A gaseous fuel containing methane and ethane is burned with excess air. The fuel enters the furnace at 25°C and 1 atm, and the air enters at 200°C and 1 atm. The stack gas leaves the furnace at 800°C and 1 atm and contains 5.32 mole% CO₂, 1.60% CO, 7.32% O₂, 12.24% H₂O, and the balance N₂.

(a) Calculate the molar percentages of methane and ethane in the fuel gas and the percentage excess air fed to the reactor.

(b) Calculate the heat (kJ) transferred from the reactor per cubic meter of fuel gas fed.

(c) A proposal has been made to lower the feed rate of air to the furnace. State advantages and a drawback of doing so.