Heating water at constant volume and pressure

[debussie]

A rigid tank has a volume of 0.01m3. It initially contains saturated water at a temperature of 200°C and a quality of 0.4. The top of the tank contains a pressure-regulating valve that maintains the vapor at constant pressure. This system undergoes a process whereby it is heated until all the liquid vaporizes. How much head (in kJ) is required? You may assume that there is no pressure drop in the exit line.

 

[JaredJames]

Please could you provide your attempt at the solution.

Jared

 

[debussie]

So far I have used the quality given, and the steam tables to calculate the total molar volume and total mass of the water:

Vm=(1-x)Vml+xVmv
m=V/Vm

I am assuming that the temperature of the system won't change because vapor will continue to leave as more vapor is created. I'm not sure where to go from here. Does Q=change in U? How do I keep track of the energy that is leaving with the vapor?