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We have shown that TiN, NbN and TiC electrodes prepared from metal or respective compound powders by a screen printing method work well as AMTEC electrode (26th IECEC). TiC electrode (Thickness:2-3μm, 800°C, 0.07Pa) shows the highest power density (0.40W/cm2) in our work. This is almost same power density of others' electrodes under same temperature. This shows that AMTEC electrode can be prepared by screen printing method from metal or ceramic powders. The maximum power densities of TiN, NbN and TiC depend markedly on the degree of vacuum of low temperature room of AMTEC. In the measurements of NbN electrode (thickness:2-3μm), the power density of AMTEC increased from 0.12W/cm2 (at 130Pa) to 0.27W/cm2 (at 0.037Pa) with improvement of vacuum. TiC electrode shows same tendency. This indicates that the transfers of sodium vapor through electrode give an effect on the power density.

Combustion properties of hydrogen with N₂ dilution were investigated. The laminar and turbulent burning velocities were examined for outwardly propagating stoichiometric H₂/O₂/N₂ flames varying the amount of diluent N₂. The unstretched laminar burning velocity, ul decreased with the increase in the amount of N₂. Markstein number, Ma, the sensitivity of the flame to the stretch due to the thermo-diffusive effects decreased with the increase in the amount of N₂.

EGR (Exhaust Gas Recirculation) is adopted to reduce NOx emission in spark ignition engines. The effects of dilution with CO₂ and N₂, the main components of EGR, on laminar flame were investigated. It had been found that CO₂ and N₂ dilutions affected not only laminar burning velocity but also the response of flame to the flame stretch due to the change in the thermo-diffusive properties of the mixtures by the dilutions. Thus, turbulent flames were also investigated at fixed flame stretch factors to examine solely the thermo-diffusive effects on turbulent flame.

The present study introduces an injection technique for Premixed Charge Compression Ignition (PCCI) combustion in marine diesel engines. It aims to improve the controllability in the spray propagation and obtain the ideal mixture formation through the use of behavior of a merged spray which is formed by a mutual spray impingement between two sprays. Experiment was carried out to confirm the feasibility of controlling the spray propagation in a constant volume chamber. Further, the effects of merged spray propagation on mixture formation, ignition and combustion process have been investigated in a Rapid Compression Machine (RCM).

With progression of so-called shale gas revolution, gas engines are expected as a strong substitute for diesel engines in marine fields, where strict emission regulations have been recently introduced. Thanks to the sulphur-free and low-carbon features of natural gas, gas engines emit much less CO2 and particulate matter than marine diesels burning heavy fuel oil. The premixed lean-burn gas engines, however, suffer two massive flaws. One is abnormal combustion called knocking and the other is a methane slip, which substantially means the unburned methane emitted into exhaust ports. One of the methane slip sources is thought to be flame quenching inside dead volumes around a combustion chamber or inside a boundary layer near a cylinder wall. Only supportive measures like cutdown of crevice volume have been conducted against the unburned methane.

Gaseous fuel originated from natural gas (NG) has been affected by industrial fields thanks to its low emission feature. The excellent knock resistance of methane, a major component of NG, is another advantage in engine applications, but the composition of NG varies depending on the production region. Methane number (MN) has been widely used to evaluate the knock resistance of certain NG. However, the selection of a reliable knock-resisting index has not been settled because of several definitions of MN, and a new index called the propane knock index was recently proposed. Moreover, the proper index could change with types of gas engines. In this study, a rapid compression-and-expansion machine (RCEM) was prepared to reproduce in-cylinder conditions and combustion processes of a pre-chamber type medium-speed gas engine, and the knocking-like combustion was intentionally generated by setting compression pressure, ignition timing, and fuel density in the mixture to the proper level.

Conventionally, turbulent burning velocity models are compared by showing the model-predicted ST/SL0 ratios in an ST/SL0 - u′/SL0 plane, where ST and SL0 are the turbulent and laminar burning velocities, respectively, with u′ being the turbulence intensity. Such a method applies to only those models which take u′ or u′/SL0 as the only variable of ST or of ST/SL0. In order to analyze and compare most recent models in which turbulence and flame spatial scales (or length scales) are also taken into account because of their importance in combustion, this paper showed the model-predicted ST/SL0 ratios as contours in three planes (Re-Da, ηκ/η0 - u′/SL0 and L/η0 - u′/SL0, where Re, Da, L, ηκ and η0 are the Reynolds number, Damköhler number, turbulence integral scale, Kolmogorov scale and laminar flame preheat zone thickness, respectively); these planes are usually used in discussing the flame structure.

The Neal-Smith criterion for handling qualities analysis of highly augmented aircraft is rewritten in terms of H∞ norms. The pitch attitude control is solved in the framework of an H∞ problem by the model matching technique to yield H∞-control pilot models. The obtained H∞ closed-loop transfer function satisfies the Neal-Smith criterion quite well, and the required pilot compensation is clearly exhibited in the H∞-control pilot model. Surveying all the flight configurations in the work by Neal and Smith, an attempt is made at pursuing the pilot compensation indices that correlate well with pilot ratings.

