This is actually a chemical engineering question but I'm hoping you chem buffs can help me out!
Methane gas is burned completely with 30% excess air at approximately atmospheric pressure. Both the methane and the air enter the furnace at 303.15k saturated with water vapor, and the flue gases leave the furnace at 1773.15K. The flue gases then pass through a heat exchanger from which they emerge at 323.15K per mol of methane, how much heat is lost from the furnace, and how much heat is transferred in the heat exchanger?