A piston–cylinder device initially contains steam at
3.5 MPa, superheated by 5°C. Now, steam loses heat to the
surroundings and the piston moves down hitting a set of stops
at which point the cylinder contains saturated liquid water.
The cooling continues until the cylinder contains water at
200°C. Determine
(a) the initial temperature,
(b) the enthalpy
change per unit mass of the steam by the time the piston first
hits the stops, and (c) the final pressure and the quality (if
mixture).