Search code examples
modelicadymolaopenmodelicajmodelica

How to pass heatPorts.T to DynamicPipe flowModel?

In the implementation of a flow models that function with Modelica Standard Library DynamicPipe (or a similar model that builds from PartialTwoPortFlow) there are examples of flow models that take place in an environment with heat transfer that requires wall properties (e.g., heatPorts.T and/or heatPorts.Q_flow) in order to calculate the pressure drop.

For example, a pressure drop model may need to calculate a new visocisty or Prandtl number based on the medium pressure and the wall temperature to capture cooling/heating effects, etc.

The heat transfer model obtains properties of the medium via passing the "states" however there is no existing connection in DynamicPipe or PartialTwoPortFlow that goes the other way.

I've tried numerous variations of ideas and have had no success, including creating a new PartialTwoPortFlow that contains all the heat transfer calls that exist in DynamicPipe.

I hesitate to post this question as I am surprised I am having so much difficulty with this and would not be surprised to find a straight forward solution. Nevertheless I need this ability and curious if others have already solved this issue as I am running short on ideas.

So my questions is:

What is a proper/efficient means of passing the heatPorts.T values to the flowModel?

Solution

  • For those familiar with the MSL Fluids library and more specifically the Pipe models provided, this answer should (hopefully) make sense.

    Aside:

    It seems the dynamic pipe could be improved a little bit by not restricting the heat transfer area to the perimeter x lengths and instead introduce a parameter (e.g., heatTransferArea) that would permit the user to define it and default to perimeter x lengths. See below 

      parameter SI.Area heatTransferArea = perimeter*lengths "Total heat transfer area";
  HeatTransfer heatTransfer(
    ...
    final surfaceAreas=heatTransferArea , //perimeter*lengths <- replaced
    ...

    End Aside:

    In order to communicate heatPorts.T to the flowModel and to not have errors when I checked each of the models I had to do the following:

    1. Make an "input" in the flowModel for Ts_w. Not parameter (take a look at how mediums.state is passed)! Might have to do some finagling with it like "diameters" (see DetailedPipeFlow) to make it be used how you think it's going to be used.
    2. Duplicate PartialTwoPortFlow and add the final Ts_w = Ts_wFM to flowModel. Additionally define the variable SI.Temperature[nFM+1] Ts_wFM in PartialTwoPortFlow and establish definitions similar to statesFM in the equation section. This will require adding a HeatPorts model to be added.
    3. Duplicate DynamicPipe and change the extension to the new PartialTwoPortFlow. Set use_HeatTransfer to true (as I've set it up this has to be true now for this to work which isn't ideal but manageable). Might be good to make it a final parameter so it can't be changed. Don't forget to connect heatPorts to the heatports added in step 2.

    I believe that this capture a quick version of how I was able to get the wall temperature passed to the flowModel. Perhaps there is a more elegant way but I though this was pretty serviceable. I now simply have one more Partial model and one more pipe model called PartialTwoPort_wTemp and GenericDynamicPipe (I also incorporated my surfaceArea correction in the new pipe).