Question

# A cylinder fixed with a piston contains saturated vapour of a refrigerant at 10∘C, the volume and pressure are 10 L and 0.681 MPa respectively. The refrigerant is compressed to 3.5 L and 2 MPa. If the saturated vapour is undergoing polytropic process as PVn= constant, where n=1.025, then calculate the work done during the process.

A
7.60 kJ
B
5.76 kJ
C
3.12 kJ
D
2.9 kJ

Solution

## The correct option is A −7.60 kJGiven,P1=681 kPa ; V1=10×10−3 m3 P2=2000 kPa ; V2=3.5×10−3 m3 Equation of state of polytropic process is given as PV1.025= constant. ∵ In a polytropic process, work done is given by W=P1V1−P2V2n−1 From the given data we get, W=681×10−2000×3.50.025=−7.60 kJ Thus, option (a) is the correct answer.

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