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The filtration efficiency of a DPF drops when it suffers a failure such as melting and cracks during regeneration. And then, on-board diagnostics (OBD) device has become needed worldwide to detect a DPF failure. In the development of an OBD soot sensor, evaluation of the sensor demands a portable instrument which can measure the soot concentration for on-board and in-field use. Some of the emission regulations require the in-field emission measurements under normal in-use operation of a vehicle. This study is intended to develop a high sensitivity and high response portable smoke meter for on-board soot measurements and a reference to OBD soot sensors under development. The smoke meter accommodates a 650 nm laser diode, and its principle is based on light extinction in high soot concentration range and backward light scattering for low soot concentration measurement.

Next-generation vehicles which include Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV) are researched and expected to reduce CO2 emissions in the future. Generally, the main factor to support high efficiency of EV and HEV is the idle stop, motor assistance and regenerative braking. The vehicle mechanism of HEV is complex, compared with conventional internal combustion engine vehicle. Certification test method of gas emissions and fuel consumption is used driving mode, which is currently reflecting the typical driving conditions in the market. And driving mode of certification test is established focusing on the reproducibility of driving by conventional internal combustion engine vehicles. It is necessary to consider that the driving mode for the vehicle used regenerative energy is reflected correctly. And high accuracy certification test method for next generation HEVs is necessary in order to evaluate exhaust gas and fuel economy.

At interurban transportation, improvement of fuel economy of hybrid electric heavy-duty diesel vehicles, which assist drive-axle by using regeneration energy, is minimum, compared to heavy-duty diesel vehicles. One of the factors is that hybrid electric heavy-duty vehicles are not able to balance regeneration energy (input) and power energy (output) at high speed driving. One reason is not opportunity to operate of braking at high speed driving for the heavy-duty vehicle. In this research, we focus on the method used for the battery energy, and propose a new concept of hybrid electric system to efficiently utilize battery energy. That system consists of electrical booster for supercharging intake air into engine cylinder. We have confirmed the feasibility of the electric system of a new HEV concept by using the simulation I created.

A plug-in hybrid vehicle (PHEV) is recently developed technology and it will be put in the market in the near future. In existing hybrid electric vehicles (HEV), it was possible to suppress the petroleum consumption by regenerating the kinetic energy of vehicles during deceleration into electrical energy. A PHEV can use petroleum fuel as with traditional vehicles including HEV, and in addition, use the electrical energy supplied from the commercial power for running energy. That is, the existing HEV technology suppresses petroleum energy consumption. In contrast, the PHEV technology alternates part of vehicle drive petroleum energy with electric energy. Commercial electric generation can use many kinds of energy source other than the fossil oil. PHEV is a promising technology to reduce the well to wheel CO2 emission and one of the solutions for energy security issue.

The applicability of several popular diesel particulate matter (PM) measurement techniques to low temperature combustion is examined. The instruments' performance in measuring low levels of PM from advanced diesel combustion is evaluated. Preliminary emissions optimization of a high-speed light-duty diesel engine was performed for two conventional and two advanced low temperature combustion engine cases. A low PM (<0.2 g/kg_fuel) and NOx (<0.07 g/kg_fuel) advanced low temperature combustion (LTC) condition with high levels of exhaust gas recirculation (EGR) and early injection timing was chosen as a baseline. The three other cases were selected by varying engine load, injection timing, injection pressure, and EGR mass fraction. All engine conditions were run with ultra-low sulfur diesel fuel. An extensive characterization of PM from these engine operating conditions is presented.

An experimental study was performed to investigate diesel particulate filter (DPF) performance during filtration with the use of real-time measurement equipment. Three operating conditions of a single-cylinder 2.3-liter D.I. heavy-duty diesel engine were selected to generate distinct types of diesel particulate matter (PM) in terms of chemical composition, concentration, and size distribution. Four substrates, with a range of geometric and physical parameters, were studied to observe the effect on filtration characteristics. Real-time filtration performance indicators such as pressure drop and filtration efficiency were investigated using real-time PM size distribution and a mass analyzer. Types of filtration efficiency included: mass-based, number-based, and fractional (based on particle diameter). In addition, time integrated measurements were taken with a Rupprecht & Patashnick Tapered Element Oscillating Microbalance (TEOM), Teflon and quartz filters.

Three distinct types of diesel particulate matter (PM) are generated in selected engine operating conditions of a single-cylinder heavy-duty diesel engine. The three types of PM are trapped using typical Cordierite diesel particulate filters (DPF) with different washcoat formulations and a commercial Silicon-Carbide DPF. Two systems, an external electric furnace and an in-situ burner, were used for regeneration. Furnace regeneration experiments allow the collected PM to be classified into two categories depending on oxidation mechanism: PM that is affected by the catalyst and PM that is oxidized by a purely thermal mechanism. The two PM categories prove to contribute differently to pressure drop and transient filtration efficiency during in-situ regeneration.

