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Technical Paper

Effect of Thermal Fatigue Phenomena of Aluminum Alloy by Artificial Aging

2002-03-04
2002-01-0584
The past efforts to develop aluminum alloy engine parts were focused on the formulation of chemical composition rather than the heat treatment conditions of aluminum alloys. Only a few studies have been made on optimizing heat treatment conditions. This paper deals with the effects of artificial aging on two aluminum alloys, A356 and A319, which have been often used for engine cylinder heads. The aluminum alloys were artificially aged under several different conditions after T6 heat treatment. The alloys were tested for such mechanical properties as pure tension, cyclic loading resistance and thermo-mechanical fatigue failure. The microstructure was observed by TEM to see the effects on microstructure in terms of mechanical properties.
Technical Paper

Low Emission and Knock-Free Combustion with Rich and Lean Biform Mixture in a Dual-Fuel CI Engine with Induced LPG as the Main Fuel

2001-09-24
2001-01-3502
Smokeless and ultra low NOx combustion without knocking in a dual-fuel diesel engine with induced LPG as the main fuel was established with a uniquely developed piston cavity divided by a lip in the sidewall. A small quantity of diesel fuel was directly injected at early compression stroke into the lower part of the cavity as an ignition source for this confined area, and this suppressed explosively rapid combustion just after ignition and spark-knock like combustion at later stage. A combination of the divided cavity, EGR, and intake air throttling was effective to simultaneously eliminate knocking, and reduce THC and NOx significantly.
Technical Paper

Ultra Low Emissions and High Performance Diesel Combustion with a Combination of High EGR, Three-Way Catalyst, and a Highly Oxygenated Fuel, Dimethoxy Methane (DMM)

2000-06-19
2000-01-1819
Ultra low emissions and high performance combustion was achieved with a combination of high EGR, a three-way catalyst, and a highly oxygenated liquid fuel, neat dimethoxy methane (DMM), in an ordinary DI diesel engine. The smokeless nature of neat DMM effectively allowed stoichiometric diesel combustion by controlling BMEP with EGR. NOx, THC, and CO emissions were reduced with a three-way catalyst. At lower BMEP with excess air, the EGR effectively reduced NOx. High-speed video in a bottom view type engine revealed that luminous flame decreased with increased fuel oxygen content and almost disappeared with DMM.
Technical Paper

HCCI Combustion Control by DME-Ethanol Binary Fuel and EGR

2012-09-10
2012-01-1577
The HCCI engine offers the potential of low NOx emissions combined with diesel engine like high efficiency, however HCCI operation is restricted to low engine speeds and torques constrained by narrow noise (HCCI knocking) and misfiring limits. Gasoline like fuel vaporizes and mixes with air, but the mixture may auto-ignite at the same time, leading to heavy HCCI knocking. Retarding the CA50 (the crank angle of the 50% burn) is well known as a method to slow the maximum pressure rise rate and reduce HCCI knocking. The CA50 can be controlled by the fuel composition, for example, di-methyl ether (DME), which is easily synthesized from natural gas, has strong low temperature heat release (LTHR) characteristics and ethanol generates strong LTHR inhibitor effects. The utilization of DME-ethanol binary blended fuels has the potential to broaden the HCCI engine load-speed range.
Technical Paper

Ultra Low Emission and High Performance Diesel Combustion with Highly Oxygenated Fuel

2000-03-06
2000-01-0231
Significant improvements in exhaust emissions and engine performance in an ordinary DI diesel engine were realized with highly oxygenated fuels. The smoke emissions decreased sharply and linearly with increases in oxygen content and entirely disappeared at an oxygen content of 38 wt-% even at stoichiometric conditions. The NOx, THC, and CO were almost all removed with a three-way catalyst under stoichiometric diesel combustion at both the higher and lower BMEP with the combination of EGR and a three-way catalyst. The engine output for the highly oxygenated fuels was significantly higher than that with the conventional diesel fuel due to the higher air utilization.
Technical Paper

An Investigation of the Transient DPF Pressure Drop under Cold Start Conditions in Diesel Engines

