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Journal Article

Gasoline Direct Injection Compression Ignition (GDCI) - Diesel-like Efficiency with Low CO2 Emissions

2011-04-12
2011-01-1386
A single-cylinder engine was used to study the potential of a high-efficiency combustion concept called gasoline direct-injection compression-ignition (GDCI). Low temperature combustion was achieved using multiple injections, intake boost, and moderate EGR to reduce engine-out NOx and PM emissions engine for stringent emissions standards. This combustion strategy benefits from the relatively long ignition delay and high volatility of regular unleaded gasoline fuel. Tests were conducted at 6 bar IMEP - 1500 rpm using various injection strategies with low-to-moderate injection pressure. Results showed that triple injection GDCI achieved about 8 percent greater indicated thermal efficiency and about 14 percent lower specific CO2 emissions relative to diesel baseline tests on the same engine. Heat release rates and combustion noise could be controlled with a multiple-late injection strategy for controlled fuel-air stratification. Estimated heat losses were significantly reduced.
Journal Article

Two-Dimensional In-Cylinder Soot Volume Fractions in Diesel Low Temperature Combustion Mode

2011-04-12
2011-01-1390
Soot Volume Fraction (SVF) measurements were performed in an IFP Energies nouvelles optical single cylinder Diesel engine operated in Low Temperature Combustion (LTC) conditions. The engine was equipped with a sapphire liner, a dedicated flat bowl piston and a six-hole common-rail high pressure injector. The piston design included four quartz windows allowing optical access into the bowl. The aim of this work was to study soot formation and oxidation during the LTC Diesel combustion process and to build a database providing soot formation and oxidation data under a set of engine conditions to help developing and testing Computational Fluid Dynamics (CFD) models. Two complementary optical diagnostic techniques were combined: Planar Laser Induced Incandescence (PLII) and Laser Extinction Method (LEM).
Technical Paper

An Investigation of Particle Size Distributions with Post Injection in DI Diesel Engines

2011-04-12
2011-01-1379
In-cylinder emission control strategies, such as modifications of injection pressure and injection timing, have been used by researchers in order to reduce exhaust emissions and to comply with the legislation standards. Since some years ago post-injections have been studied and are well known as being efficient for soot emissions reduction. Although is well known that diesel gaseous and particle mass emissions have been reduced progressively over the last twenty years in response to the restrictive emission legislation and due to the application of new technologies The aim of this work is to help develop and understand the effect of the post-injection on diesel exhaust particle size distributions. The approach is to use a modern, well instrumented research engine equipped with a flexible high pressure fuel injection system. The results of this work are available to help provide guidelines for strategies to achieve reductions of the particle size distributions in diesel engines.
Technical Paper

Ignition, Combustion and Exhaust Emission Characteristics of Micro-pilot Ignited Dual-fuel Engine Operated under PREMIER Combustion Mode

2011-08-30
2011-01-1764
The objective of this study is to investigate the performance and emissions in a pilot-ignited supercharged dual-fuel engine, fueled with different types of gaseous fuels under various equivalence ratios. It is found that if certain operating conditions are maintained, conventional dual-fuel engine combustion mode can be transformed to the combustion mode with the two-stage heat release. This mode of combustion was called the PREMIER (PREmixed Mixture Ignition in the End-gas Region) combustion. During PREMIER combustion, initially, the combustion progresses as the premixed flame propagation and then, due to the mixture autoignition in the end-gas region, ahead of the propagating flame front, the transition occurs with the rapid increase in the heat release rate.
Technical Paper

Effects of Injection Pressure, Timing and EGR on Combustion and Emissions Characteristics of Diesel PCCI Engine

2011-08-30
2011-01-1769
Effects of injection parameters on combustion and emission characteristics of diesel PCCI engine operating on optical and test engine was investigated. PCCI combustion was achieved through slightly narrow included angle injector, low compression ratio coupled with exhaust gas recirculation. Analysis based on diesel spray evolution, combustion process visualization and analysis was carried out. Spray penetration was evaluated and related to the exhaust emissions. Advancing the injection timing and EGR extended the ignition delay, decreased NOx emissions and increased HC, smoke and CO emissions. Higher injection pressure led to low emissions of NOx, smoke, HC and comparable CO. Optimum spray targeting position for minimum emission was identified. Impingement on the piston surface led to deterioration of emissions and increased fuel consumption while spray targeting the upper edge of Derby hat wall showed improvement in emission and engine performance.
Technical Paper

