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A comparative study was performed by use of blends of Jatropha oil-diesel fuel and Jatropha oil-kerosene in order to investigate the feasibility of direct utilization of Jatropha oil in a DI diesel engine. Experimental results at low load demonstrated that mixing 60 vol.% of Jatropha oil into both diesel fuel and kerosene gave less impact on indicated thermal efficiency, whereas further increase of Jatropha oil deteriorated it. Jatropha oil-kerosene decreased particulate matter compared to Jatropha oil-diesel fuel, although particulate matter increased with the increase of Jatropha oil fraction. At partial load where double injection was applied, mixing 80 vol.% of Jatropha oil gave no significant impact on indicated thermal efficiency, exhaust gas emissions and particulate matter and no significant difference was observed between diesel fuel blends and kerosene blends.

Effects of chemical reaction characteristics of premixed fuel were experimentally studied in a dual fuel compression ignition engine using port injection (PI) of gasoline-like component and direct injection (DI) of diesel fuel. Octane number of port injection fuels, direct injection timing and injection amount ratio between PI and DI were swept to assess the interaction between chemical reaction and mixture distribution in a combustion chamber. Chemical kinetic study using multi-zone modeling was also performed in order to explain experimental results under quiescent condition.

Ethanol is a promising alternative to fossil fuels because it can be made from biomass resources that are renewable. In the most cases, however, ethanol is blended with conventional fuels because of the limited amount of production. Ethanol-fuel blends are typically azeotropic and have a unique characteristic in vapor pressure and phase equilibrium, which is different from that of blends composed of simple aliphatic hydrocarbons. The current studies by the authors have developed a numerical vaporization model for ethanol-gasoline blends, which takes into account vapor-liquid equilibrium of azeotrope and high latent heat of vaporization of ethanol, in order to update the authors' multicomponent fuel spray model and to investigate effects of blending ethanol on droplet vaporization processes. In this paper, the developed vaporization model was validated through a comparison with experimentally-observed vaporization rate for single droplets of ethanol-n-heptane blends.

Jatropha biofuel is promising renewal oil to produce biodiesel fuel through transesterification method which is shown in many papers. The ideal diesel alternative fuel obtained considering Jatropha as materials is Fatty Acid Methyl Ester (FAME). It is more desirable than the viewpoint of economical efficiency and CO2 control to operate a diesel engine with Jatropha crude (JC) oil. It is the purpose of this research to examine a possibility of using advantageous JC oil direct use as diesel engine fuel, in consideration of the sustainable production of the Jatropha biofuel in Mozambique. The adaptability to the diesel engine of diesel oil and the mixed fuel of JC was examined. Jatropha crude oil contains phorbol ester (PEs) which is a promoter of cancer. Measurement of the concentration of PEs in an exhaust gas was performed using High Performance Liquid Chromatography (HPLC).

Ethanol is a promising alternative to fossil fuels because it can be produced from biomass resources that are renewable. Due to the amount of production, however, the usage would be limited to blends with other conventional fuels. Ethanol-fuel blends are azeotropic and have unique vaporization characteristics different from blends composed of aliphatic hydrocarbons, so that the present study developed a numerical scheme which takes into account the vapor-liquid equilibrium of azeotrope in order to update the author's original version of the multi-component fuel CFD model and to evaluate the effect of mixing ethanol into gasoline on the evaporation process. The numerical simulation was implemented for evaporating sprays of ethanol-n-heptane blends, which are injected through a single hole nozzle. In addition to the vapor-liquid equilibrium, the effect of the latent heat of vaporization was investigated.

Ignition, combustion and emissions characteristics of dual-component fuel spray were examined for ranges of injection timing and intake-air oxygen concentration. Fuels used were binary mixtures of gasoline-like component i-octane (cetane number 12, boiling point 372 K) and diesel fuel-like component n-tridecane (cetane number 88, boiling point 510 K). Mass fraction of i-octane was also changed as the experimental variable. The experimental study was carried out in a single cylinder compression ignition engine equipped with a common-rail injection system and an exhaust gas recirculation system. The results demonstrated that the increase of the i-octane mass fraction with optimizations of injection timing and intake oxygen concentration reduced pressure rise rate and soot and NOx emissions without deterioration of indicated thermal efficiency.

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel.

A dual fuel operation with different reactivity fuels has the possibility of optimizing performance and emissions in premixed charge compression ignition engines by controlling the spatial concentration and distribution of both fuels. In the present study, n-heptane and i-octane were independently injected through two different injectors. In-cylinder pressure analysis and emissions measurement were performed in a compression ignition engine. Injection timings, fuel quantity ratio between the injections were changed for the two cases, in which one fuel was injected using a port fuel injection system while the other was directly injected into the cylinder, in order to drastically vary mixture distributions and ignition timings. In addition, an optical diagnostic was performed in a rapid compression and expansion machine to develop an understanding of the ignition processes of the two mixtures.

The effects of the spray impinging part on the in-cylinder airflow were numerically analyzed in the combustion chamber of the impinging diffusion direct injection diesel engine using KIVA-3 code. KIVA-3 code was enhanced to cater the impinging part as an internal obstacle by adopting the virtual droplet method, which is relatively easy to implement. Numerical result shows that the turbulence generation is promoted by the impinging part and is transformed by the squish flow into the piston cavity. The secondary flow is generated beneath the impinging part as well. The secondary flow area increases as the distance between top surface of the impinging part and bottom surface of the cylinder cover increases.

This paper is concerned with the formation of Particulate Matter (PM) in direct-injection (DI) diesel engines. A system featuring an electromagnetically actuated sampling valve was used for sampling of gas directly from the combustion chamber. The concentrations of total particulate matter (TPM) and of its two components, the Soluble Organic Fractions (SOF) and the Insoluble Fractions (ISF), were determined at different locations in the combustion chamber at different sampling times (different crank angles). High concentrations of SOF were found at sampling positions along the spray flame axis. The concentrations of SOF and ISF were higher at sampling positions close to the wall than away from the wall. The results suggest that SOF formation is significantly affected by wall quenching. Also, the PM concentrations were much higher in the combustion chamber than in the exhaust.

The OSKA-DH diesel engine employed a unique system (hereafter called OSKA system) which is composed of a single-hole fuel injector, an impinging disk and a re-entrant type combustion chamber. This study is concerned with the combustion observation of both OSKA-DH diesel engine and conventional DI diesel engine by the high-speed photography and video system. This video system enables us to take combustion photographs under the warm-up condition of the engine. From the observation of those photographs, the OSKA-DH engine shows the shorter ignition delay compared with a DI diesel engine and the combustion flame of OSKA-DH diesel engine are concentrated in the center of the combustion chamber and a relatively monotonous flame intensity are observed. THE AUTHORS HAVE DEVELOPED a new type of Direct Injection Stratified Charge Engine called “Direct Fuel Injection Impingement Diffusion Stratified Charge System” (hereafter called OSKA System).