An ammonia $($NH;$)$refrigerating unit is working between the temperature limits of

$40$Cand $-10$C$.$ The load on the unit is $5$ tons. Assume the refrigerant is dry and

saturated vapor leaving the evaporator and compression is isentropic$.$ Find out the

followings:

$($a$)$ C$.$O$.$P$.$ of the system

$($b$)$ H$.$P$.$ required for the unit

If the temperature of the refrigerant required in the evaporator is $-20$C$,$ then find

out the changein C$\mathrm{.}0.$P$.$ofthe.system and H$.$P$.$ required.