Effet de la variation de la température sur les propriétés de carburants biodiesel et de mélanges biodiesel-éthanol -Cette étude a pour objectif de déterminer les effets de variations de température et de proportion d'éthanol dans un mélange biodiesel-éthanol sur les propriétés du carburant obtenu. L'ajout de l'éthanol à du biodiesel permet d'éviter l'inconvénient du démarrage à froid connu dans le cas du biodiesel. De plus, les variations de température influent sur le comportement du spray et les caractéristiques de la combustion et des émissions dans la chambre de combustion. La viscosité cinématique et la densité ont été obtenues respectivement par la mesure de la viscosité dynamique et de la gravité spécifique. Dans cette étude, on a pu observer que la gravité spécifique et la densité ont diminué linéairement lorsque la température et le taux d'éthanol dans le mélange ont augmenté. Une équation empirique a pu être obtenue à partir des valeurs mesurées ; c'est une fonction du second ordre du taux de mélange et du premier ordre de la température du mélange. Par ailleurs, les viscosités dynamiques et cinématiques ont diminué exponentiellement avec l'augmentation de la température. Basée sur ces mesures de viscosités, l'équation empirique, qui est fonction de la température, peut être étendue à chaque taux d'éthanol dans le mélange.

Simple and inexpensive single step facile novel chemical route for the preparation of polyaniline (PANi) nanofibers has been reported. These PANi nanofibers are characterized with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). Polyaniline nanofibers exhibit amorphous nature as confirmed from XRD and SAED study. Based on FESEM and TEM analysis, the formation of the polyaniline nanofibers with average diameter of about 40 nm was inferred. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that p-type conductivity PANi with room temperature conductivity of 2.77 9 10 -5 (X cm) -1 has band gap of 3.40 eV. A blue shift of 0.86 eV with characteristic absorption peak at 441 nm has been attributed due to quantized size of polyaniline nanofibers.

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This paper describes the influence of grouped-hole nozzle geometry on the atomization characteristics of a biodiesel fuel. The effects of injection rate profile, spray evolution, droplet mean diameter, and mean velocity of the droplets are investigated in a highpressure injection system.A grouped-hole nozzle with 16 holes driven by piezo stack was used in the experiments and the obtained results are compared with those obtained using a single-hole nozzle with the same overall nozzle area. The effect of using a split fuel injection strategy on the spray atomization was analysed using a grouped-hole nozzle with 12 holes. The time-based injection rate profiles for a biodiesel fuel, i.e. the mass flowrate of the fuel injector nozzle were obtained from the pressure variation generated when the fuel was injected into a tube filled with fuel. The spray and atomization performance for biodiesel fuel injected through a grouped-hole nozzle were visualized and measured by a visualization system and droplet analyser system, respectively.It was revealed that the biodiesel injection rate profile from a single-hole nozzle with the same overall nozzle area shows a similar injection rate profile to that of the grouped-hole nozzle. The injection rate profiles for a split injection strategy are lower than for a single injection and the peak value of the second injection is lower than for the first injection. The Sauter mean diameter distributions of biodiesel from the grouped-hole nozzle have a larger diameter because the small droplets injected through the grouped-hole nozzle collide and coalesce with each other, which leads to an increase in droplet diameter. From these results, it can be concluded that the use of a grouped-hole nozzle and split injection strategy does not improve on the fuel atomization performance for biodiesel fuel for a single-hole nozzle.