[jykim]

Hello all.
Currently, I am seting up the simulation of a simple heat exchanger (shell-tube type). (Actually it is evaporator)

Hot fluid water is used to heat up the cold fluid (ammonia). Both fluids are separated. Only, ammonia will go through evaporation and hot fluid water remains as water-liquid all the time.

Hot fluid - single phase.
cold fluid - two phases (ammonia-liquid, ammonia-vapor)

I am using multiphase model (VOF or mixture) for cold fluid side.
However, I would like to know how to setup the single-phase side.
What methodology or model should be used?
I will appreciate if you comment any thing.

Thank you!

[vinerm]

There are two ways to do this. Either add water as another phase and then, initialize with only water in water domain and ammonia and its vapor in the other domain. Another option is to use multicomponent (species transport) along with multiphase. Then, vapor can be one phase consisting of single specie, and liquid can be another phase consisting of water and ammonia. In this scenario as well, you just have to initialize with liquid volume fraction and water mass fraction of 1.0 in water domain and ammonia mass fraction of 1 in ammonia domain. I suppose the former option is better. You can also fix the volume fraction of water or ammonia and its vapor in both domains. You can only fix the value for secondary phases and not primary one.