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Technical Paper

Formation Process of Soot Precursors in a Laminar Flow Reactor

2007-01-23
2007-01-0061
The Poly-Aromatic Hydrocarbon (PAH) formation process from benzene was studied using a laminar flow reactor and GC-MS. In addition to PAH, acetylene and ethylene were observed. Without oxygen at temperatures over 1070 K, the amount of PAH and C2 species increased as the benzene concentration decreased. Addition of oxygen caused a linear decrease in the benzene concentration, and almost all of the benzene was consumed under stoichiometric conditions at all temperatures. At 1053 K, the concentrations of PAH and C2 species were not affected by the addition of oxygen. On the other hand, when the temperature was greater than 1070 K, the amount of PAH formed increased as the equivalence ratio increased, until the equivalence ratio was about 4. Above this equivalence ratio, the amounts decreased. Amounts of phenanthrene and biphenyl were large compared to those of other PAHs, which indicated that the dominant PAH formation path is the formation of phenanthrene via biphenyl.
Technical Paper

Optimization of Engine System for Application of Biodiesel Fuel

2007-07-23
2007-01-2028
Application of biodiesel fuel (BDF) to diesel engine is very effective to reduce CO2 emission, because biodiesel is carbon neutral in principle. However, biodiesels yield an increase in NOx emission from conventional diesel engine, compared with diesel fuel case. Therefore, some strategies are needed for meeting the future emission regulations when using biodiesel. In this study, rapeseed oil methyl ester (RME) was applied to diesel engine equipped with exhaust gas recirculation (EGR) system and NOx storage reduction (NSR) catalyst. NOx reduction rate of NSR catalyst was drastically decreased by using RME, even if injection quantity of RME for rich spike was enhanced. However, an increase in EGR rate could reduce NOx emission without the deterioration in smoke and PM emissions.
Technical Paper

A New Type Partial Flow Dilution Tunnel with Geometrical Partitioning for Diesel Particulate Measurement

2001-09-24
2001-01-3579
The authors have developed a new partial flow dilution tunnel (hereafter referred to as PPFT), whose principal device is a flux splitting gas divider, as a new means of measuring particulate emissions which can be applied to transient cycle testing of diesel engines. The advantage of this system is that it can achieve perfect constant velocity splitting by means of its structure, and theoretically can also maintain high splitting performance despite fluctuations in the exhaust flow rate, including those due to engine exhaust pulsation. We compared this system with a full tunnel by analyzing the basic performance of the system and measuring particulate matter (PM) using an actual vehicle engine.
Technical Paper

Effect of Exhaust Gas Recirculation on Exhaust Emissions from Diesel Engines Fuelled with Biodiesel

2007-09-16
2007-24-0128
Application of biodiesel fuel (BDF) to diesel engine is very effective to reduce CO2 emission, because bio-diesel is carbon neutral in principle. However, when biodiesel was applied to conventional diesel engines without modification for biodiesel, NOx emission was increased by the change in fuel characteristics. It is necessary to introduce some strategies into diesel engines fuelled with biodiesel for lower NOx emission than conventional diesel fuel case. The purpose of this study is to reveal that exhaust gas recirculation (EGR) is one of the solutions for the reduction of NOx emission and meeting the future emission regulations when using biodiesel. Neat Rapeseed oil methyl ester (RME) as a biodiesel (B100) was applied to diesel engines equipped with high pressure loop (HPL) EGR system and low pressure loop (LPL) EGR system. Cooled HPL EGR was increased during steady-state operations and JE05 transient mode tests.
Technical Paper

Study of the Effect of Boiling Point on Combustion and PM Emissions in a Compression Ignition Engine Using Two-Component n-Paraffin Fuels

2002-03-04
2002-01-0871
Fuel composition is investigated as a parameter influencing fuel/air mixing of direct injected fuel and the subsequent consequences for particulate emissions. Presumably, enhanced mixing prior to ignition results in a larger portion of fuel burning as a premixture and a smaller portion of diffusion burning around fuel-rich regions. This would potentially lower particulate emissions without overly compromising hydrocarbon emissions or high load operation. Using mixtures of n-paraffin fuels, particulate emissions were measured and the results were compared with in-cylinder visualization of the injection process and two-color method calculations of flame temperature. In general, lower boiling point fuels exhibited higher flame temperatures, less visible flame, and lower particulate emissions.
Technical Paper

