Passenger Vehicle Diesel Engines for the U.S.

Cowland, Chris; Gutmann, Peter; Herzog, Peter L.

doi:10.4271/2004-01-1452

Cited by 17 publications

(5 citation statements)

References 2 publications

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“…Diesel engines are an attractive option for automotive powerplants due to their high fuel conversion efficiency (often termed the thermal efficiency), which can exceed the fuel conversion efficiency of modern SI engines by as much as 40% [1]. However, for conventional diesel combustion regimes, emissions of NO x and particulates from these engines are excessive, and costly exhaustgas after-treatment systems are required to meet current emission regulations.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Swirl Ratio and Fuel Injection Parameters on CO Emission and Fuel Conversion Efficiency for High-Dilution, Low-Temperature Combustion in an Automotive Diesel Engine

Kook¹,

Bae²,

Miles

et al. 2006

SAE Technical Paper Series

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Engine-out CO emission and fuel conversion efficiency were measured in a highly-dilute, low-temperature diesel combustion regime over a swirl ratio range of 1.44-7.12 and a wide range of injection timing. At fixed injection timing, an optimal swirl ratio for minimum CO emission and fuel consumption was found. At fixed swirl ratio, CO emission and fuel consumption generally decreased as injection timing was advanced. Moreover, a sudden decrease in CO emission was observed at early injection timings. Multi-dimensional numerical simulations, pressure-based measurements of ignition delay and apparent heat release, estimates of peak flame temperature, imaging of natural combustion luminosity and spray/wall interactions, and Laser Doppler Velocimeter (LDV) measurements of in-cylinder turbulence levels are employed to clarify the sources of the observed behavior. Mixing processes occurring after the pre-mixed burn are found to be the likely source of the optimal swirl ratio, while enhanced pre-combustion mixing dominates the reduction in CO with earlier injection. Liquid fuel films formed on the bowl lip are not found to significantly impact CO emissions, and increased injection pressure typically reduces CO emissions at this high dilution rate. Fuel conversion efficiency is examined in terms of component efficiencies related to combustion phasing, heat loss, and combustion efficiency. The influence of swirl and injection timing on each of these efficiencies is discussed.CO emission generally stems from two primary sources. The first source, "under-mixing" of fuel, is the CO formed in the products of rich pre-mixed combustion. If mixing rates are too low, this CO will fail to mix with sufficient additional O 2 to complete the oxidation process before expansion quenches chemical reactions. The second source, "over-mixing," is associated with fuel that is mixed to very lean equivalence ratios during the ignition delay period. After ignition, these overly lean mixtures do not reach sufficiently high temperatures to complete the oxidation process on engine time scales.For thoroughly pre-mixed, very lean combustion systems, the over-mixed fuel and subsequent low peak combustion temperature is the source of engine CO emission [7]. Similarly, the results of numerical simulations point to over-mixed fuel as the principal source of CO emission from conventional diesel combustion systems [8]. However, as dilution levels increase, the correlation between CO emission and ignition delay observed in dilute, low-temperature diesel combustion systems becomes negative [9]-that is, increased ignition delay is found to correspond to reduced CO emissions for highly-dilute mixtures. Additionally, the average equivalence ratio at ignition is estimated to exceed 2, and to increase with increasing dilution level. Jointly, these observations indicate that for highly-dilute systems the dominant CO emission source more likely stems from under-mixed fuel.R CO f CO f c

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Section: Introductionmentioning

confidence: 99%

The Effect of Swirl Ratio and Fuel Injection Parameters on CO Emission and Fuel Conversion Efficiency for High-Dilution, Low-Temperature Combustion in an Automotive Diesel Engine

Kook¹,

Bae²,

Miles

et al. 2006

SAE Technical Paper Series

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“…These challenges are not only to be found in the automotive-industry sector but also to the same extent in the area of off-road or industrial engines. Diesel engines are often used in industrial applications, which are characterized by comparatively low HC and CO emissions as well as higher thermal efficiency [1,2]. However, it should be noted that diesel engines are equally known for increased NOx and soot emissions [3].…”

