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Flex Fuel Gasoline-Alcohol Engine for Near Zero Emissions Plug-In Hybrid Long-Haul Trucks

Massachusetts Institute of Technology-Daniel Cohn, Leslie Bromberg
Published 2019-04-02 by SAE International in United States
Internal combustion engines for plug-in hybrid heavy duty trucks, especially long haul trucks, could play an important role in facilitating use of battery power. Power from a low carbon electricity source could thereby be employed without an unattractive vehicle cost increase or range limitation. The ideal engine should be powered by a widely available affordable liquid fuel, should minimize air pollutant emissions, and should provide lower greenhouse gas emissions. Diesel engines could fall short in meeting these objectives, especially because of high emissions. In this paper we analyze the potential for a flex fuel gasoline-alcohol engine approach for a series hybrid powertrain. In this approach the engine would provide comparable (or possibly greater) efficiency than a diesel engine while also providing 90 around lower NOx emissions than present cleanest diesel engine vehicles. Ethanol or methanol would be employed to increase knock resistance. Engines that could be deployed in the relatively near term could also use high rpm operation and /or water injection, to allow operation with a very small amount of alcohol in addition to…
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Direct Measurement of Aftertreatment System Stored Water Levels for Improved Dew Point Management Using Radio Frequency Sensing

CTS Corporation-Alexander Sappok, Paul Ragaller, Alex Guarino, Josh Mandelbaum, Luc Lapenta, David Kolberg, Robert Newman, Xiaoxiao Lu, Douglas Cors
Massachusetts Institute of Technology-Leslie Bromberg
Published 2019-04-02 by SAE International in United States
Reducing cold-start emissions to meet increasingly stringent emissions limits requires fast activation of exhaust system sensors and aftertreatment control strategies. One factor delaying the activation time of current exhaust sensors, such as NOx and particulate matter (PM) sensors, is the need to protect these sensors from water present in the exhaust system. Exposure of the ceramic sensing element to water droplets can lead to thermal shock and failure of the sensor. In order to prevent such failures, various algorithms are employed to estimate the dew point of the exhaust gas and determine when the exhaust system is sufficiently dry to enable safe sensor operation. In contrast to these indirect, model-based approaches, this study utilized radio frequency (RF) sensors typically applied to monitor soot loading levels in diesel and gasoline particulate filters, to provide a direct measurement of stored water levels on the ceramic filter elements themselves. The results demonstrate the ability to monitor both water uptake and release from the filter, thereby providing a direct indication of when the system is sufficiently dry to safely…
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Continuous Particulate Filter State of Health Monitoring Using Radio Frequency Sensing

CTS Corporation-Alexander Sappok, Paul Ragaller, Andrew Herman
Massachusetts Institute of Technology-Leslie Bromberg
Published 2018-04-03 by SAE International in United States
Reliable means for on-board detection of particulate filter failures or malfunctions are needed to meet diagnostics (OBD) requirements. Detecting these failures, which result in tailpipe particulate matter (PM) emissions exceeding the OBD limit, over all operating conditions is challenging. Current approaches employ differential pressure sensors and downstream PM sensors, in combination with particulate filter and engine-out soot models. These conventional monitors typically operate over narrowly-defined time windows and do not provide a direct measure of the filter’s state of health. In contrast, radio frequency (RF) sensors, which transmit a wireless signal through the filter substrate provide a direct means for interrogating the condition of the filter itself. This study investigated the use of RF sensors for the continuous measurement of filter trapping efficiency, which was compared to downstream measurements with an AVL Microsoot Sensor, and a PM sampling probe simulating the geometry and installation configuration of a conventional PM sensor. The study included several particulate filter failure modes, both above and below the OBD threshold. The results confirmed the use of RF sensors to provide…
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Developing Design Guidelines for an SCR Assembly Equipped for RF Sensing of NH3 Loading

