CFD Online Discussion Forums - how to compare unsteady state problem results from FLUENT with Experimental data?

HELLO EVERYONE,

I have made a concentric heat exchanger setup in which water flows through the inner tube and steam in the outer tube. I am trying to study change in heat transfer for various water flow rates. Several trials are taken with different water flow rates keeping steam flow rate constant at a pressure of 2 bar. Here steam serves to maintain a constant wall temperature.

Now i am having trouble in modelling the same with Fluent since steam changes phase ( its in two phases ) as it passes along the length of the tube and should be treated as problem of unsteady state. How should i model this in fluent. Also how should i compare the experimental data ( conducted in steady state condition i.e. only the overall temperature increase is considered ) with Data from Fluent model of unsteady state.

Thanks in advance.