Abstract
Ethanol production is generally considered as the main option for converting lignocellulose to biofuels. However another route can produce valeric esters from lignocellulose through levulinic acid. While the process has been well characterized, only few experimental results describe their combustion behavior.
Using two engine test benches, compression ignition (CI) and spark ignition (SI), we have investigated the engine performances and emissions of methyl, ethyl, butyl and pentyl valerate. According to their physicochemical properties, pure and blends of 20%vol methyl or ethyl ester with PRF95 were tested in the SI engine, while blends of 20%vol butyl or pentyl esters with gasoil were tested in the CI engine.
In the SI experiments, we observed that the methyl and ethyl valerate have a higher flame speed than PRF95 which required a slight change of ignition timing to optimize the work output. However, both the performances and the emissions are not significantly modified.
In the CI experiments, the blends including butyl or pentyl valerate performed equally well as the diesel. The lower cetane number of the esters slightly increase the ignition delay of the blends without affecting the performances.
According to the results of this study, valeric biofuels represent very good alternative biofuels for both SI and CI engines.
KEYWORDS – valeric biofuels, spark ignition engine, compression ignition engine, biomass, levulinic acid