CTS-Alexander Sappok, Alexander Guarino, Paul Ragaller
Massachusetts Institute of Technology-Leslie Bromberg
Published 2018-04-03 by SAE International in United States
The Cu-zeolite (CuZ) SCR catalyst enables higher NOx conversion efficiency in part because it can store a significant amount of NH3. “NH3 storage control”, where diesel exhaust fluid (DEF) is dosed in accord with a target NH3 loading, is widely used with CuZ catalysts to achieve very high efficiency. The NH3 loading actually achieved on the catalyst is currently estimated through a stoichiometric calculation. With future high-capacity CuZ catalyst designs, it is likely that the accuracy of this NH3 loading estimate will become limiting for NOx conversion efficiency. Therefore, a direct measurement of NH3 loading is needed; RF sensing enables this.Relative to RF sensing of soot in a DPF (which is in commercial production), RF sensing of NH3 adsorbed on CuZ is more challenging. Therefore, more attention must be paid to the “microwave resonance cavity” created within the SCR assembly. The objective of this study was to develop design guidelines to enable and enhance RF sensing. Catalyst dimensions, cavity-defining design features, and antenna location and length were considered. RF measurements were made on a commercial…
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Dual-Fuel Gasoline-Alcohol Engines for Heavy Duty Trucks: Lower Emissions, Flexible-Fuel Alternative to Diesel Engines

Massachusetts Institute of Technology-Daniel Cohn, Leslie Bromberg
Published 2018-04-03 by SAE International in United States
Long-haul and other heavy-duty trucks, presently almost entirely powered by diesel fuel, face challenges meeting worldwide needs for greatly reducing nitrogen oxide (NOx) emissions. Dual-fuel gasoline-alcohol engines could potentially provide a means to cost-effectively meet this need at large scale in the relatively near term. They could also provide reductions in greenhouse gas emissions. These spark ignition (SI) flexible fuel engines can provide operation over a wide fuel range from mainly gasoline use to 100% alcohol use. The alcohol can be ethanol or methanol. Use of stoichiometric operation and a three-way catalytic converter can reduce NOx by around 90% relative to emissions from diesel engines with state of the art exhaust treatment.Alcohol from a second tank is used to provide increased knock resistance at higher values of torque, enabling high compression ratio, turbocharged operation that provides comparable efficiency and torque to a diesel engine in a smaller size engine. The alcohol can be neat or a high concentration blend. It can also be a hydrous alcohol (alcohol and water). Hydrous alcohol use can reduce the…
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Optimized PFI+DI Operation For Minimizing DI Gasoline Engine Particulates

Ethanol Boosting Systems LLC-Leslie Bromberg, Daniel Cohn
Published 2018-04-03 by SAE International in United States
Direct Injection (DI) fueled gasoline engines provide higher efficiency than port fueled injected (PFI) engines. However, emission of small particulates is greatly increased when DI is used. Particulate mass emission is increased by more than a factor of 10 and particulate number is increased by a factor of 10-100 relative to PFI engines leading to health concerns and to implementation and consideration of new regulations.Optimized combinations of PFI and DI can greatly reduce DI-generated particulate emissions without compromising efficiency and performance. A DI enhanced PFI mode of engine operation is employed where PFI is the dominant means in dual-injection fueling over a drive cycle, and the fuel fraction that is directly injected is reduced/minimized while still preventing knock at high loads. Further reduction can be obtained by optimal use of spark retard. The already low particulate emissions are further reduced by decreasing the percentage of DI fuel that results in particulate generation from wall wetting; this is accomplished by adjustment of injection timing, injection rate and pulse length.We have developed a computational model of DI-generated…
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On-Board Particulate Filter Failure Prevention and Failure Diagnostics Using Radio Frequency Sensing

SAE International Journal of Engines

CTS Corporation-Alexander Sappok, Paul Ragaller, Andrew Herman
Massachusetts Institute of Technology-Leslie Bromberg
  • Journal Article
  • 2017-01-0950
Published 2017-03-28 by SAE International in United States
The increasing use of diesel and gasoline particulate filters requires advanced on-board diagnostics (OBD) to prevent and detect filter failures and malfunctions. Early detection of upstream (engine-out) malfunctions is paramount to preventing irreversible damage to downstream aftertreatment system components. Such early detection can mitigate the failure of the particulate filter resulting in the escape of emissions exceeding permissible limits and extend the component life. However, despite best efforts at early detection and filter failure prevention, the OBD system must also be able to detect filter failures when they occur. In this study, radio frequency (RF) sensors were used to directly monitor the particulate filter state of health for both gasoline particulate filter (GPF) and diesel particulate filter (DPF) applications. The testing included controlled engine dynamometer evaluations, which characterized soot slip from various filter failure modes, as well as on-road fleet vehicle tests. The results show a high sensitivity to detect conditions resulting in soot leakage from the particulate filter, as well as potential for direct detection of structural failures including internal cracks and melted regions…
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Optimal Use of Ethanol in Dual Fuel Applications: Effects of Engine Downsizing, Spark Retard, and Compression Ratio on Fuel Economy

