i know in the ammonia flooded evaporators design there are two methods for liquid and vapor to separate. one is the separation is provided above the tubes in the shell, another is with an auxiliary vessel above the main evaporator.

the questions are:
1. if i take the first one, how to decide the liquid level and the tube arrangement in the shell.
2. if there is an auxiliary vessel, should the tubes arrange all of the shell or also need some space? and the liquid level?
3. how to calculate the auxiliary vessel?

is this ok with Froen??

thanks

cygbob