Browse Topic: Three-way catalysts

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Characteristics of Transient NOx Emissions of HEV under Real Road Driving2020-01-03804/14/2020
To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated. It is found that when the engine is at high-speed and heavy-load conditions, especially when fuel is injected after fuel cut, instantaneous spikes in tailpipe NO emissions could be observed, which means that traffic positions such as crosswalks, speed bumps, expressway entrances, traffic lights, would lead to higher NOx emissions, because the instantaneous fuel cut-off occurs during the acceleration shifting process, the TWC is in an oxygen-rich state. Obvious transient effects were revealed and the results could be used for further reducing NOx emissions from automotive RDE and engine calibration of RDE.
Zhang, Yonghao, Deng, Jun, Li, Qiang, Liu, Yintong, He, Bo, Hu, Zongjie, Bo, Shi, Li, Liguang
Effects of Using an Electrically Heated Catalyst on the State of Charge of the Battery Pack for Series Hybrid Electric Vehicles at Cold Start2020-01-04444/14/2020
Battery models are being developed as a component of the powertrain systems of hybrid electric vehicles (HEVs) to predict the state of charge (SOC) accurately. Electrically heated catalysts (EHCs) can be employed in the powertrains of HEVs to reach the catalyst light off temperature in advance. However, EHCs draw power from the battery pack and hence sufficient energy needs to be stored to power auxiliary components. In series HEVs, the engine is primarily used to charge the battery pack. Therefore, it is important to develop a control strategy that triggers engine start/stop conditions and reduces the frequency of engine operation to minimize the equivalent fuel consumption. In this study, a battery pack model was constructed in MATLAB-Simulink to investigate the SOC variation of a high-power lithium ion battery during extreme engine cold start conditions (-7°C) with/without application of an EHC. The EHC was simulated in MATLAB to determine the energy required to heat the catalyst during cold start conditions. The effect of the EHC in emissions purification at -7°C was studied using a three-way catalyst (TWC) model. The EHC was operated only during the initial few seconds before the engine start to increase the bed temperature of the catalyst. This was found to have a significant impact on exhaust gas emissions even under cold start conditions. However, powering the EHC lowered the SOC of the battery pack, triggering the engine to run and consume more fuel. Hence, an engine ON/OFF control strategy was proposed to control the engine operation conditions and effectively charge the battery pack. The SOC variation of the battery pack and the effects on emissions and fuel consumption were simulated and compared with/without the EHC. The battery model was validated with a control strategy proposed in simulations at 23°C and a parameter study was conducted at -7°C.
Sivakumar, Suchitra, Shingyouchi, Hajime, Yan, Xieyang, Okajima, Toshinori, Yamaguchi, Kyohei, Kusaka, Jin, Nagata, Makoto
Effects of Sub-Chamber Configuration on Heat Release Rate in a Constant Volume Chamber simulating Lean-burn Natural Gas Engines2019-32-05511/24/2020
Sub-chamber is a useful device with regard to sustaining stable operation of compressed natural gas (CNG) engines under lean burn conditions. In our previous studies, we applied a sub-chamber injection system to CNG engines, in which a single injector and a spark plug are mounted in a small sub-chamber. The aim of this study is to investigate the effect of the sub-chamber configuration on heat release in the main combustion chamber. 11 types of sub-chamber with different nozzle number, nozzle diameter, and sub-chamber volume were examined under a condition that pressure is 2.3 MPa, and global equivalence ratio is 0.6. When the sub-chamber with smaller nozzles are used, the penetration velocity of burned gas jet increases. In addition, the velocity also increases with an increasing sub-chamber volume. The high-speed penetration of burned gas jet shortens the period of initial flame development. This is because the high-temperature burned gas quickly reaches to side wall of main chamber, and immediately ignites lean mixtures existing in the main chamber. Consequently, combustion duration time until heat release reaches 90 % is also shortened. On the other hand, the velocity difference between the jets from sub-chambers with different nozzle numbers is small. To predict the penetration velocity, we proposed an empirical formula based on the volume, nozzle diameter and nozzle number of sub-chamber. The jet intensity evaluated from the formula shows correlations with duration times of combustion periods as well as penetration velocities of burned gas jets.
Nada, Yuzuru, Kidoguchi, Yoshiyuki, Yamashita, Yuto, Furukawa, Ryo, Kaya, Ryu, Nakano, Hideaki, Kobayashi, Shinichi
Event-Driven Simulation of Particle-Particle and Particle-Surface Collisions in Ice Crystal Icing2019-01-20146/10/2019
This paper describes an event-driven simulation tool for predicting particle-particle and particle-surface interactions in ice crystal icing (ICI). A new accretion model which is much less empirical than existing models for predicting ICI accretion is also described. Unlike previous models, the new “gouge/bounce model” (GBM) differentiates between (erosion) losses resulting from particle bounce and those resulting from particle gouging. A bounce threshold based on the tangential Stokes number is used to calculate most of the bounce loss. The GBM also predicts ejecta velocities and directions, at least approximately, which is important because most of the mixed-phase mass flux impacting a surface actually bounces off or erodes existing material in ICI, thereby increasing the mass flux downstream. The event-driven simulation tool, denoted COLLIDE, has been applied to two test cases in which accretion growth appeared to be affected by TWC in a manner beyond that which would be expected from the accumulation parameters. An existing correlation-based accretion model (CBM), modified to predict erosion dependence on particle diameter, is also implemented and applied to the test cases. COLLIDE predicted the observed accretion dependence on TWC in a least a qualitative fashion for the majority of model/test case permutations, supporting the hypothesis that collisions between backscattered and incident particles reduces erosion and thereby increases sticking efficiency as observed in experiments with larger particles. The predictions suggest scattering of incident particles by impacts with ejecta is the dominant mechanism responsible for the flux interference effect, not particle size reduction due to particle-particle collisions.
Currie, Thomas Charles
Analysis and Automated Detection of Ice Crystal Icing Conditions Using Geostationary Satellite Datasets and In Situ Ice Water Content Measurements2019-01-19536/10/2019
Recent studies have found that high mass concentrations of ice particles in regions of deep convective storms can adversely impact aircraft engine and air probe (e.g. pitot tube and air temperature) performance. Radar reflectivity in these regions suggests that they are safe for aircraft penetration, yet high ice water content (HIWC) is still encountered. The aviation weather community seeks additional remote sensing methods for delineating where ice particle (or crystal) icing conditions are likely to occur, including products derived from geostationary (GEO) satellite imagery that is now available in near-real time at increasingly high spatio-temporal detail from the global GEO satellite constellation. A recent study using a large sample of co-located GEO satellite and in-situ isokinetic evaporator probe (IKP-2) total water content (TWC) datasets found that optically thick clouds with tops near to or above the tropopause in close proximity (≤ 40 km) to convective updrafts were most likely to contain high TWC (TWC ≥ 1 g m-3). These parameters are detected using automated algorithms and combined to generate a HIWC probability (PHIWC) product at the NASA Langley Research Center (LaRC). Seven NASA DC-8 aircraft flights were conducted in August 2018 over the Gulf of Mexico and the tropical Pacific Ocean during the HIWC Radar II field campaign. The convection sampled during four flights was observed by GOES-16 at 1- or 5-minute intervals, providing the first opportunity to analyze product performance from this new satellite. This paper will (1) present initial comparisons between GOES-16 and IKP-2 datasets during HIWC Radar II, (2) demonstrate GOES-16 products for select periods when high TWC was encountered with an emphasis on three flights with 1-minute imagery, (3) compare GOES observations and derived products from the HIWC Radar I and II campaigns.