2017-10-08
2017-01-2372
To monitor emission-related components/systems and to evaluate the presence of malfunctioning or failures that can affect emissions, current diesel engine regulations require the use of on-board diagnostics (OBD). For diesel particulate filters (DPF), the pressure drop across the DPF is monitored by the OBD as the pressure drop is approximately linear related to the soot mass deposited in a filter. However, sudden acceleration may cause a sudden decrease in DPF pressure drop under cold start conditions. This appears to be caused by water that has condensed in the exhaust pipe, but no detailed mechanism for this decrease has been established. The present study developed an experimental apparatus that reproduces rapid increases of the exhaust gas flow under cold start conditions and enables independent control of the amount of water as well as the gas flow rate supplied to the DPF.
Technical Paper

Improvements of Diesel Combustion and Emissions with Two-stage Fuel Injection at Different Piston Positions

2000-03-06
2000-01-1180
The fuel spray distribution in a DI diesel engine with pilot injection was actively controlled by pilot and main fuel injections at different piston positions to prevent the main fuel injection from hitting the pilot flame. A CFD analysis demonstrated that the movement of the piston with a cavity divided by a central lip along the center of the sidewall effectively separates the cores of the pilot and main fuel sprays. Experiments showed that an ordinary cavity without the central lip emitted more smoke, while smokeless, low NOx operation was realized with a cavity divided by a central lip even at heavy loads where ordinary operation without pilot injection emits smoke.
Technical Paper

Improvement of Diesel Combustion and Emissions with Addition of Various Oxygenated Agents to Diesel Fuels

1996-10-01
962115
The effect of eight kinds of oxygenated agents added to diesel fuels on the combustion and emissions was investigated in a DI diesel engine. The results showed significant smoke and particulate suppression without increases in NOx with every oxygenated agent. The emissions decreased linearly with increasing oxygen content in the fuels, almost regardless of the kind of oxygenated agent. The improvement in smoke and particulate emissions with the oxygenated agent addition was more significant for lower volatility fuels. Combustion analysis with the two-dimensional two color method showed that soot concentration in the flame during the combustion process decreased with the addition of the oxygenated agent while the flame temperature distribution was almost unchanged.
Technical Paper

In-Cylinder Control of Smoke and NOx by High Turbulent Two-Stage Combustion in Diesel Engines

1996-10-01
962113
The authors have previously reported significant reductions in particulate emissions by generating strong turbulence during the combustion process. Extending this, it was attempted to reduce NOx, particulate, and fuel consumption simultaneously by two-stage combustion: forming a fuel rich mixture at the initial combustion stage to prevent NOx formation, and inducing strong turbulence in the combustion chamber at the later stage of combustion to oxidize the particulate. The purpose of this study is to examine the effect of two-stage combustion in emission control. The paper gives an evaluation of the NO reaction-kinetics of the system and experimental results for a combustion chamber specially made for the two-stage combustion. With this combustion system, it was possible to reduce NOx levels to 1/3 of the base engine. Combination of EGR and the two-stage combustion was also examined.
Technical Paper

Performance of NOX Catalyst in a DI Diesel Engine Operated with Neat Dimethyl Ether

1999-10-25
1999-01-3599
An experiment was conducted with a direct injection Diesel engine operated with neat dimethyl ether (DME). Main focus of this research is to investigate the performance of the catalysts designed for NOx reduction, such as Co–alumina and Sn–alumina catalysts, for the reduction of NOX and other unburned species contained in the exhaust gas. In the experiments, DME concentration in the exhaust gas was changed by adding extra DME before the catalytic reactor, which is the important experimental parameter in the research. Results showed that NOX reduction rate was not so high without any DME addition, because the content of unburned DME, reducing agent, is very low in the DME engine exhaust gas. However, NOX reduction rate increased with increase in DME content and it reached around 80% with enough DME addition. The NOX reduction rate increased with increase in reaction temperature up to around 300 °C.
Technical Paper

