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Technical Paper

Effects of Ethanol Additives on Diesel Particulate and NOx Emissions

2001-05-07
2001-01-1937
Particulate and nitrogen oxide emissions from a 1.9-liter Volkswagen diesel engine were measured for three different fuels: neat diesel fuel, a blend of diesel fuel with 10% ethanol, and a blend of diesel fuel with 15% ethanol. Engine-out emissions were measured on an engine dynamometer for five different speeds and five different torques using the standard engine-control unit. Results show that particulate emissions can be significantly reduced over approximately two-thirds of the engine map by using a diesel-ethanol blend. Nitrogen oxide emissions can also be significantly reduced over a smaller portion of the engine map by using a diesel-ethanol blend. Moreover, there is an overlap between the regions where particulate emissions can be reduced by up to 75% and nitrogen oxide emissions are reduced by up to 84% compared with neat diesel fuel.
Technical Paper

Ignition Characteristics of Methane-air Mixtures at Elevated Temperatures and Pressures

2005-05-11
2005-01-2189
Lean operation of natural gas fired reciprocating engines has been the preferred mode of operation as it allows low NOx emissions and simultaneous high overall efficiencies. In such engines, the operation point is often close to where the ignition boundary and the knock limiting boundary cross-over. While knocking is, to a large extent, limited by engine design, ignition of lean-mixtures is limited by the mode of ignition. Since significant benefits can be achieved by extending the lean-ignition limits, many groups have been researching alternate ways to achieve ignition reliably. One of the methods, laser ignition, appears promising as it achieves ignition at high pressures and under lean conditions relatively easily. However, most of the current knowledge about laser ignition is based on measurements performed at room temperature. In this paper, ignition studies on methane-air mixtures under in-cylinder conditions are presented.
Technical Paper

Effects of Exhaust System Components on Particulate Morphology in a Light-duty Diesel Engine

2005-04-11
2005-01-0184
The detailed morphological properties of diesel particulate matter were analyzed along the exhaust system at various engine operating conditions (in a range of 1000 - 2500 rpm and 10 - 75 % loads of maximum torques). A 1.7-L turbocharged light-duty diesel engine was powered with California low-sulfur diesel fuel injected by a common-rail injection system, of which particulate emissions were controlled by an exhaust gas recirculation (EGR) system and two oxidation catalysts. A unique thermophoretic sampling system first developed for internal combustion engine research, a high-resolution transmission electron microscope (TEM), and a customized image processing/data acquisition system were key instruments that were used for the collection of particulate matter, subsequent imaging of particle morphology, and detailed analysis of particle dimensions and fractal geometry, respectively.
Technical Paper

Evolution in Size and Morphology of Diesel Particulates Along the Exhaust System

2004-06-08
2004-01-1981
The physical and morphological properties of the particulate matter emitted from a 1.7-liter light-duty diesel engine were characterized by observing its evolution in size and fractal geometry along the exhaust system. A common-rail direct-injection diesel engine, the exhaust system of which was equipped with a turbocharger, EGR, and two oxidation catalysts, was powered with a California low-sulfur diesel fuel at various engine-operating conditions. A unique thermophoretic sampling system, a high-resolution transmission electron microscope (TEM), and customized image processing/data acquisition systems were key instruments that were used for the collection of particulate matter, subsequent imaging of particle morphology, and detailed analysis of particle dimensions and fractal geometry, respectively. The measurements were carried out at four different positions along the exhaust pipe.
Technical Paper

Membrane-Based Nitrogen-Enriched Air for NOx Reduction in Light-Duty Diesel Engines

2000-03-06
2000-01-0228
The effects of nitrogen-enriched air, supplied by an air separation membrane, on NOx emissions from a 1.9-L turbocharged direct-injection diesel engine were investigated. To enrich combustion air with more nitrogen, prototype air separation membranes were installed between the after-cooler and intake manifold without any additional controls. The effects of nitrogen-enriched combustion air on NOx emissions were compared with and without exhaust gas recirculation (EGR). At sufficient boost pressures (>50 kPag), nitrogen-enriched air from the membrane provided intake oxygen levels that were similar to those of EGR. Compared with EGR, nitrogen-enriched air provided 10-15% NOx reductions during medium to high engine loads and speeds. At part loads, when turbocharger boost pressure was low, the air separation membrane was not effective in enriching air with nitrogen. As a result, NOx reduction was lower, but it was 15-25% better than when EGR was not used.
Technical Paper

Transient Particulate Emission Measurements in Diesel Engine Exhausts

2003-10-27
2003-01-3155
This paper reports our efforts to develop an instrument, TG-1, to measure particulate emissions from diesel engines in real-time. TG-1 while based on laser-induced incandescence allows measurements at 10 Hz on typical engine exhausts. Using such an instrument, measurements were performed in the exhaust of a 1.7L Mercedes Benz engine coupled to a low-inertia dynamometer. Comparative measurements performed under engine steady state conditions showed the instrument to agree within ±12% of measurements performed with an SMPS. Moreover, the instrument had far better time response and time resolution than a TEOM® 1105. Also, TG-1 appears to surpass the shortcomings of the TEOM instrument, i.e., of yielding negative values under certain engine conditions and, being sensitive to external vibration.
Technical Paper

