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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15

Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

Low temperature and dilute homogenous charge compression ignition (HCCI) and spark-assisted compression ignition (SACI) can improve fuel efficiency and reduce engine-out NO x emissions, especially during lean operation. However, under lean operation, these combustion modes are unable to achieve Environmental Protection Agency (EPA) Tier 3 emissions standards without the use of lean aftertreatment. The three way catalyst (TWC)-SCR lean aftertreatment concept investigated in this work uses periodic-rich operation to produce NH 3 over a TWC to be stored on a selective catalytic reduction (SCR) catalyst for NO x conversion during subsequent lean operation. Experiments were performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation and between lean and rich spark-ignited (SI) combustion to evaluate NO x conversion and fuel efficiency benefits. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system calculations are also presented to allow for comparisons of system performance for different levels of stored NH 3 . With the configuration used in this study, lean/rich HCCI/SACI operation resulted in a maximum NO x conversion efficiency of only 10%, while lean/rich SI operation resulted in a maximum NO x conversion efficiency of 60%. If the low conversion efficiency of HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, calculations indicate that TWC-SCR aftertreatment has the potential to provide attractive fuel efficiency benefits and near-zero tailpipe NO x . Calculated potential fuel efficiency improvement relative to stoichiometric SI is 7–17% for lean/rich HCCI/SACI with zero tailpipe NO x and -1 to 5% for lean/rich SI with zero tailpipe NO x emissions. Although the previous work indicated that the use of HCCI/SACI increases the time for NH 3 to start forming over the TWC during rich operation, reduces NH 3 production over the TWC per fuel amount, and increases NH 3 slip over the SCR catalyst, if NO x conversion efficiency could be enhanced, improvements in fuel efficiency could be realized while meeting stringent tailpipe NO x standards.

Engineering↗

High-Performance Computing and Analysis-Led Development of High Efficiency Dilute Opposed Piston Gasoline Engine

Pinnacle is developing a multicylinder 1.2 L gasoline engine for automotive applications using high-performance computing (HPC) and analysis methods. Pinnacle and Oak Ridge National Laboratory executed large-scale multidimensional combustion analyses at the Oak Ridge Leadership Computing Facility to thoroughly explore the design space. These HPC-led investigations show high fuel efficiency (~46% gross indicated efficiency) may be achieved by operating with extremely high charge dilution levels of exhaust gas recirculation (EGR) at a light load key drive cycle condition (2000 RPM, 3 bar brake mean effective pressure (BMEP)), while simultaneously attaining high levels of fuel conversion efficiency and low NO x emissions. In this extremely dilute environment, the flame propagation event is supported by turbulence and bulk in-cylinder charge motion brought about by modulation of inlet port flow. This arrangement produces a load and speed adjustable amalgamation of swirl and counter-rotating tumble which provides the turbulence required to support stable low-temperature combustion. At higher load conditions, the engine may operate at more traditional combustion modes to generate competitive power. In this work, the numerical results from these HPC simulations are presented. Finally, further HPC simulations and test validations are underway and will be reported in future publications.

42 ENGINEERING↗

Using Machine Learning to Analyze Factors Determining Cycle-to-Cycle Variation in a Spark-Ignited Gasoline Engine

In this work, we have applied a machine learning (ML) technique to provide insights into the causes of cycle-to-cycle variation (CCV) in a gasoline spark-ignited (SI) engine. The analysis was performed on a set of large eddy simulation (LES) calculations of a single cylinder of a four-cylinder port-fueled SI engine. The operating condition was stoichiometric, without significant knock, at a load of 16 bar brake mean effective pressure (BMEP), at an engine speed of 2500 revolutions per minute. A total of 123 cycles was simulated. Of these, 49 were run in sequence, while 74 were run in parallel. For the parallel approach, each cycle is initialized with its own synthetic turbulent field to generate CCV, as part of another work performed by us. In the current work, we used 3D information from all 123 cycles to compute flame topology and pre-ignition flow-field metrics. We then evaluated correlations between these metrics, and peak cylinder pressure (PCP) employing an ML technique called random forest. The computed metrics form the inputs to the random forest model, and PCP is the output. This model captures the effect of all inputs, as well as interactions between them owing to its decision-tree structure. The goal of this work is to demonstrate (as a first step) that ML models can implicitly learn complex relationships between pre-ignition flow-fields, flame shapes, and the eventual outcome of the cycle (whether a cycle will be a high or a low cycle).

