An air heater in a large coal-fired steam generator heats fresh air entering the steam generator by cooling flue gas leaving the steam generator. One million \(\mathrm{lbm} / \mathrm{hr}\) of air at \(100{ }^{\circ} \mathrm{F}\) and \(1.1 \mathrm{million} \mathrm{lbm} / \mathrm{hr}\) of flue gas at \(720^{\circ} \mathrm{F}\) enters the air heater. The flue gas leaves at \(310^{\circ} \mathrm{F}\). Flue gas has \(c_{p}=0.26 \mathrm{Btu} / \mathrm{lbm}{ }^{\circ} \mathrm{F}\) and \(k=1.39\). Pressure changes are small and may be neglected. Calculate the temperature of the air leaving the air heater and the total entropy change for the process.