Bedka, Kristopher, Yost, Christopher, Nguyen, Louis, Strapp, J. Walter, Ratvasky, Thomas, Khlopenkov, Konstantin, Scarino, Benjamin, Bhatt, Rajendra, Spangenberg, Douglas, Palikonda, Rabindra
Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment2019-01-03154/2/2019
Increased in-cylinder hydrogen levels have been shown to improve burn durations, combustion stability, HC emissions and knock resistance which can directly translate into enhanced engine efficiency. External fuel reformation can also be used to increase the hydrogen yield. During the High-Efficiency, Dilute Gasoline Engine (HEDGE) consortium at Southwest Research Institute (SwRI), the potential of increased hydrogen production in a dedicated-exhaust gas recirculation (D-EGR) engine was evaluated exploiting the water gas shift (WGS) and steam reformation (SR) reactions. It was found that neither approach could produce sustained hydrogen enrichment in a real exhaust environment, even while utilizing a lean-rich switching regeneration strategy. Platinum group metal (PGM) and Ni WGS catalysts were tested with a focus on hydrogen production and catalyst durability. Although 4% additional hydrogen was initially produced in the EGR stream, leading to improvements in the coefficient of variation (CoV) and brake specific fuel consumption (BSFC), catalyst activity decreased within a few hours regardless of the regeneration strategy employed. With an SR catalyst, a small amount of hydrogen was produced in the EGR stream via the WGS reaction but not the SR reaction. Similar to the WGS catalyst testing, the SR catalyst deactivated quickly due to coking. While neither of these approaches displayed acceptable long-term performance, the exhaust environment still poses a significant opportunity for the production of hydrogen rich reformate to deliver improvement in engine efficiency.
Bartley, Gordon, Gukelberger, Raphael, Henderson, Robert, Henry, Cary
Diagnostics of Field-Aged Three-Way Catalyst (TWC) on Stoichiometric Natural Gas Engines2019-01-09984/2/2019
Three-way catalysts have been used in a variety of stoichiometric natural gas engines for emission control. During real-world operation, these catalysts have experienced a large number of temporary and permanent deactivations including thermal aging and chemical contamination. Thermal aging is typically induced either by high engine-out exhaust temperatures or the reaction exotherm generated on the catalysts. Chemical contamination originates from various inorganic species such as Phosphorous (P) and Sulfur (S) that contain in engine fluids, which can poison and/or mask the catalyst active components. Such deactivations are quite difficult to simulate under laboratory conditions, due to the fact that multiple deactivation modes may occur at the same time in the real-world operations. In this work, a set of field-aged TWCs has been analyzed through detailed laboratory research in order to identify and quantify the real-world aging mechanisms. Based on the measured NOx conversion efficiency, we identified that thermal aging was the major aging mechanism for all the field-aged TWCs investigated. Additionally, chemical contaminants such as Phosphorous (P) and Sulfur (S) containing species were also detected at the front portion of the catalyst location that is closer to the engine outlet, leading to decreased NOx and CH4 conversions at this location. However, the NOx and CH4 conversions at the rest of the catalyst locations were mildly impacted due to the sharp axial gradient of these chemical contaminants deposition.
Wang, Di, An, Hongmei, Gong, Jian, Li, Junhui, Kamasamudram, Krishna, Currier, Neal, Yezerets, Aleksey
High Load Expansion of Catalytic EGR-Loop Reforming under Stoichiometric Conditions for Increased Efficiency in Spark Ignition Engines2019-01-02444/2/2019
The use of fuel reformate from catalytic processes is known to have beneficial effects on the spark-ignited (SI) combustion process through enhanced dilution tolerance and decreased combustion duration, but in many cases reformate generation can incur a significant fuel penalty. In a previous investigation, the researchers showed that, by controlling the boundary conditions of the reforming catalyst, it was possible to minimize the thermodynamic expense of the reforming process, and in some cases, realize thermochemical recuperation (TCR), a form of waste heat recovery where exhaust heat is converted to usable chemical energy. The previous work, however, focused on a relatively light-load engine operating condition of 2000 rpm, 4 bar brake mean effective pressure (BMEP). The present investigation demonstrates that this operating strategy is applicable to higher engine loads, including boosted operation up to 10 bar BMEP. By controlling the reforming catalyst boundary conditions, it is possible to achieve fuel reforming without experiencing high temperature exotherms that could be damaging to the catalyst. Additionally, the thermodynamic air handling consequences of operating a highly dilute strategy at high loads is quantified. The results confirm that this operating strategy provides an efficiency benefit at all conditions investigated, with relative efficiency increases of 3-6%, and is therefore applicable over wider regions of the engine operating map.
Szybist, James P., Pihl, Josh, Huff, Shean, Kaul, Brian
Review of Vehicle Engine Efficiency and Emissions2019-01-03144/2/2019
This review paper covers major regulatory and technology developments in 2018 pertinent to tailpipe emissions of greenhouse gases and criteria pollutants. Europe has proposed ambitious reductions in CO2 limits for both light- and heavy-duty sectors. The challenge is compounded with changing measurement norms and a significant shift away from fuel efficient diesels in the light-duty (LD) space. Both incremental and step changes are being made to advance internal combustion. New studies show that in-use NOx emissions from diesels can be much lower than required by the Euro 6 regulation. Discussions have already started on Euro 7 regulations, and the leading regulatory concepts and proposed technical solutions are provided. In the heavy-duty (HD) sector, the progress is outlined in improving engine and vehicle fuel efficiency through the US Department of Energy’s (DOE’s) SuperTruck II program and other representative studies. Common approaches among the participants include hybridization, waste heat recovery, and both open- and closed cycle incremental improvements. Emissions control focus is on evaluating pathways to achieve California’s contemplated low-NOx standards, recently also supported by the US EPA through the Cleaner Trucks Initiative. The challenge is to reduce cold start and low load emissions, requiring innovative engine and after-treatment system solutions. Leading concepts include close-coupled SCR (selective catalytic reduction), use of passive NOx adsorbers, integration of SCR (selective catalytic reduction) on DPFs (diesel particulate filters), low temperature urea or ammonia injection, dual SCR, and active and passive thermal management to raise exhaust temperatures. Work is also underway on a new low load certification cycle. Continued advancement is made on after-treatment components. Aged three-way catalysts (TWCs) and diesel oxidation catalysts (DOCs) are nearing 90% conversion at 150 °C. SCR catalysts continue to improve both their low temperature conversion as well as high temperature durability. Particulate regulations in Europe, China and India are leading to widespread adoption of gasoline particulate filters (GPFs). Lean burn gasoline engines can offer significant fuel economy benefits. NOx control is a challenge, and passive SCR systems and new catalysts are proposed.
Joshi, Ameya
Optimized Driving Cycle Oriented Control for a Highly Turbocharged Gas Engine2019-01-01934/2/2019
The article is focused on a 1-D drive dynamic simulation of a highly turbocharged gas engine. A mono fuel CNG engine has been developed as a downsized replacement of the diesel engine for a medium size van. The basic engine parameters optimization is provided in a steady state operation and a control adjustment is applied to a dynamic vehicle model for a transient response improvement in highly dynamic operation modes of the WLTC (world light duty test cycle), selected for investigation. Vehicle simulation model with optimized control system is used for driving cycle fuel consumption and CO2 emissions predictions compared with the basic engine settings.
Dolecek, Vit, Vavra, Jiri, Skarohlid, Marcel
Regeneration Strategies for Gasoline Particulate Filters2019-01-09694/2/2019
Gasoline particulate filters (GPFs) are extremely effective at reducing tailpipe emissions of particulate mass and particulate number. Especially in the European and Chinese markets, where a particulate number standard is legislated, we see gasoline particulate filters being deployed in production on gasoline direct injected engines. Due to the high temperature in gasoline exhaust, most applications are expected to be passively regenerating without the help of an active regeneration strategy. However, for the few cases where a customer drive cycle has consistently low speed over a long time frame, an active regeneration strategy may be required. This involves increasing the exhaust temperature at the GPF up to around 600 degC so that soot can be combusted. We compare two different ways of achieving these temperatures, namely spark retard and air fuel ratio modulation. The former generates heat in the engine, the latter generates heat in one or more catalysts in the exhaust system. We list some benefits and drawbacks of both methods, and validate our work with experimental data.
Van Nieuwstadt, Michiel, Shah, Anil, Serban, Emil, Martin, Douglas
Investigation of an Advanced Combustion System for Stoichiometric Diesel to Reduce Soot Emissions2019-01-00231/15/2019
Diesel engines are facing increased competition from gasoline engines in the light-duty and small non-road segments, primarily due to the high relative cost of emissions control systems for lean-burn diesel engines. Advancements in gasoline engine technology have decreased the operating cost advantage of diesels and the relatively high initial-cost disadvantage is now too large to sustain a strong business position. SwRI has focused several years of research efforts toward enabling diesel engine combustion systems to operate at stoichiometric conditions, which allows the application of a low-cost three-way catalyst emission control system which has been well developed for gasoline spark-ignited engines. One of the main barriers of this combustion concept is the result of high smoke emissions from poor fuel/air mixing. The current study focuses on improving the combustion system by investigating different fuel/air mixing strategies that enhance fuel spray - piston bowl interaction while simultaneously optimizing the fuel injection system. Computational Fluid Dynamics (CFD) simulations were carried out in conjunction with engine testing to evaluate different piston bowl designs as well as injector nozzle designs with reduced hole diameters to improve in-cylinder mixing and reduce spray over penetration. By using proposed combustion strategy, it was demonstrated that smoke emissions were reduced significantly from baseline under stoichiometric diesel operation.
Chase, Avery, Miwa, Jason, Abidin, Zainal, Cung, Khanh
Optimization of Performance of Oxygen Storage Component (OSC) for NO Reduction in Three Way Catalysts to Achieve BS VI Emission Norms2019-26-01331/9/2019
Current restrictions on environmental pollution worldwide has created the need for new methodologies and technology development which should not only ensure ultra-low emission level from different categories of engine but should also use less fuel resulting in lower carbon dioxide (CO2) emissions. The state-of-art technology to achieve ultra-low emissions placed after engine in exhaust line is a ‘catalytic converter’. Catalytic converter is an after treatment device which typically oxidizes or reduces the toxic pollutants emitted by any engine to carbon dioxide (CO2), nitrogen (N2) and water (H2O). Catalytic converters used in Gasoline / CNG operated vehicles contains oxygen storage component as a key component for supplying oxygen in rich mode of operation and the oxygen concentration release rate is function of gas concentration and air to fuel ratio (A/F) or lambda (λ). Conventionally, the vehicles (two wheelers) operated using mechanical method such as carburetor, a source for injection fuel in the engine and the lambda range produced from this method is of wide window (0.95-1.06). The catalyst located downstream the engine needs an optimum amount of oxygen storage component required to supply oxygen in rich mode of operation and excess oxygen concentration released during these period results in to a significant drop in oxygen storage capacity (OSC). The drop in OSC corresponds to drop in NOx conversion efficiency. Moving from BS IV to BS VI, the NOx conversion requirement is over 90% including deterioration factor limit and thus requires a tight control in terms of lambda as well as oxygen storage component optimization. The lambda control can be achieved by switching from mechanical method of injection to electronic method i.e. electronic fuel injection (EFI) and subsequently the need for oxygen storage component optimization is required. Illustrative case studies has been presented in this paper, to demonstrate the role of oxygen storage component in NOx conversion.
Kumar, Arvind, Rajan, Bosco, Harkonen, Matti, Trigunayat, Alok, Muthusamy, Vishnuvarthan, Mishra, Sushil
Impact of Secondary Air Injection on Small Engine Motorcycle Intended for BS VI Applications2018-32-006810/30/2018
On April 2020, India will move from Bharat Stage IV to Bharat Stage VI where the combined emission limit of Total Hydrocarbons (THC) and Nitrogen oxides (NOx) of 0.79g/km will independently reduce to 0.1g/km and 0.06g/km respectively. This reduction in emission limit however may prove to be challenging for small engines (below 200 cc) with the existing generation of engines predominantly in cold operating conditions. When the vehicle is started after soaking (engine turned off for few hours), considerable amount of THC emission is generated which can be attributed to poor fuel vaporization and incomplete combustion due to flame quenching in the combustion chamber. Also, the catalyst is inactive to chemical reactions until the accumulated heat energy from the hot exhaust mass flow elevates the catalyst temperature to facilitate efficient conversion of THC, CO and NOx to H2O, CO2 and N2. This temperature point is termed as catalyst light off temperature. Hence, most of the tail pipe emissions vented out to the atmosphere in cold phase is without after-treatment. In case of two wheelers on a typical drive cycle, around 60% (fig. 3) of the total tail pipe THC emitted is before the catalyst attains light off temperature. Thus, any form of exhaust gas treatment that can lead to reduction of pre-catalyst emissions and faster catalyst light off, will prove to be beneficial in overall emission reduction. In this context, Secondary Air injection (SAI) is explored as an effective exhaust treatment method in tackling cold phase emissions. In the present study, a series of tests were conducted on a single cylinder 200cc engine fitted with a Mechanical throttle body and electronic fuel injection system. From these tests, various aspects of cold phase emissions were characterized. This paper explores in detail the impact of SAI on pre-catalytic oxidation of THC, catalyst temperatures and catalytic reactions. Present study also gives an insight into the operation of SAI such that it does not compromise the functionality of the three way catalyst (TWC). It was also observed that it is beneficial to have different modes of SAI operation such as open loop mode without oxygen sensor feedback, closed loop mode with oxygen sensor feedback and engine load specific operation of SAI. Upon application of best optimal configuration of SAI a reduction of 25% in THC and 4% of NOx was observed.
Sabu, Abhijith, Reddemreddy, Pramod, Parmar, Manojkumar
Passive Metal Hydride Module Concept for Enhanced Low-Temperature Catalyst Performance2018-01-50015/4/2018
A technology concept applicable to stoichiometric and lean burn engine operation-a metal hydride (MHx) module for the generation of H2 via reaction with gaseous H2O-was evaluated for the introduction of low levels of H2 (ca. 500 ppmv) into internal combustion engine exhaust for the enhancement of catalyst performance at low temperatures, such as during cold-start. Projected MHx module packaging volume, replacement frequency, and costs over the lifetime of a light duty vehicle are excessive, and considered prohibitive to technology viability.
Bradford, Michael C.
The Development of Low Temperature Three-Way Catalysts for High Efficiency Gasoline Engines of the Future: Part II2018-01-09394/3/2018
It is anticipated that future gasoline engines will have improved mechanical efficiency and consequently lower exhaust temperatures at low load conditions, although the exhaust temperatures at high load conditions are expected to remain the same or even increase due to the increasing use of downsized turbocharged engines. In 2014, a collaborative project was initiated at Ford Motor Company, Oak Ridge National Lab, and the University of Michigan to develop three-way catalysts with improved performance at low temperatures while maintaining the durability of current TWCs. This project is funded by the U.S. Department of Energy and is intended to show progress toward the USDRIVE target of 90% conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at 150 °C after high mileage aging. The testing protocols specified by the USDRIVE ACEC team for stoichiometric S-GDI engines were utilized during the evaluation of experimental catalysts at all three facilities. This paper summarizes work performed at Ford on the development of a catalyst formulation with significantly lower lightoff temperatures than a current production TWC after aging on a high temperature 4-mode durability cycle. The new catalyst consists of rhodium post-impregnated onto an overlayer of titanium deposited onto a silica-stabilized Al2O3 support. A rhodium loading study revealed that the lowest T90 s after 4-mode aging were obtained with 0.5% Rh. A titanium loading study showed that that the best performance after 4-mode aging was obtained with 8% titanium, which corresponded to the monolayer coverage of titanium. TEM analysis confirmed that the titanium monolayer remained well dispersed after the high temperature aging. A fresh sample of the optimized catalyst was evaluated after sulfur poisoning and after a stoichiometric desulfation.
Theis, Joseph R., Getsoian, Andrew (Bean), Lambert, Christine K.
Solid Particle Number and Ash Emissions from Heavy-Duty Natural Gas and Diesel w/SCRF Engines2018-01-03624/3/2018
Solid and metallic ash particle number (PN) and particulate matter (PM) mass emission measurements were performed on a heavy-duty (HD) on-highway diesel engine and a compressed natural gas (CNG) engine. Measurements were conducted under transient engine operation that included the FTP, WHTC and RMC. Both engines were calibrated to meet CARB ultra low NOX emission target of 0.02 g/hp-hr, a 90% reduction from current emissions limit. The HD diesel engine final exhaust configuration included a number of aftertreatement sub-systems in addition to a selective catalytic reduction filter (SCRF). The stoichiometric CNG engine final configuration included a closed coupled Three Way Catalyst (ccTWC) and an under floor TWC (ufTWC). The aftertreatment systems for both engines were aged for a full useful life (FUL) of 435,000 miles, prior to emissions testing. PM mass emissions from both engines were comparable and well below the US EPA emissions standard. However, the CNG engine emitted a substantially higher number of solid particles, larger and smaller than 25 nm in diameter, compared to the number of particles emitted from the HD diesel engine for each of the three transient cycles tested. The CNG engine metallic ash particle number emission was also much higher than that of the diesel. The stringent solid particle number regulation in the EU and China will address the CNG particle number emission problem. However, in the USA there is no such regulation to specifically address particle number emissions, which is a short coming. Ultrafine PN emissions from engines is a health concern. Reducing solid particle number emissions from old and new CNG engines to a level comparable to that of a diesel with DPF is an important task that needs to be addressed by policy makers around the globe.
