Second law analyses on oxy-fuel combustion of gaseous fuels

The exergy losses in the adiabatic premixed oxy-fuel combustion are quantitatively analysed. The global exergy loss decreases with increasing equivalence ratio. The exergy loss of chemical reaction is comparable to that of internal thermal energy exchange for low equivalence ratio while that of mixing process is negligible. To keep similar thermodynamic characteristics of conventional combustion, the O₂/CO₂ mole ratio should be 30/70 for oxy-fuel combustion. The exergy loss ratio on chemical reaction at the same combustion conditions is in the following order: CH₄ > H₂ > CO. The preheating of inlet oxidant improves exergy efficiency of combustion.