42 ENGINEERING↗

Initial Results on a New Light-Duty 2.7-L Opposed-Piston Gasoline Compression Ignition Multi-Cylinder Engine

Abstract Gasoline compression ignition (GCI) is a cost-effective approach to achieving diesel-like efficiencies with low emissions. The fundamental architecture of the two-stroke Achates Power Opposed-Piston (OP) Engine enables GCI by decoupling piston motion from cylinder scavenging, allowing for flexible and independent control of cylinder residual fraction and temperature leading to improved low-load combustion. In addition, the high peak cylinder pressure and noise challenges at high-load operation are mitigated by the lower brake mean effective pressure (BMEP) operation and faster heat release for the same pressure rise rate of the OP Engine. These advantages further solidify the performance benefits of the OP Engine and demonstrate the near-term feasibility of advanced combustion technologies, enabled by the opposed-piston architecture. This paper presents initial results from steady-state testing on a brand new 2.7-L OP GCI multi-cylinder engine (MCE) designed for light-duty truck applications. Successful GCI operation calls for a high compression ratio (CR), leading to higher combustion stability at low loads, higher efficiencies, and lower cycle HC + NOX emissions. Initial results show a cycle average brake thermal efficiency (BTE) of 31.7%, which is already greater than 11% conventional engines, after only ten weeks of testing. Emissions results suggest that Tier 3 Bin 160 levels can be achieved using a traditional diesel after-treatment system. Combustion noise was well controlled at or below the United States Council for Automotive Research limits. In addition, initial results on catalyst light-off mode with GCI are also presented.

Energy & Fuels↗

The influence of intake flow and coolant temperature on gasoline spray morphology during early-injection DISI engine operation

Multi-hole gasoline injectors operating at conditions spanning throttled early-intake stroke operation produce spray plumes that either remained separated or merge and collapse due to flash boiling. Flash boiling occurs due to the sudden expansion of gas bubbles in the liquid fuel at high fuel temperature and low ambient pressure. This study records high-speed images of spray-morphology changes due to in-cylinder flow, thereby revealing operating conditions that do and do not affect the self-induced morphology observed in quiescent vessels. Specifically, in a central-injection, four-valve, high-tumble engine, where the thermodynamic state and in-cylinder cross flow are dynamic. Motivated by cold start and hot restart operation, the fuel pressure, coolant temperature, in-cylinder air pressure, and engine rpm were systematically varied over relevant operating conditions, which bracketed the range from non- to flash-boiling sprays. The results reveal the operating conditions at which the in-cylinder cross flow disrupts the spray morphology as well as the extent of the disruption. At 650 rpm, the spray morphology was similar to that observed in quiescent vessels at nominally equivalent fuel temperature and in-cylinder pressure, indicating that the spray’s self-induced entrainment flow dominated the in-cylinder flow. However, for fuel temperature and ambient pressure near the transition between non- and flash-boiling, the intake cross flow at higher engine speed (1950 rpm) significantly disrupted the spray morphology. The high cross-flow velocity appears to induce plume merging and collapse, whereas none was evident at low rpm (650 rpm). This study led to the postulate that the spray merging and collapse are governed by the rate of atomization near the nozzle exit, presumed to be controlled by either or both aerodynamic atomization and flash-boiling intensity. It would then follow that spray modeling in CFD requires atomization models that blend the effects of both physical processes.

42 ENGINEERING↗

In-cylinder spray evolution in a motored central-injection gasoline engine: Imaging and simulating the effects of flash-boiling and intake crossflow

Accurate predictions of fuel spray behavior and mixture formation in simulations of direct-injection spark-ignition (DISI) engines are fundamental to ensure proper description of all subsequent processes including ignition, combustion, and emissions. In this work, the spray evolution in a single-cylinder optical DISI engine was studied experimentally and numerically with the goal of enabling predictive computational fluid dynamics (CFD) modeling of in-cylinder sprays. The authors explored a wide range of operating conditions characterized by several fuel injection temperatures and engine speeds, using a well-characterized nine-component gasoline surrogate known as PACE-20. The effect of flash boiling and intake crossflow on the spray is discussed, with a focus on evaluating the ability of the spray models to capture highly transient spray behavior. In the experiments, the fuel temperature was varied between 20°C and 80°C, allowing for non-flash- to flash-boiling transition to emerge with enhanced flashing intensity at the highest temperatures. Spray collapse resulted in vapor-rich regions, owing to the locally lower inertia of the fluid. Varying the engine speed from 650 to 1950 rpm promoted increasingly more turbulent in-cylinder crossflow which interacted with the spray during the injection event and resulted in enhanced spray dispersion. The CFD model was able to capture the spray morphology transition at different fuel temperatures and engine speeds adequately. Further, it is shown that the spray breakup model could capture the transitional spray behavior induced by flash boiling atomization and intake flow via proper initialization of the spray cone angle and calibration of the spray models’ constants.

