UNIFIED ENGINEERING Fall 2004
Ian A. Waitz
Problem T3 (Unified Thermodynamics)
Air (assume it behaves as a thermally perfect gas) is contained in a vertical cylinder that is fitted with a frictionless piston and a set of stops, as shown below. The piston cross-sectional area is 0.5m2 and the air inside is initially at 200kPa and 800K. The air is then slowly cooled as a result of heat transfer to the surroundings. (LO#4, LO#5)
a) Sketch these two processes on p-V and T-v diagrams
b) What is the temperature of the air inside the cylinder when the piston reaches the stops?
c) After the piston hits the stops, the cooling is continued until the temperature reaches 300K. What is the pressure at this state?
d) How much work is done by the system in the first cooling process?
e) How much work is done by the system in the second cooling process?
