There is a vapor compression type refrigeration cycle using therefrigerant HFC 134 a. In the condenser, it is isostaticallycooled, the condensation temperature is 50 ° C., and the condenseroutlet is the compressed liquid at 45 ° C. In the evaporator, it isisothermally heated, the evaporation temperature is 10 ° C. and theoutlet of the evaporator is heated steam at 15 ° C. When theexpansion valve performs isenthalpic expansion, and the adiabaticefficiency of the compressor is 0.70, answer the followingquestions.
(a) Calculate the specific enthalpy of the compressor outlettemperature, specific enthalpy, condenser outlet and evaporatoroutlet.
(b) Obtain the cooling operation coefficient of this system.
(c) Obtain the circulation amount of the refrigerant necessary forobtaining the cooling effect of 3.0 kW in this system.
Answer:
(a) Compressor outlet: 68 ° C, 445 [kJ / kg], condenser outlet: 264[kJ / kg]
Evaporator outlet: 409 [kJ / kg] (b) 4.03 (c) 0.021 [kg / s]
