Solve Problems 7.99 and 7.100 and compare your results. Why is the change in entropy of the world greater for Problem 7.100?

Problem 7.100

Steam in a piston–cylinder device initially has a volume of 0.2 m³ at 300 kPa and 540 K. The steam is compressed from 300 kPa to 700 kPa at a constant temperature of 540 K. During this process, a paddle mixes the steam for two minutes with a power of 100 W. The steam temperature in the cylinder is maintained constant during the process as a result of heat transfer to the surrounding medium at 250 K. 

Problems 7.99

Steam in a piston–cylinder device initially has a volume of 0.2 m³ at 300 kPa and 540 K. The steam is compressed reversibly from 300 kPa to 700 kPa at a constant temperature of 540 K. The steam temperature in the cylinder is maintained constant during this process as a result of heat transfer to the surrounding medium at 250 K.