SAE International Journal of Engines

Sloan Automotive Lab., Massachusetts Institute of Technology-Young Suk Jo, Leslie Bromberg, John Heywood
  • Journal Article
  • 2016-01-0786
Published 2016-04-05 by SAE International in United States
Turbocharging, increasing the compression ratio, and downsizing a spark-ignition engine are well known strategies for improving vehicle fuel economy. However, such strategies increase the likelihood of engine knock due to higher in-cylinder pressures and temperatures. A high octane fuel, such as E85, effectively suppresses knock but is not necessary in most parts of the engine operating map. To better utilize a high octane fuel, dual fuel injection has been suggested where high octane fuel is injected only when the engine is about to knock. However, the effects of downsizing, retarding spark timing, and increasing compression ratio on dual fuel applications are not well understood. To investigate these questions, GT-power simulations along with engine experiments and engine-in-vehicle simulations for a passenger vehicle and a medium-duty truck were conducted. First, engine performance maps for various boosts, compression ratios, and spark retards were created, with lines of constant fuel RON superposed. Then, parametric studies were conducted to analyze the effects of cylinder volume/boost level, spark retard, and compression ratio on the vehicle fuel consumption, ethanol usage, and the…
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Octane Requirement of a Turbocharged Spark Ignition Engine in Various Driving Cycles

Sloan Automotive Lab, Massachusetts Institute of Technology-Young Suk Jo, Leslie Bromberg, John Heywood
Published 2016-04-05 by SAE International in United States
High octane fuel (e.g., E85) effectively suppresses knock, but the octane ratings of such fuels are much above what is required under normal driving conditions. It is important, therefore, to understand the octane requirement of the engine itself over its full range of operation and apply that knowledge to practical driving cycles to understand fuel octane utilization, especially of a turbocharged engine. By carefully defining knock limits, the octane requirement of a 2-liter turbocharged spark ignition engine was experimentally quantified over a wide range of loads and speeds using PRF blends and gasoline-ethanol blends. Utilizing this knowledge and engine-in-vehicle simulations, the octane requirements of various driving cycles were calculated for a passenger car and a medium duty truck model. The effects of spark retard, engine downsizing at fixed vehicle performance, and vehicle types, on engine efficiency, fuel economy, and ethanol consumption were analyzed through parametric study. The average octane ratings of fuel needed in real-world driving were in the 60-80 RON range (the maximum RON required was 90-100.) Downsizing and vehicle loading in trucks increased…
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Real-Time Engine and Aftertreatment System Control Using Fast Response Particulate Filter Sensors

CTS Corporation Boston Innovation Office-Alexander Sappok, Paul Ragaller, Leslie Bromberg
Oak Ridge National Laboratory-Vitaly Prikhodko, John Storey, James Parks
Published 2016-04-05 by SAE International in United States
Radio frequency (RF)-based sensors provide a direct measure of the particulate filter loading state. In contrast to particulate matter (PM) sensors, which monitor the concentration of PM in the exhaust gas stream for on-board diagnostics purposes, RF sensors have historically been applied to monitor and control the particulate filter regeneration process. This work developed an RF-based particulate filter control system utilizing both conventional and fast response RF sensors, and evaluated the feasibility of applying fast-response RF sensors to provide a real-time measurement of engine-out PM emissions. Testing with a light-duty diesel engine equipped with fast response RF sensors investigated the potential to utilize the particulate filter itself as an engine-out soot sensor. Measurements of the instantaneous change in the filter PM loading state using the fast response RF sensors were compared to measurements of engine-out PM emissions using conventional test cell instrumentation including the AVL micro soot sensor and tapered element oscillating micro-balance (TEOM). The results showed a high degree of correlation between the fast response RF sensor and test cell instruments. From a practical…
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