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Is there a way to model a pipe under vacuum pressure using Simscape?

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Delika Weragoda
Delika Weragoda on 17 Jun 2021
Commented: Delika Weragoda on 16 Jul 2021
Is there a way to model fluid flow in a pipe under vaccum pressure using simscape?
  2 Comments
Delika Weragoda
Delika Weragoda on 18 Jun 2021
Hi Yifeng, So basically what I'm trying to do is model a heat pipe, which is a two phase pipe. And since it's a vacuum sealed container I was wondering if this pressure can be defined as a boundary condition using simscape blocks. So yeah, there will be liquid evaporation and condensation and the same time, but at either ends of the pipe. Hope that helps. Cheers Delika

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Answers (1)

Yifeng Tang
Yifeng Tang on 19 Jun 2021
Hey Delika,
Thanks for the clarification.
It seems to me that it's possible to model the evaporation and condensing effects at two ends of a heat pipe, using blocks from the two-phase (2P) domain. It may not be easy though.
Couple blocks that I think may be useful for you:
Receiver Accumulator (2P) https://www.mathworks.com/help/releases/R2020a/physmod/hydro/ref/receiveraccumulator2p.html This one will allow you to model the two ends of the heat pipe. I suggest this instead of a simple chamber, because you need a way to allow only the liquid phase to travel away from the cold end through wicking, and gas phase away from the hot end (by pressure?). This block gives you the option to do that. The thermal port will allow you to heat or cool the fluids.
Pipe (2P) https://www.mathworks.com/help/releases/R2020a/physmod/simscape/ref/pipe2p.html You need pipes to tranport fluid (vapor & liquid) between the two ends.
What I am not sure or clear about is how to model the wicking of liquid from the cold end to the hot end. Any correlation you are aware of for the capilliary effect that's driving the flow? You'll need to find a way to implement that on the liquid path. The vapor path, I think, will be driven by the pressure difference because the hot end will have a higher vapor pressure.
Your model could conceptually look like this:
Hope this helps.
  6 Comments
Delika Weragoda
Delika Weragoda on 16 Jul 2021
Yeah, I've set the initial conditions of the blocks to the initial pressure, but it still gives a considerable amount of pressure reading inside. That is why I could not understand as to why there's such a large reading and decided to use another block to set the vacuum pressure, which actually works (but only with the constant volume chamber but not with the receiver accumulator block, which is confusing again). I'll check if I've made a mistake in the model and see.
Thanks alot Yifeng.

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