Modelica.Fluid.Interfaces

Interfaces for steady state and unsteady, mixed-phase, multi-substance, incompressible and compressible flow

Information

Extends from Modelica.Icons.Library (Icon for library).

Package Content

Name Description

FluidPort Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)

FluidPort_a Generic fluid connector at design inlet

FluidPort_b Generic fluid connector at design outlet

FluidPorts_a Fluid connector with filled, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)

FluidPorts_b Fluid connector with outlined, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)

PartialTwoPort Partial component with two ports

PartialTwoPortTransport Partial element transporting fluid between two ports without storage of mass or energy

HeatPorts_a HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)

HeatPorts_b HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)

PartialHeatTransfer Common interface for heat transfer models

PartialLumpedVolume Lumped volume with mass and energy balance

PartialLumpedFlow Base class for a lumped momentum balance

PartialDistributedVolume Base class for distributed volume models

PartialDistributedFlow Base class for a distributed momentum balance

Name	Description
FluidPort	Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)
FluidPort_a	Generic fluid connector at design inlet
FluidPort_b	Generic fluid connector at design outlet
FluidPorts_a	Fluid connector with filled, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)
FluidPorts_b	Fluid connector with outlined, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)
PartialTwoPort	Partial component with two ports
PartialTwoPortTransport	Partial element transporting fluid between two ports without storage of mass or energy
HeatPorts_a	HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)
HeatPorts_b	HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)
PartialHeatTransfer	Common interface for heat transfer models
PartialLumpedVolume	Lumped volume with mass and energy balance
PartialLumpedFlow	Base class for a lumped momentum balance
PartialDistributedVolume	Base class for distributed volume models
PartialDistributedFlow	Base class for a distributed momentum balance

Modelica.Fluid.Interfaces.FluidPort

Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)

Type Name Description

flow MassFlowRate m_flow Mass flow rate from the connection point into the component [kg/s]

AbsolutePressure p Thermodynamic pressure in the connection point [Pa]

stream SpecificEnthalpy h_outflow Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]

stream MassFraction Xi_outflow[Medium.nXi] Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]

stream ExtraProperty C_outflow[Medium.nC] Properties c_i/m close to the connection point if m_flow < 0

Type	Name	Description
flow MassFlowRate	m_flow	Mass flow rate from the connection point into the component [kg/s]
AbsolutePressure	p	Thermodynamic pressure in the connection point [Pa]
stream SpecificEnthalpy	h_outflow	Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]
stream MassFraction	Xi_outflow[Medium.nXi]	Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]
stream ExtraProperty	C_outflow[Medium.nC]	Properties c_i/m close to the connection point if m_flow < 0

Modelica definition

connector FluidPort 
  "Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)"

  replaceable package Medium = Modelica.Media.Interfaces.PartialMedium 
    "Medium model";

  flow Medium.MassFlowRate m_flow 
    "Mass flow rate from the connection point into the component";
  Medium.AbsolutePressure p "Thermodynamic pressure in the connection point";
  stream Medium.SpecificEnthalpy h_outflow 
    "Specific thermodynamic enthalpy close to the connection point if m_flow < 0";
  stream Medium.MassFraction Xi_outflow[Medium.nXi] 
    "Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0";
  stream Medium.ExtraProperty C_outflow[Medium.nC] 
    "Properties c_i/m close to the connection point if m_flow < 0";
end FluidPort;

Modelica.Fluid.Interfaces.FluidPort_a

Generic fluid connector at design inlet

Modelica.Fluid.Interfaces.FluidPort_a

Information

Extends from FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium model

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium model

Type	Name	Description
flow MassFlowRate	m_flow	Mass flow rate from the connection point into the component [kg/s]
AbsolutePressure	p	Thermodynamic pressure in the connection point [Pa]
stream SpecificEnthalpy	h_outflow	Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]
stream MassFraction	Xi_outflow[Medium.nXi]	Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]
stream ExtraProperty	C_outflow[Medium.nC]	Properties c_i/m close to the connection point if m_flow < 0

Modelica definition

connector FluidPort_a "Generic fluid connector at design inlet"
  extends FluidPort;
end FluidPort_a;

Modelica.Fluid.Interfaces.FluidPort_b

Generic fluid connector at design outlet

Modelica.Fluid.Interfaces.FluidPort_b

Information

Extends from FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium model

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium model

Type	Name	Description
flow MassFlowRate	m_flow	Mass flow rate from the connection point into the component [kg/s]
AbsolutePressure	p	Thermodynamic pressure in the connection point [Pa]
stream SpecificEnthalpy	h_outflow	Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]
stream MassFraction	Xi_outflow[Medium.nXi]	Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]
stream ExtraProperty	C_outflow[Medium.nC]	Properties c_i/m close to the connection point if m_flow < 0

Modelica definition

connector FluidPort_b "Generic fluid connector at design outlet"
  extends FluidPort;
end FluidPort_b;

Modelica.Fluid.Interfaces.FluidPorts_a

Fluid connector with filled, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)

Modelica.Fluid.Interfaces.FluidPorts_a

Information

Extends from FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium model

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium model

Type	Name	Description
flow MassFlowRate	m_flow	Mass flow rate from the connection point into the component [kg/s]
AbsolutePressure	p	Thermodynamic pressure in the connection point [Pa]
stream SpecificEnthalpy	h_outflow	Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]
stream MassFraction	Xi_outflow[Medium.nXi]	Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]
stream ExtraProperty	C_outflow[Medium.nC]	Properties c_i/m close to the connection point if m_flow < 0