The Power Unit with Strong Hybrid System for Motorcycles

2011-08-30
2011-01-1745
A strong hybrid system is one of the best solutions to reduce the exhaust of carbon dioxide from vehicles[1]. However it could be believed as being too big and complicated for a motorcycle. Yamaha has developed a unique power unit which consists of an engine, two motors, and a planetary gear drive train in a simple one-room construction with highly stiffened casing. The power unit has been installed onto a proto-type motorcycle called “HV-X”. The HV-X attains 40% or less exhaust of carbon dioxide with no degradation of drive performances, but better acceleration.
Technical Paper

Design Optimization of Non-Catalyzed DPF from Viewpoint of Back Pressure in Ash loading State

2011-08-30
2011-01-2091
Back pressure of Diesel Particulate Filter (DPF) varies with accumulation of soot and/or ash. Soot can be cleaned in a high temperature oxidation (regeneration) process. But ash which is incombustible particulate matter derived from lubricant oil, engine wear, etc. cannot be cleaned from DPF without mechanical ash removal process and influences the back pressure perpetually. Design and control of DPF involving variation of the back pressure with ash accumulation will provide further improvement of fuel consumption and reliable operation in extended vehicle life time. Nevertheless, empirical investigations concerning ash accumulation are few because of the long testing time due to the slow accumulation rate, i.e. 0.5 - 2mg/mile [19]. In this investigation, four different designs of Cordierite (Cd) DPF were subjected to an accelerated ash accumulation test which is utilizing artificial ash powder.
Technical Paper

Experimental Investigation of Applying Raw Fuel Injection Technique for Reducing Methane in Aftertreatment of Diesel Dual Fuel Engines Operating under Medium Load Conditions

2011-08-30
2011-01-2093
Towards the effort of using natural gas as an alternative fuel for a diesel engine, the concept of Diesel Dual Fuel (DDF) engine has been shown as a strong candidate. Typically, DDF's engine-out emission species such as soot and nitrogen oxides are decreased while carbon monoxide and hydrocarbons are increased. The aftertreatment system is required in order to reduce these pollutant emissions from DDF engines. Additionally, DDF engine exhaust has a wide temperature span and is rich in oxygen, which makes HC emissions, especially methane (CH₄), difficult to treat. Until now, it is widely accepted that the key parameter influencing methane oxidation in a catalytic converter is high exhaust temperature. However, a comprehensive understanding of what variables in real DDF engine exhausts most influencing a catalytic converter performance are yet to be explored.
Technical Paper

Characterization of PM sampled from inside and outside of diffusion flame

2011-08-30
2011-01-2099
Characteristics of PM and its compositions inside and outside of flame were required to develop reduction technologies for combustion origin PM. In this paper, relationship between PM size distribution and compositions such as soot and soluble organic fraction (SOF) of PM sampled with filter were investigated. Number distributions of PM (30 nm-10 μm) were measured using an ELPI (Electrical Low Pressure Impactor). Dry-soot and SOF in PM that was captured an individual stage of ELPI were analyzed using a combustion type PM analyzer (MEXA-1370PM). It was clarified that nuclei mode particle included more SOF than accumulation mode particle. PM characterization showed that there were many differences between in-flame PM and out-flame PM. In-flame PM contained much of low boiling point SOF and dry-soot composition was thermally unstable. Further, similarities between SOF in PM sampled with filter and gaseous hydrocarbons passing through PM filter were discussed.
Journal Article

Particulate Matter Sampling and Volatile Organic Compound Removal for Characterization of Spark Ignited Direct Injection Engine Emissions

2011-08-30
2011-01-2100
More stringent emissions regulations are continually being proposed to mitigate adverse human health and environmental impacts of internal combustion engines. With that in mind, it has been proposed that vehicular particulate matter (PM) emissions should be regulated based on particle number in addition to particle mass. One aspect of this project is to study different sample handling methods for number-based aerosol measurements, specifically, two different methods for removing volatile organic compounds (VOCs). One method is a thermodenuder (TD) and the other is an evaporative chamber/diluter (EvCh). These sample-handling methods have been implemented in an engine test cell with a spark-ignited direct injection (SIDI) engine. The engine was designed for stoichiometric, homogeneous combustion.
Technical Paper

Direct Injection Spark Ignition Engine Deposit Analysis: Combustion Chamber and Intake Valve Deposits