Exhaust Emissions of a Vehicle with a Gasoline Direct-Injection Engine

1998-10-19
982605
Their high fuel economy is making light-duty vehicles with spark-ignition direct-injection (SIDI) engines attractive. However, the implications for exhaust emissions and the effects of fuel quality on emissions are not clear for this type of engine. A Mitsubishi Legnum with a 1.8-L GDI™ engine was tested on federal test procedure (FTP) and highway fuel economy cycles. The results were compared with those for a production Dodge Neon vehicle with a 2.0-L port fuel-injection (PFI) engine. The Mitsubishi was tested with Indolene, Amoco Premium Ultimate, and a low-sulfur gasoline. The Neon was tested only with Indolene. Both engine-out and tailpipe emissions were measured. Second-by-second emissions and hydrocarbon speciation were also evaluated. The SIDI engine provided up to 24% better fuel economy than the PFI engine on the highway cycle. Tailpipe emissions of oxides of nitrogen (NOx) from the SIDI vehicle using low-sulfur fuel were 40% less than those when using Indolene.
Technical Paper

Variable Air Composition with Polymer Membrane - A New Low Emissions Tool

1998-02-01
980178
Air can be enriched with oxygen and/or nitrogen by selective permeation through a nonporous polymer membrane; this concept offers numerous potential benefits for piston engines. The use of oxygen-enriched intake air can significantly reduce exhaust emissions (except NOx), improve power density, lessen ignition delay, and allow the use of lower-grade fuels. The use of nitrogen-enriched air as a diluent can lessen NOx emissions and may be considered an alternative to exhaust gas recirculation (EGR). Nitrogen-enriched air can also be used to generate a monatomic-nitrogen stream, with nonthermal plasma, to treat exhaust NOx. With such synergistic use of variable air composition from an on-board polymer membrane, many emissions problems can be solved effectively. This paper presents an overview of different applications of air separation membranes for diesel and spark-ignition engines. Membrane characteristics and operating requirements are examined for use in automotive engines.
Technical Paper

Effect of Nozzle Geometry on the Common-Rail Diesel Spray

2002-05-06
2002-01-1625
Diesel injections with various nozzle geometries were tested to investigate the spray characteristics by optical imaging techniques. Sac-nozzle and VCO nozzle with single guided needle coupled with rotary-type mechanical pump were compared in terms of macroscopic spray development and microscopic behavior. These nozzles incorporated with common-rail system were tested to see the effect of high pressure injection. Detailed investigation into spray characteristics from the holes of VCO nozzles, mostly with double guided needle, was performed. A variety of injection hole geometries were tested and compared to give tips on better injector design. Different hole sizes and taper ratio, represented as K factor, were studied through comprehensive spray imaging techniques. Global characteristics of a diesel spray, such as spray penetration, spray angle and its pattern, were observed from macroscopic images.
Technical Paper

Detailed Characterization of Morphology and Dimensions of Diesel Particulates via Thermophoretic Sampling

2001-09-24
2001-01-3572
A thermophoretic particulate sampling device was used to investigate the detailed morphology and microstructure of diesel particulates at various engine-operating conditions. A 75 HP Caterpillar single-cylinder direct-injection diesel engine was operated to sample particulate matter from the high-temperature exhaust stream. The morphology and microstructure of the collected diesel particulates were analyzed using a high-resolution transmission electron microscope and subsequent image processing/data acquisition system. The analysis revealed that spherical primary particles were agglomerated together to form large aggregate clusters for most of engine speed and load conditions. Measured primary particle sizes ranged from 34.4 to 28.5 nm at various engine-operating conditions. The smaller primary particles observed at high engine-operating conditions were believed to be caused by particle oxidation at the high combustion temperature.
Technical Paper

Parametric Examination of Filtration Processes in Diesel Particulate Filter Membranes with Channel Structure Modification

2010-04-12
2010-01-0537
The limited spatial area in conventional diesel particulate filter (DPF) systems requires frequent regenerations to remove collected particulate matter (PM) emissions, consequently resulting in higher energy consumption and potential material failure. Due to the complex geometry and difficulty in access to the internal structure of diesel particulate filters, in addition, many important characteristics in filtration processes remain unknown. In this work, therefore, the geometry of DPF membrane channels was modified basically to increase the filtration areas, and their filtration characteristics were evaluated in terms of pressure drop across the DPF membranes, effects of soot loading on pressure drop, and qualitative soot mass distribution in the membrane channels. In this evaluation, an analytical model was developed for pressure drop, which allowed a parametric study with those modified membranes.
Technical Paper

Accurate Measurements of Heat Release, Oxidation Rates, and Soluble Organic Compounds of Diesel Particulates through Thermal Reactions

2010-04-12
2010-01-0814
In an effort of providing better understanding of regeneration mechanisms of diesel particulate matter (PM), this experimental investigation focused on evaluating the amount of heat release generated during the thermal reaction of diesel PM and the concentrations of soluble organic compounds (SOCs) dissolved in PM emissions. Differences in oxidation behaviors were observed for two different diesel PM samples: a SOC-containing PM sample and a dry soot sample with no SOCs. Both samples were collected from a cordierite particulate filter membrane in a thermal reactor connected to the exhaust pipe of a light-duty diesel engine. A differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA) were used to measure the amount of heat release during oxidation, along with subsequent oxidation rates and the concentrations of SOCs dissolved in particulate samples, respectively.
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