similar technology in aircraft combustion engines) is water injection, which suppresses knocking largely by reducing local in-cylinder mixture temperatures due to its latent heat of vaporization. Addition of adequate water can lead to stoichiometric air/fuel ratio engine operation, and hence both reduction in fuel consumption and full utilization of a three-way catalytic converter (TWC). Further information about effects of various water injection parameters is required. Thus, in this study, a 4-stroke, 1.5 liter, 3-cylinder turbocharged engine with direct fuel injection and port water injection was operated on 91, 95 and 98 RON gasoline fuel to assess effects of water injection on knock mitigation, combustion phasing, required air:fuel ratios and exhaust gas temperature control. Full- and part-load curves obtained with different fuels and water injection strategies are presented and discussed.
Khatri, Jayesh, Denbratt, Ingemar, Dahlander, Petter, Koopmans, Lucien
Technologies to Achieve Future Emission Legislations with Two Stroke Motorcycles2018-32-004210/30/2018
Increasingly stringent emission regulations force manufacturers of two wheelers to develop low emission motorcycle concepts. Especially for small two-stroke engines with symmetrical port timing structure, causing high HC-emissions due to scavenge losses, this is a challenging demand that can only be met with alternative mixture formation strategies and by intensifying the use of modern development tools. Changing from EU4 to EU5, emission legislation will not only have an impact on the improvement of internal combustion but will also drastically change the after-treatment system. Nowadays, small two-stroke engines make use of a simple carburetor for external mixture preparation. The cylinders are scavenged by air/fuel mixtures. Equipped with exhaust gas after-treatment systems, such as secondary air with two or three catalytic converters, the emission limits for EURO 4 homologation can be achieved with carbureted engines. An increased number of catalytic converters in the exhaust system reduces the performance of a carbureted two stroke engine and has therewith no advantage in comparison to a four stroke engine. Electronically controlled direct injection systems with low pressure (SETC 2008-32-0059), reducing the untreated emissions by minimizing the typical scavenge losses can also be found in this market segment. Approaches to reduce the exhaust emissions with high pressure direct injection systems have been investigated in 50cm3 two-stroke applications, but they are not present as mass products on the market yet. Due to the advantage of a direct injection system, a simple oxidation catalyst, the same as in EURO 2 engines, can fulfill the EURO 4 emission standard without any performance losses. But only focusing on injection technology, it is not possible to achieve the next legislation step with two stroke engines. There are two main characteristic limits. First, a drastic reduction of cold start HC emission is necessary and second, a lambda = 1 application is forced to fulfill the EU5 emission limit in terms of NOx. A novel approach to achieve low emissions in this engine category is the main subject of this publication. By analyzing different strategies and technologies done with two stroke vehicles on the roller dynamometer, an estimation in terms of performance, exhaust emissions and costs will show a possible way to reach EU 5 emission stage. As the biggest disadvantage of two stroke engines is still the high level of scavenge losses, especially at cold start, the time of the respective effect of the different solutions is of great importance. Additionally, a combination of solutions for a 50cc Scooter shows the potential to fulfill the future emission targets.
Oswald, Roland, Kirchberger, Roland, Krimplstatter, Stefan
Emission Reduction during Cold Start by Combustion Controlled Increase of In-Cylinder Temperatures2018-01-17409/10/2018
A significant share of the emissions of a vehicle with internal combustion engine originates from the cold start. In addition to the more stringent limits for particulate emissions due the introduction of the Euro 6c standard for gasoline engines with direct injection (GDI), exhaust gas emission testing is currently performed applying the real driving emission test procedure (RDE) required by the Euro 6d TEMP standard. The RDE test procedure is not clearly defined, potentially allowing high loads immediately after the engine start. Under such circumstances the combustion chamber features low surface temperatures impairing emission performance and in particular provoking the excessive generation of hydrocarbon and particulate emissions. It is therefore important not only to examine the heating of the catalytic converter during the cold start, but also the preconditioning of the combustion chamber itself. This paper describes the influence of different catalytic converter heating strategies on the emissions during heating operation, as well as during the subsequent load demand. Furthermore, the influence of the engine temperature at engine start is investigated. In addition to a stoichiometric and a lean heating operation strategy another combustion process strategy is presented. The novel strategy provides heating of the combustion chamber, without decreasing the catalyst converter heating significantly. The studies were carried out on a 2.0 liter gasoline engine with direct injection (SIDI) on an engine test bench. Both gaseous emissions and particulate emissions were monitored. Furthermore, the origins of particulate emissions were examined in more detail by means of high-speed camera recordings of the soot radiation inside the combustion chamber. To assess the flame propagation, high-speed camera footage was combined with the signals from a fiber optical sparkplug (FOSP).
Titus, Fabian, Berlet, Peter, Sobek, Florian, Wessling, Justus
Thermo-Mechanical Fatigue Testing of Welded Tubes for Exhaust Applications2018-01-00904/3/2018
Selected ferritic stainless steel sheets for exhaust applications were tested under thermo-mechanical fatigue (TMF) condition in the temperature range of 400-800 °C with partial constraint. Straight welded tubes were used as the testing coupons to withstand large compression without buckling, and to understand the effect of welding as well. Repeated tests confirmed the observed failure scenario for each material type. The hysteresis loop behaviors were also simulated using the mechanism-based integrated creep and fatigue theory (ICFT) model. Although more development work is needed, for quick material screening purpose this type of testing could be a very cost effective solution for materials and tube weld development for exhaust applications.
Quan, Guangchun, Wu, Xijia, Lafleur, Luc, zhang, Zhong
High-Performance Rear- and Mid-Engine Vehicle Exhaust System Temperatures2018-01-14364/3/2018
Hot surface ignition of combustible material is a known cause of vehicle fires. Although the detailed mechanisms of hot surface ignition are highly complex, the surface temperature is known to play a crucial role in this process. There has been limited previous work in the literature on this topic, much of which has focused on engine or exhaust system surface temperatures of the most common types of passenger vehicles. Also, much of this work was done in an unrepeatable manner and suffered from measurement technique induced errors. The focus of the present work is on repeatable and low measurement technique induced error temperature measurements of exhaust system surface temperatures of rear- and mid-engine sports cars. Temperature measurements were made at several points along the exhaust systems of vehicles both with and without turbo chargers on a 5-mile oval track. The exhaust system surface temperatures were examined under conditions of transient acceleration and steady-state driving for vehicle speeds of up to 125 mph (201 km/h). Finally, the effect of engine rotation speed for a constant vehicle speed on exhaust surface temperature was examined. It was found that the exhaust temperatures of rear- and mid-engine sports cars have maximum surface temperatures that are within the range of temperatures reported in literature for passenger vehicles in the range of speeds for which comparison data exists. It was also found that increased engine rotation speed for a constant vehicle speed results in increased surface temperatures for all measured locations.
Papageorge, Michael, Colwell, Jeff
FEA-Based Simulation of Exhaust Hanger Forces2018-01-12884/3/2018
Exhaust systems can be a source of vibrations that transmit inside the vehicle through the exhaust hangers. These vibrations are caused by engine excitations under acceleration. During the upfront development stage, it is important to predict accurately the forces of the exhaust hangers in order to drive a robust exhaust system design and prevent objectionable noise and vibrations inside the vehicle. This paper describes an FEA-based simulation method to predict the exhaust hanger forces. It demonstrates the effect of temperature on the exhaust dynamic behavior and its importance for an accurate prediction of the exhaust hanger forces.
