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A simultaneous multi-composition analyzing (SMCA) resonance enhanced multi-photon ionization (REMPI) system was used to investigate gasoline engine exhaust. Observed peaks for exhaust were smaller mass numbers than those from diesel exhaust. However, large species up to three ring aromatics were observed suggesting that soot precursor forms even in the gasoline engine. At low catalyst temperature condition, the reduction efficiencies of a three-way catalyst were higher for higher mass numbers. This result indicates that the larger species accumulate in the catalyst or elsewhere due to their lower vapor pressures. To evaluate the emission of low volatility species, the accumulation should be taken into account. In the hot mode, reduction efficiencies for aromatic species of three-way catalyst were almost 99.5% however, they fall to 70% in the cold start condition.

Particulate matter (PM) trapping and oxidation in regeneration on the surface of a diesel particulate catalyst-membrane filter (DPMFs) were investigated in detail using an all-in-focus optical microscope. The DPMF consists of two-layer sintered filters, where a SiC-nanoparticle membrane (made from a mixture of 80 nm and 500 nm powders) covers the surface of a conventional SiC filter. Using a visualization experiment, it was shown that PMs were trapped homogeneously along fine surface pores of the membrane's top surface, whereas in the regeneration process, the particulates in contact with the membrane may have been oxidized with some catalytic effect of the SiC nanoparticles. A soot cake was reacted continuously on the nanoparticles since pushed by a gas flow. The oxidation temperature of particulate trapped on the SiC-nanoparticle membrane was about 75 degrees lower than that on the conventional diesel particulate filters (DPF) without a catalyst.

Compression ignition engines provide superior thermal efficiency over other internal combustion engines. Unfortunately the combustion process is diffusive combustion, meaning a lot of fuel is impinged the on the piston and cylinder wall. This creates cooling loss coupled with smoke, CO and THC. Minimization of the nozzle orifice diameter is a simple method widely used to shorten spray penetration. However, decreasing the nozzle orifice diameter also decreases fuel flow rate resulting in a prolonged injection and combustion process and reducing thermal efficiency. An offset orifice nozzle causes less fuel impingement by shorter fuel spray penetration without significant reduction of fuel flow rate. The offset orifice nozzle was made by shifting its alignment from the center of the sac to the edge of the sac following the swirl direction. A counterbore design was applied to maintain constant orifice length.

In a state-of-the-art lean-burn spark ignition engine, a strong in-cylinder flow field with enhanced turbulence intensity is formed, and understanding the wall heat transfer mechanism of such a complex flow is required. The flow velocity and temperature profiles inside the wall boundary layer are strongly related to the heat transfer mechanism. In this study, two-dimensional three-component (2D3C) velocity distribution near the piston top surface was measured during the compression stroke in a strong tumble flow using a rapid compression and expansion machine (RCEM) and a stereoscopic micro-PIV system. The bore, stroke, compression ratio, and compression time were 75 mm, 128 mm, 15, and 30 ms (equivalent to 1000 rpm), respectively.

The diesel particulate membrane filter (DPMF) is a good solution to the problem of high pressure drop that exists across diesel particulate filters (DPFs) as a result of the soot trapping process. Moreover, DPMFs that have a membrane layer composed of SiC nanoparticles can reduce the oxidation temperature of soot and the apparent activation energy. The SiC nanoparticles have an oxide layer on their surface, with a thickness less than 10 nm. From the visualization of soot oxidation on the surface of SiC nanoparticles by an environmental transmission electron microscope (ETEM), soot oxidation is seen to occur at the interface between the soot and oxide layers. The soot oxidation temperature dependency of the contact area between soot and SiC nanoparticles was evaluated using a temperature programmed reactor (TPR). The contact area between soot and SiC nanoparticles was varied by changing the ratio of SiC nanoparticles and carbon black (CB), which was used as an alternative to soot.

Trapping and regeneration processes in a SiC wall-flow diesel particulate filter (DPF) without a catalyst were investigated in detail through microscopic visualization. By microscopic observation of the cross section and surface, the transition from depth filtration to surface filtration could be observed clearly. The open pores on the wall surface were strongly related to the filtration depth of diesel particulate matter (PM). During the regeneration process, after the soot cake was burnt out, the particulates trapped inside the surface pores were oxidized. As a result, the particulate trapping and oxidation behaviors were strongly dependent on the microstructural surface pores.

