An insulated vertical piston$-$cylinder device initially

contains $0\mathrm{.}8m^3$ of refrigerant$-134$a at $1\mathrm{.}2$ MPa and

$120C.$ A linear spring at this point applies full force to the

piston. A valve connected to the cylinder is now opened,

and refrigerant is allowed to escape. The spring unwinds as

the piston moves down, and the pressure and volume drop

to $0\mathrm{.}6$MPa and $0\mathrm{.}5m^3$ at the end of the process. Determine

$($a$)$ The amount of refrigerant that has escaped

$($b$)$ The final temperature of the refrigerant.

A commercial refrigerator with refrigerant$-134$a

as the working fluid is used to keep the refrigerated

space at $-35C$ by rejecting waste heat to cooling

water that enters the condenser at $18C$ at a rate of

$0\mathrm{.}25k\frac{g}{s}$ and leaves at $26C.$ The refrigerant enters

the condenser at $1\mathrm{.}2$ MPa and $50C$ and leaves at the

same pressure subcooled by $5C.$ If the compressor

consumes $3\mathrm{.}3kW$ of power, determine

$($a$)$ The mass flow rate of the refrigerant

$($b$)$ The refrigeration load

$($c$)$ The COP

$($d$)$ The minimum power input to the compressor

for the same refrigeration load