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Review and Comparison of Model Co-Simulation Methods and Techniques

Southwest Research Institute-Charles Krouse, Brendan Nelson-Weiss
  • Technical Paper
  • 2020-01-0003
To be published on 2020-03-10 by SAE International in United States
The process of developing, parameterizing, validating, and maintaining models occurs within a wide variety of tools, and requires significant time and resources. To maximize model utilization, models are often shared between various toolsets and experts. Model integration is typically divided into two categories: model exchange and model co-simulation. Of these two categories, model co-simulation is typically regarded as the more complex and difficult to implement. Co-Simulation provides the ability to integrate models between different toolsets or incompatible versions of the same software. Additionally, it provides the capabilities for real-time simulations and hardware-in-the-loop test scenarios. This paper reviews some of the common co-simulation data communication methods including pipes, file input/output, sockets, and shared memory. Different synchronization mechanisms, including spin locks and mutexes, are discussed, and the differences between serial and parallel communication patterns is provided. A simple turbojet model was developed to demonstrate each of the aforementioned methods. The turbojet model was developed in a legacy version of NPSS, and this legacy model was integrated with a high fidelity turbine model developed in a newer version…
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A Gas Separation Membrane Highly Selective to CO2 in the Exhaust of Internal Combustion Engines

Southwest Research Institute-Eric Randolph, Graham Conway, Jason Herrera, Terrence Alger, Nishant Thakral, Christopher Chadwell
  • Technical Paper
  • 2019-01-2265
Published 2019-12-19 by SAE International in United States
Southwest Research Institute has developed a passive, flow-through, membrane which separates carbon dioxide (CO2) from other exhaust gas species. Stoichiometric exhaust gas for 0% ethanol fuels contain approximately 14% CO2 by concentration. The membrane consists of a ceramic substrate impregnated with lithium zirconate (Li2ZrO3). In the presence of temperatures of 400-600 °C the CO2 reacts with lithium zirconate to form lithium carbonate (Li2CO3). The new compound moves from the inner surface of the membrane via partial pressure gradient to the outer wall of the membrane and desorbs into a low concentration CO2 environment, e.g. atmospheric air with 400 ppm CO2. SwRI has tested the membrane under engine-like conditions, comparable to 2000 rpm 10 bar BMEP operation, on a standalone burner rig (ECTO-lab burner). On the SwRI ECTO-lab burner rig temperature, flow-rate and exhaust gas products can be independently varied. Results confirmed that the 150 mm membrane section could selectively reduce the CO2 concentration by 5% from the inlet to the outlet of the membrane. Tests were also performed under rich exhaust conditions with increased carbon…
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Comparing Knock between the CFR Engine and a Single Cylinder Research Engine

Southwest Research Institute-Andre Swarts, Garrett L. Anderson, Julian M. Wallace
  • Technical Paper
  • 2019-01-2156
Published 2019-12-19 by SAE International in United States
The confluence of increasing fuel economy requirements and increased use of ethanol as a gasoline blend component has led to various studies into the efficiency and performance benefits of higher octane numbers and high ethanol content fuels in modern engines. As part of a comprehensive study of the autoignition of different fuels in both the CFR octane rating engine and a modern, direct injection, turbocharged spark ignited engine, a series of fuel blends were prepared with varying composition, octane numbers and ethanol blend levels. The paper reports on the second part of this study where cylinder pressures were recorded for fuels under knocking conditions in both a single cylinder research engine (SCRE), utilizing a GM LHU head and piston, as well as the CFR engines used for octane ratings. In the SCRE, spark timing and air-fuel ratios were adjusted to achieve a consistent level of knock based on peak-to-peak values of the filtered cylinder pressures, over a range of engine speeds and manifold air pressures. The CFR engines were operated at standard RON and MON…
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Semi-Volatile Organic Compounds from a Combined Dual Port Injection/Direct-Injection Technology Light-Duty Gasoline Vehicle