2011-08-30
2011-01-2110
The delicate balance between global supply and demand for energy, in conjunction with environmental concerns related to burning fossil fuels, have resulted in vehicle designs that stress higher fuel economy. Among new engine designs is Direct Injection Spark Ignition, or DISI, which employs a more precise fuel metering system and is designed for combustion at higher compression ratios than Port Fuel Injection (PFI) engines. As a result, the performance of DISI engines can easily be altered by the presence of carbonaceous deposits on intake valves and in the combustion chamber. In this study, the characteristics of these deposits have been investigated using elemental and thermal analytical techniques. Deposits from intake valves and combustion chambers have been collected from various DISI engines (both older and more modern ones).
Technical Paper

Study on Measurement Method of Driving Force Using New Type Wheel Torque Meter in On-road Driving

2011-08-30
2011-01-2061
Exhaust emissions behavior from a vehicle under road driving condition is affected by a driving force of a vehicle. It is impossible to measure the driving force by an existing torque meter under this on-road driving condition. This study reports the development and verification of the wheel torque meter which is possible to measure driving force under the on-road driving condition and has enough strength and accuracy. The wheel torque meter developed in this study consists of a torque detector with a strain gauge type torque transducer, a telemeter receiver and a data logger. The strain gauge type torque transducer is equipped between hub and wheel at the drive axle tire, because of the narrow width of this transducer, and it is possible to be placed against vehicle without significant conversion of the vehicle. Because of these characters, this transducer is possible to be used for an on-road driving vehicle.
Technical Paper

Countering the Effects of Media Interferences and Background Contamination in Collection of Low Concentration Aldehydes and Ketones in Engine Exhaust with Dinitrophenylhydrazine (DNPH) Derivatization

2011-08-30
2011-01-2060
This paper discusses a method developed to counter the variability of media interferences for the measurement of aldehydes and ketones in automotive exhaust. Dinitrophenylhydrazine (DNPH) Derivatization Methodology for the collection of aldehyde and ketone compounds in vehicle exhaust has been in use for over thirty years. These carbonyl compounds are captured by passing diluted exhaust gas through a sample medium containing DNPH. The sampling medium can take the form of DNPH dispersed on a solid sorbent or as a DNPH solution in a solvent such as acetonitrile. Carbonyl compounds react readily to form DNPH derivatives which are stable and which absorb ultra-violet (UV) light, facilitating quantitative measurement. However, when the procedure was developed, emissions rates from vehicles were much higher than the current (2010) emissions levels.
Technical Paper

Evaluation of Exhaust Particle Emissions from a DI Diesel Engine Using a Solid Particle Counting System with Direct Sampling Unit

2011-08-30
2011-01-2057
An approach for raw exhaust gas sampling, different from the conventional diluted exhaust gas sampling method, has been adopted for a solid particle counting system developed in the previous study. The system has been applied for evaluating solid particle emission from a DI diesel engine with DPF. In addition the filtration efficiency of the DPF has been tested from the real time concentrations, measured at upstream and downstream of the DPF. High accuracy and stability of measurement of the system against high exhaust gas pressure condition have been confirmed. The system response satisfies the requirement of ISO 8178-11. Excellent correlation of direct sampling and diluted gas sampling has been achieved with this system. It is found that the filtration efficiency changes during the engine test cycle and is strongly affected by the pre-conditioning of DPF.
Technical Paper

Fuel Sulfur Effect on Nano-PM Formation from Diffusion Flame

2011-08-30
2011-01-2055
Recently, for reduction of PM emission from diesel engine, low sulfur diesel fuel was introduced and commercialized. There are some reports for effect of fuel sulfur on PM characteristics by using engine dynamometer tests. However, it is difficult to understand mechanism of PM formation and effect of fuel sulfur on PM formation process. Thus, investigation by a simple flame is effective way for understanding detail PM formation process. In this paper, effect of sulfur content in fuel on PM characteristics was investigated by using laboratory-scale PM generator. Test fuels were diesel and surrogate diesel fuel, and sulfur concentration in the surrogate fuel was controlled with thiophene addition. Effects of fuel sulfur on PM were clarified with characteristics of PM obtained from PM number distribution measurements and PM compositions analysis.
Journal Article

Development of an On-Board PM Sensor for the OBD System Based on an Electrochemical Polarization