Modelica definition

connector FluidPorts_a 
  "Fluid connector with filled, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)"
  extends FluidPort;
end FluidPorts_a;

Modelica.Fluid.Interfaces.FluidPorts_b

Fluid connector with outlined, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)

Modelica.Fluid.Interfaces.FluidPorts_b

Information

Extends from FluidPort (Interface for quasi one-dimensional fluid flow in a piping network (incompressible or compressible, one or more phases, one or more substances)).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium model

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium model

Type	Name	Description
flow MassFlowRate	m_flow	Mass flow rate from the connection point into the component [kg/s]
AbsolutePressure	p	Thermodynamic pressure in the connection point [Pa]
stream SpecificEnthalpy	h_outflow	Specific thermodynamic enthalpy close to the connection point if m_flow < 0 [J/kg]
stream MassFraction	Xi_outflow[Medium.nXi]	Independent mixture mass fractions m_i/m close to the connection point if m_flow < 0 [kg/kg]
stream ExtraProperty	C_outflow[Medium.nC]	Properties c_i/m close to the connection point if m_flow < 0

Modelica definition

connector FluidPorts_b 
  "Fluid connector with outlined, large icon to be used for vectors of FluidPorts (vector dimensions must be added after dragging)"
  extends FluidPort;
end FluidPorts_b;

Modelica.Fluid.Interfaces.PartialTwoPort

Partial component with two ports

Modelica.Fluid.Interfaces.PartialTwoPort

Information

This partial model defines an interface for components with two ports. The treatment of the design flow direction and of flow reversal are predefined based on the parameter allowFlowReversal. The component may transport fluid and may have internal storage for a given fluid Medium.

An extending model providing direct access to internal storage of mass or energy through port_a or port_b should redefine the protected parameters port_a_exposesState and port_b_exposesState appropriately. This will be visualized at the port icons, in order to improve the understanding of fluid model diagrams.

Parameters

Type Name Default Description

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Type	Name	Default	Description
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type Name Description

FluidPort_a port_a Fluid connector a (positive design flow direction is from port_a to port_b)

FluidPort_b port_b Fluid connector b (positive design flow direction is from port_a to port_b)

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)

Modelica definition

partial model PartialTwoPort "Partial component with two ports"
  import Modelica.Constants;
  outer Modelica.Fluid.System system "System wide properties";

  replaceable package Medium = 
      Modelica.Media.Interfaces.PartialMedium "Medium in the component";

  parameter Boolean allowFlowReversal = system.allowFlowReversal 
    "= true to allow flow reversal, false restricts to design direction (port_a -> port_b)";

  Modelica.Fluid.Interfaces.FluidPort_a port_a(
                                redeclare package Medium = Medium,
                     m_flow(min=if allowFlowReversal then -Constants.inf else 0)) 
    "Fluid connector a (positive design flow direction is from port_a to port_b)";
  Modelica.Fluid.Interfaces.FluidPort_b port_b(
                                redeclare package Medium = Medium,
                     m_flow(max=if allowFlowReversal then +Constants.inf else 0)) 
    "Fluid connector b (positive design flow direction is from port_a to port_b)";
  // Model structure, e.g. used for visualization
protected 
  parameter Boolean port_a_exposesState = false 
    "= true if port_a exposes the state of a fluid volume";
  parameter Boolean port_b_exposesState = false 
    "= true if port_b.p exposes the state of a fluid volume";
  parameter Boolean showDesignFlowDirection = true 
    "= false to hide the arrow in the model icon";

end PartialTwoPort;

Modelica.Fluid.Interfaces.PartialTwoPortTransport

Partial element transporting fluid between two ports without storage of mass or energy

Modelica.Fluid.Interfaces.PartialTwoPortTransport

Information

This component transports fluid between its two ports, without storing mass or energy. Energy may be exchanged with the environment though, e.g. in the form of work. PartialTwoPortTransport is intended as base class for devices like orifices, valves and simple fluid machines.

Three equations need to be added by an extending class using this component:

the momentum balance specifying the relationship between the pressure drop dp and the mass flow rate m_flow
port_b.h_outflow for flow in design direction, and
port_a.h_outflow for flow in reverse direction.

Extends from PartialTwoPort (Partial component with two ports).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Advanced

AbsolutePressure dp_start 0.01*system.p_start Guess value of dp = port_a.p - port_b.p [Pa]

MassFlowRate m_flow_start system.m_flow_start Guess value of m_flow = port_a.m_flow [kg/s]

MassFlowRate m_flow_small system.m_flow_small Small mass flow rate for regularization of zero flow [kg/s]

Diagnostics

Boolean show_T true = true, if temperatures at port_a and port_b are computed

Boolean show_V_flow true = true, if volume flow rate at inflowing port is computed

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure	dp_start	0.01*system.p_start	Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate	m_flow_start	system.m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate	m_flow_small	system.m_flow_small	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_T	true	= true, if temperatures at port_a and port_b are computed
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)

Modelica definition

partial model PartialTwoPortTransport 
  "Partial element transporting fluid between two ports without storage of mass or energy"

  extends PartialTwoPort(
    final port_a_exposesState=false,
    final port_b_exposesState=false);

  // Advanced
  parameter Medium.AbsolutePressure dp_start = 0.01*system.p_start 
    "Guess value of dp = port_a.p - port_b.p";
  parameter Medium.MassFlowRate m_flow_start = system.m_flow_start 
    "Guess value of m_flow = port_a.m_flow";
  parameter Medium.MassFlowRate m_flow_small = system.m_flow_small 
    "Small mass flow rate for regularization of zero flow";

