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Technical Paper

A Study of the Effects of Exhaust Gas Recirculation on Heavy-Duty Diesel Engine Emissions

The effects of exhaust gas recirculation (EGR) on heavy-duty diesel emissions were studied at two EPA steady-state operating conditions, old EPA mode 9* (1800 RPM, 75% Load) and old EPA mode 11 (1800 RPM, 25% Load). Data were collected at the baseline, 10% and 16% EGR rates for both EPA modes. The study was conducted using a 1995 Cummins M11-330E heavy-duty diesel engine and compared to the baseline emissions from the Cummins 1988 and 1991 L10 engines. The baseline gas-, vapor- and particle-phase emissions were measured together with the particle size distributions at all modes of operation. The total particulate matter (TPM) and vapor phase (XOC) samples were analyzed for physical, chemical and biological properties. The results showed that newer engines with electronic engine controls and higher injector pressures produce TPM decreases from the 1988 to 1991 to 1995 engines with the solids decreasing more than the soluble organic fraction (SOF) of TPM.
Technical Paper

The Use of Results from Computational Fluid Dynamic Fuel Injector Modeling to Predict Spray Characteristics

The fluid flow characteristics inside compound silicon micro machined port fuel injector nozzles were analyzed through the use of computational fluid dynamics (CFD). This study was undertaken in order to gain a better understanding of the fluid mechanics taking place in the compound orifice plate. In addition, the calculated computational results will be used to predict the fuel spray patterns and sauter mean diameters of the sprays. The influence of orifice plate geometry on calculated turbulent kinetic energies and fuel spray patterns was also studied and will be discussed. The results of this investigation indicate that the fluid flow characteristics inside the compound silicon micro machined port fuel injector nozzle are influenced by the geometries of the compound orifice plate, and that the flow characteristic inside the orifice plate effect the type of spray produced by the injector.
Technical Paper

The Effect of Fuel Injection Rate and Timing on the Physical, Chemical, and Biological Character of Particulate Emissions from a Direct Injection Diesel

Formation of pollutants from diesel combustion and methods for their control have been reviewed. Of these methods, fuel injection rate and timing were selected for a parametric study relative to total particulate, soluble organic fraction (SOF), sulfates, solids and NO and NO2 emissions from a heavy-duty, turbocharged, after-cooled, direct-injection (DI) diesel. Chemical analyses of the SOF were performed at selected engine conditions to determine the effects of injection rate and timing on each of the eight chemical subfractions comprising the SOF. Biological character of the SOF was determined using the Ames Salmonella/microsome bioassay.
Technical Paper

A Computational Investigation of Hydrotreated Vegetable Oil Sprays Using RANS and a Modified Version of the RNG k - ε Model in OpenFOAM

Hydrotreated vegetable oil (HVO) is a high-cetane number alternative fuel with the potential of drastic emissions reductions in high-pressure diesel engines. In this study the behavior of HVO sprays is investigated computationally and compared with conventional diesel fuel sprays. The simulations are performed with a modified version of the C++ open source code OpenFOAM using Reynolds-averaged conservation equations for mass, species, momentum and energy. The turbulence has been modeled with a modified version of the RNG k-ε model. In particular, the turbulence interaction between the droplets and the gas has been accounted for by introducing appropriate source terms in the turbulence model equations. The spray simulations reflect the setup of the constant-volume combustion cell from which the experimental data were obtained.
Technical Paper

Impact of Blending Gasoline with Isobutanol Compared to Ethanol on Efficiency, Performance and Emissions of a Recreational Marine 4-Stroke Engine

This study evaluates iso-butanol as a pathway to introduce higher levels of alternative fuels for recreational marine engine applications compared to ethanol. Butanol, a 4-carbon alcohol, has an energy density closer to gasoline than ethanol. Isobutanol at 16 vol% blend level in gasoline (iB16) exhibits energy content as well as oxygen content identical to E10. Tests with these two blends, as well as indolene as a reference fuel, were conducted on a Mercury 90 HP, 4-stroke outboard engine featuring computer controlled sequential multi-port Electronic Fuel Injection (EFI). The test matrix included full load curves as well as the 5-mode steady-state marine engine test cycle. Analysis of the full load tests suggests that equal full load performance is achieved across the engine speed band regardless of fuel at a 15-20°C increase in exhaust gas temperatures for the alcohol blends compared to indolene.
Journal Article

A Novel Singular Perturbation Technique for Model-Based Control of Cold Start Hydrocarbon Emission

High hydrocarbon (HC) emission during a cold start still remains one of the major emission control challenges for spark ignition (SI) engines in spite of about three decades of research in this area. This paper proposes a cold start HC emission control strategy based on a reduced order modeling technique. A novel singular perturbation approximation (SPA) technique, based on the balanced realization principle, is developed for a nonlinear experimentally validated cold start emission model. The SPA reduced model is then utilized in the design of a model-based sliding mode controller (SMC). The controller targets to reduce cumulative tailpipe HC emission using a combination of fuel injection, spark timing, and air throttle / idle speed controls. The results from the designed multi-input multi-output (MIMO) reduced order SMC are compared with those from a full order SMC. The results show the reduced SMC outperforms the full order SMC by reducing both engine-out and tailpipe HC emission.