A piston-cylinder assembly contains 0.5 lb of water. The water expands from an initial state where p1 = 40 lbf/in.2 and T1 = 300o F to a final state where p2 = 14.7 lbf/in.2 During the process, the pressure and specific volume are related by the polytropic process pv 1.2 = constant. Determine the energy transfer by work, in Btu.

W = 31.393 Btu

Explanation:

given data

piston-cylinder assembly contains water = 0.5 lb

p1 = 40 lbf/in² = 40 × 144 lbf/ft²

T1 = 300° F

p2 = 14.7 lbf/in² = 14.7  × 144 lbf/ft²

pv 1.2 = constant.

solution

we use here superheated table A 4E  to get value for p1 = 40 and t = 300

v1 = 11.04 ft³/lbm

so we know

   ,...............1

solve it we get

v2 = 25.425 ft³/lbm

and here

W =   ...............2

put here value we get

W =  

solve it we get

W = 31.393 Btu

answer:

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explanation: