C.V. Air out to the 900 K source. Since air T is lower than the source temperature we know that this is an irreversible process.
Continuity Eq.: m2 = m1 = m,
Energy Eq m(u2 – u1) = 1Q2 – 1W2
Entropy Eq m(s2 – s1) = ∫ dQ/T + 1S2 gen = 1Q2/TSOURCE + 1S2 gen
Process: P = A + BV
From the process equation we can express the work as