In order to investigate the mechanism of heat transfer on the chamber wall of direct-injection diesel engines, 2-D temperature imaging and heat flux measurement in the flame impinging region on the chamber wall were conducted using laser-induced phosphorescence technique. The temperature of the chamber wall surface was measured by the calibrated intensity variation of the 355nm-excited laser-induced phosphorescence from an electrophoretically deposited thin layer of La2O2S:Eu phosphor on a quartz glass plate placed in a rapid compression and expansion machine (RCEM). Instantaneous 2-D images of wall temperature at different timings after start of injection and time-resolved (10kHz) heat flux near the flame impinging region were obtained for combusting and non-combusting diesel sprays with impinging distance of 23.4mm at different injection pressures (80 and 120MPa).

Through microscopic visualization experiments, a process generally known as depth filtration was shown to be caused by surface pores. Moreover, the existence of a soot cake layer was an important advantage for filtration performance because it could trap most of the particulates. We proposed an ideal diesel particulate filter (DPF), in which a silicon carbide (SiC) nanoparticle membrane (made from a mixture of 80 nm and 500 nm powders) instead of a soot cake was sintered on the DPF wall surface; this improved the filtration performance at the beginning of the trapping process and reduced energy consumption during the regeneration process. The proposed filter was called a diesel particulate membrane filter (DPMF). A diesel fuel lamp was used in the trapping process to verify the trapping and oxidation mechanisms of ultrafine particulate matter. Thus, the filtration performance of the membrane filters was shown to be better than that of conventional DPFs.

This study computationally investigates the combined effects of EGR and boost pressure on HCCI autoignition using iso-octane, PRF50 and n-heptane. The computations were conducted using the single-zone model of CHEMKIN included in CHEMKIN-PRO with detailed chemical-kinetics mechanisms for iso-octane, PRF and n-heptane from Lawrence Livermore National Laboratory (LLNL). To better reproduce the state of EGR addition in real engine, the EGR composition is determined after several combustion cycles under the constant amount of fuel. All data points were acquired with a CA50 of 5°CA aTDC by adjusting initial temperature to remove the effect of combustion phasing, which can influence on HCCI autoignition from any effect of the EGR and boost pressure themselves. The results show that EGR increases the burn duration and reduces the maximum pressure-rise rate with lower peak of maximum heat-release rates for all fuels even for a boost pressure, which accelerates a HCCI autoignition propensity.

Prediction of the discharge path behavior between electrodes on a spark plug is important for efficient energy use in internal combustion engines, especially in lean combustion. In this paper, we propose a numerical model for the prediction of the spark path behaviors based on the coupling of a flow field, a Lagrangian particle model, and an equivalent circuit model. A turbulent flow around cylinders imitating electrodes is solved using a direct numerical simulation, in which Lagrangian particles along the spark path are tracked. Electric current and inter-electrode voltage are computed based on the energy conversion rate from the circuit to the mixture gas. As a result, a discharge path is reproduced with Lagrangian tracking particles virtually aligned between the cylinders. The spark path has a complicated structure along the spanwise direction due to the complex three-dimensional vortical structure of the cylinder wake.

Time-lapse images of particulate matter (PM) deposition on diesel particulate filters (DPFs) at the PM-particle scale were obtained via field-emission scanning electron microscopy (FE-SEM). This particle scale time-series visualization showed the detailed processes of PM accumulation inside the DPF. First, PM introduced into a micro-pore of the DPF wall was deposited onto the surface of SiC grains composing the DPF, where it formed dendritic structures. The dendrite structures were locally grown at the contracted flow area between the SiC grains by accumulation of PM, ultimately constructing a bridge and closing the porous channel. To investigate the dominant parameters governing bridge formation, the filtration efficiency by Brownian diffusion and by interception obtained using theoretical filtration efficiency analysis of a spherical collector model were compared with the visualization results.

In recent years, the number of reported traffic accidents due to sudden deterioration in driver’s physical condition has been increasing, it is expected to develop a system that prevents accidents even if physical condition suddenly changes while driving, or reduces damage through vehicle body control. For this purpose, it is necessary to detect sudden changes of the driver’s physical condition, and research is being conducted widely. Among them, it is reported that some of such changes may appear in the heartbeat interval. In other words, by acquiring the driver’s heartbeat interval in real time, it may be possible to detect the sudden changes, and reduce traffic accident. Even if a traffic accident occurs, the damage can be reduced by emergency evacuation immediately after detecting sudden changes.

In this study, the combustion characteristics of diesel flame achieved in a rapid compression and expansion machine (RCEM) at various patterns of oxygen distribution in the chamber are investigated in order to clarify the effect of heterogeneity of oxygen distribution in diesel engines induced by EGR on the soot and NOx emissions. To make the heterogeneous distribution of oxygen in a combustion chamber, the mixtures with different oxygen concentrations are injected through the each different port located on the cylinder wall. Results indicate that the amount of oxygen entrained into the spray upstream the luminous flame region affects the NO emission from diesel flame strongly.

