Apiston-cylinder device initially contains 1.39 l of air at 100 kpa and 25°c. the air is now compressed to a final state of 725 kpa and 150°c. the useful work input is 1.57 kj assuming the surroundings are at 100 kpa and 25°c, determine (a) the exergy of the air at the initial and the final states, x2=0.3090979kj (b) the minimum work that must be supplied to accomplish this compression process, kj wmin 0.309097 and (c) the second-law efficiency of this process η =119.687766