Pressure inside the Sweptvolume component in Modelica - simulation

Question

I model a system in Modelica, in which a fluid should be compressed from 4 bar to 500 bar. I give as boundary conditions 4 bar inlet pressure and 500 bar outlet pressure. I want to realize this compression by movement of a piston. The system can simulate when outlet pressure is defined as 10 bar. But it is not able to simulate at 500 bar outlet pressure. When outlet boundary condition is 500 bar then pressure inside the piston chamber is not higher than 500 bar. So I get negative massflow and pressure inside the piston chamber. Therefore simulation doesnt continue. When I look at pressure inside the chamber, it simply assumes medium pressure as the pressure which is defined at the ports of the piston. Compression movement of piston doesnt affect the pressure inside the piston, as pressure in piston given by the pressure at the ports of the piston. Do you know how to increase pressure inside the piston so that I can have a pressure level greater than 500 bar inside the piston?
I add the code and blockdiagram. Any help will be appreciated! Thanks a lot!
//----------------------------------------------------------------------------
// Name of Model: Hochdruckreiniger3
// Date: 11/15/20 21:16:37
// Generated from Modelica Diagram Editor
//----------------------------------------------------------------------------
model Hochdruckreiniger3
//Declaration(s)
Real V_max = 0.000003;
Real V_tod = 0.000002;
Real N = 2800;
Real opening_NP;
Real opening_HP;
replaceable package medium = Modelica.Media.Water.StandardWater( );
//Component(s)
Modelica.Fluid.Machines.SweptVolume Swept1 (
pistonCrossArea = 0.003131,
clearance = 0.000250621,
redeclare package Medium = medium,
nPorts = 3,
use_portsData = false,
p_start = system.p_start,
use_T_start = true,
T_start = 293.15);
inner Modelica.Fluid.System system;
Modelica.Mechanics.Translational.Sources.Position Posit1 (exact = true, useSupport = false);
Modelica.Blocks.Sources.Sine Sine1 (
amplitude = 0.005567,
freqHz = 46.66,
offset = 0.005567,
phase = -Modelica.Constants.pi/2);
Modelica.Fluid.Sources.FixedBoundary boundary (p = 500e5, redeclare package Medium = medium, nPorts = 1);
Modelica.Fluid.Pipes.DynamicPipe pipe2 (
length = 0.5,
diameter = 0.03,
redeclare package Medium = medium,
momentumDynamics = system.momentumDynamics,
massDynamics = Modelica.Fluid.Types.Dynamics.DynamicFreeInitial,
energyDynamics = system.energyDynamics,
allowFlowReversal = system.allowFlowReversal,
modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);
Modelica.Fluid.Pipes.DynamicPipe pipe3 (
length = 0.5,
diameter = 0.03,
redeclare package Medium = medium,
momentumDynamics = system.momentumDynamics,
massDynamics = Modelica.Fluid.Types.Dynamics.DynamicFreeInitial,
energyDynamics = system.energyDynamics,
allowFlowReversal = system.allowFlowReversal,
modelStructure = Modelica.Fluid.Types.ModelStructure.a_vb);
Modelica.Fluid.Pipes.DynamicPipe pipe4 (
length = 0.5,
diameter = 0.03,
redeclare package Medium = medium,
momentumDynamics = system.momentumDynamics,
massDynamics = Modelica.Fluid.Types.Dynamics.DynamicFreeInitial,
energyDynamics = system.energyDynamics,
allowFlowReversal = system.allowFlowReversal,
modelStructure = Modelica.Fluid.Types.ModelStructure.a_vb);
Modelica.Fluid.Sources.FixedBoundary boundary1 (p = 500e5, redeclare package Medium = medium, nPorts = 1);
Modelica.Fluid.Pipes.DynamicPipe pipe5 (
length = 0.5,
diameter = 0.3,
redeclare package Medium = medium,
momentumDynamics = system.momentumDynamics,
massDynamics = Modelica.Fluid.Types.Dynamics.DynamicFreeInitial,
energyDynamics = system.energyDynamics,
allowFlowReversal = system.allowFlowReversal,
modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);
Modelica.Blocks.Sources.Pulse Puls1 (period = 0.02142, width = 45.331);
Modelica.Blocks.Sources.Pulse Puls2 (period = 0.02142, startTime = 0.01071, width = 45.331);
Modelica.Fluid.Valves.ValveLinear NDVentile (dp_nominal = 94.35, m_flow_nominal = 0.05867441, redeclare package Medium = medium);
Modelica.Fluid.Valves.ValveLinear HDVentile (dp_nominal = 95, m_flow_nominal = 0.05867441, redeclare package Medium = medium);
Modelica.Fluid.Sensors.Pressure pressureamSweptvolume (redeclare package Medium = medium);
Modelica.Fluid.Sensors.Pressure PressureanderPipe (redeclare package Medium = medium);
Modelica.Fluid.Sensors.Pressure PressureanBeginnderHochdruckventile (redeclare package Medium = medium);
Modelica.Fluid.Sensors.Pressure Pressure_amEndederHDVentile (redeclare package Medium = medium);
Modelica.Fluid.Pipes.DynamicPipe pipe1 (
length = 0.5,
diameter = 0.03,
redeclare package Medium = medium,
momentumDynamics = system.momentumDynamics,
massDynamics = Modelica.Fluid.Types.Dynamics.DynamicFreeInitial,
energyDynamics = system.energyDynamics,
allowFlowReversal = system.allowFlowReversal,
modelStructure = Modelica.Fluid.Types.ModelStructure.a_vb);
Modelica.Fluid.Vessels.ClosedVolume volume (
V = 7e-9,
nPorts = 2,
use_portsData = false,
redeclare package Medium = medium,
p_start = 26.5e5);
equation
if der(Sine1.y)>=0 then
opening_NP=1;
opening_HP=0;
else
opening_NP=0;
opening_HP=1;
end if;
//Connection(s)
connect(Posit1.flange, Swept1.flange);
connect(Sine1.y, Posit1.s_ref);
connect(pipe2.port_b, Swept1.ports[1]);
connect(Swept1.ports[2], pipe3.port_a);
connect(pipe4.port_b, boundary1.ports[1]);
connect(boundary.ports[1], pipe5.port_a);
connect(pipe5.port_b, NDVentile.port_a);
connect(NDVentile.port_b, pipe2.port_a);
connect(NDVentile.opening, Puls1.y);
connect(Puls2.y, HDVentile.opening);
connect(pipe3.port_b, HDVentile.port_a);
connect(pressureamSweptvolume.port, Swept1.ports[3]);
connect(PressureanderPipe.port, pipe3.port_a);
connect(PressureanBeginnderHochdruckventile.port, HDVentile.port_b);
connect(Pressure_amEndederHDVentile.port, HDVentile.port_a);
connect(pipe1.port_a, PressureanBeginnderHochdruckventile.port);
connect(pipe1.port_b, volume.ports[1]);
connect(volume.ports[2], pipe4.port_a);
end Hochdruckreiniger3;

Answer 1

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