Reduction of Combustion Gases' Temperature and Heating Capacity by CO2 and H2O Dissociation and NO Formation

The combustion gases theoretical adiabatic temperatures are reduced to equilibrium temperatures mainly because of the endothermic reactions of CO2 and H2O dissociation and NO formation. Therefore, the heating capacity of the gases is reduced to the equilibrium gases enthalpy. In the paper, these reactions and the way to consider them to calculate the gases' final equilibrium are exemplified, covering an ample range of temperatures. It is shown the method sensitivity and the results are verified against some registered values. The procedure allows calculation of the NO formation, evidencing its increment with the temperature. The reductions in combustion gases' adiabatic temperature and heating capacity are proportional to the theoretical adiabatic combustion temperature, apparent when the respective percentage decrements go from 2.2 and 2.7 at 2224 K to 46.8 and 50.9 at 7427 K for the studied combustion systems. This trend points out some maximum temperature reachable by oxidation, possibly 6000 K-the approximate energy emission sun temperature. [DOI: 10.1115/1.4005983]