Tube in Tube heat exchanger( But I got error)
Dear all,
I have tried to simulate a heat exchanger. Water is flowing at outer pipe and air is flowing at a inner pipe as following sectional diagram --------------------------- water --> -------------------------- air <-- --------------------------- water --> --------------------------- I had two fluid domain (water, air) so I used "enable beta features (in option)" and turned off "constant domain physics" at simulation. But I got error message like this *********************************************** Global Statistics : Global Number of Nodes = 31926 Global Number of Elements = 96078 Total Number of Tetrahedrons = 96078 Global Number of Faces = 58222 Minimum Orthogonality Angle [degrees] = 32.3 ok Maximum Aspect Ratio = 6.4 OK Maximum Mesh Expansion Factor = 21.8 ! Domain Interface Name : Domain Interface 1 Non-overlap area fraction on side 1 = 8.89E-06 Non-overlap area fraction on side 2 = 5.07E-08 ---------------------------------- Error in subroutine FNDVAR : Error finding variable DENSITY_FL1 GETVAR originally called by subroutine GET_MFLOIP_ZIF +--------------------------------------------------------------------+ | Writing crash recovery file | +--------------------------------------------------------------------+ ---------------------------------- Error in subroutine FNDVAR : Error finding variable DENSITY_FL1 GETVAR originally called by subroutine GET_MFLOIP_ZIF +--------------------------------------------------------------------+ | An error has occurred in cfx5solve: | | | | The ANSYS CFX solver exited with return code 1. No results file | | has been created. | +--------------------------------------------------------------------+ End of solution stage. +--------------------------------------------------------------------+ | Warning! | | | | The ANSYS CFX Solver has written a crash recovery file. This file | | has been saved as F:\Thesis\prelim\test\001\model3_004.res.err and | | may be an aid to diagnosing the problem or restarting the run. | | More details should be available in the solver output section of | | the output file. Note that a lock file was left for the crash | | file when the solver exited, and so it is probably incomplete. | +--------------------------------------------------------------------+ +--------------------------------------------------------------------+ | The following user files have been saved in the directory | | F:\Thesis\prelim\test\001\model3_004: | | | | mon | +--------------------------------------------------------------------+ This run of the ANSYS CFX Solver has finished. ************************************************* Would you let me know how I get over error? and please share your exprience, if you have ever done this type heat exchanger. Thanks have a great day |
Re: Tube in Tube heat exchanger( But I got error)
Hi,
The first error says that is can't find the density for a material. Check that you have density defined for everything, or a sensible equation of state defined. Glenn Horrocks |
Re: Tube in Tube heat exchanger( But I got error)
Dear Horrocks,
Thanks your response. I use each fluid material as follows; air = Air at 25C in CFX material library, its density is 1.185 kgm^-3 Water = water in CFX material library, 997 kgm^-3 However, it makes the same error message. I suspect this issue is caused by interface condition. But I don't know what makes errors. I think it is simple crossflow heat exchanger between air tueb and water tube. Have you ever run before? Thanks |
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