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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 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.

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.

In recent years, particulate matter (PM) emitted from direct-injection gasoline vehicles is becoming an increasingly concerning problem. In addition, it is often reported that ammonia (NH3) is emitted from gasoline vehicles equipped with a three-way catalyst. These emissions might be largely emitted especially when driving in on-road driving conditions. In this study, we investigated the emissions, NOx, NH3, and PM/PN (particulate number) of a light-duty direct-injection gasoline vehicle when driving on actual roads. Using a small direct-injection gasoline vehicle equipped with a three-way catalyst, experiment was conducted 8 times on the same route, and these emissions were measured. In this study, vehicle specific power (VSP) was introduced, which can be calculated using vehicle parameters, vehicle speed, and road gradient. The effects of parameters acquired through on-board diagnostics (OBD) port and VSP on emissions were investigated.

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.

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.

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.

Dimethyl ether (DME) is a promising alternative fuel for compression ignition (CI) engines. DME features good auto ignition characteristics and soot-free combustion. In order to develop an injection system suitable for DME, it is necessary to understand its fuel properties. Sound speed is an important fuel property that affects the injection characteristics. However, the measurement data under high-pressures corresponding to those in fuel injection systems are lacking. The critical temperature of DME is lower than that of diesel fuel, and is close to the injection condition. It is important to understand the behavior of the sound speed around the critical point, since the sound speed at critical point is extremely low. In this study, sound speed in DME in a wide pressure and temperature range of 1 MPa to 80 MPa, 298.15 K to 413.15 K, including the vicinity of the critical point, was measured. The sound speed in DME decreases as either the pressure falls or the temperature rises.

Diesel engines have better fuel economy over comparable gasoline engines and are useful for the reduction of CO2 emissions. However, to meet stringent emission standards, the technology for reducing NOx and particulate matter (PM) in diesel engine exhaust needs to be improved. A conventional selective catalytic reduction (SCR) system consists of a diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and urea-SCR catalyst. Recently, more stringent regulations have led to the development of SCR systems with a larger volume and increased the cost of such systems. In order to solve these problems, an SCR catalyst-coated DPF (SCR/DPF) is proposed. An SCR/DPF system has lower volume and cost compared to the conventional SCR system. The SCR/DPF catalyst has two functions: combustion of PM and reduction of NOx emissions.

Recently, highly sensitive near-IR laser absorption spectrometers have been employed to measure ammonia (NH3) emissions. These instruments allow in-situ measurements of highly time-resolved NH3 emission levels in automobile exhaust. However, the effect of the automobile exhaust CO2 in NH3 measurements has not been studied in detail. Because the CO2 concentration in automobile exhaust is 2 to 3 orders of magnitude higher than the NH3 concentration, there is a possibility that spectral overlap by CO2 lines and/or the spectral broadening of NH3 by CO2 could affect the measured NH3 levels. This study had two major objectives. First, the effect of CO2 on the measured NH3 concentration was assessed using our developed near-IR laser absorption spectrometer. The second objective was to provide on-board NH3 measurements in the hybrid gasoline automobile exhaust using the developed spectrometer. As a result, the CO2 in automobile exhaust was found to affect the measured NH3 concentration.

Homogeneous Charge Compression Ignition (HCCI) is effective for the simultaneous reduction of soot and NOx emissions in diesel engine. In general, high octane number fuels (gasoline components or gaseous fuels) are used for HCCI operation, because these fuels briefly form lean homogeneous mixture because of long ignition delay and high volatility. However, it is necessary to improve injection systems, when these high octane number fuels are used in diesel engine. In addition, the difficulty of controlling auto-ignition timing must be resolved. On the other hand, HCCI using diesel fuel (diesel HCCI) also needs ignition control, because diesel fuel which has a low octane number causes the early ignition before TDC. The purpose of this study is the ignition and combustion control of diesel HCCI. The effects of parameters (injection timing, injection pressure, internal/external EGR, boost pressure, and variable valve timing (VVT)) on the ignition timing of diesel HCCI were investigated.

2,5-dimethylfuran (DMF) and 2-methylfuran (MF) have attracted attention as new biofuels. To utilize furans as alternative fuels, fundamental studies on the combustion characteristics are required. In this study, the ignition delay times of DMF were measured using a rapid compression machine and compared with those of gasoline and ethanol. To investigate the effect of the addition of DMF to gasoline, the ignition delay times of DMF-gasoline surrogate fuel blends were also measured. The ignition delay times of DMF were longer than those of gasoline and shorter than those of ethanol. The simulation results using the DMF kinetic model were in reasonable agreement with those of the experiments.

Dimethyl Ether (DME) is one of the major candidates for the alternative fuel for compression ignition (CI) engines. However, DME spray combustion characteristics are not well understood. There is no spray model validated against spray experiments at high-temperature and high-pressure relevant to combustion chambers of engines. DME has a lower viscosity and lower volumetric modulus of elasticity. It is difficult to increase injection pressure. The injection pressure remains low at 60 MPa even in the latest DME engine. To improve engine performance and reduce emissions from DME engines, establishing the DME spray model applicable to numerical engine simulation is required. In this study, high-speed observation of DME sprays at injection pressures up to 120 MPa with a latest common rail DME injection system was conducted in a constant volume combustion vessel, under ambient temperature and pressure of 6 MPa-920 K.

A fundamental study was performed to develop a high efficiency solar heat receiver for a solar energy experiment mission on the Japan experiment module - exposed facility of the international space station. It is composed of a solar heat absorber, thermal energy storage and heat pipes. This system is aimed to transport solar thermal energy to a bottoming system with an efficiency of 80 %. Thermal analysis of each component was performed to assess its design approach. One ground testing model of the solar receiver was designed and fabricated in 1998, and then would be experimentally evaluated in 1999 at a test vacuum chamber of National Aerospace Laboratory.