2011-08-30
2011-01-2059
An on-board particulate matter (PM) sensor, consisting of a gas-permeable electrochemical cell with a porous yttria-stabilized zirconia solid oxide electrolyte, was developed to assist the on-board diagnostics (OBD) system of a vehicle. Exhaust is pumped from the anode side to the cathode side and PM deposited on the anode is instantly oxidized by the catalytic effects of the metal component of the electrode at temperatures higher than 350°C. The PM oxidation reaction occurs at the three-phase boundary between the anode, electrolyte and gas phase, and causes a slight change in the bulk average oxygen concentration, which produces electrochemical polarization by the difference in oxygen partial pressures between the anode and cathode. The developed PM sensor has a detection limit of 2 mg/m₃, at which level will enable PM detection in the OBD system according to the EURO VI regulation.
Journal Article

Comparison of fuel economy and exhaust emission tests of 4WD vehicles using single-axis chassis dynamometer and dual-axis chassis dynamometer

2011-08-30
2011-01-2058
The demands of application of dual-axis chassis dynamometers (4WD-CHDY) have increased recently due to the improvement of performance of 4WD-CHDY and an increase in the number of 4WD vehicles which are difficult to convert to 2WD. However, there are few evaluations of any differences between fuel economy and exhaust emission levels in the case of 2WD-CHDY with conversion from 4WD to 2WD (2WD-mode) and 4WD-CHDY without conversion to 2WD (4WD-mode). Fuel economy and exhaust emission tests of 4WD vehicle equipped with a typical 4WD mechanism were performed to investigate any differences between the case of the 2WD-mode and the 4WD-mode. In these tests, we measured ‘work at wheel’ (wheel-work) using wheel torque meters. A comparison of the 2WD-mode and the 4WD-mode reveals a difference of fuel economy (2WD-mode is 1.5% better than that of 4WD-mode) and wheel-work (2WD-mode is 3.9% less than that of 4WD-mode). However, there are almost no differences of exhaust emission levels.
Journal Article

Transient simulation of NOx reduction over a Fe-Zeolite catalyst in an NH3-SCR system and study of the performance under different operating conditions

2011-08-30
2011-01-2084
The NO reduction in an ammonia SCR converter has been simulated by a 1D+1D model for a single representative channel to parametrically study the characteristics of the system under typical operating conditions. An appropriate model has been selected interpreting the chemical behavior of the system and the parameters are calibrated based on a comprehensive set of experiments with an Fe-Zeolite washcoated monolith for different feed concentrations, temperatures and flow rates. Physical and chemical properties are determined as well as kinetics and rate parameters and the model has been verified by experimental data at different operating conditions. Three different mechanisms for the surface kinetics to model NO reduction have been assessed and the results have been compared in the cases of steady DeNO performance and transient response of the system. Ammonia inhibition is considered in the model since it has a major effect specifically under transient operating conditions.
Journal Article

Modelling of Soot Oxidation by NO2 in a Diesel Particulate Filter

2011-08-30
2011-01-2083
Two approaches were adopted to study soot oxidation by NO₂; firstly microreactor tests were performed on soot produced by a soot generator over a range of NO₂ concentrations and temperatures. This enabled measurement to be made under well-controlled conditions. Secondly, soot oxidation measurements were made on an engine bench to obtain data under more realistic, if less controlled, conditions. In the microreactor work NO₂ consumption by soot oxidation and the selectivity of the soot oxidation to CO and CO₂ were measured. The latter was found to vary only slightly with temperature and to be independent of NO₂ concentration. By modeling this data using a 1-dimensional model, rate equations for the soot-NO₂ reaction were determined. These were then tested against the engine data. The soot used in this study was characterized by thermogravimetric analysis, N₂ physisorption and transmission electron microscopy.
Journal Article

ANALYSIS OF NOx CONVERSION USING A QUASI 2-D NH3-SCR MODEL WITH DETAILED REACTIONS

2011-08-30
2011-01-2081
We have constructed a quasi-2-dimensional NH₃-SCR model with detailed surface reactions to analyze the NOx conversion mechanism and reasons for its inhibition at low temperatures. The model consists of seven detailed surface reactions proposed by Grozzale et al., and calculates longitudinal gas flow, gas phase-catalyst phase mass transfer, and mass diffusion within the catalyst phase in the depth dimension. Using the model, we have analyzed the results of pulsed ammonia (NH₃) feed tests at various catalyst temperatures, and results show that ammonium nitrate (NH₄NO₃) is the inhibitor in NH₃-SCR reactions at low temperatures. In addition, we found that cutting the supply of NH₃ causes decomposition of NH₄NO₃, providing surface ammonia (NH₄+), which rapidly reacts with adjacent NOx, leading to an instantaneous rise in nitrogen (N₂) formation.
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