  // Diagnostics
  parameter Boolean show_T = true 
    "= true, if temperatures at port_a and port_b are computed";
  parameter Boolean show_V_flow = true 
    "= true, if volume flow rate at inflowing port is computed";

  // Variables
  Medium.MassFlowRate m_flow(
     min=if allowFlowReversal then -Modelica.Constants.inf else 0,
     start = m_flow_start) "Mass flow rate in design flow direction";
  Modelica.SIunits.Pressure dp(start=dp_start) 
    "Pressure difference between port_a and port_b (= port_a.p - port_b.p)";

  Modelica.SIunits.VolumeFlowRate V_flow=
      m_flow/Modelica.Fluid.Utilities.regStep(m_flow,
                  Medium.density(state_a),
                  Medium.density(state_b),
                  m_flow_small) if show_V_flow 
    "Volume flow rate at inflowing port (positive when flow from port_a to port_b)";

  Medium.Temperature port_a_T=
      Modelica.Fluid.Utilities.regStep(port_a.m_flow,
                  Medium.temperature(state_a),
                  Medium.temperature(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow)),
                  m_flow_small) if show_T 
    "Temperature close to port_a, if show_T = true";
  Medium.Temperature port_b_T=
      Modelica.Fluid.Utilities.regStep(port_b.m_flow,
                  Medium.temperature(state_b),
                  Medium.temperature(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow)),
                  m_flow_small) if show_T 
    "Temperature close to port_b, if show_T = true";
protected 
  Medium.ThermodynamicState state_a "state for medium inflowing through port_a";
  Medium.ThermodynamicState state_b "state for medium inflowing through port_b";
equation 
  // medium states
  state_a = Medium.setState_phX(port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow));
  state_b = Medium.setState_phX(port_b.p, inStream(port_b.h_outflow), inStream(port_b.Xi_outflow));

  // Pressure drop in design flow direction
  dp = port_a.p - port_b.p;

  // Design direction of mass flow rate
  m_flow = port_a.m_flow;
  assert(m_flow > -m_flow_small or allowFlowReversal, "Reverting flow occurs even though allowFlowReversal is false");

  // Mass balance (no storage)
  port_a.m_flow + port_b.m_flow = 0;

  // Transport of substances
  port_a.Xi_outflow = inStream(port_b.Xi_outflow);
  port_b.Xi_outflow = inStream(port_a.Xi_outflow);

  port_a.C_outflow = inStream(port_b.C_outflow);
  port_b.C_outflow = inStream(port_a.C_outflow);

end PartialTwoPortTransport;

Modelica.Fluid.Interfaces.HeatPorts_a

HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)

Information

Extends from Modelica.Thermal.HeatTransfer.Interfaces.HeatPort (Thermal port for 1-dim. heat transfer).

Type Name Description

Temperature T Port temperature [K]

flow HeatFlowRate Q_flow Heat flow rate (positive if flowing from outside into the component) [W]

Type	Name	Description
Temperature	T	Port temperature [K]
flow HeatFlowRate	Q_flow	Heat flow rate (positive if flowing from outside into the component) [W]

Modelica definition

connector HeatPorts_a 
  "HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)"
  extends Modelica.Thermal.HeatTransfer.Interfaces.HeatPort;
end HeatPorts_a;

Modelica.Fluid.Interfaces.HeatPorts_b

HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)

Information

Extends from Modelica.Thermal.HeatTransfer.Interfaces.HeatPort (Thermal port for 1-dim. heat transfer).

Type Name Description

Temperature T Port temperature [K]

flow HeatFlowRate Q_flow Heat flow rate (positive if flowing from outside into the component) [W]

Type	Name	Description
Temperature	T	Port temperature [K]
flow HeatFlowRate	Q_flow	Heat flow rate (positive if flowing from outside into the component) [W]

Modelica definition

connector HeatPorts_b 
  "HeatPort connector with filled, large icon to be used for vectors of HeatPorts (vector dimensions must be added after dragging)"
  extends Modelica.Thermal.HeatTransfer.Interfaces.HeatPort;
end HeatPorts_b;

Modelica.Fluid.Interfaces.PartialHeatTransfer

Common interface for heat transfer models

Modelica.Fluid.Interfaces.PartialHeatTransfer

Information

This component is a common interface for heat transfer models. The heat flow rates Q_flows[n] through the boundaries of n flow segments are obtained as function of the thermodynamic states of the flow segments for a given fluid Medium, the surfaceAreas[n] and the boundary temperatures heatPorts[n].T.

The heat loss coefficient k can be used to model a thermal isolation between heatPorts.T and T_ambient.

An extending model implementing this interface needs to define one equation: the relation between the predefined fluid temperatures Ts[n], the boundary temperatures heatPorts[n].T, and the heat flow rates Q_flows[n].