Khalek, Imad A., Badshah, Huzeifa, Premnath, Vinay, Brezny, Rasto
Water Recovery from Gasoline Engine Exhaust for Water Injection2018-01-03694/3/2018
Water injection (WI) can improve gasoline engine performance and efficiency, and on-board water recovery technology could eliminate the need for customers to refill an on-board water reservoir. In this regard, the technical feasibility of exhaust water recovery (EWR) is described in this paper. Water injection testing was conducted at a full load condition (5000 rpm/18.1 bar BMEP) and a high load condition (3000 rpm/14.0 bar BMEP) on a turbocharged gasoline direction injection (GTDI) engine. Water recovery testing was conducted both after the exhaust gas recirculation (EGR) cooler and after the charge air cooler (CAC) at a high load (3000 rpm/14.0 bar BMEP), as well as a part load (2080 rpm/6.8 bar BMEP) condition, at temperatures ca. 10-15 °C below the dew point of the flow stream. Three types of water separation designs were tested: a passive cyclone separator (CS), a passive membrane separator (MEM), and an active separator (AS). Water injection and recovery amount was also simulated on three different drive cycles: FTP, WLTP and US06. The results showed that using water injection at full load reduced fuel enrichment requirements and reduced knock, yielding a 13% fuel economy improvement. Engine testing at high load condition showed that WI had a negligible effect on three-way catalyst (TWC) conversion efficiency under stoichiometric conditions. EWR was shown to be effective both post EGR cooler and post CAC. The CS and AS showed better performance than the MEM separator for water recovery. With the CS, up to ~100% condensate separation efficiency was achieved with very low pressure drop (~1 kPa). All the condensate samples collected with low sulfur fuel showed near neutral pH levels (6.5-8.5). From the appearance of the condensate samples, MEM-collected water had better quality than the CS and AS collected water. Water collected after the CAC showed better quality and lower pH than that collected downstream of the EGR cooler. Water recovered from post-TWC EGR showed better quality and higher pH than that collected from pre-TWC EGR. Water injection and collection simulations on three different drive cycles using GT-Drive showed that more water could be collected than was required for injection on FTP and WLTP drive cycles, while 40~70% of required water for injection could be collected on the US06 cycle.
Sun, Yong, Fischer, Michael, Bradford, Michael, Kotrba, Adam, Randolph, Eric
Experimental and Kinetic Modeling of Degreened and Aged Three-way Catalysts: Aging Impact on Oxygen Storage Capacity and Catalyst Performance2018-01-09504/3/2018
The aging impact on oxygen storage capacity (OSC) and catalyst performance was investigated on one degreened and one aged (hydrothermally aged at 955 °C for 50 h) commercial three-way catalyst (TWC) by experiments and modeling. The difference of OSC between the degreened and aged TWCs was dependent on catalyst temperature. The largest difference was found at 600 °C, at which the amount of OSC decreased by 45.5%. Catalyst performance was evaluated through lightoff tests at two simulated engine exhaust conditions (lean and rich) on a micro-reactor. The aging impact on the catalyst performance was different under lean and rich environments and investigated separately. At the lean condition, oxidation of CO and C3H6 was significantly suppressed while oxidation of C3H8 was relatively less degraded. At the rich condition, the inhibition effect was more pronounced on the aged TWC and inhibiting hydrocarbon species from C3H6 partial oxidation can survive at temperatures up to 450 °C. However, NO reduction activity declined less compared to CO and C3H6 oxidation. More NH3 formed at low temperature and N2O formation was suppressed on the aged TWC. A generic TWC model including a dual-site oxygen storage sub-model and PGM kinetics was developed to predict the aging impact on dynamic OSC and catalyst performance. The PGM kinetics include oxidation of H2, CO, and hydrocarbons as well as water-gas shift (WGS) and hydrocarbon steam reforming. NO reduction kinetics including N2O and NH3 formation and decomposition were also considered. The TWC models were calibrated on the degreened and aged TWCs separately based on experimental data. With the dual-site OSC model and calibrated kinetics, the dynamic OSC and lightoff performance on the fresh and aged TWCs were successfully predicted. The resulting changes of the OSC as well as lightoff performance due to aging were quantified and discussed with the help of the TWC models.
Gong, Jian, Wang, Di, Li, Junhui, Kamasamudram, Krishna, Currier, Neal, Yezerets, Aleksey
Development of Three-Way Catalysts Enhanced NOx Purifying Activity2018-01-09424/3/2018
Growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. One of the key technologies is a new OSC material that has low surface area (SA) and high OSC performance. We enhanced the pyrochlore- ceria/zirconia (CZ) which has a very small SA. In order to enhance the heat resistance and promote the OSC reaction, we selected and optimized the additive element. This material showed high OSC performance especially in the temperature range of 400 degrees or less. Another key technology is washcoat structure that has high gas diffusivity by making connected pore in the washcoat (New pore forming technology). The connected pore means that some pores are connected each other unlike conventional structure which has isolated pores. Compared with the conventional washcoat structure, the new technology has high gas diffusivity. As a result, the developed catalyst showed high NOx purifying activity which enabled nearly 30% reduction of precious metal usage.
Chinzei, Isao, Saito, Yoshinori, Morikawa, Akira, Kato, Satoru, Ohashi, Tatsuya, Hirao, Tetsuhiro
Modelling of a Coupled Catalyst and Particulate Filter for Gasoline Direct Injection Engines2018-01-09864/3/2018
There has been extensive research in the development of Gasoline Direct Injection ‘GDI’ engine exhaust systems with the aim of reducing engine-out emissions and meeting legislation requirements. Depending on the room available for packaging the exhaust system, the engine may be equipped with a single catalyst or two catalysts one close to the engine and another one located further downstream. With the strict particulate matter emission regulations of GDI engine, the engine has to be equipped with a Gasoline Particulate Filter ‘GPF’ in addition to the Closed Coupled Catalyst ‘CCC’. The common practice is to have the GPF further downstream the catalyst. In this paper, an assessment method is carried for a new design of a hot end exhaust system. The new design brings the GPF closer to ‘CCC’ to be packed in the same enclosure. The gas flow velocity and pressure distributions inside the exhaust system are identified using CFD for a uniform exhaust gas flow inlet conditions. The system also has been investigated considering a typical inlet exhaust gas flow conditions from a GDI engine turbocharger. Results showed that the new design offers better flow uniformity in both the catalyst and GPF. Moreover, lower pressure drop across the whole system is observed relative to the baseline design with the GPF separated from the catalyst through an intermediate exhaust pipe. The GPF enclosure end shape is found to have influence on the flow uniformity and pressure drop.
Cirstea, Remus, Abo-Serie, Essam F., Bastien, Christophe, Guo, Hua
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
Effects of NO X Storage Component on Ammonia Formation in TWC for Passive SCR NO X Control in Lean Gasoline Engines2018-01-09464/3/2018
A prototype three-way catalyst (TWC) with NOX storage component was evaluated for ammonia (NH3) generation on a 2.0-liter BMW lean burn gasoline direct injection engine as a component in a passive ammonia selective catalytic reduction (SCR) system. The passive NH3 SCR system is a potential approach for controlling nitrogen oxides (NOX) emissions from lean burn gasoline engines. In this system, NH3 is generated over a close-coupled TWC during periodic slightly-rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. Adding a NOX storage component to a TWC provides two benefits in the context of a passive SCR system: (1) enabling longer lean operation by storing NOX upstream and preserving NH3 inventory on the downstream SCR catalyst; and (2) increasing the quantity and rate of NH3 production during rich operation. Since the fuel penalty associated with passive SCR NOX control depends on the fraction of time that the engine is running rich rather than lean, both benefits (longer lean times and shorter rich times achieved via improved NH3 production) will decrease the passive SCR fuel penalty. However, these benefits are primarily realized at low to moderate temperatures (300-500 °C), where the NOX storage component is able to store NOX, with little to no benefit at higher temperatures (>500 °C), where NOX storage is no longer effective. This study discusses engine parameters and control strategies affecting the NH3 generation over a TWC with NOX storage component.1
Prikhodko, Vitaly, Pihl, Josh, Toops, Todd, Parks, James
Study of an Aftertreatment System for HLSI Lean-burn Engine2018-01-09454/3/2018
Lean-burn is an effective means of reducing CO2 emissions. To date, Homogenous Lean Charge Spark Ignition (HLSI) combustion, which lowers emissions of both CO2 and NOx, has been studied. Although HLSI realizes lower emission, it is a major challenge for lean-burn engines to meet SULEV regulations, so we have developed a new aftertreatment system for HLSI engines. It consists of three types of catalysts that have different functions, as well as special engine control methods. As the first stage in achieving SULEV emissions, this study focused on enhancing performance under lean conditions. HLSI engine exhaust gases contain high concentrations of hydrocarbons, including a large amount of paraffin, which are difficult to purify, rather than low concentrations of NOx. Therefore, the key point in low emissions is to purify not only NOx, but also high concentrations of paraffin at the same time. Other issues include maintaining high performance under stoichiometry operation and reducing N2O emissions. To resolve these issues, it is important to focus on the division of catalyst roles and their arrangement, and the modification of catalyst material. In this study, an aftertreatment system with three catalysts was developed. TWC was applied for the first catalyst to purify stoichiometry exhaust gases, and a new type of catalyst was used for the second and third catalysts in order to purify hydrocarbon and NOx under lean conditions. The new catalyst was an improvement based on a lean NOx trap catalyst, and was added to a paraffin purification material that highly enhances PGM activity by suppressing oxygen poisoning in PGMs, which hinders paraffin oxidation. The approach to enhancing NOx purification and reducing N2O emissions is to arrange the second and third catalysts with the optimal temperature properties in each position. This layout covers a wide temperature range for NOx performance and reduces N2O emissions. This system was evaluated on an engine bench using a steady lean-rich cycle test. High performance under lean conditions was confirmed.
