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Phenomenological Investigations of Mid-Channel Ash Deposit Formation and Characteristics in Diesel Particulate Filters

Massachusetts Institute of Technology-Carl Justin Kamp, Sujay Bagi
Cummins Inc.-Yujun Wang
Published 2019-04-02 by SAE International in United States
Accumulation of lubricant and fuel derived ash in the diesel particulate filter (DPF) during vehicle operation results in a significant increase of pressure drop across the after-treatment system leading to loss of fuel economy and reduced soot storage capacity over time. Under certain operating conditions, the accumulated ash and/or soot cake layer can collapse resulting in ash deposits upstream from the typical ash plug section, henceforth termed mid-channel ash deposits. In addition, ash particles can bond (either physically or chemically) with neighboring particles resulting in formation of bridges across the channels that effectively block access to the remainder of the channel for the incoming exhaust gas stream. This phenomenon creates serious long-term durability issues for the DPF, which often must be replaced. Mid-channel deposits and ash bridges are extremely difficult to remove from the channels as they often sinter to the substrate.The current study is comprised of analyzing field-return/field-aged DPF units exhibiting variations in ash bridging, characterized by high resolution X-ray CT, XRD, XRF and SEM-EDS. X-ray CT with a transmission X-ray source (voxel size…
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Modeling of Oil Transport between Piston Skirt and Cylinder Liner in Internal Combustion Engines

Massachusetts Institute of Technology-Zhen Meng, Sebastian Ahling, Tian Tian
Published 2019-04-02 by SAE International in United States
The distribution of lubricating oil plays a critical role in determining the friction between piston skirt and cylinder liner, which is one of the major contributors to the total friction loss in internal combustion engines. In this work, based upon the experimental observation an existing model for the piston secondary motion and skirt lubrication was improved with a physics-based model describing the oil film separation from full film to partial film. Then the model was applied to a modern turbo-charged SI engine. The piston-skirt FMEP predicted by the model decreased with larger installation clearance, which was also observed from the measurements using IMEP method at the rated. It was found that the main period of the cycle exhibiting friction reduction is in the expansion stroke when the skirt only contacts the thrust side for all tested installation clearances. The main reason for lower skirt friction with larger clearance is greater amount of oil available during the expansion stroke.
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Reliable Processes of Simulating Liner Roughness and Its Lubrication Properties

Massachusetts Institute of Technology-Renze Wang, Chongjie Gu, Tian Tian
Published 2019-04-02 by SAE International in United States
Topology of liner finish is critical to the performance of internal combustion engines. Proper liner finish simulation processes lead to efficient engine design and research. Fourier methods have been well studied to numerically generate liner topology. However, three major issues wait to be addressed to make the generation processes feasible and reliable. First, in order to simulate real plateau honed liners, approaches should be developed to calculate accurate liner geometric parameters. These parameters are served as the input of the generation algorithm. Material ratio curve, the common geometry calculation method, should be modified so that accurate root mean square of plateau height distribution could be obtained. Second, the set of geometric parameters used in generating liner finish (ISO 13565-2) is different from the set of parameters used in manufacturing industry (ISO 13565-3). Quantitative relations between these two sets should be studied. Third, numerically generated liners should be run in deterministic lubrication, dry contact, and engine cycle models. Their outcome behavior should be compared with experimental data. In this article, efforts were made to fill all…
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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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Experiments and Analyses on Stability/Mid-Channel Collapse of Ash-Deposit Wall Layers and Pre-Mature Clogging of Diesel Particulate Filters

Massachusetts Institute of Technology-Yuesen Wang, Jun Zhang, Ian Tracy, Victor Wong
Industrial Power Alliance, Ltd.-Yosuke Obuchi
Published 2019-04-02 by SAE International in United States
The conventional concept of soot and ash wall deposits (i.e. cake-layers) gradually building up along the channels of a ceramic honeycomb and then periodically or continuously being swept downstream toward the end-plugs of the channels may not always occur in practice. When deposits irregularly form on or detach from the walls, causing premature clogging usually around the mid-sections of the channels (also known as Mid-Channel Collapse), and the particulate filter is prone to experiencing significantly elevated back pressure, resulting in the need for earlier repair or replacement than desired. Here we describe related experiments that were performed, accompanied by analysis and simulation, in order to investigate the factors that contribute to the patterns of wall deposits that form-particularly of ash-and the effects of these irregular patterns.Experiments attempting to duplicate conditions in which irregular deposits occur were carried out with a combination of actual engine and diesel-burner exhaust to achieve a variety of exhaust conditions, such as changing soot and ash concentrations and their relative ratios, flow rates (space velocities), and exhaust temperatures. In this study,…
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Optimization-Based Robust Architecture Design for Autonomous Driving System