Parameters

Type Name Default Description

Ambient

CoefficientOfHeatTransfer k 0 Heat transfer coefficient to ambient [W/(m2.K)]

Temperature T_ambient system.T_ambient Ambient temperature [K]

Internal Interface

Integer n 1 Number of heat transfer segments

Boolean use_k false = true to use k value for thermal isolation

Type	Name	Default	Description
Ambient
CoefficientOfHeatTransfer	k	0	Heat transfer coefficient to ambient [W/(m2.K)]
Temperature	T_ambient	system.T_ambient	Ambient temperature [K]
Internal Interface
Integer	n	1	Number of heat transfer segments
Boolean	use_k	false	= true to use k value for thermal isolation

Connectors

Type Name Description

HeatPorts_a heatPorts[n] Heat port to component boundary

Type	Name	Description
HeatPorts_a	heatPorts[n]	Heat port to component boundary

Modelica definition

partial model PartialHeatTransfer 
  "Common interface for heat transfer models"

  // Parameters
  replaceable package Medium=Modelica.Media.Interfaces.PartialMedium 
    "Medium in the component";

  parameter Integer n=1 "Number of heat transfer segments";

  // Inputs provided to heat transfer model
  input Medium.ThermodynamicState[n] states 
    "Thermodynamic states of flow segments";

  input SI.Area[n] surfaceAreas "Heat transfer areas";

  // Outputs defined by heat transfer model
  output SI.HeatFlowRate[n] Q_flows "Heat flow rates";

  // Parameters
  parameter Boolean use_k = false "= true to use k value for thermal isolation";
  parameter SI.CoefficientOfHeatTransfer k = 0 
    "Heat transfer coefficient to ambient";
  parameter SI.Temperature T_ambient = system.T_ambient "Ambient temperature";
  outer Modelica.Fluid.System system "System wide properties";

  // Heat ports
  Modelica.Fluid.Interfaces.HeatPorts_a[n] heatPorts 
    "Heat port to component boundary";

  // Variables
  SI.Temperature[n] Ts = Medium.temperature(states) 
    "Temperatures defined by fluid states";

equation 
  if use_k then
    Q_flows = heatPorts.Q_flow + {k*surfaceAreas[i]*(T_ambient - heatPorts[i].T) for i in 1:n};
  else
    Q_flows = heatPorts.Q_flow;
  end if;

end PartialHeatTransfer;

Modelica.Fluid.Interfaces.PartialLumpedVolume

Lumped volume with mass and energy balance

Information

Interface and base class for an ideally mixed fluid volume with the ability to store mass and energy. The following boundary flow and source terms are part of the energy balance and must be specified in an extending class:

Qb_flow, e.g. convective or latent heat flow rate across segment boundary, and
Wb_flow, work term, e.g. p*der(fluidVolume) if the volume is not constant.

The component volume fluidVolume is an input that needs to be set in the extending class to complete the model.

Further source terms must be defined by an extending class for fluid flow across the segment boundary:

Hb_flow, enthalpy flow,
mb_flow, mass flow,
mbXi_flow, substance mass flow, and
mbC_flow, trace substance mass flow.

Parameters

Type Name Default Description

Assumptions

Dynamics

Dynamics energyDynamics system.energyDynamics Formulation of energy balance

Dynamics massDynamics system.massDynamics Formulation of mass balance

Initialization

AbsolutePressure p_start system.p_start Start value of pressure [Pa]

Boolean use_T_start true = true, use T_start, otherwise h_start

Temperature T_start if use_T_start then system.T... Start value of temperature [K]

SpecificEnthalpy h_start if use_T_start then Medium.s... Start value of specific enthalpy [J/kg]

MassFraction X_start[Medium.nX] Medium.X_default Start value of mass fractions m_i/m [kg/kg]

ExtraProperty C_start[Medium.nC] fill(0, Medium.nC) Start value of trace substances

Type	Name	Default	Description
Assumptions
Dynamics
Dynamics	energyDynamics	system.energyDynamics	Formulation of energy balance
Dynamics	massDynamics	system.massDynamics	Formulation of mass balance
Initialization
AbsolutePressure	p_start	system.p_start	Start value of pressure [Pa]
Boolean	use_T_start	true	= true, use T_start, otherwise h_start
Temperature	T_start	if use_T_start then system.T...	Start value of temperature [K]
SpecificEnthalpy	h_start	if use_T_start then Medium.s...	Start value of specific enthalpy [J/kg]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances

Modelica definition

partial model PartialLumpedVolume 
  "Lumped volume with mass and energy balance"
import Modelica.Fluid.Types;
import Modelica.Fluid.Types.Dynamics;

  outer Modelica.Fluid.System system "System properties";
  replaceable package Medium = 
    Modelica.Media.Interfaces.PartialMedium "Medium in the component";

  // Inputs provided to the volume model
  input SI.Volume fluidVolume "Volume";

  // Assumptions
  parameter Types.Dynamics energyDynamics=system.energyDynamics 
    "Formulation of energy balance";
  parameter Types.Dynamics massDynamics=system.massDynamics 
    "Formulation of mass balance";
  final parameter Types.Dynamics substanceDynamics=massDynamics 
    "Formulation of substance balance";
  final parameter Types.Dynamics traceDynamics=massDynamics 
    "Formulation of trace substance balance";

  // Initialization
  parameter Medium.AbsolutePressure p_start = system.p_start 
    "Start value of pressure";
  parameter Boolean use_T_start = true "= true, use T_start, otherwise h_start";
  parameter Medium.Temperature T_start=
    if use_T_start then system.T_start else Medium.temperature_phX(p_start,h_start,X_start) 
    "Start value of temperature";
  parameter Medium.SpecificEnthalpy h_start=
    if use_T_start then Medium.specificEnthalpy_pTX(p_start, T_start, X_start) else Medium.h_default 
    "Start value of specific enthalpy";
  parameter Medium.MassFraction X_start[Medium.nX] = Medium.X_default 
    "Start value of mass fractions m_i/m";
  parameter Medium.ExtraProperty C_start[Medium.nC](
       quantity=Medium.extraPropertiesNames)=fill(0, Medium.nC) 
    "Start value of trace substances";

