- 11 54 Consider A Two Stage Cascade Refrigeration System Operating Between The Pressure Limits Of 1 4 Mpa And 160 Kpa Wit 1 (172.32 KiB) Viewed 21 times
11-54 Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.4 MPa and 160 kPa with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where the pressure in the upper and lower cycles are 0.4 and 0.5 MPa, respectively. In both cycles, the refrigerant is a saturated liquid at the condenser exit and a saturated vapor at the compressor inlet, and the isentropic effi- ciency of the compressor is 80 percent. If the mass flow rate of the refrigerant through the lower cycle is 0.25 kg/s, determine (a) the mass flow rate of the refrigerant through the upper cycle, (b) the rate of heat removal from the refrigerated space, and (c) the COP of this refrigerator. Answers: (a) 0.384 kg/s, (b) 42.0 kW, (c) 2.12 QH 7 TANT (6) Condenser Win Compressor (2) Win Compressor T Expansion valve 8 (3 Expansion valve 10 Evaporator Heat Condenser Evaporator OL UDR