A refrigeration reciprocating compressor has a displacement volume of 0.06 m3 with a volumetric efficiency of 84.6%. It operates at 600 rpm (revolutions per minute) and receives R134a at 101.325 kPa and -20 °C. The compression process is isentropic with a discharge pressure of 600kPa. The compression and expansion processes in the cycle follow the relationship pv^n =constant, where n=1.13. a) Plot the cycle on a P-V diagram and indicate the area which represents the power input for one cycle. b) Calculate the mass flow rate of the refrigerant c) Calculate the power required for the compression process when the properties of R134a are obtained from the table attached. d) Find the power required for the compression process if the vapour is considered as ideal gas, and compare it with the value in c). e) If the above compression process is achieved by two-stage compression process (in series) with an intercooler, plot the cycle on the P-V diagram, indicate the area which represents the power input for one cycle, and compare it with the one in a).
A refrigeration reciprocating compressor has a displacement volume of 0.06 m3 with a volumetric efficiency of 84.6%. It operates at 600 rpm (revolutions per minute) and receives R134a at 101.325 kPa and -20 °C. The compression process is isentropic with a discharge pressure of 600kPa. The compression and expansion processes in the cycle follow the relationship pv^n =constant, where n=1.13.
a) Plot the cycle on a P-V diagram and indicate the area which represents the power input for one cycle.
b) Calculate the mass flow rate of the refrigerant
c) Calculate the power required for the compression process when the properties of R134a are obtained from the table attached.
d) Find the power required for the compression process if the vapour is considered as ideal gas, and compare it with the value in c).
e) If the above compression process is achieved by two-stage compression process (in series) with an intercooler, plot the cycle on the P-V diagram, indicate the area which represents the power input for one cycle, and compare it with the one in a).
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