Performance and Emission Characteristics of a DI Diesel Engine Operated on Dimethyl Ether Applying EGR with Supercharging

2000-06-19
2000-01-1809
This research investigates engine performance and the possibility of reducing exhaust emissions by using Dimethyl Ether (DME). There are high expectations for DME as a new alternative fuel for diesel engines for heavy-duty vehicles. In this experiment, a single cylinder direct-injection diesel engine with displacement of 1.05 liter and a compression ratio of 18:1 was used as a base engine. Common rail type DME fuel injection equipment for the single cylinder engine experiment was installed, and direct injection in the cylinder of DME was tried. Results indicated that high injection pressure, high swirl ratio, and supercharging using multi-hole injectors are effective for combustion promotion in the DME fueled diesel engine (DME engine). The output of the DME engine using supercharging with an intercooler and EGR was higher than that of a diesel engine. By increasing the EGR rate Nox emission was reduced to about 1/3 that of the diesel engine. Smoke was not completely emitted.
Technical Paper

Analysis of Reaction Mechanisms Controlling Cool and Thermal Flame with DME Fueled HCCI Engines

2006-10-16
2006-01-3299
Autoignition in the homogeneous charge compression ignition (HCCI) process typically exhibits heat release in two stages called cool flame and thermal flame. The mechanisms governing these two stages were investigated using a DME-fueled HCCI engine and numerical simulations. Composition analysis after cool flame showed that the cool flame is explained by a chain reaction mechanism in which the chain terminator is the intermediate species formed in cool flame. In the case of thermal flame, although the chain reaction mechanism is complex, the behavior is clearly described by thermal explosion theory in which the rate-determining reaction is H2O2 decomposition.
Technical Paper

Evaluation of Regulated Materials and Ultra Fine Particle Emission from Trial Production of Heavy-Duty CNG Engine

2006-10-16
2006-01-3397
A prototype CNG engine for heavy-duty trucks has been developed. The engine had sufficient output in practical use, and the green-house gas emission rate was below that of the base diesel engine. Furthermore, the NOx emission rate was reduced to 0.16 g/kWh in the JE05 mode as results of having fully adjusted air fuel ratio control. The measured emission characteristics of particles from the prototype CNG engine demonstrated that oil consumption was related to the number of particles. Moreover, when oil consumption is at an appropriate level, the accumulation mode particles are significantly reduced, and the nuclei mode particles are fewer than those of diesel-fueled engines.
Technical Paper

SOF Component of Lubricant Oil on Diesel PM in a High Boosted and Cooled EGR Engine

2007-04-16
2007-01-0123
The engine in the research is a single cylinder DI diesel using the emission reduction techniques such as high boost, high injection pressure and broad range and high quantity of exhaust gas recirculation (EGR). The study especially focuses on the reduction of particulate matter (PM) under the engine operating conditions. In the experiment the authors measured engine performance, exhaust gases and mass of PM by low sulfur fuel such as 3 ppm and low sulfur lubricant oil such as 0.26%. Then the PM components were divided into soluble organic fraction (SOF) and insoluble organic fraction (ISOF) and they were measured at each engine condition. The mass of SOF was measured from the fuel fraction and lubricant oil fraction by gas chromatography. Also each mass of soot fraction and sulfate fraction was measured as components of ISOF. The experiment was conducted at BMEP = 2.0 MPa as full load condition of the engine and changing EGR rate from 0% to 40 %.
Technical Paper

Advanced Diesel Combustion Using of Wide Range, High Boosted and Cooled EGR System by Single Cylinder Engine

2006-04-03
2006-01-0077
For reducing exhaust emissions of heavy-duty diesel engines, the authors made an experimental study of diesel combustion using a single cylinder engine. The engine performance and exhaust emissions have been measured using a wide range and high EGR rate under the conditions of high boost intake pressure. The engine test cell has been equipped the external supercharger that is able to raise the boost pressure to 500 kPa, and also equipped the EGR system to increase the EGR rate until 50% under the 500 kPa boost condition. In various test conditions of load and engine speeds the authors have obtained the results, that is, NOx has been reduced drastically without increasing Particulate Matter (PM).
Technical Paper

