Modelica Standard Pumps (Both Directions) - modelica

Question

Hello
My model has a pump with dp = 1 bar and a pipe which reduce the dp of 1 bar. The pump must work in both directions.
Additionally, there is a three-way valve which provides the side with the lower pressure with 3 bar.
But there is a problem with my model: Always if I want to use a pump from the standard library, it does not work… Does anybody have any ideas how to solve this problem, if possible with standard library blocks? (I would like to have standard library blocks because of the parameters like pump characteristics, …)
Here is the image: Model
Thank you!
model Modell_online
Pump_mflow pump_mflow3(redeclare package Medium =
Modelica.Media.Water.ConstantPropertyLiquidWater, show_T=true)
annotation (Placement(transformation(
extent={{-10,-10},{10,10}},
rotation=270,
origin={-50,10})));
Modelica.Fluid.Pipes.StaticPipe pipe(
redeclare package Medium =
Modelica.Media.Water.ConstantPropertyLiquidWater,
length=0.5,
diameter=0.1,
redeclare model FlowModel =
Modelica.Fluid.Pipes.BaseClasses.FlowModels.NominalLaminarFlow (
dp_nominal=100000, m_flow_nominal=3),
p_a_start=400000,
p_b_start=300000) annotation (Placement(transformation(
extent={{-10,-10},{10,10}},
rotation=90,
origin={-10,10})));
Modelica.Blocks.Sources.Pulse pulse(
amplitude=2,
offset=-1,
period(displayUnit="min") = 600)
annotation (Placement(transformation(extent={{-100,60},{-80,80}})));
inner Modelica.Fluid.System system
annotation (Placement(transformation(extent={{-140,80},{-120,100}})));
Modelica.Fluid.Sources.Boundary_pT p_source(
redeclare package Medium =
Modelica.Media.Water.ConstantPropertyLiquidWater,
nPorts=1,
p=300000) annotation (Placement(transformation(
extent={{10,-10},{-10,10}},
rotation=0,
origin={70,10})));
Modelica.Blocks.Continuous.FirstOrder firstOrder(T(displayUnit="s") = 10)
annotation (Placement(transformation(extent={{-60,60},{-40,80}})));
VarEx VarEx_1(redeclare package Medium =
Modelica.Media.Water.ConstantPropertyLiquidWater) annotation (Placement(
transformation(
extent={{10,-10},{-10,10}},
rotation=270,
origin={30,10})));
equation
connect(pump_mflow3.port_b, pipe.port_a) annotation (Line(points={{-50,0},{-50,
-20},{-10,-20},{-10,0}}, color={0,127,255}));
connect(pipe.port_b,pump_mflow3. port_a) annotation (Line(points={{-10,20},{-10,
40},{-50,40},{-50,20}}, color={0,127,255}));
connect(pulse.y, firstOrder.u)
annotation (Line(points={{-79,70},{-62,70}}, color={0,0,127}));
connect(p_source.ports[1], VarEx_1.port_ExpansionVessel)
annotation (Line(points={{60,10},{40,10}}, color={0,127,255}));
connect(VarEx_1.port_warm, pump_mflow3.port_a) annotation (Line(points={{30,20},
{30,40},{-50,40},{-50,20}}, color={0,127,255}));
connect(VarEx_1.port_cold, pipe.port_a) annotation (Line(points={{30,0},{30,-20},
{-10,-20},{-10,0}}, color={0,127,255}));
connect(firstOrder.y, pump_mflow3.m_flow_set) annotation (Line(points={{-39,70},
{-30,70},{-30,10},{-38,10}}, color={0,0,127}));
annotation (Icon(coordinateSystem(preserveAspectRatio=false, extent={{-140,
-100},{140,100}})), Diagram(coordinateSystem(preserveAspectRatio=
false, extent[enter image description here][1]={{-140,-100},{140,100}})),
experiment(StopTime=1200));
end Modell_online;

Answer 1

A similar question was asked in Backflow Orifice (Zeta).
You'll need a heat sink to remove the heat generated by the pump in a closed circuit.
The MSL pumps have limited capability of flow reversal.
I made a small package with some examples here https://drive.google.com/file/d/1LEn2_ifoFTrdX33JEe2awQmvePBERVVz/view?usp=sharing
In example 3, note that it is not a true closed circuit since the pressure sink also acts as a heat sink.
The paper On the formulation of steady-state initialization problems in object-oriented models of thermo-hydraulic systems might be of interest to you.
Best regards,
Rene Just Nielsen