Lean-burn is the most attractive way to lower emissions of NOx while improving the fuel consumption simultaneously in spark ignition engines. A Pulsed Combustion Jet (PCJ) ignition system has a great potential to enhance ignition reliability and burning rate of lean fuel-air mixtures. Its action is based on the utilization of turbulent plumes formed by jets produced by generators, in the shape and size of an ordinary spark plug, that embody a small (500 mm3 or less) cavity, capped with an orifice plate and outfitted with a hollow electrode. Performance characteristics of PCJ were established by combustion tests carried out in a diskshaped, constant volume combustion chamber using lean methane-air mixtures. The results were compared to those obtained with Pulsed Plasma Jet (PPJ) an standard spark plug ignition systems. Lean limit was extended most by PCJ ignition under both quiescent and swirl conditions.

The effect of Si-phase on the axial, low-cycle fatigue behavior of Al-Si eutectic alloys was investigated using test specimens prepared from alloys processed either by continuous casting or extrusion. Results indicate that, for continuous casting, all fatigue fractures resulted from shear-type crack initiation and propagation with an attendant shortening of fatigue life. For extruded material, fatigue cracks originated in the Si phase. In both instances, initiation and growth mechanisms were essentially identical to those observed in high-cycle fatigue. Cyclic properties obtained from phenomenological models are presented and discussed.

Mercury porosimetry (MP) is one of the analytical methods to measure the porosity and the pore size distribution of porous materials. We have developed a new method of digital mercury porosimetry (DMP) for characterizing the porous structure by simulating the measuring processes of MP without using any mercury. Firstly, the contact angle between the mercury and the substance surfaces is theoretically calculated by quantum chemical molecular dynamics. Secondly, a group of images showing the porous structure is obtained with an X-ray computed tomography scanner, and then a three-dimensional digital model is reconstructed connecting the pores/substances boundaries between each image. Thirdly, mercury intrusion which is a fundamental process of the MP method is digitally simulated. The digital mercury intrudes into pores of the digital model from its circumference with the theoretically calculated contact angle.

Cu-based and noble metal catalysts for CO removal from methanol reformed gas were investigated for application to polymer electrolyte fuel cells. Over Cu-based catalysts, Oxygen-assisted low-temperature CO shift reaction (combined shift reaction and CO oxidation) enhanced CO removal considerably by the addition of a small amount of oxygen. While the Cu/Al2O3-ZnO catalyst exhibited a comparable activity with noble metal catalysts at low CO concentration, it demonstrated a higher activity than Pt/Al2O3 at high CO concentration.

In internal combustion engines, lean-burn is particularly attractive for minimizing pollutant emissions, in particular NOx, with a concomitant improvement in fuel economy. For combustion in lean fuel-air mixtures, achievement of adequate reliability of ignition and sufficiently high burning rate requires special devices. The most effective among them is the injection of active radicals by means of PFJ (Pulsed Flame Jet) ignition system. Presented here is an experimental proof of the action of the hydroxyl (OH) radical produced by such an ignition system. The measuring apparatus used for this purpose was based on PLIF (Planar Laser-Induced Fluorescence), and the effects of equivalence ratio of the mixture in the cavity, cavity volume, and orifice diameter on the variation of OH fluorescence area in the jet and their intensity were revealed quantitatively.

The discrete multi-component model for residual heavy fuel oil (HFO), developed in the mid-2000s, proved to be a simple but practical approximation in reproduction of the combustion process of HFO sprays on a couple of CFD simulation codes. The model succeeded in providing qualitative explanation about the spray and flame progression of HFO inside constant-volume chambers (CVC), but its practical use is still underway because of its higher calculation costs. Two-component HFO model, which was introduced relatively recently, separates every spray droplet virtually into two smaller droplets of each component to calculate their evaporation process separately. The model showed good agreement with the observation results on the various HFO spray behaviors in some visualized CVCs (VCVCs).

Syngas, is an alternative fuel consisting mainly of hydrogen and carbon monoxide in various proportions. An understanding of the effects of the varying constituents on the combustion characteristics is important for improvement of the thermal efficiency of syngas-fueled engines. The effects of hydrogen concentration and mixture pressure on the turbulent burning velocity of outwardly propagating stoichiometric flames of hydrogen-carbon monoxide-air were studied in a constant volume fan-stirred combustion chamber at a constant mixture temperature of 350 K. The mole fraction of hydrogen in the binary fuel was varied from 0 to 1.0, at mixture pressures of 0.10, 0.25 and 0.50 MPa. The turbulence intensity was kept constant at 3.27 m/s. For fixed mixture pressures, it was found that the turbulent burning velocity increased with an increase in hydrogen fraction primarily due to increase in the unstretched laminar burning velocity.