4. (25 pts) An ideal vapor-compression refrigeration cycle that uses refrigerant 134a as its working uid...
An ideal vapor-compression refrigeration cycle that uses refrigerant R-134a as its working fluid maintains a condenser at 800 kPa and the evaporator at -12C. (a) Determine this system's COP and the amount of power required to service a 150kW cooling load. (b) Determine the P,T, h, S and exergy of R-134a at all four states of the entire cycle. Assume the ambient temperature to be 25C.
11-11 A refrigerator operates on the ideal vapor-compression refrigeration cycle and uses refrigerant-134a as the working fluid. The condenser operates at 1.6 MPa and the evaporator at -6oC. If an adiabatic, reversible expansion device were available and used to expand the liquid leaving the condenser, how much would the COP improve by using this device instead of the throttle device?
A two-stage compression refrigeration system with an adiabatic liquid-vapor separation unit uses refrigerant-134a as working fluid. The system operates the evaporator at 0.4 MPa, the condenser at 1.6 MPa, and the separator at 0.8 MPa. The compressors use 25 kW of power. Given that the refrigerant is saturated liquid at the inlet of each expansion valve and saturated vapor at the inlet of each compressor, and the compressors are isentropic: (0) show the process on a T-s diagram; ) calculate...
1. An industrial freezer uses a multi-stage vapor-compression cycle with R-134a as the working fluid. The evaporator operates at 140 kPa, the condenser at 1600 kPa, and the flash chamber 600 kPa. The refrigerant leaves the evaporator as a super-heated vapor at -15°C, and leaves the condenser as a sub-cooled liquid at 50°C. Both compressors used in the system have isentropic efficiencies of 85%. For a cooling load of 25 kW, (a) What is the mass flow rate of refrigerant...
A two-stage compression refrigeration system with an adiabatic liquid-vapor separation unit uses refrigerant-134a as working fluid. the system operates the evaporator at 0.4Mpa, the condenser at 1.6Mpa and the separator at 0.8 Mpa. The compressors use 25kW of power. Given that the refrigerant is saturated liquid at the inlet of each compressor, and the compressors are isentropic: i) show the process on a T-s diagram, ii) calculate the rate of cooling provided by the evaporator, the COP of the heat...
A freezer is designed, based on vapor-compression refrigeration cycle. The designed conditions are: R-134a as refrigerant, with a cooling capacity of 500 kW; compressor of 70% efficiency, with a superheat of 10°C before compressor inlet; operation temperature of -10°C inside the refrigerator, with the environment temperature of 25°C outside the refrigerator; Determine the pressure range of refrigeration cycle if a 10°C difference is required to ensure effective heat transfer of evaporator and condenser; Plot the refrigeration cycle on P-h diagram;...
A refrigerator operates on an ideal vapor compression refrigeration cycle with R-134a as the working fluid. The evaporator pressure is 0.12 MPa and the condenser pressure is 0.8 MPa. If the rate of heat removal from the refrigerated space is 32 kJ/s, the mass flow rate of refrigerant is
A vapor compression refrigeration cycle utilizes R-134a as the working fluid. The refrigerant flow rate is 50 g/s. Vapor at 150 kPa and -10 0C enters the compressor and leaves at 1.2 MPa and 75 0C. The power input to the non-adiabatic compressor is measured and found to be 2.4 kW. The refrigerant enters the expansion valve at 1.15 MPa and 40 0C and leaves the evaporator at 160 kPa and -15 0C. Determine the entropy generation in the compression...
(12 points) A refrigerator using refrigerant-134a as the working fluid operates on the vapor compression cycle. The cycle operates between 200 kPa and 1.2 MPa. The refrigerant flows through the cycle at a rate of 0.019 kg/s. The (actual) refrigerator has a compressor with an isentropic efficiency of 85%. The refrigerant enters the compressor slightly superheated by 56 C hint add this to the saturation temperature). The refrigerant leaves the condenser slightly subcooled by 1.9°C. What is the rate of...
An ideal vapor compression refrigeration cycle uses refrigerant 12 as a working fluid in an air conditioning system. The refrigerant enter the compressor as saturated vapor at 5oC and leaves the condenser as saturated liquid at 55oC. The mass flow rate of refrigerant is 0.7 kg/s. Heat is transferred from a reservoir at 15oC (the cool space) to the refrigerant in the evaporator and the heat rejected by the condenser is transferred to the environment which is at a temperature...