Takeori, Hiroki, Wada, Katsuji, Matsuo, Yuichi, Morita, Tomoko, Konomoto, Takashi, Murata, Yuichiro, Kimura, Munekazu, Miyauchi, Atsuhiro
Cold-Start Hydrocarbon Speciation and Trap Materials for Gasoline Engines2018-01-09404/3/2018
Efficient hydrocarbon (HC) trap materials have been developed to trap the major emitting HC compounds from gasoline direct injection engines. Online FTIR measurements on different test cycles and catalytic systems showed that AHC, C5 compounds, and CH4 were the most emitted species at cold-start phase (up to 100 sec). Making AHC and C5 as targets for improving the HC light-off, lab scale reactor set-up was established with toluene and iso-pentane feed pumping system along with propane-propene mixture. TGA screening experiments conducted with ex-situ toluene adsorption and the results revealed that BEA type materials have moderate to higher HC trapping temperature and HC storage capacity. In the present investigation, BEA-HS exhibited outstanding stability and trapping ability even after 850 °C hydrothermal aging. PGM and TM based BEA materials were evaluated for HC-TPD experiments with TWC gas composition. Interestingly, adsorption properties of the samples at various aging temperatures are well correlated with pore size and structure. Functionalized micro-pore materials with transition based metals showed substantial improvement on toluene desorption temperature. Based on these studies and the test results, advanced HC trap catalysts have been designed which demonstrated potential advantage over conventional TWC.
Narayana Rao, Komateedi, Kim, Mi-Young, Song, Jinwoo, Na, SeungChul, Han, Hyun Sik
Benefits of Pd Doped Zeolites for Cold Start HC/NOx Emission Reductions for Gasoline and E85 Fueled Vehicles2018-01-09484/3/2018
In the development of HC traps (HCT) for reducing vehicle cold start hydrocarbon (HC)/nitrogen oxide (NOx) emissions, zeolite-based adsorbent materials were studied as key components for the capture and release of the main gasoline-type HC/NOx species in the vehicle exhaust gas. Typical zeolite materials capture and release certain HC and NOx species at low temperatures (<200°C), which is lower than the light-off temperature of a typical three-way catalyst (TWC) (≥250°C). Therefore, a zeolite alone is not effective in enhancing cold start HC/NOx emission control. We have found that a small amount of Pd (<0.5 wt%) dispersed in the zeolite (i.e., BEA) can significantly increase the conversion efficiency of certain HC/NOx species by increasing their release temperature. Pd was also found to modify the adsorption process from pure physisorption to chemisorption and may have played a role in the transformation of the adsorbed HCs to higher molecular weight species. Both these processes led to desorption at higher temperatures and more efficient conversion. Laboratory studies on BEA zeolite, with and without Pd, are described. These studies show the benefits of Pd-zeolite on the capture and release of HC/NOx species such as ethanol, ethylene, propylene, and toluene. It was also observed that the benefit of Pd in the zeolite was not stable under high-temperature rich conditions. This indicates a possible limitation for the application of Pd-beta in stoichiometric engine exhaust. A base metal was also added to the Pd-zeolite that stabilized emissions trapping after high-temperature rich aging conditions. Parallel vehicle emission test results also confirmed the benefits of the base metal-stabilized Pd-BEA zeolite in reducing cold start HC emissions.
Xu, Lifeng, Lupescu, Jason, Ura, Justin, Harwell, Amy, Paxton, William A., Nunan, John, Alltizer, Chad
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
A New Catalyzed HC Trap Technology that Enhances the Conversion of Gasoline Fuel Cold-Start Emissions2018-01-09384/3/2018
Passive in-line catalyzed hydrocarbon (HC) traps have been used by some manufacturers in the automotive industry to reduce regulated tailpipe (TP) emissions of non-methane organic gas (NMOG) during engine cold-start conditions. However, most NMOG molecules produced during gasoline combustion are only weakly adsorbed via physisorption onto the zeolites typically used in a HC trap. As a consequence, NMOG desorption occurs at low temperatures resulting in the use of very high platinum group metal (PGM) loadings in an effort to combust NMOG before it escapes from a HC trap. In the current study, a 2.0 L direct-injection (DI) Ford Focus running on gasoline fuel was evaluated with full useful life aftertreatment where the underbody converter was either a three-way catalyst (TWC) or a HC trap. A new HC trap technology developed by Ford and Umicore demonstrated reduced TP NMOG emissions of 50% over the TWC-only system without any increase in oxides of oxygen (NOx) emissions. Other HC trap technologies had at best a 25% NMOG emission reduction. Parallel laboratory reactor studies were conducted in an effort to understand the improved trapping and NMOG combustion features of the newly developed HC trap. Increased trapping efficiency of certain aromatics (toluene) and alkenes (2-methylpropene) was assigned to rapid and efficient polymerization of these species due to a combination of strong Brønsted acidity, precious metal (i.e., Pd), and base redox active metals. During the emissions desorption phase, the combustion of the adsorbed NMOG occurred without gas-phase oxygen due to the delayed desorption of the large NMOG molecules coupled with the high activity of the base redox active metal in the presence of steam. Besides acting as a source of oxygen during combustion, the ion-exchanged form of the base metal also stabilized Pd against sintering during the hot, four-mode aging process.
Lupescu, Jason, Xu, Lifeng, Jen, Hung-Wen, Harwell, Amy, Nunan, John, Alltizer, Chad, Denison, Gregory
Numerical Analysis of the Impact of Water Injection on Combustion and Thermodynamics in a Gasoline Engine Using Detailed Chemistry2018-01-02004/3/2018
Water injection is a promising technology to improve the fuel efficiency of turbocharged gasoline engines due to the possibility to suppress engine knock. Additionally, this technology is believed to enable the efficient operation of the three-way catalyst also at high-load conditions, through limiting the exhaust temperature. In this numerical study, we investigate the effect of water on the chemical and thermodynamic processes using 3D computational fluid dynamics (CFD) Reynolds-averaged Navier–Stokes (RANS) with detailed chemistry. In the first step, the influence of different amounts of water vapor on ignition delay time, laminar flame speed, and heat capacity is investigated. In the second step, the impact of water vaporization is analyzed for port and direct injection. For this purpose, the water mass flow and the injection pressure are varied. A steady-state, medium-speed, high-load engine operating point is investigated with focus on the effect of water injection on knock tendency and exhaust temperature. The impact of water injection on oxidation chemistry and auto-ignition is investigated using a detailed ethanol toluene reference fuel (ETRF) (ethanol, iso-octane, n-heptane, and toluene) reaction scheme. The combustion is predicted using the level-set method for flame propagation and a well-stirred reactor model in the unburned zone to predict auto-ignition. The laminar flame speed is retrieved from precompiled look-up tables calculated for each specific composition (surrogate, diluents, and oxidizer). Engine knock is evaluated using Bradley’s detonation diagram (Bradley et al. 2002, Gu et al. 2003). With numerical models, we are able to separate the influence of chemical and thermodynamic properties by using different flame speed tables, thermodynamic properties, and third body efficiencies for pressure-dependent reactions. This allows to quantify and rank the impact of the investigated properties. The impact on the knock limit spark advance in descending order of importance is found to be laminar flame speed, heat of vaporization, chemical equilibrium, water vapor heat capacity, third body efficiency, and ignition delay time.