Xu, Zefang, Gummadi, Nagesh, Woytowich, Daniel, Zouani, Abdelkrim
Modelling the Variation in Precious Metal Dispersion in a Three Way Catalytic Converter after Aging2018-01-09594/3/2018
With emission legislations becoming ever more stringent, there is an increased pressure on after-treatment systems and more specifically three-way catalysts. With recent developments in emission legislations, there is a requirement for more complex after-treatment systems and understanding of the aging process. Whilst the body of understanding on catalyst deactivation and, in particular, catalyst aging is growing, there are still significant gaps in understanding, particularly how real world variations in temperature, flow rate and gas concentrations affect catalyst behavior. Under normal driving conditions, the catalyst can experience varying oxygen concentrations, such as under heavy acceleration or cruising down a hill will show a variation in oxygen from the engine emissions. The effect that varying oxygen concentrations has on the rate of aging is not fully understood and hence the total deactivation and conversion efficiencies are not known throughout the catalyst lifetime. Traditionally, catalyst specification has relied heavily on catalyst testing over a wide range of mileage, with catalyst aging being conducted via vehicle/bench testing, focusing on 3 main parameters; flow (space velocity), temperature (inlet/bed) and lambda (oxygen concentration). The main drawback of this approach, particularly in the early stages of powertrain development, is the cost and resource required to conduct the testing. It is in this area of development that a kinetic model to predict the catalyst performance taking into account aging time, temperature, flow rate and exposure to oxygen concentration would be of great benefit. This paper presents a continuation of previous work into the investigation of the effect of varying oxygen concentration on the rate of catalyst aging. A number of commercially available palladium three-way catalysts were aged over a precise temperature cycle at varying oxygen concentrations for different aging times related back to a mileage. The results were analyzed in detail and fed into a catalyst model in which a built in optimizer calculated the initial pre-exponential and activation energy for characterization tests. Once optimized, the model then calculated the variation in dispersion for the catalysts aged under varying levels of oxygen at a range of set mileage. The variation in dispersion over aging is presented and compared with predictions based on the standard aging algorithm and with others proposed in literature.
Irwin, Kurtis, Douglas, Roy, Stewart, Jonathan David, Pedlow, Andrew, Woods, Andrew
Passive Hydrocarbon Trap to Enable SULEV-30 Tailpipe Emissions from a Flex-Fuel Vehicle on E85 Fuel2018-01-09444/3/2018
Future LEV-III tailpipe (TP) emission regulations pose an enormous challenge forcing the fleet average of light-duty vehicles produced in the 2025 model year to perform at the super ultralow emission vehicle (SULEV-30) certification levels (versus less than 20% produced today). To achieve SULEV-30, regulated TP emissions of non-methane organic gas (NMOG) hydrocarbons (HCs) and oxygenates plus oxides of nitrogen (NOx) must be below a combined 30 mg/mi (18.6 mg/km) standard as measured on the federal emissions certification cycle (FTP-75). However, when flex-fuel vehicles use E85 fuel instead of gasoline, NMOG emissions at cold start are nearly doubled, before the catalytic converter is active. Passive HC traps (HCTs) are a potential solution to reduce TP NMOG emissions. The conventional HCT design was modified by changing the zeolite chemistry so as to improve HC retention coupled with more efficient combustion during the desorption phase. Increased trapping efficiently was achieved by (a) modifying the acidic properties of the zeolite, (b) inclusion of Pd in order to more efficiently trap alkenes and NOx, and (c) the introduction of a new redox function that promoted HC combustion prior to the full desorption phase of the trap. A 2.0 L direct-injection Ford Focus with E85 fuel, utilizing the newly designed HCT developed by Ford and Umicore and having a significantly reduced platinum group metal (PGM) loading of only 0.53 g/L, was able to lower NMOG emissions by about 60% compared to the baseline underbody three-way catalyst (TWC). This in turn achieved combined NMOG + NOx emissions at an average of 19 mg/mi (11.8 mg/km), just below the SULEV-20 limit. The new trap formulation not only improved HC storage and conversion efficiency but substantially decreased the PGM content in line with current LEV-II partial zero-emission vehicle (PZEV) underbody loadings and will ensure continued sales of future flex-fuel vehicles.
Lupescu, Jason, Xu, Lifeng, Nunan, John, Alltizer, Chad
Reducing Harmful Emissions of the Vehicular Engine by Rapid After-Start Heating of the Catalytic Converter Using Thermal Accumulator2018-01-07844/3/2018
The article examines the peculiarities of evaluating the vehicular engine harmful emissions in different heating modes when using thermal development system of the catalytic converter within phase-transitional thermal accumulators. The system under review uses thermal energy from different sources of the vehicular engine during its operation to accumulate it in thermal accumulators. The functional scheme of thermal development of the “vehicular engine - thermal accumulator - catalytic converter” system is shown. The functional scheme takes into account fuel consumption, mechanical energy and harmful emissions when operating the vehicular engine equipped with the exhaust gases cleaning system and the thermal development system with phase-transitional thermal accumulator. The article shows main mathematical dependencies to describe the processes of thermal development of the vehicular engine and the catalytic converter when using thermal development system with phase-transitional thermal accumulator. The article presents experimental research results of the catalytic converter temperature condition when using thermal development system of the vehicular engine in different heating modes. To investigate the impact of thermal development system design and regulation parameters on thermal development performance of the vehicular engine and exhaust system, the information system structure is shown. A numerical experiment has shown that without additional heating means rapid thermal development of the catalytic converter to Light-off point is possible only when the vehicle is in motion. Using thermal development system of the vehicular engine catalytic converter can reduce the time of achieving the vehicular engine complete heating and the catalytic converter Light-off point by 54.5% -61.1% under changing operating conditions.
Gritsuk, Igor V., Mateichyk, Vasyl, Tsiuman, Mykola, Gutarevych, Yurii, Smieszek, Miroslaw, Goridko, Nataliia
Q&A: Dr. Abhaya Datye, Distinguished Professor, Department of Chemical and Biological Engineering, University of New Mexico, AlbuquerqueTBMG-287054/1/2018
Researchers at Washington State University, Pacific Northwest National Laboratory, and the University of New Mexico have created a catalyst capable of reducing pollutants at the lower temperatures expected in advanced engines. Their work presents a new way to create a more powerful catalyst while using smaller amounts of platinum — the most expensive component of emission-control catalysts.
Experimental Investigation of Cold Start Emission using Dynamic Catalytic Converter with Pre-Catalyst and Hot Air Injector on a Multi Cylinder Spark Ignition Engine2017-01-236710/8/2017
Control of harmful emissions during cold start of the engine has become a challenging task over the years due to the ever increasing stringent emission norms. Positioning the catalytic converter closer to the exhaust manifold is an efficient way of achieving rapid light-off temperature. On the other hand, the resulting higher thermal loading under high-load engine operation may substantially cause thermal degradation and accelerate catalyst ageing. The objective of the present work is to reduce the light-off time of the catalyst and at the same time reduce the thermal degradation and ageing of the catalyst to the minimum possible extent by adopting an approach with Dynamic Catalytic Converter System (DCCS). The emission tests were conducted at the cold start of a 4 cylinder spark ignition engine with DCCS at different positions of the catalyst at no load conditions. Also emission tests were conducted with pre-catalysts of 20% volume and 40% volume of the main catalytic converter and with air pre-heater at the exhaust manifold prior to main catalytic converter. It was established that considerable reduction in the time to light off was achieved by using DCCS and light-off time was further reduced by using pre-catalysts and air pre-heater as compared to the conventional catalysts. It was observed that DCCS with air pre-heater delivering air at 80°C and at 20lpm air flow rate brings down the time to light off to 10 seconds.
Mahadevan, Ganesan, Subramanian, Sendilvelan
An Implementation of CH 4 Kinetic Model with H 2 O into 1-D and 3-D Catalytic Converter Simulation Codes2017-01-238210/8/2017
The diesel dual fuel engine emits CH4 in the exhaust gas. This makes the exhaust gas more difficult to treat comparing to the exhaust gas from the conventional engine since CH4 requires high exhaust temperature to oxidize. In addition, another parameter such as exhaust flow rate, specie concentrations, especially CO, C3H8, and H2O have tremendous impact on Diesel Oxidation Catalyst performance on reducing CH4. This research is aimed to propose a kinetic model based on Langmuir Hinshelwood mechanisms that includes several terms such as CH4, C3H8, CO, O2, and H2O concentrations in order to gain a better understanding on the catalytic reaction and to provide a simulation with an accurate prediction. The model’s kinetic parameters are determined from the experiment by using synthetic gas. The composition of synthetic gas is simulated to be similar to the real exhaust gas from diesel dual fuel engines. By comparing the simulation to the experiment, this kinetic model can give accurate results with the kinetic model that can be used to predict the conversion rate of the exhaust gas in diesel oxidation catalyst.
