$($b$)$ Consider an ideal vapour$-$compression refrigeration cycle which works between the

pressure of $8$ bar and $2$ bar. The working fluid is R$-134$a$.$ Draw the p$-$h diagram.

Determine $($i$)$ the temperature and enthalpy at all states, $($ii$)$ COP $($iii$)$ refrigeration

capacity in terms of tons of refrigeration if mass flow rate of refrigerant is $0\mathrm{.}25k\frac{g}{s}.$

$($iv$)$ Determine COP if the lower pressure decrease from $2$ bar to $1$ bar. Assume the

specific heat at constant pressure for superheated R$-134$a vapour as $0\mathrm{.}996k\frac{J}{k}g*K.$

The properties of the R$-134$a are given below: