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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.

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.

An on-board diesel particulate measurement (OBS-TRPM) instrument is developed to measure on-road exhaust PM emission at Horiba. It is used to characterize particulate matter (PM) emission from a gasoline vehicle, the 1999 Ford Windstar with California Ultra Low Emission (ULEV) certification. PM emissions from three test cycles, EPA FTP 72, SFTP-US06, and new European drive cycle (NEDC), are evaluated. It is found that the PM emission from the SFTP-US06 with the cold start is roughly two times higher than PM emissions from the cold FTP 72 and the cold NEDC. This may be due to aggressive drive patterns for the US06 while the vehicle is still cold. The aggressive drive pattern for the US06 makes the gasoline vehicle emit a much higher fraction of elemental carbon (EC), and lower fraction of organic carbon (OC). Fractions of the EC from the vehicle are 9.1% for the FTP 72, 6.3% for the NEDC, and 56.6% for the US06.

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.

The cordierite filter has been widely studied because of it's inherent, high capacities in the collection efficiency and heat-resistance. During the regeneration process of a cordierite filter, failure of ignition or incomplete burning propagation occurs, and additionally melts or cracks develop sometimes. In this study, the problems stated above are considered from a new standpoint, and a regeneration method that does not strictly depend on accumulated soot quantity is discussed. A filter made of SiC (Silicon carbide) possesses the requisite electric resistance and it's possible to heat it uniformly by using electricity. Accumulated soot can be uniformly incinerated not by burning propagation but by simultaneous ignition and burning of all accumulated soot. Silicon carbide has a higher resistance to heat than cordierite. Therefore, a self-heating filter made of SiC makes it possible to regenerate the filter in a wider range of accumulated soot.

A Solid Particle Counting System (SPCS) has been developed according to the ECE draft regulation proposed by the particle measurement program (PMP). In the previous report the basic performance of the SPCS has been mentioned in detail [1, 2, 3, 4, 5 and 6]. It has been reported that the SPCS demonstrates very stable dilution of sample with air and the error of real time dilution factor is less than 6% up to the total dilution factor of 1000. Penetration of solid particles through the SPCS is over 95% and volatile particles removal efficiency is over 99%. In this study the SPCS has been used to investigate the soot emission behavior from different vehicles with different after-treatment technologies. Direct injection (DI) diesel vehicles without diesel particulate filter (DPF), and with different DPFs (catalyzed and non-catalyzed) have been tested. Direct injection gasoline (DIG) vehicle with oxidation and NOx reduction catalysts have also been tested.

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 %.

For reducing NOx emissions, EGR is effective, but an excessive EGR rate causes the deterioration of smoke emission. Here, we have defined the EGR rate before the smoke emission deterioration while the EGR rate is increasing as the limiting EGR rate. In this study, the high rate of EGR is demonstrated to reduce BSNOx. The adapted methods are a high fuel injection pressure such as 200 MPa, a high boost pressure as 451.3 kPa at 2 MPa BMEP, and the air intake port that maintains a high air flow rate so as to achieve low exhaust emissions. Furthermore, for withstanding 2 MPa BMEP of engine load and high boosting, a ductile cast iron (FCD) piston was used. As the final effect, the installations of the new air intake port increased the limiting EGR rate by 5%, and fuel injection pressure of 200 MPa raised the limiting EGR rate by an additional 5%. By the demonstration of increasing boost pressure to 450 kPa from 400 kPa, the limiting EGR rate was achieved to 50%.

Real-time analysis of benzene in automobile exhaust gas was performed using the Jet-REMPI (supersonic jet / resonance enhanced multi-photon ionization) method. Real-time benzene concentration of two diesel trucks and one gasoline vehicle driving in Japanese driving modes were observed under ppm level at 1 s intervals. As a result, it became obvious that there were many differences in their emission tendencies, because of their car types, driving conditions, and catalyst conditions. In two diesel vehicle, benzene emission tendencies were opposite. And, in a gasoline vehicle, emission pattern were different between hot and cold conditions due to the catalyst conditions.

The prototype solid particle counting system (SPCS) has been used to study solid particle emission from gasoline and diesel vehicles. As recommended by the PMP draft proposal, exhaust is diluted by a Constant Volume Sampler (CVS). The SPCS takes the sample from the CVS tunnel. Transient test cycles such as EPA FTP 75, EPA HWFET (EPA Highway Fuel Economy Cycle), and NEDC (New European Driving Cycle) were tested. The repeatability of the instrument was evaluated on the diesel vehicle for three continuous days. The instrument exhibits good repeatability. The differences for the EPA ftp 75, the EPA HWFET, and the NEDC in three continuous tests are ± 3.5%. The instrument is very sensitive as well and detects the driving differences. A large number of solid particles are found during the hard acceleration from both the gasoline and the diesel vehicles. Solid particle emissions decrease quickly at deceleration and when vehicles approach constant speed.

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.

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.

Two Euro 4 light-duty diesel vehicles were retrofitted with Diesel Particulate Filters (DPF). One was retrofitted with a low efficiency flow-through DPF. And, the other was retrofitted with a high efficiency wall-flow DPF. PM emissions from both vehicles were evaluated under the new European drive cycle (NEDC) on a chassis dynamometer. Several instruments were used to measure particulate matter (PM) emissions simultaneously from different aspects for two retrofitted vehicles. The PM mass emission from the vehicle retrofitted with the low efficiency DPF is close to 5.0 mg/km Euro 5 mass emission standard. However, the solid particle number emission is about 30 times higher than the Euro 5 solid particle number emission standard. Mass and number emissions from the vehicle retrofitted with the high efficiency DPF are well below Euro 5 emission standards.

Repeatabilities of PM measurements on a heavy-duty diesel engine equipped with a diesel particulate filter (DPF) using a filter weighing method and a number counting method with a full flow dilution system and a partial flow system were evaluated. The filter method with partial flow exhibited the best repeatability. However, a good correlation between the full flow and the partial flow number counting results suggests that the fluctuations observed using the number counting method were caused by changes in the engine exhaust. Applying a strict preconditioning procedure should improve the repeatability of the number counting method because this method is more sensitive than the filter weighing method. In addition, the effects of the specifications for the number counting method were evaluated. The results indicate that the hose length from the tip of the sampling probe to the inlet of the number counting system had a negligible effect.

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.

As alternatives to heavy-duty vehicles, this project seeks to promote the development of Next-Generation EFVs, which will present a solution to the severe air pollution problem particularly in big cities, and drastically improve exhaust gas emissions and reduce carbon dioxide emissions in order to lessen the contribution to global warming. Ministry of Land, Infrastructure, Transport and Tourism (MLIT) started the Next-Generation Environmentally Friendly Vehicles Development and Commercialization Project in 2002. MLIT at that time entrusted this project to National Traffic Safety and Environment Laboratory (NTSEL). NTSEL as a core research organization organized a cooperative system with automobile manufacturers, suppliers, universities, academic experts, that is to say, “industry-academic-government” and launched the development activities.

A family of cordierite DPF filters were developed and studied for their efficacy for catalyzed soot filter applications. In addition to porosity and median pore size of DPF filters, breadth of pore size distribution, microstructure, and pore connectivity have a profound influence not only in filter performance (pressure drop, catalyst coatability, and filtration efficiency) but also on mechanical and physical properties. Through filter material composition development, optimum values for the %porosity, median pore diameter, and breadth of the pore size distribution for minimizing pressure drop have been identified, leading to the development of a new family of high-porosity cordierite diesel particulate filters that possess a unique combination of high filtration efficiency, high strength, and very low clean and soot-loaded pressure drop in both the catalyzed and non-catalyzed states. By controlling the microstructure, the impact of the catalyst on pressure drop has been minimized.

Direct injection natural gas engines need to produce in the mixing process between the fuel jet and the air in the cylinder a “stratified” fuel-air mixture, with an easily ignitable composition near the spark plug at the time of ignition. Stratified-charge engines have a tendency to produce high NOx emissions due to the high temperature of burning areas at the start of combustion since the fuel-air mixture is not uniform. Therefore, it is necessary to reduce NOx emissions from direct injection natural gas engines. The objective of this study is to investigate measures to reduce emissions, especially NOx emissions, from direct injection natural gas engines. A single cylinder test engine was equipped with a newly developed high-pressure electromagnetic injector and a spark plug.

Flash-boiling occurs when a fuel is injected to a combustion chamber where the ambient pressure is lower than the saturation pressure of the fuel. It has been known that flashing is a favorable mechanism for atomizing liquid fuels. On the other hand, alternative fuels, such as gaseous fuels and oxygenated fuels, are used to achieve low exhaust emissions in recent years. In general, most of these alternative fuels have high volatility and flash-boiling takes place easily in fuel spray, when they are injected into the combustion chamber of an internal combustion engine under high pressure. In addition, fuel design concept the multicomponent fuel with high and low volatility fuels has been proposed in the previous study in order to control the spray and combustion processes in internal combustion engine. It is found that the multicomponent fuel produce flash-boiling with an increase in the initial fuel temperature.

Exhaust emissions and particulate matter (PM) from an engine with a conventional continuous regeneration diesel particulate filter (DPF) were measured to evaluate DPF performance under the Japan 13-mode cycle, European Stationary Cycle and various transient cycles: U.S. transient cycle, Japan Automobile Research Institute cycle, and World-wide Heavy Duty Cycle. The emission tendencies with and without DPF under these conditions were clarified. According to these experiments, accumulated PM in the DPF under the driving modes mentioned above has influence on measurement errors. It is necessary to estimate the amount of accumulated PM in the DPF to evaluate the PM reduction rate correctly. This study also measured particle size distribution of diesel exhaust particulates (DEP) downstream of the DPF using an electrical low-pressure impactor (ELPI). As a result, we determined that most of the particles not trapped by the DPF are less than 110nm.