Natural gas, we assume methane, is burned with 200% theoretical air and the reactants are supplied as

Question:

Natural gas, we assume methane, is burned with 200% theoretical air and the reactants are supplied as gases at the reference temperature and pressure. The products are flowing through a heat exchanger and then out the exhaust, as in Fig. P14.79. What is the adiabatic flame temperature right after combustion before the heat exchanger?