Etude de la combustion de gaz de synthèse issus d'un processus de ...
Etude de la combustion de gaz de synthèse issus d'un processus de ... Etude de la combustion de gaz de synthèse issus d'un processus de ...
COMBUSTION STUDY OF MIXTURES RESULTING FROM A GASIFICATION PROCESS OF FOREST BIOMASS Abstract tel-00623090, version 1 - 13 Sep 2011 Syngas is being recognized as a viable energy source worldwide, particularly for stationary power generation. In the current work, three typical syngas compositions have been considered as representative of the syngas resultant from forest biomass gasification, and the possibility of using it in internal combustion engines is studied. First, laminar burning velocities have been determined from schlieren flame images at normal temperature and pressure, over a range of equivalence ratios within the flammability limits. The study of the effects of flame stretch rate is performed through the determination of Karlovitz and Markstein numbers. Second, because of the gaps in the fundamental understand of syngas combustion characteristics, especially at elevated pressures that are relevant to practical combustors, constant volume spherical expanding flames were employed to measure the laminar burning velocity for pressures ranges up to 20 bar. This information on laminar burning velocity of syngasair flames is then applied in a multi-zone heat transfer simulation code of the wall-flame interaction in order to predict the quenching distance of typical syngas-air flames. Engine-like turbulent conditions were experimentally reproduced in a rapid compression machine (RCM) when working on two strokes mode simulating a single cycle of an internal combustion engine. Stationary power applications usually use natural gas as fuel, thus a methane-air mixture is also included in this work as a reference fuel for comparison with the typical syngas compositions under study. Single compression tests were also performed in the RCM operating with and without combustion in order to identify different parameters related with its operation, namely the heat transfer to the walls. A simulation code for the power cycle of syngas-fuelled engines has been developed. Model validation has been carried on over detailed experimental data available in literature for hydrogen and methane. An attempt to adapt the model to the RCM is made by changing several aspects of the model namely the in-cylinder volume function and burning rate model. Conclusion could e drawn that the adapted code is able to reproduce the in-cylinder pressure. The validated model is then applied to a syngas-fuelled engine in order determine its performance. Conclusion can be drawn that typical syngas compositions besides its lower heat values and burning velocities can be used on SI engines even at elevated rotation speeds. Keywords: Gasification – Syngas - Combustion – Burning velocity – Rapid compression machine - Multi-zone modeling.
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COMBUSTION STUDY OF MIXTURES RESULTING FROM A GASIFICATION<br />
PROCESS OF FOREST BIOMASS<br />
Abstract<br />
tel-00623090, version 1 - 13 Sep 2011<br />
Syngas is being recognized as a viable energy source worldwi<strong>de</strong>, particu<strong>la</strong>rly for<br />
stationary power generation. In the current work, three typical syngas compositions<br />
have been consi<strong>de</strong>red as representative of the syngas resultant from forest biomass<br />
gasification, and the possibility of using it in internal <strong>combustion</strong> engines is studied.<br />
First, <strong>la</strong>minar burning velocities have been <strong>de</strong>termined from schlieren f<strong>la</strong>me images at<br />
normal temperature and pressure, over a range of equivalence ratios within the<br />
f<strong>la</strong>mmability limits. The study of the effects of f<strong>la</strong>me stretch rate is performed through<br />
the <strong>de</strong>termination of Karlovitz and Markstein numbers. Second, because of the gaps in<br />
the fundamental un<strong>de</strong>rstand of syngas <strong>combustion</strong> characteristics, especially at<br />
elevated pressures that are relevant to practical combustors, constant volume spherical<br />
expanding f<strong>la</strong>mes were employed to measure the <strong>la</strong>minar burning velocity for<br />
pressures ranges up to 20 bar. This information on <strong>la</strong>minar burning velocity of syngasair<br />
f<strong>la</strong>mes is then applied in a multi-zone heat transfer simu<strong>la</strong>tion co<strong>de</strong> of the wall-f<strong>la</strong>me<br />
interaction in or<strong>de</strong>r to predict the quenching distance of typical syngas-air f<strong>la</strong>mes.<br />
Engine-like turbulent conditions were experimentally reproduced in a rapid<br />
compression machine (RCM) when working on two strokes mo<strong>de</strong> simu<strong>la</strong>ting a single<br />
cycle of an internal <strong>combustion</strong> engine. Stationary power applications usually use<br />
natural gas as fuel, thus a methane-air mixture is also inclu<strong>de</strong>d in this work as a<br />
reference fuel for comparison with the typical syngas compositions un<strong>de</strong>r study. Single<br />
compression tests were also performed in the RCM operating with and without<br />
<strong>combustion</strong> in or<strong>de</strong>r to i<strong>de</strong>ntify different parameters re<strong>la</strong>ted with its operation, namely<br />
the heat transfer to the walls. A simu<strong>la</strong>tion co<strong>de</strong> for the power cycle of syngas-fuelled<br />
engines has been <strong>de</strong>veloped. Mo<strong>de</strong>l validation has been carried on over <strong>de</strong>tailed<br />
experimental data avai<strong>la</strong>ble in literature for hydrogen and methane. An attempt to<br />
adapt the mo<strong>de</strong>l to the RCM is ma<strong>de</strong> by changing several aspects of the mo<strong>de</strong>l namely<br />
the in-cylin<strong>de</strong>r volume function and burning rate mo<strong>de</strong>l. Conclusion could e drawn that<br />
the adapted co<strong>de</strong> is able to reproduce the in-cylin<strong>de</strong>r pressure. The validated mo<strong>de</strong>l is<br />
then applied to a syngas-fuelled engine in or<strong>de</strong>r <strong>de</strong>termine its performance. Conclusion<br />
can be drawn that typical syngas compositions besi<strong>de</strong>s its lower heat values and<br />
burning velocities can be used on SI engines even at elevated rotation speeds.<br />
Keywords: Gasification – Syngas - Combustion – Burning velocity – Rapid<br />
compression machine - Multi-zone mo<strong>de</strong>ling.