  Medium.BaseProperties medium(
    preferredMediumStates=true,
    p(start=p_start),
    h(start=h_start),
    T(start=T_start),
    Xi(start=X_start[1:Medium.nXi]));
  SI.Energy U "Internal energy of fluid";
  SI.Mass m "Mass of fluid";
  SI.Mass[Medium.nXi] mXi "Masses of independent components in the fluid";
  SI.Mass[Medium.nC] mC "Masses of trace substances in the fluid";
  // C need to be added here because unlike for Xi, which has medium.Xi,
  // there is no variable medium.C
  Medium.ExtraProperty C[Medium.nC] "Trace substance mixture content";

  // variables that need to be defined by an extending class
  SI.MassFlowRate mb_flow "Mass flows across boundaries";
  SI.MassFlowRate[Medium.nXi] mbXi_flow 
    "Substance mass flows across boundaries";
  Medium.ExtraPropertyFlowRate[Medium.nC] mbC_flow 
    "Trace substance mass flows across boundaries";
  SI.EnthalpyFlowRate Hb_flow 
    "Enthalpy flow across boundaries or energy source/sink";
  SI.HeatFlowRate Qb_flow "Heat flow across boundaries or energy source/sink";
  SI.Power Wb_flow "Work flow across boundaries or source term";
protected 
  parameter Boolean initialize_p = not Medium.singleState 
    "= true to set up initial equations for pressure";
equation 
  assert(not (energyDynamics<>Dynamics.SteadyState and massDynamics==Dynamics.SteadyState) or Medium.singleState,
         "Bad combination of dynamics options and Medium not conserving mass if fluidVolume is fixed.");

  // Total quantities
  m = fluidVolume*medium.d;
  mXi = m*medium.Xi;
  U = m*medium.u;
  mC = m*C;

  // Energy and mass balances
  if energyDynamics == Dynamics.SteadyState then
    0 = Hb_flow + Qb_flow + Wb_flow;
  else
    der(U) = Hb_flow + Qb_flow + Wb_flow;
  end if;

  if massDynamics == Dynamics.SteadyState then
    0 = mb_flow;
  else
    der(m) = mb_flow;
  end if;

  if substanceDynamics == Dynamics.SteadyState then
    zeros(Medium.nXi) = mbXi_flow;
  else
    der(mXi) = mbXi_flow;
  end if;

  if traceDynamics == Dynamics.SteadyState then
    zeros(Medium.nC)  = mbC_flow;
  else
    der(mC)  = mbC_flow;
  end if;

initial equation 
  // initialization of balances
  if energyDynamics == Dynamics.FixedInitial then
    if use_T_start then
      medium.T = T_start;
    else
      medium.h = h_start;
    end if;
  elseif energyDynamics == Dynamics.SteadyStateInitial then
    if use_T_start then
      der(medium.T) = 0;
    else
      der(medium.h) = 0;
    end if;
  end if;

  if massDynamics == Dynamics.FixedInitial then
    if initialize_p then
      medium.p = p_start;
    end if;
  elseif massDynamics == Dynamics.SteadyStateInitial then
    if initialize_p then
      der(medium.p) = 0;
    end if;
  end if;

  if substanceDynamics == Dynamics.FixedInitial then
    medium.Xi = X_start[1:Medium.nXi];
  elseif substanceDynamics == Dynamics.SteadyStateInitial then
    der(medium.Xi) = zeros(Medium.nXi);
  end if;

  if traceDynamics == Dynamics.FixedInitial then
    C = C_start[1:Medium.nC];
  elseif traceDynamics == Dynamics.SteadyStateInitial then
    der(C) = zeros(Medium.nC);
  end if;

end PartialLumpedVolume;

Modelica.Fluid.Interfaces.PartialLumpedFlow

Base class for a lumped momentum balance

Information

Interface and base class for a momentum balance, defining the mass flow rate m_flow of a given Medium in a flow model.

The following boundary flow and force terms are part of the momentum balance and must be specified in an extending model (to zero if not considered):

Ib_flow, the flow of momentum across model boundaries,
F_p[m], pressure force, and
F_fg[m], friction and gravity forces.

The length of the flow path pathLength is an input that needs to be set in an extending class to complete the model.

Parameters

Type Name Default Description

replaceable package Medium Modelica.Media.Interfaces.Pa... Medium in the component

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (m_flow >= 0)

Dynamics

Dynamics momentumDynamics system.momentumDynamics Formulation of momentum balance

Initialization

MassFlowRate m_flow_start system.m_flow_start Start value of mass flow rates [kg/s]

Type	Name	Default	Description
replaceable package Medium	Modelica.Media.Interfaces.Pa...	Medium in the component
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (m_flow >= 0)
Dynamics
Dynamics	momentumDynamics	system.momentumDynamics	Formulation of momentum balance
Initialization
MassFlowRate	m_flow_start	system.m_flow_start	Start value of mass flow rates [kg/s]

Connectors

Type Name Description

replaceable package Medium Medium in the component

Type	Name	Description
replaceable package Medium	Medium in the component

Modelica definition

partial model PartialLumpedFlow 
  "Base class for a lumped momentum balance"

  outer Modelica.Fluid.System system "System properties";

  replaceable package Medium = 
    Modelica.Media.Interfaces.PartialMedium "Medium in the component";

  parameter Boolean allowFlowReversal = system.allowFlowReversal 
    "= true to allow flow reversal, false restricts to design direction (m_flow >= 0)";