Netzer, Corinna, Franken, Tim, Seidel, Lars, Lehtiniemi, Harry, Mauss, Fabian
Impacts of Drive Cycle and Ambient Temperature on Modelled Gasoline Particulate Filter Soot Accumulation and Regeneration2018-01-09494/3/2018
Gasoline particulate filters (GPF) are used as an efficient solution to reduce particulate matter (PM) emissions on gasoline vehicles. GPFs are ceramic wall-flow filters and are normally located downstream of conventional three-way catalysts (TWC) [1]. The study in this paper is intended to evaluate the impact of drive cycle and ambient temperature on modelled GPF soot accumulation and regeneration. The test data were obtained through real road testing in Chinese cities including Nanjing, Hainan and Harbin. Five 2.0 L gasoline turbo direct-injection (GTDI) prototype vehicles from several China Stage 6 applications were employed for the road tests. The results of the testing indicated that a drive cycle with low engine speed and engine load, like a typical city road in rush hour traffic in Nanjing, had a low probability of generating high GPF temperatures (> 600 °C) and sufficient oxygen to regenerate the GPF. However, the soot accumulation model performed as expected [2] and the soot regeneration model demonstrated sufficient opportunity to oxidize soot prior to excessive soot accumulation, even under the limited city drive cycle conditions. Ambient temperatures during cold engine starts played a significant role in the amount of modeled soot being generated during any given drive cycle. Considerably more soot was generated during cold starts at low ambient conditions (< 0 °C) due to the increase in fuel mass and the use and duration of compression injection to aid in catalyst heating.
Yue, Hongchao, Lehmen, Allen, Van Nieuwstadt, Michiel, Mason, Gregory, Barwick, Matt, Warm, David, Pebley, Kirk
Development of Highly Durable Zeolites as Hydrocarbon Trap Materials for Automotive Catalysts2018-01-09474/3/2018
Low-temperature activity is an important requirement for automotive catalysts. In particular, most of the tailpipe emissions occur right after the engine starts (cold emissions). These emissions can be effectively reduced by using a trap material such as zeolite for hydrocarbon (HC) adsorption [1, 2, 3, 4, 5, 6, 7, 8, 9]. However, using zeolite as a trap material in automotive catalyst is limited due to its low durability under hydrothermal aging conditions. That is the reason why zeolites can be often used for diesel engines which usually run at lower temperature than the gasoline engines during entire mode driving. In most cases, zeolites need to be placed away from large thermal loads in order to take advantage of their adsorption abilities. In general, the thermal endurance of close-coupled catalysts for gasoline powered vehicles proceeds at about 1000 °C in the presence of water. Under these conditions, the zeolite structure would be decomposed by the dissociation of aluminum from the zeolite frameworks [10]. Through this study, we show that the hydrothermal durability of zeolite can be dramatically improved by chemical modification of zeolite with zirconium phosphate. This improvement strategy works well, especially for β-type zeolites (BEAs) with low SiO2/Al2O3 ratio, which can be easily decomposed by hydrothermal aging at around 1000 °C. We also found that this modified BEA worked well as HC trap material and showed an enormous reduction of cold HC emissions with Pd/Rh three-way catalyst (TWC). In the engine test evaluations with the close-coupled TWC + TWC and TWC + HC trap system as aged catalysts, effects of this HC trap catalyst on cold emissions were observed. It is found that HC emission decrease by up to 43% when compared to those from the corresponding TWC + TWC system which does not have any zeolite. In addition, a detailed analysis of this effect proved this improvement to be due to the adsorption-desorption process of zeolite and the purification process by TWCs.
Endo, Yoshinori, Nishikawa, Joe, Iwakura, Hironori, Inamura, Masaaki, Wakabayashi, Takashi, Nakahara, Yuunosuke, Ogasawara, Masataka, Kato, Sumio
Numerical Optimization of the Combustion System of a HD Compression Ignition Engine Fueled with DME Considering Current and Future Emission Standards2018-01-02474/3/2018
A genetic algorithm (GA) optimization methodology is applied to the design of the combustion system of a heavy-duty (HD) Diesel engine fueled with dimethyl ether (DME). The study has two objectives, the optimization of a conventional diffusion-controlled combustion system aiming to achieve US2010 targets and the optimization of a stoichiometric combustion system coupled with a three way catalyst (TWC) to further control NOx emissions and achieve US2030 emission standards. These optimizations include the key combustion system related hardware, bowl geometry and injection nozzle design as input factors, together with the most relevant air management and injection settings. The GA was linked to the KIVA CFD code and an automated grid generation tool to perform a single-objective optimization. The target of the optimizations is to improve net indicated efficiency (NIE) while keeping NOx emissions, peak pressure and pressure rise rate under their corresponding target levels. Compared to the baseline engine fueled with DME, the results of the study provide an optimum conventional diesel combustion system with 3.3% NIE improvement and an optimum stoichiometric combustion system that offers a 0.6% NIE improvement keeping tailpipe NOx values below 1% of the original levels. Due to the methodology, not only the optimum combustion system configuration is described, but also the cause-effect relations between the most relevant inputs and the optimization outputs are identified and analyzed. The new geometry shapes reduce heat transfer (HT) losses by controlling the surface area while EGR is still critical to control NOx emissions for both combustion systems. This study confirms the potential of DME as a promising fuel for the future generation of compression ignition engines, and demonstrates the benefits of co-optimizing the fuel properties, combustion chamber hardware and air management plus injection settings.
Benajes, Jesus, Novella, Ricardo, Hernández-López, Alberto, Kokjohn, Sage
Impact of Siloxanes in Biomethane on the Performance of a CNG Vehicle04-11-01-00033/23/2018
In this article, the results of experiments to determine the effects of silicon-containing compounds in biogas on the performance of spark-ignited gas engines for use in CNG vehicles are presented. Initial research was performed on micro-CHP units, which have many features common with automotive engines, to identify engine components sensitive for silica deposition prior to investigating a practical CNG engine. The experiments on the micro-CHP units revealed that the catalyst was the most sensitive part for silica fouling, with strong impact on the reduction of NOx. With the insight gained from these experiments, an 9-week endurance test was performed on a light-duty CNG vehicle. While the wideband-type lambda sensor originally installed upstream of the catalyst did not fail during the test, an additional switching-type lambda sensor positioned upstream of the catalyst was found to be most sensitive to silica deposition, causing a false signal regarding the oxygen content in the exhaust gas (“failure”). In contrast to the micro-CHP test, the catalyst used in the CNG vehicle was not affected by silica deposition under the experimental conditions used. Micro-CHP experiments revealed that different catalyst types can show different sensitivity towards silica deposition, which explain the relative robustness of the vehicle catalyst regarding silica deposition. Investigation of the performance of the different catalysts used in the market for CNG vehicles is required to quantify the potential impact of siloxanes in biomethane on the installed fleet.
van Essen, Martijn, Visser, Pieter, Gersen, Sander, Levinsky, Howard
A Theoretical Study of Interaction between Platinum and Oxide Support for Exhaust-Gas Purification Catalyst2017-32-000911/5/2017
We investigated the interaction between the platinum and oxide support based on the HSAB (Hard-Soft-Acid-Base) concept to obtain guidelines for a superior exhaust-gas purification catalyst. The Density Functional Theory (DFT) calculation provided the chemical potential (μ) and chemical hardness (η) via the eigenvalue of the Valence Band Maximum and Conduction Band Minimum. Moreover, it was found that the interaction depends on the μ and η, e.g., the metallic Pt cluster (Pt1, Pt3) had a greater interaction with the oxide supports having a lower η, on the other hand, the oxidized Pt cluster (Pt1O1, Pt1O2, Pt1O3, Pt1O4, Pt3O6) tends to be stabilized on the oxide support with a higher μ. These results could be explained by the HSAB concept. It was also found that the oxidation energy of the supported Pt cluster well corresponds to the actual valency of the supported Pt, furthermore, the particle size of the Pt after the thermal treatment depends on the μ of the oxide supports. The activities of the Pt catalysts were successfully analyzed by a regression analysis. The activities of the supported Pt catalysts also depended on the μ and η values. Hence, the catalytic activities might be predicted by estimation of μ and η, i.e., the DFT calculation should be able to accelerate the development of the exhaust-gas purification catalyst with a higher efficiency and reasonable cost.
