I am trying to create a heat transfer across the surface of tube. there is a fluid domain inside and outside the tube and tube itself is a solid domain. What boundary condition should I apply? I am trying to validate the experimental data so all I have is inlet temp of hot and cold fluid and overall heat transfer coefficient of 200 W/m2.K . Cold  fluid enters at 300K and leaves at 341K but tube fluid is not transferring heat. 
I have system coupling with wall thickness but that's not working.

Having the same problem. What is the solution?