First of all i want you to asked this question to yourself:
1. What is clearance between coil and the pipe?
2. Why do you think that the simulation result is wrong do you have an actual data that you trying to replicate or did you have some hand calculation and the result is not the same with the simulation.
To be honest people in this forum will also tell this to you,
"If you do not have actual data or some hand calculation for you to compare with your simulation then"
My Advise is to try to model and simulate a simpler model that can be hand calculated or model and simulate actual model that has data result, so that you can compare the result which will give you confidence in evaluating the result of your study analysis.
why not upload you model and also the way you set up your analysis like boundary conditions etc. for a reference of the people so that they can advise you directly to the point.
I dont know SW thermal study is suitable for heat exchanger.
ı useFlow Simulation for exchanger
I was thinking the same thing. But I do not know how I could add the temperature of the center pipe to a flow simulation and the convection of the coil.
you can define inlet flow with tepreture. You should add 2 fluid subdomains.
SW Flow automatically calculate the convention coefficent.