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temperatures calculated based on the relationship between initial temperature and
equivalence ratio of the mixture.
Figure 3.4
shows the theoretical complete com-
bustion temperatures and the chemical equilibrium temperatures for air preheated
to the temperature range of 300 to 1400 K and the equivalence ratio range of 0
to 2.
Figure 3.5
shows these results plotted on a plane, the coordinates of which
are the theoretical complete combustion temperature and the equilibrium temper-
ature. We can see a simple relationship between them for the fuel-lean side and
stoichiometric mixtures, regardless of the initial temperature of the mixture. For
the fuel-rich mixtures, in contrast, the complete combustion temperature and the
equilibrium temperature are not correlated by a single relationship since the
generation of intermediates having high calorific values, such as CO and H
2
, is
significant. From these results, there are two conclusions. One is that the virtual
3500
Temperature of mixture
1400K
3000
1000K
2500
500K
300K
2000
1500
1000
500
0
0
0.5
1.0
1.5
2.0
Equivalence ratio
(a) Theoretical complete combustion model
3500
Temperature of mixture
3000
1400K
2500
1000K
500K
2000
300K
1500
1000
500
0
0
0.5
1.0
1.5
2.0
Equivalence ratio
(b) Chemical equilibrium model
FIGURE 3.4
Influence of preheated air on adiabatic combustion temperature.
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