If your combustion is done with air the major contributor by volume to your product gases is nitrogen, not CO2.
The specific heat values (cal/g.K) aren't much affected by a pressure rise from 1 bar to 16 bar. For CO2 the drop would be less than 0.5 %, and less than 1% for nitrogen and H2O. Thus using the Cp values for 1 bar wouldn't introduce appreciable errors. Perry VI might serve as a good source of information.
As for the estimation of the adiabatic temperature you may visit thread610-50077 as a reference.
The effect of using oxygen-enriched air would be a reduction in the volume of combustion gases by having less nitrogen, thus increasing the adiabatic theoretical temperature that would otherwise be obtained with air.
A quick approximation for this temperature could be obtained from
t=[P+Q1+Q2+140(CO2)+200(H2O)+70(N2)]/[0.649(CO2)+0.561(H2O)+0.389(N2)
where,
P is the lower calorific value of the fuel, kcal/m
3 at normal conditions
Q1,Q2, the enthalpy of the air and fuel entering the combustion process
CO2, H2O, N2 are the volumes of product gases of combustion in m
3 at normal conditions, as obtained from a stoichiometric equation when burning 1 normal cubic meter of gas.
For example, when burning 1 normal cubic meter of a refinery gas with a composition C
1.6H
4.8 (P=12420 kcal/normal m
3) with air (21% oxygen), the resulting volume of product gases at normal conditions: 1.6 CO2; 2.4 H2O; 10.5 N2.
Thus, the estimated adiabatic temperature of combustion, assuming Q1=Q2=0, would be:
t=(12420+0+0+140x1.6+200x2.4+70x10.5)/(0.649x1.6)+0.561x2.4+0389x10.5)= 2135
oC
I leave to you the temperature estimation for a 40% oxygen-rich air.
A Rosin-Fehling H-T graph with 0% xs air would tell us that the corrected "maximum" for 12420/14.5=857 kcal/Nm
3 of combustion gases would be 1980
oC.
This means that the cooling effect resulting from the endothermic dissociation of CO2 and H2O brings about a drop of ~7.3% in the initially estimated temperature value.
As an aside, please note that the "corrected" maximum for burning hydrocarbon fuels moves somewhat to lower-than-theoretical air.
Besides, the same adiabatic temperature, +/- 10
oC, is obtained when burning refinery gas or fuel oil, provided one uses equal xs air percentages!