A refrigerator with Freon-12 as refrigerant operates with an evaporator temperature of 248 K (P = 1.2bar, S = 0.7130 kJ/kg-K, H = 176.22 kJ/kg) and a condensation temperature of 298 K (P = 6.2 bar, S = 0.224 kJ/kg-K, H = 59.17 kJ/kg). The saturated liquid leaving the condenser is passed through an expansion valve and an evaporator. The vapor leaving evaporator is saturated.

c) The liquid leaving the condenser is passed through a counter current heat exchanger where it

gives off its heat to the vapor leaving the evaporator. The liquid leaving the condenser is at 298 K and the vapor leaving the evaporator is at 248 K. In the exchanger the vapor gets heated to 292 K (P = 1.2 bar, S = 0.8164 kJ/kg-K, H = 203.53 kJ/kg). What would be the circulation rate of Freon-12?

d) What is the COP in each of the above cases?

a) If the refrigerator is rated at 1.5 ton, what is the circulation rate of Freon-12?

b) By how much circulation rate would be reduced, if the throttle valve were replaced by a turbine?