Application of Biodiesel Fuel to Modern Diesel Engine

2006-04-03
2006-01-0233
The 1997 Kyoto protocol came into effect in February, 2005 to reduce greenhouse gases within the period 2008-2012 by at least 5 % with respect to 1990 levels. Application of biodiesel fuel (BDF) to diesel engine is very effective to reduce CO2 emission, because BDF is carbon neutral in principle. The purpose of this project is to produce a light-duty biodiesel truck which can be suitable for emission regulation in next generation. The effect of BDF on the performance and emissions of modern diesel engine which was equipped with the aftertreatment for PM and NOx emissions was investigated without modifications of engine components and parameters, as a first step for research and development of biodiesel engine. Rapeseed oil methyl ester (RME) was selected in behalf of BDF, and combustion characteristics, engine performance and exhaust emissions were made a comparison between RME and petroleum diesel fuel by steady operation and Japan transient mode (JE05) tests.
Technical Paper

Achievement of Medium Engine Speed and Load Premixed Diesel Combustion with Variable Valve Timing

2006-04-03
2006-01-0203
A variable valve timing (VVT) mechanism was applied to achieve premixed diesel combustion at higher load for low emissions and high thermal efficiency in a light duty diesel engine. By means of late intake valve closing (LIVC), compressed gas temperatures near the top dead center are lowered, thereby preventing too early ignition and increasing ignition delay to enhance fuel-air mixing. The variability of effective compression ratio has significant potential for ignition timing control of conventional diesel fuel mixtures. At the same time, the expansion ratio is kept constant to ensure thermal efficiency. Combining the control of LIVC, EGR, supercharging systems and high-pressure fuel injection equipment can simultaneously reduce NOx and smoke. The NOx and smoke suppression mechanism in the premixed diesel combustion was analyzed using the 3D-CFD code combined with detailed chemistry.
Technical Paper

The Cold Flow Performance and the Combustion Characteristics with Ethanol Blended Biodiesel Fuel

2005-10-24
2005-01-3707
The purpose of this study is to improve low-temperature flow-properties of biodiesel fuels (BDF) by blending with ethanol and to analyze the combustion characteristics in a diesel engine fueled with BDF/ethanol blended fuel. Because ethanol has a lower solidifying temperature, higher oxygen content, lower cetane number, and higher volatility than BDF, ethanol blending would have a large effect on cold flow performance, mixture formation, ignition, combustion, and exhaust emissions. The engine experiments in the study were performed with a diesel engine and blends of BDF and ethanol at different blending ratios. The cold flow performance of the blended fuels was evaluated by determining the fuel cloud point. The experimental results show that the ethanol blending lowers the cloud point of the blended fuel and significantly reduces smoke emissions from the engine without deteriorating other emissions or thermal efficiency.
Technical Paper

Trapping Performance of Fine Particles from a Diesel Engine by Various DPFs with Different Surface Structures

2004-03-08
2004-01-0598
The regulation of particulate matter (PM) from diesel engines is coming to be very stringent at present. The usage of diesel particulate filter (DPF) is now under consideration in many heavy-duty diesel vehicle manufacturers to reduce PM emission from a diesel engine. The possibility that very fine particles may pass through DPF is suggested. The understanding of fine particles emission behaviors and the countermeasure of reducing particle emissions from DPF will come to be important in near future. The behavior of particle size distribution after DPF has not been studied enough yet. In this study, fine particles generated by a diesel engine are introduced to honeycomb type and SiC (Silicon Carbite) fiber type DPFs and the collection performances of fine particles by various DPFs with different surface structures have been examined.
Technical Paper

Influence of Dilution Process on Engine Exhaust Nano-Particles

2004-03-08
2004-01-0963
Recently, particulate matter (PM) emission from internal combustion engines, especially particles having the diameter of less than 100 nm (Nano-particles) are being considered for their potential hazards posed to human health and the environment. Nano-particles are unstable and easily influenced by the conditions of engine operation and measurement techniques. In this study, the influences of cooling and dilution processes on nano- particles are presented to understand the generation and dilution mechanisms, and to further development of an accurate measurement method. It is found that the thermo-dilurter is necessary for measuring the nano-particles with higher accuracy. Accurate measurement of nano-particles requires immediate dilution of the exhaust gases by hot air.
Technical Paper

Thermal Conditioning of Exhaust Gas: Potential for Stabilizing Diesel Nano-Particles

