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

Experimental and numerical laminar syngas combustion
40
1000
Pressure (bar)
30
20
10
Experimental P
Numerical P
Qw
800
600
400
200
Qw (kW/m 2 )
0
0 30 60 90 120 150
Time (ms)
0
Figure 4.48 – Pressure and heat flux for updraft syngas-air at 5.0 bar and 293 K.
tel-00623090, version 1 - 13 Sep 2011
Pressure (bar)
40
30
20
10
0
Experimental P
Numerical P
Qw
0 10 20 30 40 50 60 70 80 90 100
Time (ms)
1000
800
600
400
200
0
Qw (kW/m 2 )
Figure 4.49 – Pressure and heat flux for downdraft syngas-air at 5.0 bar and 293 K.
As reported in 4.1.1.1 cellular flame are present in syngas-air flames for initial
pressures higher than 2.0 bar. Therefore, pressure curves of 5.0 bar are not perfectly
spherical, which makes the flame to reach the wall non-uniformly. Thus, the heat flux
peak is not synchronized in the entire chamber surface, which explains that the
pressure peak is reached after some relaxation. This behavior was also observed by
Boust, (2006) when dealing with lean (φ=0.7) methane-air mixtures.
Notice that the code reproduces well the pressure evolution beyond the validity of the
burning velocity correlation established in 4.1.2.3 for updraft and downdraft syngas
compositions. For these syngas compositions, the experimental correlation is valid up
to 20 bar, however we show numerically that value could be used beyond 33 bar.
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