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As an alternative to second generation ethanol, valeric esters can be produced from lignocellulose through levulinic acid. While some data on these fuels are available, only few experiments have been performed to analyze their combustion characteristics under engine conditions. Using a traditional spark ignition engine converted to mono-cylinder operation, we have investigated the engine performances and emissions of methyl and ethyl valerates. This paper compares the experimental results for pure valeric esters and for blends of 20% of esters in PRF95, with PRF95 as the reference fuel. The esters propagate faster than PRF95 which requires a slight change of ignition timing to optimise the work output. However, both the performances and the emissions are not significantly changed compared to the reference. Accordingly, methyl and ethyl valerate represent very good alternatives as biofuels for SI engines.

Multi-dimensional models represent today consolidated tools to simulate the combustion process in HCCI and diesel engines. Various approaches are available for this purpose, it is however widely accepted that detailed chemistry represents a fundamental prerequisite to obtain satisfactory results when the engine runs with complex injection strategies or advanced combustion modes. Yet, integrating such mechanisms generally results in prohibitive computational cost. This paper presents a comprehensive methodology for fast and efficient simulations of combustion in internal combustion engines using detailed chemistry. For this purpose, techniques to tabulate the species reaction rates and to reduce the chemical mechanisms on the fly have been coupled.

HCCI mode has shown its potential to improve emissions and efficiency in internal combustion engines. In addition, it has open the possibility to use a wider range of fuels than in SI and CI engines. However, the engine running zone is still one of the main challenges that HCCI has to face. We have investigated this zone in the case of ethyl acetate using CFD simulations with a simplified combustion mechanism. This paper describes how ethyl acetate influences the running zone of HCCI engines compared to iso-octane. Biochemical conversion of fermentable biomass can produce large quantities of esters by the reaction of ethanol with volatile organic acids. Among them, ethyl acetate has a low vaporization temperature and a high auto-ignition temperature. Preliminary experiments on SI engines have shown that it ignites more slowly than gasoline even if their physical properties are similar.