A significant drawback to HCCI engines is the knocking caused by rapid increases in pressure. Such knocking limits the capacity for high-load operation. To solve this problem, thermal stratification in the combustion chamber has been suggested as possible solution. Thermal stratification has the potential to reduce the maximum value of the rate of pressure increase combustion by affecting the local combustion start time and extending the duration of combustion. The purpose of this study was to experimentally obtain fundamental knowledge about the effect of thermal stratification on the HCCI combustion process. Experiments were conducted in a rapid compression machine (RCM) equipped with a quartz window to provide optical access to the combustion chamber. The machine was fueled with DME, n-Butane, n-Heptane and iso-Octane, all of which are currently being investigated as alternative fuels and have different low temperature characteristics.

This paper experimentally and analytically evaluates the heat rejection/retention performance of a reversible thermal panel (RTP) which can autonomously change thermal performance depending on its own thermal conditions. The RTP is considered as a candidate methodology for thermal control of Venus mission, PLANET-C, in order to save survival heater power. An RTP prototype was tested and evaluated. An analytical thermal model of the RTP was also developed, and basic performances of the RTP were evaluated. Thermal performance of the RTP when applied to the longwave camera (LIR) of the PLANET-C was evaluated with an analytical thermal model as functions of fin deployment directions and rear surface properties of the RTP's fin. The analytical results showed that the RTP can save heater power in comparison to a conventional radiator.

The Homogeneous Charge Compression Ignition (HCCI) engine is possible to achieve high thermal efficiency and low emissions. One of the main challenges with HCCI engines is structuring the systems to control combustion phasing, crank angle of 50% heat release (CA50), for keeping high thermal efficiency and avoiding an excessive rate of pressure rise which causes knocking, when operating conditions vary. Though some HCCI combustion control systems, for example Variable Valve Timing System and Variable Compression Ratio System, have been suggested, these control systems are complex and heavy. In this study, for the development of a lightweight and small-sized generator HCCI engine fuelled with Dimethyl Ether (DME) which is low-emission and easy to autoignite, a simple HCCI combustion control system is suggested, and the control system is evaluated experimentally.

The purpose of this study was to gain a better understanding of the effects of in-cylinder gas temperature stratification on reducing the pressure-rise rate in HCCI combustion. HCCI combustion was investigated using an optically accessible engine and direct visualization of the combustion chemiluminescence. The engine was fueled with Di-Methyl Ether. Computational work was conducted on the gas compression and expansion strokes in HCCI engine with simple 0-dimensinal multi-zones model. When fuel inhomogeneous charging in experiment, maximum heat release rate decreased. Combustion duration got longer. Maximum pressure-rise rate decreased. Chemiluminescence, of which transition was identified from the side of intake valve to the side of exhaust valve, was observed. It is need for total moderate heat release to get local moderate combustion with not overall but continuous combustion in chamber.

The method was established to identify the dynamic stiffness of the engine mount using modal parameters acquired from experimental modal analysis. Vibration tests were conducted using actual large outboard motor the BF225 (165 kW), and the dynamic stiffness of the mounts was identified. The results show that this method can identify the engine mount dynamic stiffness more adequately than the conventional method, even when the engine mounts are subjected to loads corresponding to thrust force or even in the case that the stiffness of the parts supporting an outboard motor is low.

Trapping of diesel particulates and phenomena of chemical reaction in regeneration were investigated by visualization through the cross-sectional area of a diesel-particulate-filter wall, using a digital-microscope with a high focusing depth. Herein, SiC-DPF walls were polished up to make a uniform height and to create a mirror-like surface on each SiC-particle-grain. At the beginning of the trapping process, it was observed that large particulates were trapped once in the small pores inside the wall, and then, since the flow-pattern was changed drastically, the trapped particulates were pushed out and blown off again, and finally, trapped in a region further downstream. As time passed, image analysis disclosed that since fine particulates were deposited around the SiC-particle-grain surface, the flow-channels became increasingly narrow.

A newly developed small-sized IES (inductive energy storage) circuit with static induction thyristor at turn-off action was successfully applied to an ignition system. This IEC circuit can generate repetitive nanosecond pulse discharges. In this paper, the ignition system using repetitive nanosecond pulse discharges was investigated as an alternative to conventional spark ignition systems. The experiments were conducted using spherically expanding flame configuration for CH4 and C3H8-air mixtures under various conditions. In conclusions, the ignition system using repetitive nanosecond pulse discharges was found to extend lean flammability limits compared with conventional spark ignition systems. In addition, the ignition system using repetitive nanosecond pulse discharges could shorten ignition delay time.