2 Replies Latest reply on Nov 17, 2015 4:45 AM by Thomas Annet

    Heat source dependent on time AND temperature

    Thomas Annet
    Thomas Annet Oct 28, 2015 9:04 AM

      Hello everybody,

       

      I am trying to model a battery module and its heat transfer under Flow Simulation with a time dependent study. The aim is to know the final temperature of the battery under different environment.

      I have a current (I) profile from the battery module as an input to determine the temperature increase of the module.

      I am having problems with calculating the heat production (the heat source input in FlowSim) of the battery module since :

      Using Joules formula :

       

      Heat losses = Internal resistance of the battery*current^2        =>   Heat Losses = R*I²                         (neglecting other heat losses)

       

      The problem is that the internal resistance R is dependent on the temperature, decreasing when the temperature increases, so I would need the direct measure of the temperature from the model to be accurate. I cannot calculate the heat losses on an excel sheet since I don't know what the temperature profile will be.  

       

      My question is :

       

      Is it possible to implement in the heat source parameters, as a time dependent table, a power formula related to a temperature goal for each time step ?

       

      Example: (Ri*(0.5*{PG Internal Temperature})*I^2

      With   Ri = constant

                I = depending on current profile

                PG Internal Temperature = depending on temperature of the battery at each time step

       

      I hope I was clear enough, don't hesitate to ask me anything if I was not.

       

      Thank you in advance,

       

      Thomas

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        • Re: Heat source dependent on time AND temperature
          Attilio Colangelo
          Attilio Colangelo Nov 12, 2015 9:41 AM (in response to Thomas Annet)

          I would recommend setting this up in Solidworks Simulation (not Flow) initially.  You can define heat generation as a function of the battery temperature (Thermal Loads -> Heat Power -> Temperature Curve).  Setting up the curve does require some effort but I think it will allow you to understand the problem without getting into a complex  Flow Simulation. Just my opinion.

           

          Also, you may want to run this as steady state initially and then switch to transient when you are comfortable with boundary condition, etc.

            • Re: Heat source dependent on time AND temperature
              Thomas Annet
              Thomas Annet Nov 17, 2015 4:45 AM (in response to Attilio Colangelo)

              Hello,

               

              Thank you for your answer, I will try to do what you explained.

              I will also run the Flow simulation with the average heat losses in steady state to see if everything looks OK.

               

              I already ran some calculation in transient, and the results seem quiet good when comparing to real tests, only thing is that it takes a very long time and I think I cannot go with a lower timestep or a lower mesh.

               

              Again thank you for your answer, I am also going to send an "improvement demand" to SolidWorks to see if this can be solved directly in the next FlowSimulation update (or the next one ;-) )

               

              Thomas