33 ADVANCED PROPULSION SYSTEMS↗

Lean Gasoline System Development for Fuel Efficient Small Cars

The General Motors and DOE cooperative agreement program DE-EE0003379 is completed. The program has integrated and demonstrated a lean-stratified gasoline engine, a lean aftertreatment system, a 12V Stop/Start system and an Active Thermal Management system along with the necessary controls that significantly improves fuel efficiency for small cars. The fuel economy objective of an increase of 25% over a 2010 Chevrolet Malibu and the emission objective of EPA T2B2 compliance have been accomplished. A brief review of the program, summarized from the narrative is: The program accelerates development and synergistic integration of four cost competitive technologies to improve fuel economy of a light-duty vehicle by at least 25% while meeting Tier 2 Bin 2 emissions standards. These technologies can be broadly implemented across the U.S. light-duty vehicle product line between 2015 and 2025 and are compatible with future and renewable biofuels. The technologies in this program are: lean combustion, innovative passive selective catalyst reduction lean aftertreatment, 12V stop/start and active thermal management. The technologies will be calibrated in a 2010 Chevrolet Malibu mid-size sedan for final fuel economy demonstration.

33 ADVANCED PROPULSION SYSTEMS↗

Gasoline Ultra Efficient Fuel Vehicle with Advanced Low Temperature Combustion

The objective of this program was to develop, implement and demonstrate fuel consumption reduction technologies which are focused on reduction of friction and parasitic losses and on the improvement of thermal efficiency from in-cylinder combustion. The program was executed in two phases. The conclusion of each phase was marked by an on-vehicle technology demonstration. Phase I concentrated on short term goals to achieve technologies to reduce friction and parasitic losses. The duration of Phase I was approximately two years and the target fuel economy improvement over the baseline was 20% for the Phase I demonstration. Phase II was focused on the development and demonstration of a breakthrough low temperature combustion process called Gasoline Direct- Injection Compression Ignition (GDCI). The duration of Phase II was approximately four years and the targeted fuel economy improvement was 35% over the baseline for the Phase II demonstration vehicle. The targeted tailpipe emissions for this demonstration were Tier 2 Bin 2 emissions standards.

33 ADVANCED PROPULSION SYSTEMS↗

Supply Chain Sustainability Analysis of Indirect Liquefaction of Blended Biomass to Produce High Octane Gasoline

The Department of Energy’s (DOE) Bioenergy Technologies Office (BETO) aims at developing and deploying technologies to transform renewable biomass resources into commercially viable, high-performance biofuels, bioproducts and biopower through public and private partnerships (DOE, 2015). BETO also performs a supply chain sustainability analysis (SCSA). This report describes the SCSA of the production of renewable high octane gasoline (HOG) via indirect liquefaction (IDL) of lignocellulosic biomass. This SCSA was developed for the 2017 design case for feedstock logistics (INL, 2014) and for the 2022 target case for HOG production via IDL (Tan et al., 2015). The design includes advancements that are likely and targeted to be achieved by 2017 for the feedstock logistics and 2022 for the IDL conversion process. The 2017 design case for feedstock logistics demonstrated a delivered feedstock cost of $80 per dry U.S. short ton by the year 2017 (INL, 2014). The 2022 design case for the conversion process, as modeled in Tan et al. (2015), uses the feedstock 2017 design case blend of biomass feedstocks consisting of pulpwood, wood residue, switchgrass, and construction and demolition waste (C&D) with performance properties consistent with a sole woody feedstock type (e.g., pine or poplar). The HOG SCSA case considers the 2017 feedstock design case (the blend) as well as individual feedstock cases separately as alternative scenarios when the feedstock blend ratio varies as a result of a change in feedstock availability. These scenarios could be viewed as bounding SCSA results because of distinctive requirements for energy and chemical inputs for the production and logistics of different components of the blend feedstocks.

Cai, Hao↗

Process Design and Economics for the Conversion of Lignocellulosic Biomass to High Octane Gasoline: Thermochemical Research Pathway with Indirect Gasification and Methanol Intermediate

The U.S. Department of Energy (DOE) promotes research for enabling cost-competitive liquid fuels production from lignocellulosic biomass feedstocks. The research is geared to advance the state of technology (SOT) of biomass feedstock supply and logistics, conversion, and overall system sustainability. As part of their involvement in this program, the National Renewable Energy Laboratory (NREL) and the Pacific Northwest National Laboratory (PNNL) investigate the economics of conversion pathways through the development of conceptual biorefinery process models. This report describes in detail one potential conversion process for the production of high octane gasoline blendstock via indirect liquefaction (IDL). The steps involve the conversion of biomass to syngas via indirect gasification followed by gas cleanup and catalytic syngas conversion to a methanol intermediate; methanol is then further catalytically converted to high octane hydrocarbons. The conversion process model leverages technologies previously advanced by research funded by the Bioenergy Technologies Office (BETO) and demonstrated in 2012 with the production of mixed alcohols from biomass. Biomass-derived syngas cleanup via tar and hydrocarbons reforming was one of the key technology advancements as part of that research. The process described in this report evaluates a new technology area with downstream utilization of clean biomass-syngas for the production of high octane hydrocarbon products through a methanol intermediate, i.e., dehydration of methanol to dimethyl ether (DME) which subsequently undergoes homologation to high octane hydrocarbon products.

