A piston-and-cylinder machine contains 0.5 kg of steam at 60 bar and 360 C. The steam expands adiabatically to 1.5 bar and 160 C.
a) Determine the actual work done and the useful work done (kJ/kg).
b) Determine the irreversibility if the surroundings are at 1 bar and 25 C.
c) Suppose the initial state is as in the above and the final pressure is 1.5 bar but the expansion is adiabatic and reversible. Determine the final temperature and the useful work done.
d) Calculate the maximum useful work for both processes. Then compare the difference in actual useful work for the two processes. Why isn't this the same as the irreversibility?