Massachusetts Institute of Technology-Anne Collin, Afreen Siddiqi, Eric Rebentisch
Hitachi America, Ltd.-Yuto Imanishi
Published 2019-04-02 by SAE International in United States
With the recent advancement in sensing and controller technologies architecture design of an autonomous driving system becomes an important issue. Researchers have been developing different sensors and data processing technologies to solve the issues associated with fast processing, diverse weather, reliability, long distance recognition performance, etc. Necessary considerations of diverse traffic situations and safety factors of autonomous driving have also increased the complexity of embedded software as well as architecture of autonomous driving. In these circumstances, there are almost countless numbers of possible architecture designs. However, these design considerations have significant impacts on cost, controllability, and system reliability. Thus, it is crucial for the designers to make a challenging and critical design decision under several uncertainties during the conceptual design phase. This paper proposes an optimization-based robust architecture design framework for an autonomous driving system. The proposed framework focuses mainly on two design processes. The first one deals with the hardware integration issue. In this process, processors and buses need to be selected from an available hardware list and connected to realize the hardware system.…
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Analyzing the Limitations of the Rider and Electric Motorcycle at the Pikes Peak International Hill Climb Race

Massachusetts Institute of Technology-Lennon Rodgers, Mark Jeunnette
Brunel University-Koen Matthys
Published 2019-04-02 by SAE International in United States
This paper describes a post-race analysis of team KOMMIT EVT’s electric motorcycle data collected during the 2016 Pikes Peak International Hill Climb (PPIHC). The motorcycle consumed approximately 4 kWh of battery energy with an average and maximum speed of 107 km/h and 149 km/h, respectively. It was the second fastest electric motorcycle with a finishing time of 11:10.480. Data was logged of the motorcycle’s speed, acceleration, motor speed, power, currents, voltages, temperatures, throttle position, GPS position, rider’s heart rate and the ambient environment (air temperature, pressure and humidity). The data was used to understand the following factors that may have prevented a faster time: physical fitness of the rider, thermal limits of the motor and controller, available battery energy and the sprocket ratio between the motor and rear wheel. Even though the rider’s heart rate implied a vigorous exercise intensity level, throttle values indicated that the rider wanted to go faster ~33% of the time. The motor reached a steady-state temperature that was approximately 30°C below the maximum allowable temperature and thus could have handled…
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Direct Measurement of Aftertreatment System Stored Water Levels for Improved Dew Point Management Using Radio Frequency Sensing

Massachusetts Institute of Technology-Leslie Bromberg
CTS Corporation-Alexander Sappok, Paul Ragaller, Alex Guarino, Josh Mandelbaum, Luc Lapenta, David Kolberg, Robert Newman, Xiaoxiao Lu, Douglas Cors
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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A Method for Turbocharging Single-Cylinder, Four-Stroke Engines

SAE International Journal of Engines

Massachusetts Institute of Technology-Michael Buchman, Devarajan Ramanujan, Amos G. Winter
  • Journal Article
  • 03-11-04-0028
Published 2018-07-24 by SAE International in United States
Turbocharging can provide a low cost means for increasing the power output and fuel economy of an internal combustion engine. Currently, turbocharging is common in multi-cylinder engines, but due to the inconsistent nature of intake air flow, it is not commonly used in single-cylinder engines. In this article, we propose a novel method for turbocharging single-cylinder, four-stroke engines. Our method adds an air capacitor-an additional volume in series with the intake manifold, between the turbocharger compressor and the engine intake-to buffer the output from the turbocharger compressor and deliver pressurized air during the intake stroke. We analyzed the theoretical feasibility of air capacitor-based turbocharging for a single-cylinder engine, focusing on fill time, optimal volume, density gain, and thermal effects due to adiabatic compression of the intake air. Our computational model for air flow through the intake manifold predicted an intake air density gain of 37-60% depending on heat transfer rates; this density translates to a proportional to power gain. An experimental setup was constructed to measure peak power, density gain, and manifold pressure. With an…
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Evaluating How Functional Performance in Aerospace Components Is Affected by Geometric Variation

SAE International Journal of Aerospace

Massachusetts Institute of Technology-Daniel Frey
Chalmers University of Technology-Anders Forslund, Julia Madrid, Rikard Söderberg, Ola Isaksson
  • Journal Article
  • 01-11-01-0001
Published 2018-06-05 by SAE International in United States
Geometric variation stemming from manufacturing can be a limiting factor for the quality and reliability of products. Therefore, manufacturing assessments are increasingly being performed during the early stages of product development. In the aerospace industry, products are complex engineering systems, the development of which require multidisciplinary expertise. In such contexts, there are significant barriers against assessing the effects of geometric variation on the functionality of products. To overcome these barriers, this article introduces a new methodology consisting of a modelling approach linked to a multidisciplinary simulation environment. The modelling approach is based on the parametric point method, which allows point-scanned data to be transferred to parameterised CAD models. In a case study, the methodology is implemented in an industrial setting. The capability of the methodology is demonstrated through a few applications, in which the effects of geometric variation on the aerodynamic, thermal, and structural performance of a load-bearing turbofan component are analysed. The proposed methodology overcomes many of the current barriers, making it more feasible to assess the effects of geometric variation during the early…
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