. Air is contained in a piston-cylinder apparatus, as shown in Figure 1 below. The cylinder contains stops which limit the movement of the piston between the upper and lower volumes of
0.6 and 0.2 m3
, respectively. The piston may be considered frictionless and “floats” in between
the stops when the pressure is 500 kPa. Initially, 3.66 kg of air at a temperature of 127 oC and
volume of 0.6 m3
is contained in the cylinder. The air is then slowly cooled until the volume drops
to one-half its initial value.
(a) What is the initial pressure (kPa) of the air? State any assumptions made. (15 points)
(b) What is the final pressure (kPa) of the air? (10 points)
(c) What is the final temperature (oC) of the air? (10 points)
(d) How much work is done during the process? (Hint: When pressure moves from P1 to P2, this
is done at constant volume and then the volume decreases to V2 at constant P2) (15 points)
(e) Calculate the heat transfer during the process and comment on the answer. (10 points)
(f) BONUS: Sketch the PV diagram for this process and indicate the work done. (10 points)
Figure 1: Piston –cylinder apparatus (not drawn to scale)