1 kg of air expands from a pressure of 700 kPa and a temperature of 650 K to a pressure of 200 kPa and a temperature of 480 K. Calculate the entropy change in this process under each of the conditions given below. (a) When the specific heat ratio of air k=1.4. (b) when the specific heat of air is a function of temperature

Water at the initial pressure and temperature of P1 = 40 bar and T1 = 553.15K, respectively, is cooled at constant volume, while heat is transferred to the surroundings at T0= 288.15K. At the end of the cooling process, the pressure is P2 = 9 bar. Questions: (a) Calculate the entropy change of the water during the process. (b) Calculate the entropy produced during the process.

3. Helium enters an adiabatic 100-mm-diameter pipe steadily, with a velocity of 75 m/s. At the pipe entrance, the gas is at 200 kPa and 20°C; and at the exit, it is at 180 kPa and 18°C. Calculate the rate at which entropy is generated in the pipe, in W/K. (Assume ideal gas behavior and cold-air-standard)

1 kg of air is compressed isothermally and reversibly from 1 bar and 30oCto 5 bar. Calculate the work done on the air and the heat flow to or from the air.. (140 kJ, -140kJ)