Suthiprasert, Tul, Jirawongnuson, Sirichai, Wirojsakunchai, Ekathai, Aroonsrisopon, Tanet, Wannatong, Krisada, Salee, Atsawin
Self-Healing, Self-Lubricating TribofilmTBMG-2769710/1/2017
Tribologists have developed a diamond-like film that is generated by the heat and pressure of an automotive engine. The ultra-durable, self-lubricating tribofilm — a film that forms between moving surfaces — can be made to develop self-healing, diamondlike carbon (DLC) tribofilms. The film generates itself by breaking down the molecules of the lubricating oil, and can regenerate the tribofilm as it is worn away.
Model Based Control of a Three-way Catalytic Converter Based on the Oxygen Storage Level of the Catalyst2017-01-09603/28/2017
Traditionally, a three-way catalyst (TWC) is controlled to a set heated exhaust gas oxygen (HEGO) sensor voltage (typically placed after the monitored catalyst) that corresponds to optimal catalyst efficiency. This limits the control action, as we rely on emissions breakthrough at the HEGO sensor to infer the state of catalyst. In order to robustly meet the super ultra-low emission regulations, a more precise TWC control around the oxidation level of catalyst is desirable. In this work, we developed a comprehensive set of models to predict the oxygen storage capacity using measured in-vehicle signals only. This is accomplished by developing three models; the first model is a linear in parameter regression model to predict the feed gas emissions from measured signals like engine speed and air-to-fuel ratio (A/F). The second model is a low-dimensional physics based model of the three-way catalyst to predict the exhaust emissions and oxidation state of the catalyst. The third model computes the tailpipe A/F as a function of the exhaust emissions. These models were implemented and validated in vehicle using a rapid prototyping tool such as ATI NoHooks and validated over multiple FTP cycles and road tests. Finally, these models were used to design an outer-loop catalyst control (proportional-integral (PI) controller with an anti-windup loop) designed to achieve the desired fractional oxidation state (FOS) or the oxygen storage level. The experimental results confirm that the system is controllable and show improvement in catalyst control by reducing tail pipe emissions compared to current production strategy.
Kumar, Pankaj, Makki, Imad
Vehicle Fires Resulting from Hot Surface Ignition of Grass and Leaves2017-01-13543/28/2017
One potential fire ignition source in a motor vehicle is the hot surfaces on the engine exhaust system. These hot surfaces can come into contact with combustible and flammable liquids (such as engine oil, transmission fluid, brake fluid, gasoline, or Diesel fuel) due to a fluid leak, or during a vehicle collision. If the surface temperature is higher than the hot surface ignition temperature of the combustible or flammable liquid in a given geometry, a fire can potentially ignite and propagate. In addition to automotive fluids, another potential fuel in post-collision vehicle fires is grass, leaves, or other vegetation. Studies of hot surface ignition of dried vegetation have found that ignition depends on the type of vegetation, surface temperature, duration of contact, and ambient conditions such as temperature and wind speed. Ignition can occur at surface temperatures as low as 300 °C, if the vegetation is in contact with the surface for 10 minutes or longer. At surface temperatures of 400 °C, ignition can occur in 3 minutes, and at surface temperatures of 500 °C, ignition can occur in a few seconds. We made measurements of the surface temperature at various locations along the exhaust system of a passenger vehicle, including on the catalytic converter, under different transient conditions. The temperatures were measured using thermocouples welded to the exhaust system. The tests show that the maximum external surfaces temperatures occur under transient conditions after the vehicle comes to a sudden stop. Thus, testing that only measures steady-state temperatures or temperatures while the vehicle is moving will not necessarily capture the worst-case temperatures. For the vehicle tested, exhaust system components can reach temperatures of 400 °C and these temperatures can be sustained for minutes after the vehicle stops, and thus are capable of igniting dried vegetation.
Morse, Timothy, Cundy, Michael, Kytomaa, Harri
Three-Way Catalyst Diagnostics and Prognostics Based on Support Vector Machines2017-01-09753/28/2017
A three-way catalytic converter (TWC) is an emissions control device, used to treat the exhaust gases in a gasoline engine. The conversion efficiency of the catalyst, however, drops with age or customer usage and needs to be monitored on-line to meet the on board diagnostics (OBD II) regulations. In this work, a non-intrusive catalyst monitor is developed to diagnose the track the remaining useful life of the catalyst based on measured in-vehicle signals. Using air mass and the air-fuel ratio (A/F) at the front (upstream) and rear (downstream) of the catalyst, the catalyst oxygen storage capacity is estimated. The catalyst capacity and operating exhaust temperature are used as an input features for developing a Support Vector Machine (SVM) algorithm based classifier to identify a threshold catalyst. In addition, the distance of the data points in hyperspace from the calibrated threshold plane is used to compute the remaining useful life left. To further improve the monitor robustness and reduce the number of support vectors, clustering techniques are proposed, implemented and evaluated. The model was tested and validated on multiple vehicles with differently configured catalyst systems and was found to be robust and accurate for on-board implementation. In addition, this approach for catalyst monitor is generic and has been successfully extended for other vehicle diagnostics applications such as universal exhaust gas oxygen (UEGO) sensor diagnostics and vehicle rollover detection.
Kumar, Pankaj, Makki, Imad
Development of a New Ceramic Substrate with Gas Flow Control Functionality2017-01-09193/28/2017
Emission regulations in many countries and regions around the world are becoming stricter in reaction to the increasing awareness of environment protections, and it has now become necessary to improve the performance of catalytic converters to achieve these goals. A catalytic converter is composed of a catalytically active material coated onto a ceramic honeycomb-structured substrate. Honeycomb substrates play the role of ensuring intimate contact between the exhaust gas and the catalyst within the substrate’s flow channels. In recent years, high-load test cycles have been introduced which require increased robustness to maintain low emissions during the wide range of load changes. Therefore, it is extremely important to increase the probability of contact between the exhaust gas and catalyst. To achieve this contact, several measures were considered such as increasing active sites or geometrical surface areas by utilizing substrates with higher cell densities or larger volumes. These measures, however, led to greater consumption of precious metals and decreased vehicle power by increasing pressure losses. Therefore, a new concept substrate, which focuses on gas flow redistribution, has been developed to overcome these negatives. The key points of this development include a compound cell structure design which consists of a higher cell density area in the center portion of the substrate completely surrounded by a lower cell density area and optimization of the cell design for each portion to improve the efficiency of the catalytic converter. As a result, this newly developed honeycomb substrate shifts the trend line relationship of catalytic performance and pressure loss to a higher level. In addition, it reduces precious metal usage, as well as the volume of catalytic converters while maintaining catalytic performance equivalent to that of a conventional honeycomb substrate (400 cell density).
Yoshida, Takeru, Suzuki, Hiromasa, Aoki, Yuki, Hayashi, Naohiro, Ito, Kenichi
Dynamic Misfire Threshold Determination Based On Zone-Level and Buffer-Level Adaptations for Internal Combustion Engines2017-01-05993/28/2017
Misfire is generally defined as be no or partial combustion during the power stroke of internal combustion engine. Because a misfired engine will dramatically increase the exhaust emission and potentially cause permanent damage to the catalytic converters, California Air Resources Board (CARB), as well as most of other countries’ on-board diagnostic regulations mandates the detection of misfire. Currently almost all the OEMs utilize crankshaft position sensors as the main input to their misfire detection algorithm. The detailed detection approaches vary among different manufacturers. For example, some chooses the crankshaft angular velocity calculated from the raw output of the crankshaft positon sensor as the measurement to distinguish misfires from normal firing events, while others use crankshaft angular acceleration or the associated torque index derived from the crankshaft position sensor readings as the measurement of misfire detection. Regardless which measurement is chosen, an optimized threshold setting that clearly separates misfiring and normal firing cylinder events is desired. Traditionally, the threshold setting is determined during pre-launch calibration process with test data obtained from development vehicles. The threshold for each speed-load zone is typically a fixed value by looking up of a 3D calibration table. Such threshold setting approach, however, faces more and more challenges from the application of new engine technologies, because the crankshaft position sensor outputs could gradually change over the vehicle’s life cycle, and could even change swiftly under stable engine speed and load conditions due to the application of certain new technologies. A fixed misfire threshold setting will yield false detections and result in regulation compliance concerns as well as unsatisfactory of the customers. To address this issue, this article propose a unique approach to dynamically determine the misfire threshold with zone-level adaptation to adjust thresholds for vehicle life-cycle changes and buffer-level adaption to address the needs to quickly adjust misfire thresholds in the same speed-load zone.