Cycle-to-cycle Transient Characteristics of Diesel Emissions during Starting

1999-10-25
1999-01-3495
Changes in exhaust gas emissions during starting in a DI diesel engine were investigated. The THC after starting increased until around the 50th cycle when the fuel deposited on the combustion chamber showed the maximum, and THC then decreased to reach a steady value after about 1000 cycles when the piston wall temperature became constant. The NOx showed an initial higher peak just after starting, and increased to a steady value after about 1000 cycles. Exhaust odor had a strong correlation with THC, and at the early stage odor was stronger than would be expected from the THC concentration. The THC increased with increased fuel injection amounts, decreased cranking speeds, and fuels with higher viscosity, higher 90% distillation temperature, and lower ignitability.
Technical Paper

Development of a Micro-Reactor HC-SCR System and the Evaluation of NOx Reduction Characteristics

2015-09-01
2015-01-2021
To reduce NOx emissions from diesel engines, the urea-SCR (selective catalytic reduction) system has been introduced commercially. In urea-SCR, the freezing point of the urea aqueous solution, the deoxidizer, is −11°C, and the handling of the deoxidizer under cold weather conditions is a problem. Further, the ammonia escape from the catalyst and the generation of N2O emissions are also problems. To overcome these disadvantages of the urea-SCR system, the addition of a hydrocarbon deoxidizer has attracted attention. In this paper, a micro-reactor SCR system was developed and attached to the exhaust pipe of a single cylinder diesel engine. With the micro-reactor, the catalyst temperature, quantity of deoxidizer, and the space velocity can be controlled, and it is possible to use it with gas and liquid phase deoxidizers. The catalyst used in the tests reported here is Ag(1wt%)-γAl2O3.
Journal Article

Combustion Characteristics of Emulsified Blends of Water and Diesel Fuel in a Diesel Engine with Cooled EGR and Pilot Injection

2013-10-15
2013-32-9022
Water and diesel fuel emulsions containing 13% and 26% water by volume were investigated in a modern diesel engine with relatively early pilot injection, supercharging, and cooled EGR. The heat release from the pilot injection with water emulsions is retarded toward the top dead center due to the poor ignitability, which enables larger pilot and smaller main injection quantities. This characteristic results in improvements in the thermal efficiency due to the larger heat release near the top dead center and the smaller afterburning. With the 26% water emulsion, mild, smokeless, and very low NOx operation is possible at an optimum pilot injection quantity and 15% intake oxygen with EGR at or below 0.9 MPa IMEP, a condition where large smoke emissions are unavoidable with regular unblended diesel fuel. Heat transfer analysis with Woschni's equation did not show the decrease in cooling loss with the water emulsion fuels.
Technical Paper

Semi-Premixed Diesel Combustion with Twin Peak Shaped Heat Release Using Two-Stage Fuel Injection

2016-04-05
2016-01-0741
Characteristics of semi-premixed diesel combustion with a twin peak shaped heat release (twin combustion) were investigated under several in-cylinder gas conditions in a 0.55 L single cylinder diesel engine with common-rail fuel injection, super-charged, and with low pressure loop cooled EGR. The first-stage combustion fraction, the second injection timing, the intake oxygen concentration, and the intake gas pressure influence on thermal efficiency related parameters, the engine noise, and the exhaust gas emissions was systematically examined at a middle engine speed and load condition (2000 rpm, 0.7 MPa IMEP). The twin peak shaped heat release was realized with the first-stage premixed combustion with a sufficient premixing duration from the first fuel injection and with the second fuel injection taking place just after the end of the first-stage combustion.
Technical Paper

Analysis of Temperature Prediction of Friction Surface over Multi Plate Lock-Up Clutch for Torque Converter

2014-04-01
2014-01-1750
A Lock-Up clutch is installed inside a Torque Converter to improve fuel efficiency. The Lock-Up facing generates heat, and the temperature of the friction surface rises during Slipping Lock-Up. The temperature must be maintained below the acceptable level for ATF (Automatic Transmission Fluid). Therefore, a prediction technics is required at the development stage. Heat flow analysis by CFD (Computational Fluid Dynamics) has been conducted to predict the temperature of the Lock-Up clutch friction surface. In this paper, the target is a Torque Converter with multi plate Lock-Up clutch. An appropriate boundary condition was applied to the flow simulation in order to set the correct total flow rate in the torque converter, and by verifying analysis results, it is confirmed that the prediction of friction surface temperature is close to the data from the experiment. In addition, it is realized that the flow rate has great influence on the temperature of friction surface.
Journal Article

