A refrigerator operates between 120 kPa and 800 kPa in an ideal vapour compression cycle with R-134a as the refrigerant. The refrigerant enters the compressor as saturated vapour and leaves the condenser as saturated liquid The mass flow rate of the refrigerant is 0.2 kg/s. Properties for R – 134a are as follows Saturated R – 134a P(kPa) T°C hf (kJ/kg) hg (kJ/ kg) Sf (kJ / kg.k) Sg(kJ /kg.k) 120 -22.32 22.5 237 0.093 0.95 800 31.31 95.5 267.3 0.354 0.918 Superheated R – 134a P(kPa) T°C h (kJ/ kg) S (kJ / kg.k) 800 40 276.45 0.95
The power required for the compressor in kW is
7.9
Isentropic compression preserves s=0.95, so the superheated table gives h₂=276.45 kJ/kg. Compressor power is 0.2(276.45−237)=7.89 kW≈7.9 kW.
Important Questions from Vapour Compression (V-C) Cycle
A refrigeration plant works on an ideal vapour-compression refrigeration cycle with refrigerant as R-12 and develops a refrigeration capacity of 10 TR. If the refrigeration effect produced is 100 kJ/kg, what will be the mass flow rate of the refrigerant? [Assuming, 1 TR = 3.5 kW]
In vapour compression refrigeration system, the effect of liquid refrigerant under cooling is to
If vapour is NOT superheated after compression, it is called ________.
The amount of heat removed in the evaporator per unit mass flow of refrigerant is called:
In a vapor compression system, the highest temperature of the refrigerant during the cycle occurs after
