Buildings.Fluid.Interfaces

Package with interfaces for fluid models

Information

This package contains basic classes that are used to build component models that change the state of the fluid. The classes are not directly usable, but can be extended when building a new model.

Extends from Modelica.Icons.InterfacesPackage (Icon for packages containing interfaces).

Package Content

Name Description

PartialDynamicFourPortTransformer Partial model transporting two fluid streams between four ports with storing mass or energy

PartialStaticFourPortHeatMassTransfer Partial model transporting two fluid streams between four ports without storing mass or energy

PartialStaticFourPortInterface Partial model transporting fluid between two ports without storing mass or energy

PartialFourPort Partial model with four ports

FourPortFlowResistanceParameters Parameters for flow resistance for models with four ports

PartialDynamicTwoPortTransformer Partial model transporting one fluid stream with storing mass or energy

PartialStaticTwoPortHeatMassTransfer Partial model transporting fluid between two ports without storing mass or energy

PartialStaticTwoPortInterface Partial model transporting fluid between two ports without storing mass or energy

TwoPortFlowResistanceParameters Parameters for flow resistance for models with two ports

PartialLumpedVolume Lumped volume with mass and energy balance

Examples Collection of models that illustrate model use and test models

Name	Description
PartialDynamicFourPortTransformer	Partial model transporting two fluid streams between four ports with storing mass or energy
PartialStaticFourPortHeatMassTransfer	Partial model transporting two fluid streams between four ports without storing mass or energy
PartialStaticFourPortInterface	Partial model transporting fluid between two ports without storing mass or energy
PartialFourPort	Partial model with four ports
FourPortFlowResistanceParameters	Parameters for flow resistance for models with four ports
PartialDynamicTwoPortTransformer	Partial model transporting one fluid stream with storing mass or energy
PartialStaticTwoPortHeatMassTransfer	Partial model transporting fluid between two ports without storing mass or energy
PartialStaticTwoPortInterface	Partial model transporting fluid between two ports without storing mass or energy
TwoPortFlowResistanceParameters	Parameters for flow resistance for models with two ports
PartialLumpedVolume	Lumped volume with mass and energy balance
Examples	Collection of models that illustrate model use and test models

Buildings.Fluid.Interfaces.PartialDynamicFourPortTransformer

Partial model transporting two fluid streams between four ports with storing mass or energy

Buildings.Fluid.Interfaces.PartialDynamicFourPortTransformer

Information

This component transports two fluid streams between four ports. It provides the basic model for implementing a dynamic heat exchanger. It is used by HeatExchangers.BaseClasses.HexElement. The variable names follow the conventions used in Modelica.Fluid.HeatExchangers.BasicHX.

Extends from Buildings.Fluid.Interfaces.PartialStaticFourPortInterface (Partial model transporting fluid between two ports without storing mass or energy), Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters (Parameters for flow resistance for models with four ports).

Parameters

Type Name Default Description

replaceable package Medium1 PartialMedium Medium 1 in the component

replaceable package Medium2 PartialMedium Medium 2 in the component

MixingVolume vol2 redeclare Buildings.Fluid.Mi... Volume for fluid 2

Nominal condition

MassFlowRate m1_flow_nominal Nominal mass flow rate [kg/s]

MassFlowRate m2_flow_nominal Nominal mass flow rate [kg/s]

Pressure dp1_nominal Pressure [Pa]

Pressure dp2_nominal Pressure [Pa]

Time tau1 60 Time constant at nominal flow [s]

Time tau2 60 Time constant at nominal flow [s]

Initialization

MassFlowRate m1_flow.start 0 Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) [kg/s]

Pressure dp1.start 0 Pressure difference between port_a1 and port_b1 [Pa]

MassFlowRate m2_flow.start 0 Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) [kg/s]

Pressure dp2.start 0 Pressure difference between port_a2 and port_b2 [Pa]

Assumptions

Boolean allowFlowReversal1 system.allowFlowReversal = true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)

Boolean allowFlowReversal2 system.allowFlowReversal = true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)

Dynamics

Dynamics energyDynamics system.energyDynamics Formulation of energy balance

Dynamics massDynamics system.massDynamics Formulation of mass balance

Dynamics substanceDynamics energyDynamics Formulation of substance balance

Dynamics traceDynamics energyDynamics Formulation of trace substance balance

Initialization

SpecificEnthalpy h_outflow_a1_start Medium1.h_default Start value for enthalpy flowing out of port a1 [J/kg]

