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Technical Paper
Graham Conway, Dennis Robertson, Chris Chadwell, Joseph McDonald, John Kargul, Daniel Barba, Mark Stuhldreher
Low-pressure loop (LPL) EGR combined with higher compression ratio is a technology package that has been the focus of significant research to increase engine thermal efficiency on downsized, turbocharge GDI engines. Research shows that the addition of LPL-EGR reduces the propensity to knock that is experienced at higher compression ratios [1]. To investigate the interaction and compatibility between increased compression ratio and LPL-EGR, a 1.6 L Turbocharged GDI engine was modified to run with LPL-EGR at a higher compression ratio (12:1 versus 10.5:1) via a piston change. The paper presents the results of the baseline testing on a PSA engine run with a prototype SwRI controller and initially tuned to mimic OEM baseline control strategy running on premium fuel (92.8 AKI). The paper then presents test results after first adding LPL-EGR to the baseline engine, and then also increasing CR (using 12:1 pistons).
Technical Paper
Logan Smith, Ian Smith, Scott Hotz, Mark Stuhldreher
Modern engine hardware and controls are very complex, requiring equally complex testing methodologies when performing powertrain benchmarking. Tethered benchmarking connects an engine in a test cell to a complete vehicle through an extended wire harness, enabling evaluation of stock powertrain calibration without manufacturer support. This test method can be used to develop brake specific fuel consumption maps and evaluate control strategies. However, this testing is limited to factory “on calibration” test points. To enable the evaluation of off-calibration powertrain operation, the selective interrupt and control (SIC) test capability was developed as part of an EPA evaluation of a 1.6 L EcoBoost® engine. A control and data acquisition device sits between the stock powertrain controller and the engine; the device selectively passes through, or modifies, control signals while also simulating feedback signals.
Technical Paper
Graham Conway, Dennis Robertson, Chris Chadwell, Joseph McDonald, Daniel Barba, Mark Stuhldreher, Aaron Birckett
The thermal efficiency benefits of low-pressure loop (LPL) EGR on spark-ignition engine combustion are well known. One of the greatest barriers facing adoption of LPL-EGR, on high power-density applications, is the challenge of boosting. Variable nozzle turbines (VNT) have recently been developed for gasoline applications operating at high exhaust gas temperatures (EGT). The use of a single VNT as a boost device was preferred to two-stage boosting system or a 48 V electronic boost device for this study. A predictive model was created based on engine testing results from a 1.6 L turbocharged GDI engine [1]. The model was tuned so that it predicted burn-rates and end-gas knock over an engine operating map with varying speed, load, EGR rate and fuel type.
Technical Paper
Mark Stuhldreher, John Kargul, Daniel Barba, Paul Dekraker, Stanislav Bohac, Joseph McDonald
As part of the U.S. Environmental Protection Agency’s continuing assessment of advanced light-duty automotive technologies to support the setting of appropriate national greenhouse gas standards, and to evaluate the impact of new technologies on in-use emissions, a 2016 Honda Civic with a 4-cylinder 1.5-liter engine and continuously variable transmission (CVT) was benchmarked. The test method involves installing the engine and its CVT in an engine dynamometer test cell with the engine wiring harness tethered to its vehicle parked outside the test cell. Engine and transmission torque, fuel flow, tailpipe emissions, in-cylinder pressure, key engine temperatures and pressures, and OBD/epid CAN bus data were recorded. The paper documents test results with EPA Tier 2 and Tier 3 test fuels for idle, low, medium and high load engine operation, as well as motoring torque, wide-open throttle torque, and fuel consumption during transient operation.
