First solve for initial conditions failed to converge in Simscape model

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Thijs van den Dungen
Thijs van den Dungen on 29 Oct 2019
Answered: Yifeng Tang on 28 Jun 2021
I have the following model of the recovery of refrigerant (R134A from REFPROP) from a heat exchanger to a recovery cylinder, respectively heated by a resistance and cooled by ice to induce the pressure difference. However, with the initial conditions that I set for the pressure in the heat exchanger and cylinder I get the following warning and it solves for other initial conditions:
First solve for initial conditions failed to converge. Trying again with all high priorities relaxed to low.
Unable to satisfy all initial conditions. The variables involved are listed below. The following variables are involved in a constraint that conflicts with their targets: 'Heat_Exchanger.p_I' (Pressure of fluid volume) 'Recovery_Cylinder.p_I' (Pressure of fluid volume) Here are the equations involved: all components involved'simulation/Heat Exchanger'Equation location is: 'C:\Program Files\MATLAB\R2019b\toolbox\physmod\simscape\library\m\+foundation\+two_phase_fluid\+elements\constant_volume_chamber.ssc' (line 153) 'simulation/Recovery Cylinder'Equation location is: 'C:\Program Files\MATLAB\R2019b\toolbox\physmod\simscape\library\m\+foundation\+two_phase_fluid\+elements\constant_volume_chamber.ssc' (line 153)
Could someone help me and please tell what is going wrong?
simulink.PNG
  3 Comments
Yifeng Tang
Yifeng Tang on 17 Aug 2020
I suspect this may have to with the two "A" ports connected directly to each other, meaning there is no volume or flow resistance between them, and they have to share the same pressure, enthalpy, etc. Try adding a pipe or orifice in between and see whether things improve.

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Answers (1)

Yifeng Tang
Yifeng Tang on 28 Jun 2021
I suspect this may have to with the two "A" ports connected directly to each other, meaning there is no volume or flow resistance between them, and they have to share the same pressure, enthalpy, etc. Try adding a pipe or orifice in between and see whether things improve.

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