Guo, Yichao
Methodology for the Effective Stabilization of Tin-Oxide-Based Oxidation/Reduction CatalystsTBMG-263492/1/2017
NASA Langley researchers, in work spanning more than a decade, have developed a portfolio of technologies for low-temperature gas catalysis. Originally developed to support space-based CO2 lasers, the technology has evolved into an array of performance capabilities and processing approaches, with potential applications ranging from indoor air filtration to automotive catalytic converters and industrial smokestack applications. The technology has been used commercially in systems that provide clean air to racecar drivers, as well as incorporated into commercially available filtration systems for diesel mining equipment. Backed with extensive research on these technologies, NASA welcomes interest in the portfolio for other commercial and industrial applications.
Multiscale, Multiphysics Computational Chemistry Methods Based on Artificial Intelligence Integrated Ultra-Accelerated Quantum Molecular Dynamics for the Application to Automotive Emission Control2016-32-006711/8/2016
On the basis of extensive experimental works about heterogeneous catalysts, we developed various software for the design of automotive catalysts such as Ultra-Accelerated Quantum Chemical Molecular Dynamics (UA-QCMD), which is 10 million times faster than the conventional first principles molecular dynamics, mesoscopic modeling software for supported catalysts (POCO2), and mesoscopic sintering simulator (SINTA) to calculate sintering behavior of both precious metals (e.g., Pt, Pd, Rh) and supports (e.g., Al2O3, ZrO2, CeO2, or CeO2-ZrO2). We integrated the previous programs in a multiscale, multiphysics approach for the design of automotive catalysts. The method was efficient for a variety of important catalytic reactions in the scope of the automotive emission control. We demonstrated the efficiency of our approach by comparing our data with experimental results including both simple laboratory experiments and chassis dynamometer exhaust gas emission control experiments. We also demonstrated that the UA-QCMD method is an efficient tool for the estimation of mesoscopic sintering activation energies for both precious metals and supports. On the basis of our successful applications of the UA-QCMD to various important chemical processes of exhaust emission controls and sintering predictions of both precious metals and support of automotive catalysts, we employed in the present study artificial intelligence to determine fundamental parameters from all electron density functional methods and thermodynamic results. This new technique was proven highly efficient for optimizing parameters necessary in our simulations.
Miyamoto, Akira, Inaba, Kenji, Ishizawa, Yukie, Sato, Manami, Komuro, Rei, Sato, Masashi, Sato, Ryo, Bonnaud, Patrick, Miura, Ryuji, Suzuki, Ai, Miyamoto, Naoto, Hatakeyama, Nozomu, Hariyama, Masanori
Development of High-Performance 25 cm 3 Two-Stroke SI Engine for Light Weight Arborist-Chainsaw2016-32-004911/8/2016
A new air-cooled SI two-stroke gasoline engine has been developed for an arborist-chainsaw. This engine has a displacement of 25 cm3 and generates about 1.1 kW and complies with the latest CARB and EPA exhaust regulations by optimizing scavenging flows and the use of a catalytic converter. Characteristics of lightweight, compact and high power-to-weight ratio are required for handheld chainsaws, especially for arborist chainsaws. As a matter of course, these characteristics are needed for engine itself in order to satisfy such market requirements for hand-held power equipment. To realize lightweight and compact design, the placement of catalytic converter is optimized for the engine and a two-piece crankshaft is adopted. Moreover, as preliminary studies, computer analyses such as CFD simulations of in-cylinder flow and cooling air flow, boundary pressure of piston surface during piston movement were performed to estimate output power, short circuit losses of fuel-air mixture, engine cooling performance and anti-seizure performance. Then, these performances were evaluated and modified by experimental studies. This paper presents overview of the arborist chainsaw, results of the simulation analyses and experimental evaluations.
Eto, Kuniyoshi, Nozawa, Masaru, Nara, Masato, Kobayashi, Buhei, Shibasaki, Daiki, Shirai, Ken
Design of Catalytic Devices by Means of Genetic Algorithm: Comparison Between Open-Cell Foam and Honeycomb Type Substrates2016-01-09654/5/2016
Metallic foams or sponges are materials with a cell structure suitable for many industrial applications, such as reformers, heat catalytic converters, etc. The success of these materials is due to the combination of various characteristics such as mechanical strength, low density, high specific surface, good thermal exchange properties, low flow resistance and sound absorption. Different materials and manufacturing processes produce different type of structure and properties for various applications. In this work a genetic algorithm has been developed and applied to support the design of catalytic devices. In particular, two substrates were considered, namely the traditional honeycomb and an alternative open-cell foam type. CFD simulations of pressure losses and literature based correlations for the heat and mass transfer were used to support the genetic algorithm in finding the best compromise between flow resistance and pollutant abatement. The CFD analysis was conducted by means of numerical simulations carried out on a geometry sample obtained by the micro-tomography technique to investigate the flow regime type and to extract pressure drop information. The result of this analysis was used to set guideline for the design of foam type substrate and to provide a first estimation of cost effectiveness of new type of substrates.
Falfari, Stefania, Micci, Giacomo, Bianchi, Gian Marco, Brusiani, Federico, Montenegro, Gianluca, Della Torre, Augusto, Onorati, Angelo
Experimental and Numerical Analysis for a Urea-SCR Catalytic Converter2016-01-09734/5/2016
Urea-SCR (Selective Catalytic Reduction) systems are getting a lot of attention as the most promising NOx reduction technology for heavy-duty diesel engine exhaust. In order to promote an effective development for an optimal urea-SCR after-treatment system, it is important to clarify the decomposition behavior of the injected urea and a detailed reaction chemistry of the reactants on the catalyst surface in exhaust gases. In this paper we discuss experimental and numerical studies for the development of a numerical simulation model for the urea-SCR catalyst converter. As a first step, in order to clarify the behavior of reductants in an urea-SCR converter, two types of diagnostic technique were developed; one is for measuring the amount of NH3, and the other is for measuring the amount of total reductants including unreacted urea and iso-cyanic acid. These techniques were applied to examine the behavior of reductants at the inlet and inside the SCR converter. This revealed i) urea to NH3 conversion rates and spatial distributions of reductants at the inlet of the catalyst, and ii) temporal and spatial profiles of urea to NH3 conversion inside the catalyst. Secondly, we developed a urea-SCR reaction model with detailed surface chemistry for the NH3-NO/NO2 reacting system over a Fezeolite catalyst, which is combined with a simple reaction model for urea-decomposition reactions. The reaction parameters of the urea-decomposition model were determined by the urea to NH3 conversion rates and spatial distributions of reductants, which were directly measured at the inlet and inside the catalyst converter mentioned above. This model successfully predicted gas emissions (such as NOx and NH3) from urea-SCR converters under various vehicle-test conditions.
Yamauchi, Takafumi, Takatori, Yoshiki, Fukuda, Koichiro, Maruyama, Masatoshi
Optimal Energy and Emission Management of a Diesel Hybrid Electric Vehicle Equipped with a Selective Catalytic Reduction System2015-24-25489/6/2015
This paper deals with the problem of obtaining the optimal energy and emission management strategy for a diesel hybrid electric vehicle. The vehicle is assumed to be equipped with a selective catalytic reduction device for the removal of harmful NOx emissions. The authors present a model-based procedure: The energy flows of the hybrid vehicle are modelled in a standard way, while the engine-out emissions are calculated based on a temperature-corrected engine map. For the simulation of the SCR system a combination of two existing first-principle physical models is used. The optimal energy and emission strategy for a given driving cycle is then obtained using dynamic programming. In terms of results, three case studies are presented. One case study illustrates the trade-off between fuel consumption and tailpipe NOx emissions for various relative weights of these objectives. The second case study investigates the influence of the size of the SCR system on fuel consumption and tailpipe NOx emissions. The third case study shows the influence of neglecting the thermal effects and the emission considerations in the derivation of the optimal control strategy.