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.

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.

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.

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.

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.

Fuel formulation for premixed charge compression ignition (PCCI) combustion has been attempted based on the mixture formation and auto-ignition behavior of normal paraffin fuels. Different pure and mixed fuels with different blending ratios are tested. The mixture formation behavior is investigated photographically in a constant volume combustion chamber (CVCC) at elevated temperature and pressure. Auto-ignition behavior is tested in a Fuel Ignition Analyzer under different test conditions. It is found that the evaporation rate of pure n-paraffin fuel increases and the ignition delay becomes longer with decreases in the chain length. In the range of test condition used in this study, the flash-boiling phenomenon affects the fuel evaporation rate and ignition delay to some extent. Based on the experimental results a mixture of a very light mixture promoting component (MPC) and a moderately dense igniting component (IC) at a ratio of 3:1 is found to be optimum for PCCI combustion.

To clarify the effect of fuel properties on diesel exhaust emissions, direct injection of two component fuels with approximately zero aromatic content and sulfur were attempted in a diesel engine. Fuels were prepared using paraffins having different cetane numbers and boiling points. Parameters considered are the Average Boiling Point (ABP) by volume and the difference of component characteristics for the same ABP. The results indicate that the trade off relation between NOx and particulate matter (PM) emissions depends significantly on ABP or density and is independent of the fuel component. On the other hand, components of the mixed fuels have significant influence on SOF and THC emissions. Fuels having higher amount of low boiling point components emit higher THC. Mixtures of low boiling point-high cetane number fuel and high boiling point-low cetane number fuel or fuel that contains normal paraffins only emit higher SOF.

In the actual spray combustion fields, coupled combustion process should be occurred, between the pre-evaporate fuel component and remaining liquid droplets. Therefore it is insufficient to clarify the fundamental spray combustion mechanism with use of only droplet or only premixed mixture analyze method. In this study, the premixed mixture - droplets coupled combustion field was focused as a model of the actual spray combustion field. In the experiments, the effect of the flame pattern and the combustion rate constant by the interference between the droplets were clarified with the variation of fuels used by droplets. Besides, the effect of the premixed gas surrounding the droplets was clarified by the experiment on coupled combustion. The experiments were carried out under the normal gravity field and the micro gravity field to estimate the effect of convection in combustion field

The accuracy of the injection rate meter based on W. Zeuch's method in the measurement of multiple injection rate and amount was calibrated using a small cam driven piston that is driven by an electric motor. For the pre- or early-injection, a sensor with a high sensitivity can be applied to measure the small pressure increase due to the small injection amount. In case of the multiple injection that has the post and/or late injection, a pressure sensor with a low sensitivity must cover not only the large pressure increase due to the main injection but also the small pressure increase due to the post and/or late injection because the output of the high sensitivity sensor is saturated after the main injection. So the linearity of the low sensitivity pressure sensor was calibrated with the cam driven piston prior to the experiment with the actual injection system.

To investigate the ignition process in a diesel spray, the ignition in a transient fuel spray is analyzed numerically by a discrete droplet spray model (DDM) coupled with the Shell kinetics model at various operating conditions. Predicted results show that the fuel mixture injected at the start of injection, which travels along midway between the spray axis and the spray periphery, contributes heavily to the first ignition in a spray. The equivalence ratio and temperature of the first ignited mixture are kept nearly constant until the start of hot ignition. The temperature of the first ignited mixture is kept at a constant value of higher temperature than the thermodynamic equilibrium temperature of the mixture before the hot ignition starts. The equivalence ratio of the first ignited mixture is around 1.6 at initial gas temperatures between 750 K and 850 K.

The time of, and location where ignition first occurs in a diesel fuel spray were investigated in a rapid compression machine (RCM) using the two–dimensional techniques of silicone oil particle scattering imaging (SSI), and the planar laser induced fluorescence (LIF) of formaldehyde. Formaldehyde has been hypothesized to be one of the stable intermediate species marking the start of oxidation reactions in a transient spray under compression ignition conditions. In this study, the LIF images of the formaldehyde formed in a diesel fuel spray during ignition process have been successfully obtained for the first time by exciting formaldehyde with the 3rd harmonic of the Nd:YAG laser. SSI images of the vaporizing spray, and the LIF images of formaldehyde were obtained together with the corresponding time record of combustion chamber pressures at initial ambient temperatures ranging from 580 K to 790 K.

The injection rate meter based on W. Zeuch's method was improved to meet the recent requirement for precise measurement of the multiple injection rate and amount in CDI (Common rail Direct Injection) diesel engines. A pressure sensor with a high sensitivity was added to measure the small pressure increase due to the pilot injection and after injection. At the same time a flow meter having a high accuracy was installed in the discharge pipe line to obtain a correction factor to the modulus of elasticity of volume. As a result it became possible to measure the multiple injection amount at an accuracy of ±0.2mm3/stroke in a range up to 40mm3/stroke.