Southwest Research Institute-Robert Fanick, Svitlana Kroll
  • Technical Paper
  • 2019-24-0051
Published 2019-09-09 by SAE International in United States
Gasoline direct injection (GDI) has changed the exhaust composition in comparison with the older port fuel injection (PFI) systems. More recently, light-duty vehicle engine manufactures have combined these two technologies to take advantage of the knock benefits and fuel economy of GDI with the low particulate emission of PFI. These dual injection strategy engines have made a change in the combustion emission composition produced by these engines. Understanding the impact of these changes is essential for automotive companies and aftertreatment developers.A novel sampling system was designed to sample the exhaust generated by a dual injection strategy gasoline vehicle using the United States Federal Test Procedure (FTP). This sampling system was capable of measuring the regulated emissions as well as collecting the entire exhaust from the vehicle for measuring unregulated emissions. For this study, the unregulated emissions included hydrocarbon speciation and semi-volatile organic compounds (SVOC) in the form of polycyclic aromatic hydrocarbons (PAH), nitro-polycyclic aromatic hydrocarbons (NPAH), and oxygenated PAH (Oxy PAH). This novel sampling system allowed the quantification of the particulate-phase SVOC as part of…
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Deposit Reduction in SCR Aftertreatment Systems by Addition of Ti-Based Coordination Complex to UWS

Southwest Research Institute-Cary Henry, Scott Eakle
University of Texas-San Antonio-Ryan Hartley, Zachary Tonzetich
Published 2019-04-02 by SAE International in United States
Formation of urea-derived deposits in selective catalytic reduction (SCR) aftertreatment systems continues to be problematic at temperatures at and below 215 °C. Several consequences of deposit formation include: NOx and NH3 slip, exhaust flow maldistribution, increased engine backpressure, and corrosion of aftertreatment components. Numerous methods have been developed to reduce deposit formation, but to date, there has been no solution for continuous low-temperature dosing of Urea-Water Solution (UWS). This manuscript presents a novel methodology for reducing low-temperature deposit formation in SCR aftertreatment systems. The methodology described herein involves incorporation and dissolution of an HNCO hydrolysis catalyst directly into the UWS. HNCO is a transient species formed by the thermolysis of urea upon injection of UWS into the aftertreatment system. Ideally HNCO undergoes hydrolysis to form NH3 and CO2, but under certain conditions HNCO may polymerize or react with other constituents in the exhaust. Reaction of HNCO with species other than water generally results in the formation of deposits in the aftertreatment system. Addition of an HNCO hydrolysis catalyst directly into the UWS provides maximum contact…
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Combined Benefits of Variable Valve Actuation and Low-Pressure EGR on SI Engine Efficiency Part 1: Part Load

Southwest Research Institute-Yanyu Wang, Graham Conway, Chris Chadwell
Published 2019-04-02 by SAE International in United States
Modern spark ignited engines face multiple barriers to achieving higher thermal efficiency. This study investigated the potential of utilizing both continuously variable valve actuation (VVA) and low-pressure cooled exhaust gas recirculation (EGR) to improve engine thermal efficiency at part-load conditions. Six speed / load points were investigated on a 1.6 L turbocharged gasoline direct injection engine. A design of experiment (DoE) approach using the Box-Behnken surface response model was conducted. The DoE results revealed different brake specific fuel consumption (BSFC) responses to the valve phasing and the intake valve lift at different operating conditions. Further engine testing was carried out at each speed / load point to confirm the engine efficiency and combustion performance when targeting different valvetrain controls and EGR strategies. The results indicated that utilizing the VVA system could always reduce BSFC at the studied operating conditions. The BSFC reduction was attributed to reduced pumping and incomplete combustion losses. The reduction in losses was attributed to optimizing the amount of hot trapped residuals compared with the fixed valve configuration, and load control through…
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Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment

Raphael Gukelberger
Southwest Research Institute-Robert Henderson, Cary Henry
Published 2019-04-02 by SAE International in United States
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…
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Benchmarking a 2018 Toyota Camry 2.5-Liter Atkinson Cycle Engine with Cooled-EGR

