This is a $1$st and $2$nd law thermodynamics problem to be solved with a mass balance, energy balance and entropy balance. To solve this problem, we need to first treat as a closed system. Find the worj required to displace the air. Then trear it as an open system where the outlet gas is attached to a carnot engine to find the maximum amount of joules that could be available for heating. all other solutions to this problem currently solved on Chegf are incorrect.