An insulated vertical piston–cylinder device initially contains 0.8 m
3of refrigerant-134a at 1.2 MPa and 120°C. A
linear spring at this point applies full force to the piston. A
valve connected to the cylinder is now opened, and refrigerant is allowed to escape. The spring unwinds as the piston moves
down, and the pressure and volume drop to 0.6 MPa and 0.5
m3
at the end of the process. Determine (a) the amount of
refrigerant that has escaped and (b) the final temperature of
the refrigerant. why would you average enthalpy ?

Question

An insulated vertical piston–cylinder device initially contains 0.8 m
3of refrigerant-134a at 1.2 MPa and 120°C. A
linear spring at this point applies full force to the piston. A
valve connected to the cylinder is now opened, and refrigerant is allowed to escape. The spring unwinds as the piston moves
down, and the pressure and volume drop to 0.6 MPa and 0.5
m3
at the end of the process. Determine (a) the amount of
refrigerant that has escaped and (b) the final temperature of
the refrigerant. why would you average enthalpy ?