Seeking guidance on setting up FLOW sim on a shell & tube chiller evaporator.  Purpose of the test is to create a base-case control model for comparison to a new tube design.

My model has a fluid subdomain for the water flow through the tube side.  The shell side is R134a refrigerant.  I understand that FLOW cannot do "phase change" in the refrigerant.  I will adjust the refrigerant flow/pressure/temp to get close to the 10 degree f DT on the tubes.

Problem I am running into is with Wall Condition.  As I am searching for correct heat transfer through the tube wall I want the Copper material properties to drive the heat transfer.  If I apply a heat transfer coefficient, heat generation rate, or wall temp it defeats the test intent.  If I leave the Wall Condition at the default Adiabatic there will not be any transfer through the tube wall. Also attempted analysis type "External" and went into space. 

Any guidance will be most appreciated.

Thank you,

Art