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A piston-cylinder device initially contains air at 150 kPa and 27°C. At this state, the volume is 400 litre. The mass of the piston is such that a 350 kPa pressure is required to move it. The air is now heated until its volume has doubled. Determine the total heat transferred to the air.

A piston-cylinder device initially contains air at 150 kPa and 27°C. At this state, the volume is 400 litre. The mass of the piston is such that a 350 kPa pressure is required to move it. The air is now heated until its volume has doubled. Determine the total heat transferred to the air. Correct Answer 767 kJ

Qin – Wout = ΔU = m(u3 –u1) m = P1V1/RT1 = 0.697 kg u1 = u@ 300 K = 214.36 kJ/kg u3 = u@ 1400 K = 1113.43 kJ/kg Therefore Qin = 767 kJ.

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