| Résumé | Varying levels of carburization (fouling) were observed when vaporizing ultra-low sulphur diesel fuels and biofuel blends for use in a Homogeneous Charge Compression Ignition (HCCI) engine to study fuel performance and characteristics in a well controlled research test cell. The fouling propensity of fuels and fuel blends, which is directly related to compatibility and thermal stability characteristics, was investigated to understand the chemistry involved in foulant precursor formation The base fuel was a commercial ULSD diesel fuel. The two blending stocks were a fatty acid methyl ester (FAME) biodiesel derived from canola oil and a renewable diesel blending component (biodiesel-B) obtained by hydrotreating vegetable oil. Compatibility tests indicated that petroleum ULSD and specific biofuels are compatible with each other at any blending ratio. Fouling tests suggested that, for all the diesel blends, the fouling propensity was very low level. Thermal stability tests-fuel thermal oxidation test (JFTOT), breakpoint temperature, oxidation stability, induction time, and peroxide number-indicated that the renewable diesel and biodiesel blends with ULSD have good thermal stability. However, stability consequences of different fuel samples can be described as: ULSD > Biodiesel-B B5 > Biodiesel-B B20 > FAME B5 > FAME B20. The fouling observed in HCCI engine operation could be caused by the heating configuration used in engine design combined with temperature and oxygen levels. The hydrodynamic conditions, mass and heat transfer could lead to fouling and need further research. |
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