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Error Temperature of liquid volume must be less than or equal to Maximum valid temperature

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I am trying to simulate a Liquid cooling circuit and started by building the hydraulic resistances into the model. Therefore i only want the pressure drop / volume flow of the flow network. But an Error calling "Temperature of liquid volume must be less than or equal to Maximum valid temperature" is blocking the solve process. Does anyone have a solution for this? I also tried out ways to set a reference temperature - i have a feeling that the reference temperature doesnt fit because of 0K value. Therefore i tried out the perfect insulator.
I attached my Simulink file.
Thanks a lot!
  1 Comment
Divyanshu on 19 Dec 2023
Hi Johannes,
A possible reason for this "Temperature of liquid volume must be less than or equal to Maximum valid temperature" assertion getting triggered in the model can be due to a sudden pressure drop.
The error might not be related to temperature , I tried to make some changes in the model and simulate it again.
I have the following observations:
  • Firstly there is some parameter mismatch or some unxpected value is specified for some parameter in the blocks 'Ideal Angular Velocity source' or 'Centrifugal Pump' inside Subsystem 'Pumpenmodul'.
  • When these two blocks 'Ideal Angular Velocity Source' & 'Centrigual Pump' are replaced with 'Flow Coefficient Parameterized Valve' the error is gone and model simulates successfully.
You can try something around these observations to proceed further.
Please refer the following documentation for further details about 'Flow Coefficient Parameterized Valve':
Hope it helps!

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Answers (1)

Yifeng Tang
Yifeng Tang on 2 Jan 2024
Hi Johannes,
I took a look at your model. Two minor things, both in the pump subsystem, I'd suggest that you change:
  1. the unit of the Simulink-PS converter should be 'rpm'. The default unit of 1 will be interpreted as rad/s and it's a bit toooo fast.
  2. you may need to start the pump more slowly, instead of asking it to run at 3500 rpm at t=0. I put in a step to "turn on" the pump and a transfer function to slow down the step to mimic the gradual increase of speed.
with these two changes, the model seems to run OK.


Find more on Upgrading Hydraulic Models to Use Isothermal Liquid Blocks in Help Center and File Exchange




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