09 BIOMASS FUELS↗

Supply Chain Sustainability Analysis of Indirect Liquefaction of Blended Biomass to Produce High Octane Gasoline

This report describes the SCSA of the production of renewable high octane gasoline (HOG) via indirect liquefaction (IDL) of lignocellulosic biomass. This SCSA was developed for both the 2015 SOT (Hartley et al., 2015; ANL, 2016; DOE, 2016) and the 2017 design case for feedstock logistics (INL, 2014) and for both the 2015 SOT (Tan et al., 2015a) and the 2022 target case for HOG production via IDL (Tan et al., 2015b). The design includes advancements that are likely and targeted to be achieved by 2017 for the feedstock logistics and 2022 for the IDL conversion process. In the SCSA, the 2015 SOT case for the conversion process, as modeled in Tan et al. (2015b), uses the 2015 SOT feedstock blend of pulpwood, wood residue, and construction and demolition waste (C&D). Moreover, the 2022 design case for the conversion process, as described in Tan et al. (2015a), uses the 2017 design case blend of pulpwood, wood residue, switchgrass, and C&D. The performance characteristics of this blend are consistent with those of a single woody feedstock (e.g., pine or poplar). We also examined the influence of using a single feedstock type on SCSA results for the design case. These single feedstock scenarios could be viewed as bounding SCSA results given that the different components of the feedstock blend have varying energy and material demands for production and logistics.

09 BIOMASS FUELS↗

The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability

This report summarizes activities conducted in support of the project “The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability” under COOPERATIVE AGREEMENT NUMBER DE-EE0005654, as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated May 2012.

33 ADVANCED PROPULSION SYSTEMS↗

Advanced Gasoline Turbocharged Direction Injection (GTDI) Engine Development

This program was undertaken in response to US Department of Energy Solicitation DE-FOA-0000079, resulting in a cooperative agreement with Ford and MTU to demonstrate improvement of fuel efficiency in a vehicle equipped with an advanced GTDI engine. Ford Motor Company has invested significantly in GTDI engine technology as a cost effective, high volume, fuel economy solution, marketed globally as EcoBoost technology. Ford envisions additional fuel economy improvement in the medium and long term by further advancing EcoBoost technology. The approach for the project was to engineer a comprehensive suite of gasoline engine systems technologies to achieve the project objectives, and to progressively demonstrate the objectives via concept analysis / computer modeling, single-cylinder and multi-cylinder engine testing on engine dynamometer, and vehicle level testing on chassis rolls.

33 ADVANCED PROPULSION SYSTEMS↗

Consumptive Water Use in the Production of Ethanol and Petroleum Gasoline — 2018 Update

The production of energy feedstocks and fuels requires substantial water input. Not only do biofuel feedstocks like corn, switchgrass, and agricultural residues need water for growth and conversion to ethanol, but petroleum feedstocks like crude oil and oil sands also require large volumes of water for drilling, extraction, and conversion into petroleum products. Moreover, in many cases, crude oil production is increasingly water dependent. Competing uses strain available water resources and raise the specter of resource depletion and environmental degradation. Water management has become a key feature of existing projects and a potential issue in new ones. This report examines the growing issue of water use in energy production by characterizing current consumptive water use in liquid fuel production. As used throughout this report, “consumptive water use” is the sum total of water input less water output that is recycled and reused for the process. The estimate applies to surface and groundwater sources for irrigation but does not include precipitation. Water requirements are evaluated for five fuel pathways: bioethanol from corn, ethanol from cellulosic feedstocks, gasoline from Canadian oil sands, Saudi Arabian crude, and U.S. conventional crude from onshore wells. Regional variations and historic trends are noted, as are opportunities to reduce water use.

02 PETROLEUM↗

Gasoline vehicle travel

Fuel consumption for 1 mile of gasoline vehicle travel. To access the model referenced in the report, please visit https://www.netl.doe.gov/energy-analysis/details?id=580B1AAA-897B-4422-8E12-717B69644688

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Coal/Biomass to Methanol to Gasoline

The conversion of coal or coal and switchgrass to methanol and then to gasoline. To access the model referenced in the report, please visit https://www.netl.doe.gov/energy-analysis/details?id=599A51F9-5A75-4A5F-851B-ABF2540F6EFD

01 COAL, LIGNITE, AND PEAT↗