Question

A cylinder fitted with a frictionless piston contains 10 lbm of superheated refrigerant R-134a vapor at 100 lbf/in.², 300 F. The setup is cooled at constant pressure until the R-134a reaches a quality of 25%. Calculate the work done in the process.  

Answer 1

Constant pressure process boundary work.

State  State 1:  v₁ = 0.76629 ft³/lbm;

State 2: v₂ = 0.013331 + 0.25 × 0.46652 = 0.12996 ft³/lbm 

Interpolated to be at 100 psia, numbers at 101.5 psia could have been used.