A well insulated tank is maintained at a constant pressure by a free floating piston. The space below the piston initially contains 10 kg of R134a at a temperature of 21 degrees celsius and a quality of 0.6. This space is connected to a supply line carrying R134a at 900 kPa and 100 degrees celsius. The properties of R134a at the conditions in the supply line are: enthalpy (h) = 336.2 kJ/kg entropy (s) = 1.114 kJ/kg-K internal energy (u) = 308.3 kJ/kg The manual valve between the supply line and the tank is opened allowing the hot R134a to enter the tank. The valve is shut off at the instant when all of the liquid in the tank has vaporized. a) How much refrigerant was added to the tank in kg? b) How much entropy was generated by this process in kJ/K?