What's going on here?

Hi, all!

I need help understanding why my results are like this. On the left is temperature contours of freon flowing inside a copper tube, which also has temperature contours on the right. The copper tube is being heated by hot fluid. The inner tubing should be interfacing with the Freon walls, but...

Thank you

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Answers

  • RobRob UKForum Coordinator

    That looks like the freon domain isn't connected to the tube. Check for connectivity and the presence of interface zones if you're using Fluent.

  • Hello again and thanks for your help! There is a mapped-coupled interface between the two walls.

  • RobRob UKForum Coordinator

    That should work. Can you post a temperature plot on a plane that's on the axis. Node values off and zoom into one (or a few) of the tubes. If you do a heat flux report over the wall between the metal & freon how much heat is transferred?

  • Sorry this took a while,

    Here is a temperature plot of the fluid domain that is supposed to be heating the tubes and cavity, where the sources is coming from the bottom:

    I got a heat-flux report using the calculator of the post processor. These are the total and average values:

    Area Average of Heat Flux on freonwalls:  -576.223 [W m^-2], Area Average of Heat Flux on innertubes:  -3.97661e+07 [W m^-2]

    Sum of Heat Flux on freonwalls:  -2.27914e+08 [W m^-2], Sum of Heat Flux on innertubes:  -1.62972e+13 [W m^-2]

    I'm not sure why it's negative. I couldn't get a heat flux report from the solver because fluent deleted all my results for some reason, but at leastthe post processor preserved them. Lastly, here are images of the mesh:

    Could that gap be an issue? The entire mesh has 14,019,939 nodes.

  • RobRob UKForum Coordinator

    Is that a gap between the pipe and the core? You need the nodes to be common to both volumes or for them to be close enough that a non-conformal boundary will work (ie the surfaces are near enough the same but not connected in the geometry stage). If there's a physical gap nothing can pass over it: it means the two parts of the model are separate and no data can pass between the volumes.

    Same goes for the outside: it must full surround and connect to the pipe.

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