Section: Introductionmentioning

confidence: 99%

Computational Investigation on the Performance Increase of a Small Industrial Diesel Engine Regarding the Effects of Compression Ratio, Piston Bowl Shape and Injection Strategy

et al. 2022

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This paper describes the simulative approach to calibrate an already extremely highly turbocharged industrial diesel engine for higher low-speed torque. The engine, which is already operating at its cylinder-pressure maximum, is to achieve close to 30 bar effective mean pressure through suitable calibration between the compression ratio, piston-bowl shape and injection strategy. The basic idea of the study is to lower the compression ratio for even higher injection masses and boost pressures, with the resulting disadvantages in the area of emissions and fuel consumption being partially compensated for by optimizations in the areas of piston shape and injection strategy. The simulations primarily involve the use of the 3D CFD software Converge CFD for in-cylinder calibration and a fully predictive 1D full-engine model in GT Suite. The simulations are based on a two-stage turbocharged 1950 cc four-cylinder industrial diesel engine, which is used for validation of the initial simulation. With the maximum increase in fuel mass and boost pressure, the effective mean pressure could be increased up to 28 bar, while specific consumption increased only slightly. Depending on the geometry, NOx or CO and UHC emissions could be reduced.

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“…The diesel engine has been proven to be a feasible solution for passenger cars in the European market [1] and has great potential for the US market [2], owing to its high fuel conversion efficiency, which can be 40 per cent more than that of modern spark ignition engines. The current focus of engine research is on the simultaneous reduction in the soot and nitrogen oxide (NO x ) to meet increasingly strict regulations, while maintaining reasonable fuel economy.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a high-speed direct-injection diesel engine at low-load operation using computational fluid dynamics with detailed chemistry and a multi-objective genetic algorithm

Shi

Reitz

et al. 2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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A passenger car high-speed direct-injection diesel engine operating at low-load conditions in the modulated kinetic combustion mode was optimized using a multi-dimensional computational fluid dynamics code and a multi-objective genetic algorithm. Spray targeting, piston bowl geometry, and swirl ratio were optimized. Since the combustion is mainly kinetics controlled, detailed chemistry was considered through a recently developed adaptive multi-grid chemistry (AMC) model. The numerical results from the AMC model, including the pressure and pollutant emissions, were first validated on the baseline engine for a parametric sweep by comparison with the results from the standard KIVA—CHEMKIN model. The AMC model was found to give consistent results with the KIVA—CHEMKIN model, with a computational cost that is less than half that of the KIVA—CHEMKIN model. Optimal designs from the optimization were also validated using the full KIVA—CHEMKIN model and were found to reduce the fuel consumption and/or pollutant emissions. Start-of-injection timing was found to be the primary parameter influencing the fuel consumption and soot emissions for the engine operating in the low-load condition. Later injection benefits the fuel consumption and soot reduction. However, further retardation of the injection timing leads to reduced combustion efficiency and even misfire, and results in higher unburned hydrocarbon emissions. Different piston bowl shapes have different responses to bulk flow motions and the resulting geometry-generated turbulence will affect soot formation and oxidation.

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Passenger Vehicle Diesel Engines for the U.S.

Cited by 17 publications

References 2 publications

The Effect of Swirl Ratio and Fuel Injection Parameters on CO Emission and Fuel Conversion Efficiency for High-Dilution, Low-Temperature Combustion in an Automotive Diesel Engine

The Effect of Swirl Ratio and Fuel Injection Parameters on CO Emission and Fuel Conversion Efficiency for High-Dilution, Low-Temperature Combustion in an Automotive Diesel Engine

Computational Investigation on the Performance Increase of a Small Industrial Diesel Engine Regarding the Effects of Compression Ratio, Piston Bowl Shape and Injection Strategy

Optimization of a high-speed direct-injection diesel engine at low-load operation using computational fluid dynamics with detailed chemistry and a multi-objective genetic algorithm

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