A - Refrigerant-134a initially at -8 ^oC and a quality of 40% is contained in a 1.2-m³ tank. Heat transfer to the refrigerant from a source at 50 ^oC occurs until the pressure reaches 300 kPa. Calculate (a) the total heat transfer, and (b) the total entropy change for this process.

B - A piston-cylinder assembly contains 2 kg of air initially at 100^o C and 750 kPa. Heat transfer occurs until the air comes into equilibrium with the surroundings which are maintained at 25^oC. During this process, the pressure is kept constant. Assuming that air behaves as an ideal gas with variable specific heats, calculate:

a) the total heat transfer,

b) the total entropy production for the process, and

c) briefly indicate whether the process is feasible and why.