Question

Refrigerant-12 in a piston/cylinder arrangement is initially at 50°C, x = 1. It is then expanded in a process so that P = Cv−1 to a pressure of 100 kPa. Find the final temperature and specific volume.

Answer 1

State 1: 50°C, x = 1 P1 = 1219.3 kPa, v1 = 0.01417 m3/kg

Process: Pv = C = P1v1; => P2 = C/v2= P1v1/v2

State 2: 100 kPa and v2 = v1P1/P2 = 0.1728 m3/kg

T2 ≅ -13.2°C

Notice T not constant