Tschopp, Florian, Nüesch, Tobias, Wang, Mu, Onder, Christopher
Development of Alternate Split Cat-Con - Muffler Configuration Solution for Front Engine Low Floor Bus2015-01-23116/15/2015
Development of split Catalytic Converter (Cat-Con)-Muffler system was done to be used in front engine low floor (FELF) Bus from perspective of cost saving, modularity and reduction in complexity. This system is developed as an alternate to an existing solution of integrated Cat-Con and muffler. The paper describes the development of a split Cat-Con and muffler exhaust system for a FELF Bus, so as to meet cost and time considerations. The development also had to achieve a feasible solution, which could be installed within the packaging volume of the existing configuration of FELF while meeting the regulatory requirements [1] for Pass by noise (PBN), and at the same time conforming to backpressure limits set for optimum engine performance. Multiple design - prototypes - test iterations were carried out to meet the PBN and back pressure target for FELF Bus. The final solution was developed which achieved both the requirements within the specified space constraints. Solution is based on configuration used in Front Engine Semi Low Floor (FESLF) Bus where a split Cat-Con configuration was already used as it had higher scope for volume where PBN and back pressure conflict didn't rise.
Palsule, Aditya, Budama, Arun, Somasundaraeswer, Nandakumar
High Porosity Substrates for Fast-Light-Off Applications2015-01-10094/14/2015
Regulations that limit emissions of pollutants from gasoline-powered cars and trucks continue to tighten. More than 75% of emissions through an FTP-75 regulatory test are released in the first few seconds after cold-start. A factor that controls the time to catalytic light-off is the heat capacity of the catalytic converter substrate. Historically, substrates with thinner walls and lower heat capacity have been developed to improve cold-start performance. Another approach is to increase porosity of the substrate. A new material and process technology has been developed to significantly raise the porosity of thin wall substrates (2-3 mil) from 27-35% to 55% while maintaining strength. The heat capacity of the material is 30-38% lower than existing substrates. The reduction in substrate heat capacity enables faster thermal response and lower tailpipe emissions. The reliance on costly precious metals in the washcoat is demonstrated to be lessened. The microstructure of the new substrate material is optimized for washcoat compatibility and to maintain strength. The new materials are confirmed to be thermomechanically robust for service in the harsh exhaust system environment.
Tanner, Cameron W., Twiggs, Kenneth, Tao, Tinghong, Bronfenbrenner, David, Matsuzono, Yoshiaki, Otsuka, Shinichiro, Suehiro, Yukio, Koyama, Hiroshi
Development of a Target Sensitivity Function based A/F F/B Controller by Sensor Response Characteristics2015-01-16314/14/2015
Recently, automotive emission regulations are being further tightened, such as the Tier III/LEV III in the U.S. As a result, reducing cost of after-treatment systems to meet these strict regulations has become an urgent issue, and then the demand for high-precision air-fuel ratio (A/F) control which can achieve this cost reduction is high [1]. On the other hand, in order to meet rapidly changing market needs, it is becoming difficult to keep enough development periods that enable sufficient calibration by trial-and-error, such as feedback-gain calibration. This leads to an increase in three-way catalytic converter costs in some cases. For these reasons, it is necessary to construct control system that can make full use of hardware capabilities, can shorten development periods regardless of the skill level of engineers. A new robust control method is accomplished in this study, which can provide optimal performance in accordance with the Universal Exhaust Gas Oxygen (UEGO) sensor response, which changes according to the vehicle operating condition, and also eliminates trial-and-error elements, enables direct calibration. The results of these investigations showed that it is possible to obtain a feedback controller with a target disturbance sensitivity function. It is confirmed that all parameters can be determined by measuring the UEGO sensor response characteristics, and the A/F control accuracy was enhanced by 35% compared to conventional feedback control, when the deviation between the target equivalence ratio and the actual equivalence ratio is used as the evaluation index.
Tani, Michinori, Miyauchi, Atsuhiro, Matsuzono, Yoshiaki
Influence of Linear and Parabolic Elements in Structural Rigidity of Converter Mounting Brackets2015-01-13264/14/2015
Generation of discretization with prescribed element sizes are adapted to the geometry. From the rules of thumb, for a complicated geometry it is important to select the reasonable element order, shapes and size for accurate results. In order to that, this paper describes the influence of elemental algorithm of the catalytic converter mounting brackets. Brackets are main source of mounting of various systems mainly intake and exhaust in the engine. In hot end exhaust system, a bracket design plays a vital role because it has to withstand heavy structural vibrations without isolation combined with thermal loads. Bracket design and stiffness determines the whole catalytic converter system's rigidity. So, here discretization of converter brackets by linear and parabolic elements is studied with different elements types and compared. The study shows disparity in the structural accuracies of the brackets in each of elemental orders respect to the element shapes i.e. in the stiffness and resonance frequencies. For an optimized proposal it is significant to predict the accurate resonances along with desired stiffness target in less time consumption. To accomplish these, a detailed perspective is given for selection of elemental orders and shapes.
Rajadurai, Sivanandi, Mani, Guru Prasad, Raja, Kavin, Mohan, Sundaravadivelu
Regulated and Unregulated Emissions from a Flex Fuel Motorcycle Fuelled with Various Gasoline/Ethanol Blends2014-32-003211/11/2014
Motorcycle sales have increased consistently during the last decade mostly in developing countries, especially in the BRICS. Low cost and less fuel consumption comparing to cars associated to the economic growth are the main reason for such trend. Emission limits have become stricter and the use of gas after treatment devices is widely present in new models. Flex fuel motorcycles have now become available, but effects of the combination of diverse gasoline/ethanol blends on the emissions are still an open issue that requires further understanding. This paper presents the most recent results regarding regulated and unregulated emissions from a Flex Fuel motorcycle fuelled with 4 different gasoline/ethanol blends: E22, E61, E85 and 100% ethanol. Both regulated (CO, THC, NOx) and unregulated emissions (Aldehydes, NMHC, NH3, N2O) were studied. The main conclusion is that motorcycles equipped with three-way catalytic converters presented significant ammonia emissions in the tailpipe when compared to pre catalyst emissions. The same trend was observed with nitrous oxide.
Daemme, Luiz Carlos, Penteado, Renato, Zotin, Fatima, Errera, Marcelo
Development of a Miller Cycle Powersports Engine2014-32-009011/11/2014
Operation of snowmobiles in national parks is restricted to vehicles meeting the Best Available Technology standard for exhaust and noise emissions as established by the National Parks Service. An engine exceeding these standards while operating on a blend of gasoline and bio-isobutanol has been developed based on a production four-stroke snowmobile engine. Miller cycle operation was achieved via late intake valve closing and turbocharging. The production Rotax ACE 600cc 2 cylinder engine was modeled using Ricardo WAVE. After this model was validated with physical testing, different valve lift profiles were evaluated for brake specific fuel consumption and brake power. The results from this analysis were used to determine a camshaft profile for Miller cycle operation. This was done to reduce part load pumping losses and increase engine efficiency while maintaining production power density. A catalytic converter was added to reduce exhaust gas emissions, as measured by the EPA 40 CFR Part 1051 5-mode emissions test cycle. Laboratory testing was conducted on the engine using a water brake dynamometer and in-cylinder pressure transducers. The result is an engine that exceeds BAT standards for pollutant and noise emissions and delivers improved fuel efficiency, while maintaining production performance and driveability.
Blair, Jeffrey, Bower, Glenn
Assessment and Experimental Validation of a 3D Acoustic Model of a Motorcycle Muffler2014-32-012211/11/2014
The intake and exhaust lines provide the main abatement of the acoustic emissions of an Internal Combustion Engine (ICE). Many different numerical approaches can be used to evaluate the acoustic attenuation, which is commonly expressed by the Transmission Loss. One-dimensional (1D) and three-dimensional (3D) simulations are conventionally carried out only considering the acoustic domain of the muffler or of the air-box. The walls of the acoustic filter are considered fully rigid and the interaction between the acoustic waves and the structure is consequently negligible. Moreover, the effect of the manufacturing characteristics and the attenuation of the acoustic waves due to the fluid viscous-thermal effects are also commonly disregarded in the numerical analysis of the filters. In addition, the presence of a catalytic converter or a filter cartridge may have an influence on the numerical results. All these aspects, however, can remarkably affect the matching between simulations and experiments both at high frequencies and at medium-low ones. In the present study, the effect of the aforementioned issues on the prediction capabilities of a 3D FEM model are analysed, with particular attention to the prediction of the acoustic attenuation of a commercial muffler. In detail, simplified models were developed in order to include the manufacturing features into acoustic simulations with almost negligible increase of the computational time. Numerical models were applied to a commercial motorcycle muffler featuring three chambers and a catalytic converter, and then validated by means of a specific experimental campaign that was carried out on an acoustic test rig. The tests were run at ambient temperature and no-flow conditions, obtaining good agreement between theory and experiments.