Miura, Kazuya, Tsuda, Toyofumi, Hikasa, Akio, Minokoshi, Hiroyuki, Kimata, Fumikazu, Watanabe, Ryo, Fukuhara, Choji
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
Two Concepts of Pumping Fuel in a Gasoline Injector2017-24-01029/4/2017
In this paper, two concepts of fuel pumping methods using solenoid, for gasoline injection in engines, are discussed. The fuel pump is integrated within the injector in these concepts, which makes the fueling system, simple, compact and less expensive. This integrated gasoline pump injector (GPI) is aimed at catering to the upcoming stringent emission norms, as it enables the usage of closed-loop fuel correction with the help of an electronic control unit (ECU), based on the exhaust lambda feedback. A solenoid and spring arrangement is used in this injector design, where the fuel gets pressurized in a pumping chamber, and the pressurized fuel is then injected through orifices to produce spray in the intake port. Two concepts are used for pressurizing the fuel. First concept uses a spring to pump the fuel and a solenoid to retract the plunger. Second concept uses solenoid to pump the fuel and spring to retract the plunger. The magnetic and hydraulic behaviors of the injector are different in the studied cases and offers choice to choose the concept according to the application. The first concept relies on the spring for the injector’s hydraulic performance and control, whereas the second one relies on the solenoid. The solenoid responds faster than the spring, and by virtue of this, the second concept is seen more suitable for better hydraulic discharge control. The electromagnetic and hydraulic characteristics of both the concepts are studied using simulation and tests, and the results are presented in this work
Balasubramanian, N, Sethuraman, Jayabalan, Iwaszkiewicz, Titus
Lean Breakthrough Phenomena Analysis for TWC OBD on a Natural Gas Engine using a Dual-Site Dynamic Oxygen Storage Capacity Model2017-01-09623/28/2017
Oxygen storage capacity (OSC) is one of the most critical characteristics of a three-way catalyst (TWC) and is closely related to the catalyst aging and performance. In this study, a dynamic OSC model involving two oxygen storage sites with distinct kinetics was developed. The dual-site OSC model was validated on a bench reactor and a natural gas engine. The model was capable of predicting temperature dependence on OSC with H2, CO and CH4 as reductants. Also, the effects of oxygen concentration and space velocity on the amount of OSC were captured by the model. The validated OSC model was applied to simulate lean breakthrough phenomena with varied space velocities and oxygen concentrations. It is found that OSC during lean breakthrough is not a constant for a particular TWC catalyst and is dependent on space velocity and oxygen concentration. Specifically, breakthrough time exhibits a non-linear, inverse correlation to oxygen flux. Breakthrough OSC increases slightly with oxygen concentration and increases significantly as space velocity decreases. Moreover, at high space velocities, the majority of breakthrough OSC is from the PGM-ceria surface site (kinetically controlled). At low space velocities, there is a substantial amount of breakthrough OSC from the sub-surface ceria site (diffusion controlled). Correlations of breakthrough time and breakthrough OSC as a function of oxygen concentration and space velocity were established. An alternative methodology of TWC OBD with the use of developed correlations was presented and discussed.
Gong, Jian, Wang, Di, Brahma, Avra, Li, Junhui, Currier, Neal, Yezerets, Aleksey, Chen, Pingen
Impact of Substrate Geometry on Automotive TWC Gasoline (Three Way Catalyst) Performance2017-01-09233/28/2017
Tightening global emissions standards are driving automotive Original Equipment Manufacturer’s (OEM’s) to utilize Three Way Catalyst (TWC) aftertreatment systems that can perform with greater efficiency and greater measured control of Precious Group Metals (PGM) use. At the same time, TWC aftertreatment systems minimize exhaust system pressure drops. This study will determine the influence of catalyst substrate cell geometry on emission and PGM usage. Additionally, a study of lightoff and backpressure comparisons will be conducted. The two substrate configurations used are hex/750cpsi and square/750cpsi.
Szczepanski, Ed, Koda, Akinori, Sweeney, Daniel, Polcyn, Nick, Ota, Mitsunori
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
Reducing Catalyst Zone Flow for Robust Emissions Performance in the Presence of Engine Air Fuel Ratio Imbalance2017-01-09613/28/2017
In recent years, the EPA has implemented a requirement for monitoring the air fuel ratio balance in multi-cylinder engines such that those imbalances may not be so great as to cause the tailpipe emissions level to exceed 1.5 times the nominal emissions standard. Such imbalances may be the result of production fuel injector variation, contamination, leaks, or other malfunctions which cause the air or fuel rate to vary across the cylinders controlled by a single oxygen sensor. For many diagnostic systems that rely on the signal from the oxygen sensor, to achieve compliance to the new diagnostic standard, the sensor must see the signal from each cylinder equally. The aftertreatment system must also be robust to individual cylinder air fuel ratio variation. This paper introduces the concept of catalyst zone flow, a condition in which different cylinders of a multi-cylinder engine use different portions of the catalyst brick. When the air fuel ratio is maldistributed, different portions of the catalyst brick may be operating with different air fuel ratios, despite good overall control of the mean air fuel ratio. This condition can result in poor three-way catalyst efficiency. A CAE metric called the zone flow index is defined, which quantifies the level of velocity overlap that occurs within the catalyst brick for each cylinder as it blows down. A highly close coupled catalyst brick test case is examined, with measurements that support the existence of catalyst zone flow. The correlation to CFD is discussed, and a patented strategy to reduce catalyst zone flow is introduced as one means of addressing the problem.
Host, Ray, Ranspach, Paul, Anderson, Bruce, Collareno, Michael, Tapos, George, Henderson, Cornelius
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
Virtual Exhaust Gas Temperature Measurement2017-01-10653/28/2017
Exhaust temperature models are widely used in the automotive industry to estimate catalyst and exhaust gas temperatures and to protect the catalyst and other vehicle hardware against over-temperature conditions. Modeled exhaust temperatures rely on air, fuel, and spark measurements to make their estimate. Errors in any of these measurements can have a large impact on the accuracy of the model. Furthermore, air-fuel imbalances, air leaks, engine coolant temperature (ECT) or air charge temperature (ACT) inaccuracies, or any unforeseen source of heat entering the exhaust may have a large impact on the accuracy of the modeled estimate. Modern universal exhaust gas oxygen (UEGO) sensors have heaters with controllers to precisely regulate the oxygen sensing element temperature. These controllers are duty cycle based and supply more or less current to the heating element depending on the temperature of the surrounding exhaust gas. This paper proposes and analyzes a method for using the UEGO heater controller duty cycle to measure exhaust gas temperature at no incremental cost. The analysis shows that such a method can provide an accurate measurement of exhaust gas temperature both in nominal dynamic drive conditions and in the presence of an exotherm from unmodelled sources.
Martin, Douglas R., Rocci, Benjamin
The Benefits and Challenges Faced by Aftermarket Catalyst Manufacturers in Implementing Advanced Coating Techniques in TWC (Gasoline Applications)2017-01-09213/28/2017
The automotive aftermarket industry is an extremely cost competitive market to say the least. Aftermarket manufacturers are sought by customers primarily for their ability to replace an OES (Original Equipment Supplier) for a fraction of the cost. This forces the manufacturers to yield on performance abilities to get a share in the market place. The TWC system in gasoline vehicles not only acts as an emissions reduction device but is an integral part of the overall vehicle performance itself, especially since the introduction of OBD (On-Board Diagnostics) II systems in 1995. An inefficient catalyst not only leads to excessive tailpipe emissions but also acts detrimental to vehicle fueling and hence overall performance. The aftermarket catalyst industry which is regulated by EPA (United States Environmental Protection Agency) and CARB (California Air Resource Board) for gasoline engines is subject to meeting a mandatory performance standard for the same reason. There are several advancements in catalyst technologies to gain performance but this may or may not apply to the aftermarket manufacturers. This paper will discuss three established coating techniques in TWC (Three Way Catalyst) catalyst and their influence on PGM (Precious Group Metal) reduction, emissions performance, and cost reduction and production feasibility. The first method is referred to as slurry coating and possibly the easiest coating method, PGM+WC (Wash Coat) slurry where all precious metals and the supporting washcoat is mixed and applied as one slurry. The second method is referred to as layer coating where the Palladium is in the slurry solution with the washcoat and coated as the first layer on the substrate and then the Rhodium is layered on top as a metal impregnation. The third method is referred to as zone coating where the palladium is in the slurry with the washcoat and it is coated in the inlet of the substrate, while the Rhodium is in the slurry with the washcoat and it is coated in the outlet of the substrate.