SAE International Journal of Advances and Current Practices in Mobility

Southwest Research Institute-Josh Alden
US Environmental Protection Agency-John Kargul, Mark Stuhldreher, Daniel Barba, Charles Schenk, Stanislav Bohac, Joseph McDonald, Paul Dekraker
  • Journal Article
  • 2019-01-0249
Published 2019-04-02 by SAE International in United States
As part of the U.S. Environmental Protection Agency’s (EPA’s) continuing assessment of advanced light-duty automotive technologies in support of regulatory and compliance programs, a 2018 Toyota Camry A25A-FKS 4-cylinder, 2.5-liter, naturally aspirated, Atkinson Cycle engine with cooled exhaust gas recirculation (cEGR) was benchmarked. The engine was tested on an engine dynamometer with and without its 8-speed automatic transmission, and with the engine wiring harness tethered to a complete vehicle parked outside of the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, onboard diagnostics (OBD) data, and Controller Area Network (CAN) bus data were recorded. This paper documents the test results under idle, low, medium, and high load engine operation. Motoring torque, wide open throttle (WOT) torque and fuel consumption are measured during transient operation using both EPA Tier 2 and Tier 3 test fuels. The design and performance of this 2018 2.5-liter engine is described and compared to Toyota’s published data and to EPA’s previous projections of the efficiency of an Atkinson Cycle engine with cEGR. The Brake Thermal Efficiency…
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Evaluation of Gasoline Additive Packages to Assess Their Ability to Clean Up Intake Valve Deposits in Automotive Engines

Southwest Research Institute-Matthew Hinojosa, Brent Shoffner
Shell Global Solutions (US) Inc.-Vivek Raja Raj Mohan, Edward Nelson, Jannik Reitz, Jennifer Kensler, Varun Gauba
Published 2019-04-02 by SAE International in United States
The majority of passenger car and light-duty trucks, especially in North America, operate using port-fuel injection (PFI) engines. In PFI engines, the fuel is injected onto the intake valves and then pulled into the combustion chamber during the intake stroke. Components of the fuel are unstable in this environment and form deposits on the upstream face of the intake valve. These deposits have been found to affect a vehicle’s drivability, emissions and engine performance. Therefore, it is critical for the gasoline to be blended with additives containing detergents capable of removing the harmful intake valve deposits (IVDs).Established standards are available to measure the propensity of IVD formation, for example the ASTM D6201 engine test and ASTM D5500 vehicle test. However, rigorous testing conducted in a modern fleet of vehicles in a statistically robust design can provide greater insight into the actual performance of modern PFI engines with available gasoline additive packages. In this study, an optimized mileage accumulation protocol was used to assess the performance of new experimental gasoline additive packages in removing the IVDs…
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Development of a Natural Gas Engine with Diesel Engine-like Efficiency Using Computational Fluid Dynamics

Southwest Research Institute-Ahmed Abdul Moiz, Zainal Abidin, Robert Mitchell, Michael Kocsis
Published 2019-04-02 by SAE International in United States
Present day natural gas engines have a significant efficiency disadvantage but benefit with low carbon-dioxide emissions and cheap three-way catalysis aftertreatment. The aim of this work is to improve the efficiency of a natural gas engine on par with a diesel engine. A Cummins-Westport ISX12-G (diesel) engine is used for the study. A baseline model is validated in three-dimensional Computational Fluid Dynamics (CFD). The challenge of this project is adapting the diesel engine for the natural gas fuel, so that the increased squish area of the diesel engine piston can be used to accomplish faster natural gas burn rates. A further increase efficiency is achieved by switching to D-EGR technology. D-EGR is a concept where one or more cylinders are run with excess fueling and its exhaust stream, containing H2 and CO, is cooled and fed into the intake stream. With D-EGR although there is an in-cylinder presence of a reactive H2-CO reformate, there is also higher levels of dilution. A new piston was designed that can match the high squish burn rates with not…
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