Etude de la combustion de gaz de synthèse issus d'un processus de ...

Numerical simulation of a syngas-fuelled engine
In order to compare pressure evolution of the different fuels at the same ignition timing,
figure 6.13 shows this cylinder pressure comparison.
50
Pressure (bar)
40
30
20
Updraft
Dow ndraft
Methane
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0
240 270 300 330 360 390 420 450 480
Crank Angle (degrees)
Figure 6.13- Cylinder pressure versus crank angle for various fuels. ε= 8.5, IT= 20º BTDC, 900
rpm.
Figure 6.13 shows that higher peak pressure is obtained for methane-air (39 bar)
mixture in comparison to both syngas compositions. Syngas compositions have similar
behavior. Peak pressures are 35 bar for downdraft syngas and 34 bar for updraft
syngas. These results are qualitatively in agreement with the RCM experimental
results. However, quantitatively the difference in the maximum pressure is not as high
as in RCM. This could be endorsed to the different characteristics of the experimental
set ups, emphasized in sections 6.3.1 and 6.3.2.
6.5 Conclusion
A simulation code for the power cycle of syngas-fuelled engines has been described,
using a quasi-dimensional model with ‘standard’ modeling assumptions. A combustion
model consisting of two differential equations was used, one for the mass conservation
and one for energy conservation.
Model testing has been carried on over detailed experimental data available in
literature for hydrogen and methane, two of the main constituents of syngas. The very
good agreement found allows validating the developed model and applied it to typical
syngas compositions.
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. The comparison
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