[looee]

Hi everyone!

My problem is as follows:
I modelate a pipe counter heat exchager. It includes a lot of pipes, so I've decided to consider one elementary cell (even its quater) - see first 2 picture. So hot water (a coolant) flows into one side within pipe (without phase change), and the cold water flows from the other side in shell side, where it starts boiling.
All parallel the pipe axis planes have symmetry BC.
Inlet BC: inlet velocity
outlet BC: outlet pressure (for both medium)

After I got a decision, I saw a really strange oddity: The tempreture of water for both medium doesn't change at the start of flowing. You can see a little plateau in the both charts. Of course it desagrees the real situation.

Maybe somebody knows what is it?

(The solver did about 1500 itarations and the residuals stopped changing after 500-700 itarations).