A rigid tank contains 9 L of saturated liquid refrigerant-134a and the same volume of saturated vapor refrigerant-134a at 0oC. The tank is connected to a refrigerant 134-a feeding line. A safety valve is installed on the top of the tank such that the pressure inside the tank never exceeds 600 kPa (mass will leave the tank through the valve when the pressure reaches 600 kPa). The valve of the feeding line is opened and R134a at 16oC, 900 kPa flows in the tank and closed when 4.2 kg has entered. At the end of the process, only 6.8 kg of R-134a remains inside the tank.
(a) How much mass has left the tank through the safety valve during the entire process?
(b) Determine the amount of heat transfer during the process.