International audienceLean burn natural gas fuelled spark-ignition engines are particularly attractive regarding environmental performance. Nevertheless, few data exist concerning lean combustion in gas engines in terms of ignition delay, combustion duration and combustion rate. Such data are necessary when using thermodynamic models to predict energy and environmental performance. The present study proposes a contribution to such combustion characterization as a function of spark timing, air excess and engine load. This work is based on experimental cylinder pressure measurements in an open chamber engine on the one hand, and on a one-zone thermodynamic model used as a heat release analysis tool on the other hand. Results obtained, such as mass fraction burned, ignition delay and combustion duration, allow identification of the parameters used in the Wiebe function, a semi-empirical law that is frequently used to describe the combustion in predictive models
International audienceThe valorization of Scenedesmus sp. microalgae byproducts was investigated, as a potential route for the production of road binders from renewable sources. Under hydrothermal liquefaction conditions, a water-insoluble viscous material was obtained in a ca. 55% yield, which consists of an oily fatty acid-based fraction mixed with organic and inorganic solid residues (up to 22%). Although the chemical composition of the obtained materials completely differs from that of petroleum-based bitumen, similar viscoelastic properties were observed in some cases, depending on the hydrothermal liquefaction experimental conditions. A rheological simple material could thus be obtained, which compared well with a bitumen reference
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