Q$2$:

A piston$-$cylinder device initially contains $1\mathrm{.}4$ kg of refrigerant$-134$a at $100$ kPa and $20C.$ Heat is

now transferred to the refrigerant from a source at $150C,$ and the piston, which is resting on a set of stops,

starts moving when the pressure insice reaches $120$ kPa $.$ Heat transfer continues until the temperature

reaches $80C.$ Assuming the surroundings to be at $25C$ and $100$ kPa $,$ determine $($a$)$ the work done, $($b$)$

the heat transfer, $(c)$ the exergy destroyed, and $(d)$ the second$-$law efficiency of this process.