Technical Paper
Mark Stuhldreher, Youngki Kim, John Kargul, Andrew Moskalik, Daniel Barba
Abstract As part of its midterm evaluation of the 2022-2025 light-duty greenhouse gas (GHG) standards, the Environmental Protection Agency (EPA) has been acquiring fuel efficiency data from testing of recent engines and vehicles. The benchmarking data are used as inputs to EPA’s Advanced Light Duty Powertrain and Hybrid Analysis (ALPHA) vehicle simulation model created to estimate GHG emissions from light-duty vehicles. For complete powertrain modeling, ALPHA needs both detailed engine fuel consumption maps and transmission efficiency maps. EPA’s National Vehicle and Fuels Emissions Laboratory has previously relied on contractors to provide full characterization of transmission efficiency maps. To add to its benchmarking resources, EPA developed a streamlined more cost-effective in-house method of transmission testing, capable of gathering a dataset sufficient to broadly characterize transmissions within ALPHA.
Journal Article
Paul Dekraker, Mark Stuhldreher, Youngki Kim
Abstract The U.S. Environmental Protection Agency’s (EPA’s) Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created to estimate greenhouse gas (GHG) emissions from light-duty vehicles. ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types with different powertrain technologies, showing realistic vehicle behavior, and auditing of all energy flows in the model. In preparation for the midterm evaluation (MTE) of the 2017-2025 light-duty GHG emissions rule, ALPHA has been refined and revalidated using newly acquired data from model year 2013-2016 engines and vehicles. The robustness of EPA’s vehicle and engine testing for the MTE coupled with further validation of the ALPHA model has highlighted some areas where additional data can be used to add fidelity to the engine model within ALPHA.
Technical Paper
Mark Stuhldreher
Abstract As part of the midterm evaluation of the 2022-2025 light-duty GHG emissions rule, the Environmental Protection Agency (EPA) has been evaluating fuel efficiency data from tests on newer model engines and vehicles. The data is used as inputs to an EPA vehicle simulation model created to estimate greenhouse gas (GHG) emissions from light-duty vehicles. The Advanced Light Duty Powertrain and Hybrid Analysis (ALPHA) model is a physics-based, full vehicle computer simulation capable of analyzing various vehicle types with different powertrain technologies and showing realistic vehicle behavior and auditing of all internal energy flows in the model. Under the new light-duty fuel economy standards vehicle powertrains must become significantly more efficient. Cylinder deactivation engine technology is capable of deactivating one or more of its combustion cylinders when not needed to meet power demand.
Technical Paper
Mark Stuhldreher, Charles Schenk, Jessica Brakora, David Hawkins, Andrew Moskalik, Paul DeKraker
Abstract Light-duty vehicle greenhouse gas (GHG) and fuel economy (FE) standards for MYs 2012-2025 are requiring vehicle powertrains to become much more efficient. One key technology strategy that vehicle manufacturers are using to help comply with GHG and FE standards is to replace naturally aspirated engines with smaller displacement “downsized” boosted engines. In order to understand and measure the effects of this technology, the Environmental Protection Agency (EPA) benchmarked a 2013 Ford Escape with an EcoBoost® 1.6L engine. This paper describes a “tethered” engine dyno benchmarking method used to develop a fuel efficiency map for the 1.6L EcoBoost® engine. The engine was mounted in a dyno test cell and tethered with a lengthened engine wire harness to a complete 2013 Ford Escape vehicle outside the test cell. This method allowed engine mapping with the stock ECU and calibrations.
Technical Paper
Matthew Brusstar, Mark Stuhldreher, David Swain, William Pidgeon
Ongoing work with methanol- and ethanol-fueled engines at the EPA's National Vehicle and Fuel Emissions Laboratory has demonstrated improved brake thermal efficiencies over the baseline diesel engine and low steady state NOx, HC and CO, along with inherently low PM emissions. In addition, the engine is expected to have significant system cost advantages compared with a similar diesel, mainly by virtue of its low-pressure port fuel injection (PFI) system. While recognizing the considerable challenge associated with cold start, the alcohol-fueled engine nonetheless offers the advantages of being a more efficient, cleaner alternative to gasoline and diesel engines. The unique EPA engine used for this work is a turbocharged, PFI spark-ignited 1.9L, 4-cylinder engine with 19.5:1 compression ratio. The engine operates unthrottled using stoichiometric fueling from full power to near idle conditions, using exhaust gas recirculation (EGR) and intake manifold pressure to modulate engine load.
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