Concentric tube heat exchanger (Air-Water)

Young

Dear all,

I have tried to run a certain concentric pipe heat exchanger but now I'm frustrated.

I made a model in design modeler of workbench as follows:

1) make inner circle and extrude it then the cylinder was freezed. 2) Make outter circle and extrude it then it is an encloser of the inner circle 3) Using "Form a part" to make two solids as one.

Then I execute the mesh. There is no problem.

In the CFX-Pre, I checked interface and inlet outlet condition.

But It makes always the same error ;

Writing crash recovery file | +--------------------------------------------------------------------+ ---------------------------------- Error in subroutine FNDVAR : Error finding variable DENSITY_FL1 GETVAR originally called by subroutine GET_MFLOIP_ZIF

__________________________________________________ ___

I used the air at STC and Water at 25C, which have the density value (I have checked millon times)

but CFX can not find the fluid density.

Is it mesh problem?

Is it geometry problem?

I thought it is a simple heat exchanger problem but it's not.

Who is the man to sucess running a concentric heat exchanger?

Would you let me know how you do model and run the heat exchanger problem?