[Reza_computational]

Hello Guys
I want to model a liquid evaporation problem in which water injects through hot air stream (about 300 degree) and then the water evaporates and the air is cooled. I know that I have to define air as a variable mixture involving air and water vapor and a homogeneous binary mixture that consists of liquid and gaseous phases but i encounter some errors:
1:When using a homogeneous binary mixture one equilibrium constraint and one equilibrium fraction must be
specified.
2:the air must be defined as a "constraint" (but there is no such option when I define a binary mixture)
Can anybody help?
Thank you in advance...