Analysis of the Trade-off between Soot and Nitrogen Oxides in Diesel-Like Combustion by Chemical Kinetic Calculation

2011-08-30
2011-01-1847
This study makes use of the detailed mechanisms of n-heptane combustion, from gas reactions to soot particle formation and oxidation, and a two-stage model based on the CHEMKIN reactor network is developed and used to investigate the trade-off between soot and NOx emissions. The effects of the equivalence ratio, EGR, ambient pressure and temperature, and initial particle diameter are observed for various residence times. The results show that high rates of NOx formation are unavoidable under conditions where high reduction rates of soot particles are obtained. This suggests that suppression of the amount of soot during the formation stage is essential for simultaneous reductions in engine-out soot and NOx emissions.
Journal Article

Improvement in DME-HCCI Combustion with Ethanol as a Low-Temperature Oxidation Inhibitor

2011-08-30
2011-01-1791
Port injection of ethanol addition as an ignition inhibitor was implemented to control ignition timing and expand the operating range in DME fueled HCCI combustion. The ethanol reduced the rate of low-temperature oxidation and consequently delayed the onset of the high-temperature reaction with ultra-low NOx over a wide operating range. Along with the ethanol addition, changes in intake temperature, overall equivalence ratio, and engine speed are investigated and shown to be effective in HCCI combustion control and to enable an extension of operation range. A chemical reaction analysis was performed to elucidate details of the ignition inhibition on low-temperature oxidation of DME-HCCI combustion.
Technical Paper

Significant NOx Reductions with Direct Water Injection into the Sub-Chamber of an IDI Diesel Engine

1995-02-01
950609
The effect of direct water injection into the combustion chamber on NOx reduction in an IDI diesel engine was investigated. The temperature distribution in the swirl chamber was analyzed quantitatively with high speed photography and the two color method. Direct water injection into a swirl chamber prior to fuel injection reduced NOx emission significantly over a wide output range without sacrifice of BSFC. Other emissions were almost unchanged or slightly decreased with water injection. Water injection reduced the flame temperature at the center of the swirl chamber, while the mean gas temperature in the cylinder and the rate of heat release changed little.
Technical Paper

An Investigation on the Simultaneous Reduction of Particulate and NOx by Controlling Both the Turbulence and the Mixture Formation in DI Diesel Engines

1993-10-01
932797
This paper presents experimental results of the reduction of both particulate and NOx emitted from direct injection diesel engines by a two stage combustion process. The primary combustion is made very rich to reduce NOx and then the particulate is oxidized by strong turbulence generated during the secondary combustion. The rich mixture is formed by low pressure fuel injection and a small cavity combustion chamber configuration. The strong turbulence is generated by a jet of burned gas from an auxiliary chamber installed at the cylinder head. The results showed that NOx was reduced significantly while maintaining fuel consumption and particulate emissions. An investigation was also carried out on the particulate reduction process in the combustion chamber with the turbulence by gas sampling and in-cylinder observation with an optical fiber scope and a high speed camera.
Technical Paper

Study on Exhaust Control Valves and Direct Air-Fuel Injection for Improving Scavenging Process in Two-Stroke Gasoline Engines

1996-02-01
960367
A critical factor in improving performance of crankcase-scavenged two-stroke gasoline engines is to reduce the short-circuiting of the fresh charge to the exhaust in the scavenging process. To achieve this, the authors developed a reciprocating exhaust control valve mechanism and direct air-fuel injection system. This paper investigates the effects of exhaust control valve and direct air-fuel injection in the all aspect of engine performance and exhaust emissions over a wide range of loads and engine speeds. The experimental results indicate that the exhaust control valve and direct air-fuel injection system can improve specific fuel consumption, and that HC emissions can be significantly reduced by the reduction in fresh charge losses. The pressure variation also decreased by the improved combustion process. CRANKCASE SCAVENGED two-stroke gasoline engines suffer from fresh charge losses leading to poor fuel economy and it is a reason for large increases of HC in the exhaust.
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