  // Inputs provided to the flow model
  input SI.Length pathLength "Length flow path";

  // Variables defined by the flow model
  Medium.MassFlowRate m_flow(
     min=if allowFlowReversal then -Modelica.Constants.inf else 0,
     start = m_flow_start,
     stateSelect = if momentumDynamics == Types.Dynamics.SteadyState then StateSelect.default else 
                               StateSelect.prefer) 
    "mass flow rates between states";

  // Parameters
  parameter Modelica.Fluid.Types.Dynamics momentumDynamics=system.momentumDynamics 
    "Formulation of momentum balance";

  parameter Medium.MassFlowRate m_flow_start=system.m_flow_start 
    "Start value of mass flow rates";

  // Total quantities
  SI.Momentum I "Momentums of flow segments";

  // Source terms and forces to be defined by an extending model (zero if not used)
  SI.Force Ib_flow "Flow of momentum across boudaries";
  SI.Force F_p "Pressure force";
  SI.Force F_fg "Friction and gravity force";

equation 
  // Total quantities
  I = m_flow*pathLength;

  // Momentum balances
  if momentumDynamics == Types.Dynamics.SteadyState then
    0 = Ib_flow - F_p - F_fg;
  else
    der(I) = Ib_flow - F_p - F_fg;
  end if;

initial equation 
  if momentumDynamics == Types.Dynamics.FixedInitial then
    m_flow = m_flow_start;
  elseif momentumDynamics == Types.Dynamics.SteadyStateInitial then
    der(m_flow) = 0;
  end if;

end PartialLumpedFlow;

Modelica.Fluid.Interfaces.PartialDistributedVolume

Base class for distributed volume models

Information

Interface and base class for n ideally mixed fluid volumes with the ability to store mass and energy. It is inteded to model a one-dimensional spatial discretization of fluid flow according to the finite volume method. The following boundary flow and source terms are part of the energy balance and must be specified in an extending class:

Qb_flows[n], heat flow term, e.g. conductive heat flows across segment boundaries, and
Wb_flows[n], work term.

The component volumes fluidVolumes[n] are an input that needs to be set in an extending class to complete the model.

Further source terms must be defined by an extending class for fluid flow across the segment boundary:

Hb_flows[n], enthalpy flow,
mb_flows[n], mass flow,
mbXi_flows[n], substance mass flow, and
mbC_flows[n], trace substance mass flow.

Parameters

Type Name Default Description

Integer n 2 Number of discrete volumes

Assumptions

Dynamics

Dynamics energyDynamics system.energyDynamics Formulation of energy balances

Dynamics massDynamics system.massDynamics Formulation of mass balances

Initialization

AbsolutePressure p_a_start system.p_start Start value of pressure at port a [Pa]

AbsolutePressure p_b_start p_a_start Start value of pressure at port b [Pa]

Boolean use_T_start true Use T_start if true, otherwise h_start

Temperature T_start if use_T_start then system.T... Start value of temperature [K]

SpecificEnthalpy h_start if use_T_start then Medium.s... Start value of specific enthalpy [J/kg]

MassFraction X_start[Medium.nX] Medium.X_default Start value of mass fractions m_i/m [kg/kg]

ExtraProperty C_start[Medium.nC] fill(0, Medium.nC) Start value of trace substances

Type	Name	Default	Description
Integer	n	2	Number of discrete volumes
Assumptions
Dynamics
Dynamics	energyDynamics	system.energyDynamics	Formulation of energy balances
Dynamics	massDynamics	system.massDynamics	Formulation of mass balances
Initialization
AbsolutePressure	p_a_start	system.p_start	Start value of pressure at port a [Pa]
AbsolutePressure	p_b_start	p_a_start	Start value of pressure at port b [Pa]
Boolean	use_T_start	true	Use T_start if true, otherwise h_start
Temperature	T_start	if use_T_start then system.T...	Start value of temperature [K]
SpecificEnthalpy	h_start	if use_T_start then Medium.s...	Start value of specific enthalpy [J/kg]
MassFraction	X_start[Medium.nX]	Medium.X_default	Start value of mass fractions m_i/m [kg/kg]
ExtraProperty	C_start[Medium.nC]	fill(0, Medium.nC)	Start value of trace substances

Modelica definition

partial model PartialDistributedVolume 
  "Base class for distributed volume models"
    import Modelica.Fluid.Types;
    import Modelica.Fluid.Types.Dynamics;
  outer Modelica.Fluid.System system "System properties";

  replaceable package Medium = 
    Modelica.Media.Interfaces.PartialMedium "Medium in the component";

  // Discretization
  parameter Integer n=2 "Number of discrete volumes";

  // Inputs provided to the volume model
  input SI.Volume[n] fluidVolumes 
    "Discretized volume, determine in inheriting class";

  // Assumptions
  parameter Types.Dynamics energyDynamics=system.energyDynamics 
    "Formulation of energy balances";
  parameter Types.Dynamics massDynamics=system.massDynamics 
    "Formulation of mass balances";
  final parameter Types.Dynamics substanceDynamics=massDynamics 
    "Formulation of substance balances";
  final parameter Types.Dynamics traceDynamics=massDynamics 
    "Formulation of trace substance balances";