Fioravanti, Andrea, Lenzi, Giulio, Vichi, Giovanni, Ferrara, Giovanni, Ricci, Stefano, Bagnoli, Leonardo
Strategies for Emission Reduction on Small Capacity Two-Wheelers with Regard to Future Legislative Limits2014-32-003111/11/2014
Looking at upcoming emission legislations for two-wheelers, it is quite obvious that the fulfilment of these targets will become one of the biggest challenges within the engine development process. The gradual harmonization of emission limits for two-wheelers with existing automotive standards will subsequently lead to new approaches regarding mixture preparation and exhaust gas aftertreatment. Referring to these future scenarios, a state-of-the-art in development of catalytic converters for two- or three-wheeler applications should be presented. After choosing a suitable test carrier, which has already been equipped with EFI components including an oxygen sensor for λ=1 operation mode, a basic injection system calibration was used to optimize the combustion process. Based on this setup, a variable exhaust system was manufactured to be able to integrate different catalyst configurations. To improve cold start characteristics, the position of the lambda probe and the catalyst were optimized to achieve short light-off times. Thus, the possibility for investigations on exhaust gas aftertreatment was given. Initially, the vehicle was operated with a metallic foil monolith without precious metal coating to identify the level of untreated emissions under comparable conditions with regard to backpressure in the exhaust system. In succession, different precious metal and washcoat loadings were tested with the same monolith structure to get insight in the individual conversion behavior. Hence, an optimized configuration in terms of exhaust gas aftertreatment capabilities was derived. These investigations should serve as a basis to illustrate the emission reduction potential of small capacity two-wheelers by means of technological improvements, paying attention to the upcoming EURO 4 and EURO 5 legislation. Finally, a possible system cost reduction was contemplated. Starting from the most sophisticated setup, a reduction of cell density was investigated. Therewith, low-cost configurations were derived that could be of interest for applications being subject to less stringent emission regulations.
Tromayer, Juergen, Neumann, Gerd, Bonifer, Marcus, Kiemel, Rainer
A Comprehensive Evaluation of Performance and Emissions from UltraClean™ Diesel in Medium Duty Engines2014-01-276610/13/2014
Bioethanol and plant oil-derived biodiesel are generally considered first generation biofuels. More sustainable and cost effective new biofuels are being designed and produced using modern tools of metabolic engineering and synthetic biology. These new microbial fuels have great potential to become viable alternatives and supplements for petroleum-derived liquid transportation fuels. MAN Latin America has worked in cooperation with REG Life Sciences, a North American industrial biotechnological company, to help in the development of high quality fuels for automotive purposes. The aim of this paper is to present the test engine results of a novel microbially produced fatty acid methyl ester (FAME), under the banner of UltraClean™ Diesel, in a Proconve P7 (Euro V) MAN D0834, diesel engine. Described are a comprehensive performance and emissions evaluation as well as an interpretation of the primary fuel properties. The test engine was operated with 100% standard Brazilian diesel (S50), blend of 20% of UltraClean™ Diesel with 80% of S50 and 100% UltraClean™ Diesel. Tests were conducted in Brazil using an original 4.58 liter, 166 kW engine, equipped with common rail fuel injection system, external cooled EGR, and an oxidation catalytic converter.
Marques, Gian, Izquierdo, Lian, Coutinho, Camila
Optimization of Kinetic Parameters for an Aftertreatment Catalyst2014-01-281410/13/2014
Mathematical modelling has become an essential tool in the design of modern catalytic systems. Emissions legislation is becoming increasingly stringent, and so mathematical models of aftertreatment systems must become more accurate in order to provide confidence that a catalyst will convert pollutants over the required range of conditions. Automotive catalytic converter models contain several sub-models that represent processes such as mass and heat transfer, and the rates at which the reactions proceed on the surface of the precious metal. Of these sub-models, the prediction of the surface reaction rates is by far the most challenging due to the complexity of the reaction system and the large number of gas species involved. The reaction rate sub-model uses global reaction kinetics to describe the surface reaction rate of the gas species and is based on the Langmuir Hinshelwood equation further developed by Voltz et al. [1] The reactions can be modelled using the pre-exponential and activation energies of the Arrhenius equations and the inhibition terms. The reaction kinetic parameters of aftertreatment models are found from experimental data, where a measured light-off curve is compared against a predicted curve produced by a mathematical model. The kinetic parameters are usually manually tuned to minimize the error between the measured and predicted data. This process is most commonly long, laborious and prone to misinterpretation due to the large number of parameters and the risk of multiple sets of parameters giving acceptable fits. Moreover, the number of coefficients increases greatly with the number of reactions. Therefore, with the growing number of reactions, the task of manually tuning the coefficients is becoming increasingly challenging. In the presented work, the authors have developed and implemented a multi-objective genetic algorithm to automatically optimize reaction parameters in AxiSuite®, [2] a commercial aftertreatment model. The genetic algorithm was developed and expanded from the code presented by Michalewicz et al. [3] and was linked to AxiSuite using the Simulink add-on for Matlab. The default kinetic values stored within the AxiSuite model were used to generate a series of light-off curves under rich conditions for a number of gas species, including CO, NO, C3H8 and C3H6. These light-off curves were used to generate an objective function. This objective function was used to generate a measure of fit for the kinetic parameters. The multi-objective genetic algorithm was subsequently used to search between specified limits to attempt to match the objective function. In total the pre-exponential factors and activation energies of ten reactions were simultaneously optimized. The results reported here demonstrate that, given accurate experimental data, the optimization algorithm is successful and robust in defining the correct kinetic parameters of a global kinetic model describing aftertreatment processes.
Pedlow, Andrew, McCullough, Geoffrey, Goguet, Alexandre, Hansen, Ken
Design of the Exhaust Manifold of a Turbo Charged Gasoline Engine Based on a Transient Thermal Mechanical Analysis Approach2014-01-288210/13/2014
The present paper describes a CAE analysis approach to evaluate the design of exhaust manifold of a turbo charged gasoline engine. It allows design engineers to identify structural weakness at the early stage or to find the root cause of exhaust manifold failures. A transient none-linear finite element method is used to calculate the plastic deformation and thermal mechanical behaviors of the exhaust manifold assembly during thermal shock cycles, which include rated speed full load, rated speed motored and idle speed conditions. A transient heat transfer simulation is performed to provide thermal boundary conditions for the nonlinear stress/strain analysis. The finite element model includes a part of cylinder head, exhaust manifold, gaskets, turbo charger housing, catalytic converter, brackets, bolts and nuts. The results show that plastic deformation is the main cause of manifold cracking and the manifold flange distortion causes the exhaust leakage. The simulation results indicate that predicted crack locations and leak area are in agreement with that from the engine durability test. Based on the baseline calculation results, local geometric modifications are made, which include changed shape of the inlet flange, changed location of anchor bolt hole and removing the internal baffle. For the modified design of the exhaust manifold, the cumulated equivalent plastic strain and the gasket sealing pressure at the end of third cycle meet the guideline limits. The modified exhaust manifold successfully passed all tests. Finally, general design recommendations of exhaust manifold are summarized in the paper.
Chen, Ming, Wang, Yanjun, Wu, Wenrui, Xin, Jun
The Effects of Diesel Oxidation Catalyst on Particulate Emission of Ethanol-Biodiesel Blend Fuel2014-01-273010/13/2014
Because of its cleanness and renewability, biodiesel has a great potential as the alternative of diesel fuel to confront with the increasing energy crisis and environment pollution. In this study, diesel oxidation catalyst (DOC) was used to reduce the typical regulated emission and particulate emission. The combined method of fuel design concept with diesel oxidation catalyst was applied in this study. DOC with Pt catalyst was equipped in the engine test bench in this study. The effects of DOC on diesel engine particulate emission fueled with Euro V diesel fuel, biodiesel and ethanol-biodiesel blends were investigated in this study. It was found that DOC seemed have no effects on NOx emission, while it could improve the oxidation reaction from NO to NO2. In the section of particulate emission, DOC could reduce the particulate mass and number concentration, especially in the range of smaller diameter particles. The SOF could be reduced effectively with DOC. With the increase of ethanol, the smaller particles (d<50nm) of ethanol-biodiesel blend fuels were more likely to be oxidized with diesel oxidation catalyst. The relationship between fuel oxygen content and the emission reduction with DOC was investigated in this study. With the increase of fuel oxygen content, the reduction of particulate mass and number concentration with DOC increased. The nano-structure of biofuel particulate and higher NO2 emission of biofuel could prove that the biofuel particulate have great potential to be oxidized. This property combined with DOC could help to improve the regeneration of diesel particle filter (DPF).
Zhu, Lei, zhang, Wugao, Huang, Zhen, Fang, Junhua
Partial Controlled Canning for Thin Wall and Ultra Thin Wall Substrates - A New Approach2014-01-23489/30/2014
The trend lately has shifted towards usage of thin wall and ultra-thin wall substrates. This change has come to existence due to the increased acting surface area available in these substrates. However these types of substrates have reduced isostatic strength comparatively, reducing its canning durability. This phenomenon has induced a new canning methodology which shall not disturb the substrate integrity during canning and also perform effectively to the requirements. This can be achieved by controlled canning which includes a huge investment and so a new methodology has been devised using the available resources and a partial controlled canning process is established and verified for canning performance and found to be effective. The paper shall include the procedural explanation and a set of results obtained by the new methodology to support its effectiveness.
Rajadurai, Sivanandi, Krishnan, Prakash, Sridharan, Naveen, Sethuramasubramaniyam, Manimaran
Influence of Coupled Analysis for a Hot End Exhaust System Validation2014-01-23549/30/2014
Simulation's drive towards reality boundary conditions is the toughest challenge. Experience has shown that often the most significant source of error in thermal and dynamic analyses is associated within specified boundary conditions. Typically, validating the system by considering both thermal and dynamic loads with predefined assumptions is time consuming and inconclusive when confronted with reality boundary conditions. Thus, the solution comes in unique way of combining thermal and dynamic loads with specified boundary conditions and will convey computational results closer to the real scenario. As a consequence, strain concentrated regions due to thermal expansion are aggregated more, when coupled with dynamic loading. The stress generated by the coupled analyses will prove to be critical in concerning the durability issue of the hot end system. These conditions are evaluated by a finite element model through linear and non-linear approaches and results summarized.
Rajadurai, Sivanandi, Mani, Guru Prasad, Mohan, Sundaravadivelu, Raja, Kavin
Catalyst for Treatment and Control of Post-Combustion EmissionsTBMG-199046/1/2014
Emissions from fossil-fuel combustion contribute significantly to smog, acid rain, and global warming problems, and are subject to stringent environmental regulations. These regulations are expected to become more stringent as state and regional authorities become more involved in addressing these environmental problems. Better systems are needed for catalytic control.
Zone Length Optimization to Improve PGM Utility2014-01-15084/1/2014
“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. This study shows how the competing forces of active PGM site concentration and available surface area interact in modern three way catalyst design.
Johnson, Stephen, Croswell, Peter, Smith, Michael
Systematic Optimization of an Exhaust System to Meet Noise Radiation Criteria at Idle2014-01-00064/1/2014
Exhaust noise is a major contributor to the radiated noise level of a vehicle, especially at idle. The radiated noise level has to meet a certain criteria based on regulation and consumer demand. In many cases, the problem appears after the vehicle is manufactured and the tailpipe noise measurement is performed indicating a high noise level that needs to be reduced. This paper describes one of those cases where the radiated noise level of a certain passenger car at idle was required to be reduced by 6 dB(A). The exhaust system consists of one main muffler and one auxiliary muffler. A 1D two-port model of the exhaust system including the two mufflers was built using commercial software. This model was validated against the measurement of the two-port matrix of both mufflers. The model was then used together with tailpipe noise measurements to estimate the characteristics of the source strength and impedance. Using a 1D model of the complete system, it was possible to propose several modifications for the vehicle manufacturer to choose from. A systematic optimization approach is presented in this paper describing several suggestions to reduce the radiated tailpipe noise.
Elnady, Tamer, Abom, Mats, Yang, Yong
Test Method Development for Material Selection of Diesel Exhaust LineSAE-PAPER-2014-01-14934/1/2014
The evolution of emission control standards on particulate matter and NOx has led to a significant increase of complexity of the diesel exhaust line which includes catalytic converter, particulate filter and selective catalytic reduction systems. The exhaust line is no longer a component that customers can change easily; its durability has to be studied for longer lifespan and if possible to be predicted. From a corrosion point of view, emission control systems have led to more and more severe conditions for stainless steel material used in the exhaust line. In particular, mufflers are exposed to higher temperature during the regeneration of the particle filter and also to acidification of gas condensates due to high sulphur content that can be found in diesel. To assess material performance in these severe conditions, a test method was developed to simulate the environment of the inner part of a muffler through corrosion cycles composed of oxidation steps in a furnace and dipping steps in a synthetic condensate. This dip/dry test simulates the most severe kind of corrosion encountered in mufflers, the crevice corrosion. In that fully automatic test, different cycles (oxidation/ immersion/ emission) can be applied according to the studied driving environment; urban or highway. Furthermore, the impact of the various parameters (sulphur content and pH, impact of biodiesel condensates) on the aggressiveness of the condensate can also be also studied. After the test, the depth of the pits is measured on each sample and extreme value statistics method is applied to predict corrosion kinetic and perforation probability. In such tests, 17% Cr ferritic steels offer a good behaviour. Among them, stabilized ferritic with molybdenum AISI 444 EN 1.4521 (K44X) and AISI 436Ti EN 1.4513 (K33X) are good technical and economical alternative materials to austenitic AISI 316L EN 1.4404 and AISI 304 EN 1.4301 respectively.
Miraval, Claudine, Santacreu, Pierre-Olivier, Saedlou, Saghi, Acher, Antoine
Optimal Catalytic Converter Heating in Hybrid Vehicles2014-01-13514/1/2014
In this paper, a hybrid optimal control problem (HOCP) for the optimal heating of the three-way catalytic converter is solved. We propose a model for a hybrid vehicle that beneath State of Charge and fuel consumption includes thermal system states like engine cooling water temperature and catalytic converter temperature. Since models for noxious emissions with appropriate computational demand are not yet available for optimization purposes, an artificial state that resembles the emissions produced is introduced. A hybrid optimal control problem is then formulated for the beginning of the FTP-75 drive cycle whose target is to minimize the energy loss during the catalytic converter and engine cooling water heating phase. The corresponding input values to be optimized are continuous variables as ignition angle and cylinder charge as well as discrete decisions such as different injection schemes. As additional constraint, an upper limit is imposed on the artificial emissions state. A self-developed algorithm is then used to optimize the system with respect to the constraints and results are presented accordingly. The results obtained provide a valuable help for the calibration of the catalytic heating process and to obtain a solution that fulfills today's complex legal requirements.
Schori, Markus, Boehme, Thomas, Jeinsch, Torsten, Schultalbers, Matthias
Damage Mechanisms of Stainless Steels under Thermal Fatigue2014-01-09174/1/2014
Thermal fatigue of austenitic and ferritic stainless steel grades has been experimentally and numerically investigated. A special test has been developed to determine the thermal fatigue resistance of clamped V-shaped specimens. This test permits to impose thermal cycle by alternating resistance heating and air cooling. The thermal fatigue life of a specimen is expressed as the number of cycles to failure. For a given grade, the fatigue life depends on the maximal and minimal temperature of the cycle, holding time at the maximal temperature and specimen thickness. The advantage of this V-shape test is that it is a simple procedure quite representative of the thermal fatigue process occurring in an exhaust manifold. This test is well suited to perform a study of damage mechanisms and to compare stainless steel grades. Examination of the failed specimens indicated that cracks could be mainly attributed to out-of-phase (OP) thermal fatigue process especially in case of ferritic grades. For austenitic steels (AISI304 EN1.4301, AISI321 EN1.4541 or AISI308 EN1.4828) at a critical temperature or above, an in-phase (IP) thermal fatigue mechanism is coupled with oxidation and creep, which are further significantly reducing the lifetime. Therefore, the service temperature range of austenitic grades is more limited than ferritic grades. Despite their lower yield stress at high temperature, ferritic grades exhibit a very good thermal fatigue resistance at elevated peak temperatures because of their very good cyclic oxidation behavior, creep resistance and their low coefficient of thermal expansion. Consequently a dedicated titanium or niobium stabilized ferritic offer was developed for the hot part of the exhaust system (from manifold to catalytic converter) that includes 14%Cr (K11X 429/425 1.4595), 17%Cr (K41X 441 1.4509) and 19%Cr (K44X modified 444 1.4521) grades in order to cover the peak temperature range from 900°C to 1050°C.
