A piston cylinder device initially contains 10 ft3 of helium gas at 25 psia and 40oF. The

Question:

A piston cylinder device initially contains 10 ft3 of helium gas at 25 psia and 40oF. The gas is then compressed in a polytrophic process ( pv1.3= constant) to 70 psia. Determine (a) the minimum work with which this process could be accomplished and (b) second-law efficiency. Assume the surroundings to be at 14.7 psia and 70oF.