  //Initialization
  parameter Medium.AbsolutePressure p_a_start=system.p_start 
    "Start value of pressure at port a";
  parameter Medium.AbsolutePressure p_b_start=p_a_start 
    "Start value of pressure at port b";
  final parameter Medium.AbsolutePressure[n] ps_start=if n > 1 then linspace(
        p_a_start, p_b_start, n) else {(p_a_start + p_b_start)/2} 
    "Start value of pressure";

  parameter Boolean use_T_start=true "Use T_start if true, otherwise h_start";

  parameter Medium.Temperature T_start=if use_T_start then system.T_start else 
              Medium.temperature_phX(
        (p_a_start + p_b_start)/2,
        h_start,
        X_start) "Start value of temperature";
  parameter Medium.SpecificEnthalpy h_start=if use_T_start then 
        Medium.specificEnthalpy_pTX(
        (p_a_start + p_b_start)/2,
        T_start,
        X_start) else Medium.h_default "Start value of specific enthalpy";
  parameter Medium.MassFraction X_start[Medium.nX]=Medium.X_default 
    "Start value of mass fractions m_i/m";
  parameter Medium.ExtraProperty C_start[Medium.nC](
       quantity=Medium.extraPropertiesNames)=fill(0, Medium.nC) 
    "Start value of trace substances";

  // Total quantities
  SI.Energy[n] Us "Internal energy of fluid";
  SI.Mass[n] ms "Fluid mass";
  SI.Mass[n,Medium.nXi] mXis "Substance mass";
  SI.Mass[n,Medium.nC] mCs "Trace substance mass";
  // C need to be added here because unlike for Xi, which has medium[:].Xi,
  // there is no variable medium[:].C
  Medium.ExtraProperty Cs[n, Medium.nC] "Trace substance mixture content";

  Medium.BaseProperties[n] mediums(
    each preferredMediumStates=true,
    p(start=ps_start),
    each h(start=h_start),
    each T(start=T_start),
    each Xi(start=X_start[1:Medium.nXi]));

  //Source terms, have to be defined by an extending model (to zero if not used)
  Medium.MassFlowRate[n] mb_flows "Mass flow rate, source or sink";
  Medium.MassFlowRate[n,Medium.nXi] mbXi_flows 
    "Independent mass flow rates, source or sink";
  Medium.ExtraPropertyFlowRate[n,Medium.nC] mbC_flows 
    "Trace substance mass flow rates, source or sink";
  SI.EnthalpyFlowRate[n] Hb_flows "Enthalpy flow rate, source or sink";
  SI.HeatFlowRate[n] Qb_flows "Heat flow rate, source or sink";
  SI.Power[n] Wb_flows "Mechanical power, p*der(V) etc.";

protected 
  parameter Boolean initialize_p = not Medium.singleState 
    "= true to set up initial equations for pressure";

equation 
  assert(not (energyDynamics<>Dynamics.SteadyState and massDynamics==Dynamics.SteadyState) or Medium.singleState,
         "Bad combination of dynamics options and Medium not conserving mass if fluidVolumes are fixed.");

  // Total quantities
  for i in 1:n loop
    ms[i] =fluidVolumes[i]*mediums[i].d;
    mXis[i, :] = ms[i]*mediums[i].Xi;
    mCs[i, :]  = ms[i]*Cs[i, :];
    Us[i] = ms[i]*mediums[i].u;
  end for;

  // Energy and mass balances
  if energyDynamics == Dynamics.SteadyState then
    for i in 1:n loop
      0 = Hb_flows[i] + Wb_flows[i] + Qb_flows[i];
    end for;
  else
    for i in 1:n loop
      der(Us[i]) = Hb_flows[i] + Wb_flows[i] + Qb_flows[i];
    end for;
  end if;
  if massDynamics == Dynamics.SteadyState then
    for i in 1:n loop
      0 = mb_flows[i];
    end for;
  else
    for i in 1:n loop
      der(ms[i]) = mb_flows[i];
    end for;
  end if;
  if substanceDynamics == Dynamics.SteadyState then
    for i in 1:n loop
      zeros(Medium.nXi) = mbXi_flows[i, :];
    end for;
  else
    for i in 1:n loop
      der(mXis[i, :]) = mbXi_flows[i, :];
    end for;
  end if;
  if traceDynamics == Dynamics.SteadyState then
    for i in 1:n loop
      zeros(Medium.nC)  = mbC_flows[i, :];
    end for;
  else
    for i in 1:n loop
      der(mCs[i, :])  = mbC_flows[i, :];
    end for;
  end if;

initial equation 
  // initialization of balances
  if energyDynamics == Dynamics.FixedInitial then
    if use_T_start then
      mediums.T = fill(T_start, n);
    else
      mediums.h = fill(h_start, n);
    end if;
  elseif energyDynamics == Dynamics.SteadyStateInitial then
    if use_T_start then
      der(mediums.T) = zeros(n);
    else
      der(mediums.h) = zeros(n);
    end if;
  end if;

  if massDynamics == Dynamics.FixedInitial then
    if initialize_p then
      mediums.p = ps_start;
    end if;
  elseif massDynamics == Dynamics.SteadyStateInitial then
    if initialize_p then
      der(mediums.p) = zeros(n);
    end if;
  end if;

  if substanceDynamics == Dynamics.FixedInitial then
    mediums.Xi = fill(X_start[1:Medium.nXi], n);
  elseif substanceDynamics == Dynamics.SteadyStateInitial then
    for i in 1:n loop
      der(mediums[i].Xi) = zeros(Medium.nXi);
    end for;
  end if;

  if traceDynamics == Dynamics.FixedInitial then
    Cs = fill(C_start[1:Medium.nC], n);
  elseif traceDynamics == Dynamics.SteadyStateInitial then
    for i in 1:n loop
      der(mCs[i,:])      = zeros(Medium.nC);
    end for;
  end if;

end PartialDistributedVolume;

Modelica.Fluid.Interfaces.PartialDistributedFlow

Base class for a distributed momentum balance

Information

Interface and base class for m momentum balances, defining the mass flow rates m_flows[m] of a given Medium in m flow segments.

