Evaporation and Condersation problem
 

I try to use the ccm+ to simulation the problem of liquid's evaporation and condersation.
I used the VOF to simulate it.
I want to calcualate the mass flow rate of liquid in the outlet.
I used tow method to calculate it.
One is the report mass flow (phase) at the outlet, anthor used the suface average of mass flow of liquid (field function).
I found the result poor 1000 times.
I don't know why?
Which is the correct?
If anybody know the reseason, please tell me.
Thanks .