Sathiamoorthy, Bharadwaj, Graper, Alex, McIntosh, Andrew, Kaminski, William
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
Experimental Study on High-Load Extension of Gasoline/PODE Dual-Fuel RCCI Operation Using Late Intake Valve Closing2017-01-07543/28/2017
The dual-fuel Reactivity Controlled Compression Ignition (RCCI) combustion could achieve high efficiency and low emissions over a wide range of operating conditions. However, further high load extension is limited by the excessive pressure rise rate and soot emission. Polyoxymethylene dimethyl ethers (PODE), a novel diesel alternative fuel, has the capability to achieve stoichiometric smoke-free RCCI combustion due to its high oxygen content and unique molecule structure. In this study, experimental investigations on high load extension of gasoline/PODE RCCI operation were conducted using late intake valve closing (LIVC) strategy and intake boosting in a single-cylinder, heavy-duty diesel engine. The experimental results show that the upper load can be effectively extended through boosting and LIVC with gasoline/PODE stoichiometric operation. With the retarding of LIVC timing and increase of cyclic fuel quantity, higher boosting pressure and lower Exhaust Gas Recirculation (EGR) ratio were required to maintain sufficient available oxygen. The upper load of gasoline/PODE RCCI operation could be extended up to 23 bar indicated mean effective pressure (IMEP), while still maintaining ultra-low smoke/NOx emissions and acceptable peak in-cylinder pressure and pressure rise rate (PRR). In addition, stoichiometric combustion also enables the application of a low-cost three-way catalyst to further reduce HC and CO emissions. However, LIVC results in slight reduction of indicated thermal efficiency (ITE) due to the lower effective compression ratio and more incomplete combustion with stoichiometric operation, thus further combustion optimization is necessary for ITE improvement. The study reveals that gasoline/PODE RCCI offers a very competitive pathway to achieve clean and highly efficient combustion over the full load conditions.
Wang, Hu, Tong, Laihui, Zheng, Zunqing, Yao, Mingfa
The Development of Low Temperature Three-Way Catalysts for High Efficiency Gasoline Engines of the Future2017-01-09183/28/2017
In anticipation that future gasoline engines will have improved fuel efficiency and therefore lower exhaust temperatures during low load operation, a project was initiated in 2014 to develop three-way catalysts (TWC) with improved activity at lower temperatures while maintaining the durability of current TWCs. This project is a collaboration between Ford Motor Company, Oak Ridge National Laboratory, and the University of Michigan and is funded by the U.S. Department of Energy. The ultimate goal is to show progress towards the USDRIVE goal of 90% conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at 150°C after high mileage aging. A reactor was set up at Ford to follow the catalyst testing protocols established by the USDRIVE ACEC tech team for evaluating catalysts for stoichiometric gasoline direct-injection (S-GDI) engines; this protocol specifies a stoichiometric blend of CO/H2, NO, C3H6, C2H4, C3H8, O2, H2O, and CO2 for the evaluations. This paper summarizes some of the lessons learned from the reactor testing at Ford and also discusses the results on some initial catalyst formulations at Ford that consisted of palladium (Pd) on various oxide supports. The temperature ramp rate had little effect on the lightoff performance, but the O2 level around stoichiometry and interactions between the gas species were found to significantly affect the light off temperatures. Al2O3 and ZrO2 catalysts with 2% Pd were fairly robust to lean aging at 1000°C, but a TiO2 powder with 2% Pd suffered significant degradation after lean aging at only 800°C.
Theis, Joseph R., Getsoian, Andrew, Lambert, Christine
Development and Testing of the Ultera ® Dual Stage Catalyst System on Gasoline-Fueled Light Duty Vehicles (LDV’s)2017-01-09203/28/2017
All vehicles sold today are required to meet emissions standards based on specific driving cycles. Emissions standards are getting tighter and the introduction of real driving tests is imminent, potentially calling for improved aftertreatment systems. A dual stage catalyst system, with exhaust temperature control, can provide a robust solution to meet challenging modes of operation such as rapid acceleration and other heavy-duty transients. The Ultera® technology, developed and successfully implemented on stationary natural gas CHP (Combined Heat and Power) engines, introduces a second stage catalyst downstream of a three-way catalyst. Air is injected between the two stages to provide oxygen required for the second stage reaction that removes additional CO and NMOG. Critical to the process is to avoid the reformation of NOx. This is achieved by cooling the exhaust gas prior to the second stage, to a temperature range in which CO and NMOG oxidation is extremely effective, while no new NOx is created. The objective of this research was to apply this technology to vehicle engines, with the primary interest being gasoline-fuel, direct fuel injection, and more dramatic transient loading. Testing of a ULEV compliant light duty truck (LDT) and a European passenger vehicle was conducted using a chassis dynamometer. Optimization of control temperature and air- injection flow was studied. Also examined were customized catalyst formulations for enhanced hydrocarbon reduction. Results showed significant reductions of CO and NMOG, with no negative impact on NOx. There was also no measurable impact on fuel economy, but further study is required to include the parasitic loads of cooling and air injection in order to fully quantify the impact to mpg. Future development work can provide opportunities to further reduce NOx emissions through chemistry and integration with engine operation.
Roy, Jean P., Ghoniem, Ahmed, Panora, Robert, Gehret, Joseph, Falls, Bruce, Wallace, David, Ott, Daniel
Reduction of Soot Formation in an Optical Single-Cylinder Gasoline Direct-Injected Engine Operated in Stratified Mode Using 350 Bar Fuel Injection Pressure, Dual-Coil and High-Frequency Ignition Systems2017-01-92783/14/2017
The current trend toward more fuel efficient vehicles with lower emission levels has prompted development of new combustion techniques for use in gasoline engines. Stratified combustion has been shown to be a promising approach for increasing the fuel efficiency. However, this technique is hampered by drawbacks such as increased particulate and standard emissions. This study attempts to address the issues of increased emission levels by investigating the influence of high frequency ionizing ignition systems, 350 bar fuel injection pressure and various tumble levels on particulate emissions and combustion characteristics in an optical SGDI engine operated in stratified mode on isooctane. Tests were performed at one engine load of 2.63 bar BMEP and speed of 1200 rpm. Combustion was recorded with two high speed color cameras from bottom and side views using optical filters for OH and soot luminescence. The results indicated that increasing the fuel injection pressure led to faster burn as well as a reduction in soot luminescence. The ionizing ignition system generated faster initial combustion. Increasing the tumble level reduced the soot luminescence at all injection pressures, but the influence was largest at the lowest fuel injection pressure. The combination of an ionizing ignition system and high fuel pressure was most beneficial for lowering soot luminescence.
Johansson, Anders N., Hemdal, Stina, Dahlander, Petter
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 Base Metal Catalyst and Its Compatibility Study for Motorcycle Applications2016-32-007111/8/2016
We developed a copper catalyst using zero Platinum group metals (hereafter PGMs) to fit motorcycle specific emission gas environment. Though many research reports to develop catalyst without using PGMs that are precious and costly resources are available, no reports had proven Base Metal Catalyst development to meet actual emission regulation equivalent to PGM catalysts. Compared to conventional PGM catalysts, higher temperature is required to keep high catalytic conversion efficiency by utilizing properties of this Base Metal Catalyst. Thus, this Base Metal Catalyst is located in cross coupling position, though it is rare case in motorcycle. This catalyst location could cause negative impacts on engine knocking, engine performance and drivability. This time, to overcome such negative impacts we optimized whole exhaust system, including parts around catalyst. In this paper, we report our vehicle development with Base Metal Catalyst to fit current emission regulation, while meeting required features for real vehicle, including vehicle appearance, and noise regulation.
Ueno, Koji, Horimura, Hiroyuki, Iwasa, Akiko, Kurasawa, Yuji, Tran, Pascaline, Liu, Ye
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