2005-04-11
2005-01-0187
Conditioning of diluted exhaust gas by Thermo-Conditioner prior to measurement has been proposed by the GRPE/PMP Research Council of the United Nation in order to achieve stability in nano-particle measurement. In this study the effect of thermo-conditioner on the thermo-physical behavior of nano-particle under different conditions have been clarified. Stability in measurement was also attempted depending on the characteristics of nano-particles. Quality of the raw exhaust gas, the dilution ratio and temperature, and the thermal conditioning temperature were considered as the main parameters. Exhaust gas from a medium duty DI diesel engine was used for analysis. Scanning Mobility Particle Sizer was used for measuring the concentration of nano-particles. It was concluded that the concentration of nuclei-mode particles within the size range of 15∼30 nm are significantly influenced by the thermal conditioning temperature.
Technical Paper

Comparative Measurement of Nano-Particulates in Diesel Engine Exhaust Gas by Laser-Induced Incandescence (LII) and Scanning Mobility Particle Sizer (SMPS)

2004-06-08
2004-01-1982
Particulate Matter (PM) from diesel engines is thought to be seriously hazardous for human health. Generally, it is said that the hazard depends on the total number and surface area of particles rather than total mass of PM. In the conventional gravimetric method, only the total mass of PM is measured. Therefore, it is very important to measure not only the mass of PM but also size and number density of particulates. Laser-Induced Incandescence (LII) is a useful diagnostic for transient measurement of soot particulate volume fraction and primary particle size. On the other hand, Scanning Mobility Particle Sizer (SMPS) is also used to measure the size distribution of soot aggregate particulates at a steady state condition. However, the measurement processes and the phenomena used to acquire the information on soot particulate are quite different between the LII and SMPS methods. Therefore, it is necessary to understand the detailed characteristics of both LII and SMPS.
Technical Paper

Real-Time Measurement of Particle Size Distribution From Diesel Engines Equipped With Continuous Regenerative DPF Under a Transient Driving Condition

2004-06-08
2004-01-1984
A new PM measurement method, such as particle measurement equipments, samplings and so on, is being studied at present for a type approval test in the future. Particles emitted from diesel engines, especially the particles that are called “Nuclei Mode Particles” are very unstable and easily influenced by the engine operating conditions and the measurement conditions. Most of nuclei mode particles are said to consist of volatile organic particles with mainly high carbon numbers. It is said that a continuous regenerative type DPF (Diesel Particulate Filter) consisting of oxidation catalyst and ceramic filter will prevail in the near future. These particles may be able to be reduced by an oxidation catalyst in this DPF.
Technical Paper

Effects of Fuel Properties on Combustion and Exhaust Emissions of Homogeneous Charge Compression Ignition (HCCI) Engine

2004-06-08
2004-01-1966
Homogeneous Charge Compression Ignition (HCCI) is effective for the simultaneous reduction of soot and NOx emissions from diesel engine. In general, high octane number and volatility fuels (gasoline components or gaseous fuels) are used for HCCI operation, because very lean mixture must be formed during ignition delay of the fuel. However, it is necessary to improve fuel injection systems, when these fuels are used in diesel engine. The purpose of the present study is the achievement of HCCI combustion in DI diesel engine without the large-scale improvements of engine components. Various high octane number fuels are mixed with diesel fuel as a base fuel, and the mixed fuels are directly applied to DI diesel engine. At first, the cylinder pressure and heat release rate of each mixed fuel are analyzed. The ignition delay of HCCI operation decreases with an increase in the operation load, although that of conventional diesel operation does not almost varied.
Technical Paper

Visualization Experiment in a Transparent Engine With Pure and Mixed Normal Paraffin Fuels

2004-06-08
2004-01-2018
In the previous study design of two-component normal paraffin fuel was attempted considering the components and blending ratio. Only the thermodynamic analysis of combustion and analysis of emission characteristics were performed to evaluate the design performance. In this study mixture formation behavior and combustion phenomena of pure and mixed n-paraffin fuels were investigated by direct visualization in an AVL engine with bottom view piston. The experiments included laser-illuminated high-speed photography of the fuel injection phase and combustion phase to investigate physical differences. The results obtained for the proposed fuels are compared with the results of conventional diesel fuel. It was found that the two component normal paraffin fuels with similar thermo physical properties have very similar spray development pattern but evaporation rates are different.
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