4 Replies Latest reply on Aug 5, 2011 2:27 PM by Rich Bayless

    Conjugate Heat Transfer -What am I doing wrong?

    sandeep pawar

      Hi,

       

      I am working on a model where I need to find the flow/temp distribution in a room. An internal fan blows the air on an equipment. I have defined the porosity for that equipment. I have also defined the volume heat generation rate for that equipment. I still don't get the temp distribnution. What am I doing wrong?

       

      Please see the attached. I am using SW 2010.

       

      Thanks,

      SP

        • Re: Conjugate Heat Transfer -What am I doing wrong?
          Cnu Vasu

          Could you explain your boundary conditions?

          • Re: Conjugate Heat Transfer -What am I doing wrong?
            Rich Bayless

            Hello,

             

            Your model ran fine for me, after I disabled the 'equipment' component.

             

            In order to use either heat generation or porous media, you have to disable the appropriate component.

             

            Open Help, Flow Sim Help, and search for Component Control, and follow the instructions.

             

            Rich.

              • Re: Conjugate Heat Transfer -What am I doing wrong?
                sandeep pawar

                Rich,

                 

                Thanks for your reply. If I disable the component, the rectangular box (which I am treating as a porous body to account for the pressure drop) will not be taken into consideration in the study. Is that correct? I want to find out the temp distribution on that rectangular part.

                 

                What I found was, to calculate heat transfer through the porous body I need to define the thermophysical props of the porous medium (by checking 'Heat Conductivity of porous matrix") otherwise the properties of the fluid will be used. In defining the properties of the porous matrix, I can't figure out what volumetric heat exchange coeffcient is. Any idea?

                 

                Another question I have is, in the wall condition, how is outer wall defined? Is it all the surfaces that come in contact with the fluid or is it just the outermost walls that encapsulate the assembly?

                 

                Thanks for taking time to reply.

                 

                Regards,

                SP

                  • Re: Conjugate Heat Transfer -What am I doing wrong?
                    Rich Bayless

                    Hello,

                     

                    The porous media has to be disabled for the analysis to run. 

                     

                    Judging from the velocity cut plots, the porous media is being taken into consideration in the study.  Using porous media for your equipment, basically a box of screen doors, is an interesting shortcut, but may not be a good model in the long run.

                     

                    It may be time for you to create a more detailed model of your equipment, with passages for the fluid and solids for the enclosure.

                     

                    For the wall condition, I believe it to be the outermost wall of the solid enclosure, particularly when heat conduction is selected.  If the outer wall in your model was, say six inches thick, and you fixed the outer wall temperature, you would see a temperature profile due to conduction through the outer wall.

                     

                    Rich.