Santacreu, Pierre-Olivier, Faivre, Laurent, Acher, Antoine
The Development of Turbine Volute Surface Temperature Models for 3D CFD Vehicle Thermal Management Simulations: Part 3: Exhaust Radial Turbine Volute Systems2014-01-06484/1/2014
Modern exhaust systems contain not only a piping network to transport hot gas from the engine to the atmosphere, but also functional components such as the catalytic converter and turbocharger. The turbocharger is common place in the automotive industry due to their capability to increase the specific power output of reciprocating engines. As the exhaust system is a main heat source for the under body of the vehicle and the turbocharger is located within the engine bay, it is imperative that accurate surface temperatures are achieved. A study by K. Haehndel [1] implemented a 1D fluid stream as a replacement to solving 3D fluid dynamics of the internal exhaust flow. To incorporate the 3D effects of internal fluid flow, augmented Nusselt correlations were used to produce heat transfer coefficients. It was found that the developed correlations for the exhaust system did not adequately represent the heat transfer of the turbocharger. This paper addresses the fluid flow phenomena present in the turbine volute and applies augmented Nusselt correlations to accurately represent the heat transfer coefficients of the internal volute surface. Due to the broad range of operating conditions that are applicable to the turbocharger and the varied states of fluid flow that occur, algorithms are used to apply the appropriate Nusslet correlations and augmentations. Furthermore, the turbocharger extracts enthalpy from the working fluid; therefore to accurately calculate surface temperatures of downstream components and that of the turbocharger itself, an energy extraction model is used. Validation was conducted with four vehicle configurations. The hot-end of each configuration was aimed to be distinctly different to test the robustness of the prediction model. A tolerance range of +50/−20K was used for the study, however temperature differences were generally well within the tolerance range.
De Vos, Steve, Haehndel, Kristian, Frank, Torsten, Christel, Frieder, Abanteriba, Sylvester
Thermal Analysis of the Exhaust Line Focused on the Cool-Down Process2014-01-06554/1/2014
At the engine restart, when the temperature of the catalytic converter is low, additional fuel consumption would be required to warm up the catalyst for controlling exhaust emission.The aim of this study is to find a thermally optimal way to reduce fuel consumption for the catalyst warm up at the engine restart, by improving the thermal retention of the catalytic converter in the cool down process after the previous trip. To make analysis of the thermal flow around the catalytic converter, a 2-D thermal flow model was constructed using the thermal network method. This model simulates the following processes: 1) heat conduction between the substrate and the stainless steel case, 2) heat convection between the stainless steel case and the ambient air, 3) heat convection between the substrate and the gas inside the substrate, 4) heat generation due to chemical reactions. The points to be especially noted are: a) in the cool down process, free convection of the gas inside the substrate was based on Darcy's law, b) in the engine operating condition, chemical phenomena and species mass balance in gas phase and catalyst surface was considered. The model was verified by comparing calculated results with experimental measurements. According to this thermal flow model, in the cool down process, heat from the substrate was mainly conducted through the stainless steel case, and dissipated to the ambient air. The effect of free convection of the gas inside the substrate was predicted to be small. Therefore, an effective way to improve the thermal retention of the catalytic converter was to interrupt the heat conduction between the substrate and the boundary surface to the ambient. In this paper, we propose an optimal way to improve the thermal retention of the catalytic converter while not to deteriorate its cooling performance at high load operation.
Hosoi, Akihito, Morita, Atsushi, Suzuki, Naoto
Performance Analysis of 18% HCNG fuel on Heavy Duty Engine2014-01-14534/1/2014
Advances in renewable energy sources and impact of green house gases on climate change have led intense research in the area of renewable energy for transport and power generation sectors. All over the world gaseous fuels have gained momentum as an ideal alternative fuel for meeting future energy needs. Hydrogen enriched compressed natural gas (HCNG) may be considered as an alternative automotive fuel which does not require any major modification in the existing CNG engine and infrastructure. Several studies of HCNG fuel were reported on small and light duty engines / vehicles, but limited reports are available on heavy duty engines. In this study, experimental investigations were carried out on a 6 cylinder heavy duty CNG engine which has been optimized for 18 percent HCNG. Initial performance of the engine on HCNG was compared vis-à-vis CNG and, thereafter, the engine was subjected to endurance test as per BIS 10000 norms for 100 hours (severe cycle) with HCNG. Performance of the engine was monitored at every 10 hours interval and at the end of the endurance cycle performance of the engine was assessed as per European Transient Cycle (ETC) with emission measurements before and after catalytic converter and reported. It was observed from the test results that HCNG has shown reduction of CO, THC & CH4 emissions by 39, 25 & 25 percent respectively and NOx increased by 32 percent as compared to CNG. The average power output was nearly same with HCNG at the end of the endurance test. Further, the results after the endurance test showed increase in CO emission whereas THC, CH4, NOx & CO2 emissions reduced further but were well below Euro-IV limits. The conversion efficiency of catalytic converter was about 95-97 percent at the end of the durability test. There has been no significant change in Specific Energy Consumption (SEC) at the end of the endurance test. The performance of the engine lubricant at the end of the endurance test with HCNG has also shown no significant changes in viscosity, TBN and wear elements compared to fresh lubricant.
Subramanian, M.
The Study on Catalyst Light-Off Time and Emission Reduction of Turbo Gasoline Direct Injection EU5 Exhaust System2013-01-260810/14/2013
The future powertrain development is characterized by better fuel economy. To meet this, using turbo system in the engine is becoming more frequent in the vehicle development. But using turbo in the engine is only good for power and fuel economy, and not good for emission. That is because the turbo equipped engine loses lots of heat energy at the cold start due to the turbo mass. And thus for turbo engine, it is required to apply the technologies to shorten the catalyst light-off time to reduce the exhaust emissions. Especially when the turbo equipped vehicle is tested on NEDC cycle which is tested on urban low speed cycle at the start of the cycle, its emission is too much to meet the Euro5 regulation. This paper investigates the successful ways to reduce the catalyst light-off time and exhaust emissions to meet the EU5 emission regulation in turbo gasoline direct injection(Turbo GDI) engine. So we do the comprehensive emission tests like increasing the precious metal and cell density, shortening the distance to the catalyst and applying additional device like secondary air. With these diverse tests, we come closer to meeting the EU5 emission.
Jang, ChunSoon, Kim, Sangbeom, Park, Cheolho
Estimated Cost of Emission Control Technologies for Light-Duty Vehicles Part 1 - Gasoline2013-01-05344/8/2013
The cost of meeting standards for conventional pollutant emissions is a perennial bone of contention in arguments over vehicle emission regulations. The public health benefits of the most stringent standards have been repeatedly and conclusively demonstrated, and the control technologies are readily available. Nevertheless, countries with the largest vehicle markets worldwide differ greatly in the rates at which they are willing to adopt the most stringent emission standards-and some of those whose populations would benefit most lag furthest behind. Among the reasons often given for delaying the implementation of stricter standards is the extra cost added to the vehicle by the emission control system. This two-part series paper assesses separately the cost of emission control technologies for gasoline and diesel light duty vehicles. In part one, the paper addresses the cost of gasoline light-duty emission control technology by regulatory level, from early stages to upcoming levels. Focus is given to Three-Way Catalytic converters. Technologies and costs are studied for the two main regulatory programs followed globally, the European and the U.S. emission standards. The paper presents an update on early U.S. and EU emission standards compliance costs as the original estimates have never been updated to reflect actual experience and incorporate the substantial improvements in emission control technologies and reductions in cost that have occurred over time. The paper assesses the costs of required technologies in current terms, using both direct and indirect methods to account for technology changes, correct for inflation, and pull in feedback from experts. Estimates reveal that the cost of taking a 2.0 L, 4-cylinder vehicle, from Euro 1 technology controls to the most stringent proposed EU standard (Euro 6) is close to US$150. Similar costs are found for technologies following the US program.
Posada, Francisco, Bandivadekar, Anup, German, John
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