The following boundary flow and force terms are part of the momentum balances and must be specified in an extending model (to zero if not considered):

Ib_flows[m], the flows of momentum across segment boundaries,
Fs_p[m], pressure forces, and
Fs_fg[m], friction and gravity forces.

The lengths along the flow path pathLengths[m] are an input that needs to be set in an extending class to complete the model.

Parameters

Type Name Default Description

replaceable package Medium Modelica.Media.Interfaces.Pa... Medium in the component

Integer m 1 Number of flow segments

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (m_flows >= zeros(m))

Dynamics

Dynamics momentumDynamics system.momentumDynamics Formulation of momentum balance

Initialization

MassFlowRate m_flow_start system.m_flow_start Start value of mass flow rates [kg/s]

Type	Name	Default	Description
replaceable package Medium	Modelica.Media.Interfaces.Pa...	Medium in the component
Integer	m	1	Number of flow segments
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (m_flows >= zeros(m))
Dynamics
Dynamics	momentumDynamics	system.momentumDynamics	Formulation of momentum balance
Initialization
MassFlowRate	m_flow_start	system.m_flow_start	Start value of mass flow rates [kg/s]

Connectors

Type Name Description

replaceable package Medium Medium in the component

Type	Name	Description
replaceable package Medium	Medium in the component

Modelica definition

partial model PartialDistributedFlow 
  "Base class for a distributed momentum balance"

  outer Modelica.Fluid.System system "System properties";

  replaceable package Medium = 
    Modelica.Media.Interfaces.PartialMedium "Medium in the component";

  parameter Boolean allowFlowReversal = system.allowFlowReversal 
    "= true to allow flow reversal, false restricts to design direction (m_flows >= zeros(m))";

  // Discretization
  parameter Integer m=1 "Number of flow segments";

  // Inputs provided to the flow model
  input SI.Length[m] pathLengths "Lengths along flow path";

  // Variables defined by momentum model
  Medium.MassFlowRate[m] m_flows(
     each min=if allowFlowReversal then -Modelica.Constants.inf else 0,
     each start = m_flow_start,
     each stateSelect = if momentumDynamics == Types.Dynamics.SteadyState then StateSelect.default else 
                               StateSelect.prefer) 
    "mass flow rates between states";

  // Parameters
  parameter Modelica.Fluid.Types.Dynamics momentumDynamics=system.momentumDynamics 
    "Formulation of momentum balance";

  parameter Medium.MassFlowRate m_flow_start=system.m_flow_start 
    "Start value of mass flow rates";

  // Total quantities
  SI.Momentum[m] Is "Momentums of flow segments";

  // Source terms and forces to be defined by an extending model (zero if not used)
  SI.Force[m] Ib_flows "Flow of momentum across boudaries";
  SI.Force[m] Fs_p "Pressure forces";
  SI.Force[m] Fs_fg "Friction and gravity forces";

equation 
  // Total quantities
  Is = {m_flows[i]*pathLengths[i] for i in 1:m};

  // Momentum balances
  if momentumDynamics == Types.Dynamics.SteadyState then
    zeros(m) = Ib_flows - Fs_p - Fs_fg;
  else
    der(Is) = Ib_flows - Fs_p - Fs_fg;
  end if;

initial equation 
  if momentumDynamics == Types.Dynamics.FixedInitial then
    m_flows = fill(m_flow_start, m);
  elseif momentumDynamics == Types.Dynamics.SteadyStateInitial then
    der(m_flows) = zeros(m);
  end if;

end PartialDistributedFlow;

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Modelica.Fluid.Interfaces

Information

Package Content

Modelica.Fluid.Interfaces.FluidPort

Contents

Modelica definition

Modelica.Fluid.Interfaces.FluidPort_a

Information

Parameters

Contents

Modelica definition

Modelica.Fluid.Interfaces.FluidPort_b

Information

Parameters

Contents

Modelica definition

Modelica.Fluid.Interfaces.FluidPorts_a

Information

Parameters

Contents

Modelica definition

Modelica.Fluid.Interfaces.FluidPorts_b

Information

Parameters

Contents

Modelica definition

Modelica.Fluid.Interfaces.PartialTwoPort

Information

Parameters

Connectors

Modelica definition

Modelica.Fluid.Interfaces.PartialTwoPortTransport

Information

Parameters

Connectors

Modelica definition

Modelica.Fluid.Interfaces.HeatPorts_a

Information

Contents

Modelica definition

Modelica.Fluid.Interfaces.HeatPorts_b

Information

Contents

Modelica definition

Modelica.Fluid.Interfaces.PartialHeatTransfer

Information

Parameters

Connectors

Modelica definition

Modelica.Fluid.Interfaces.PartialLumpedVolume

Information

Parameters

Modelica definition

Modelica.Fluid.Interfaces.PartialLumpedFlow

Information

Parameters

Connectors

Modelica definition

Modelica.Fluid.Interfaces.PartialDistributedVolume

Information

Parameters

Modelica definition

Modelica.Fluid.Interfaces.PartialDistributedFlow

Information

Parameters

Connectors

Modelica definition