SpecificEnthalpy h_outflow_b1_start Medium1.h_default Start value for enthalpy flowing out of port b1 [J/kg]

SpecificEnthalpy h_outflow_a2_start Medium2.h_default Start value for enthalpy flowing out of port a2 [J/kg]

SpecificEnthalpy h_outflow_b2_start Medium2.h_default Start value for enthalpy flowing out of port b2 [J/kg]

Advanced

MassFlowRate m1_flow_small 1E-4*abs(m1_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

MassFlowRate m2_flow_small 1E-4*abs(m2_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Flow resistance

Medium 1

Boolean computeFlowResistance1 true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp1 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance1 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM1 0.1 Fraction of nominal flow rate where flow transitions to laminar

Medium 2

Boolean computeFlowResistance2 true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp2 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance2 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM2 0.1 Fraction of nominal flow rate where flow transitions to laminar

Type	Name	Default	Description
replaceable package Medium1	PartialMedium	Medium 1 in the component
replaceable package Medium2	PartialMedium	Medium 2 in the component
MixingVolume	vol2	redeclare Buildings.Fluid.Mi...	Volume for fluid 2
Nominal condition
MassFlowRate	m1_flow_nominal		Nominal mass flow rate [kg/s]
MassFlowRate	m2_flow_nominal		Nominal mass flow rate [kg/s]
Pressure	dp1_nominal		Pressure [Pa]
Pressure	dp2_nominal		Pressure [Pa]
Time	tau1	60	Time constant at nominal flow [s]
Time	tau2	60	Time constant at nominal flow [s]
Initialization
MassFlowRate	m1_flow.start	0	Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) [kg/s]
Pressure	dp1.start	0	Pressure difference between port_a1 and port_b1 [Pa]
MassFlowRate	m2_flow.start	0	Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) [kg/s]
Pressure	dp2.start	0	Pressure difference between port_a2 and port_b2 [Pa]
Assumptions
Boolean	allowFlowReversal1	system.allowFlowReversal	= true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)
Boolean	allowFlowReversal2	system.allowFlowReversal	= true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)
Dynamics
Dynamics	energyDynamics	system.energyDynamics	Formulation of energy balance
Dynamics	massDynamics	system.massDynamics	Formulation of mass balance
Dynamics	substanceDynamics	energyDynamics	Formulation of substance balance
Dynamics	traceDynamics	energyDynamics	Formulation of trace substance balance
Initialization
SpecificEnthalpy	h_outflow_a1_start	Medium1.h_default	Start value for enthalpy flowing out of port a1 [J/kg]
SpecificEnthalpy	h_outflow_b1_start	Medium1.h_default	Start value for enthalpy flowing out of port b1 [J/kg]
SpecificEnthalpy	h_outflow_a2_start	Medium2.h_default	Start value for enthalpy flowing out of port a2 [J/kg]
SpecificEnthalpy	h_outflow_b2_start	Medium2.h_default	Start value for enthalpy flowing out of port b2 [J/kg]
Advanced
MassFlowRate	m1_flow_small	1E-4*abs(m1_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
MassFlowRate	m2_flow_small	1E-4*abs(m2_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)
Flow resistance
Medium 1
Boolean	computeFlowResistance1	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp1	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance1	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM1	0.1	Fraction of nominal flow rate where flow transitions to laminar
Medium 2
Boolean	computeFlowResistance2	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp2	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance2	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM2	0.1	Fraction of nominal flow rate where flow transitions to laminar

Connectors

Type Name Description

FluidPort_a port_a1 Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)

FluidPort_b port_b1 Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)

FluidPort_a port_a2 Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)

FluidPort_b port_b2 Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)

Type	Name	Description
FluidPort_a	port_a1	Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_b	port_b1	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_a	port_a2	Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_b	port_b2	Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)

Modelica definition

partial model PartialDynamicFourPortTransformer 
  "Partial model transporting two fluid streams between four ports with storing mass or energy"
  extends Buildings.Fluid.Interfaces.PartialStaticFourPortInterface;
  extends Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters(
     final computeFlowResistance1=true, final computeFlowResistance2=true);
  import Modelica.Constants;

  Buildings.Fluid.MixingVolumes.MixingVolume vol1(
    redeclare package Medium = Medium1,
    nPorts = 2,
    V=m1_flow_nominal*tau1/rho1_nominal,
    medium(T(stateSelect=StateSelect.always)),
    final use_HeatTransfer=true,
    redeclare model HeatTransfer =
        Modelica.Fluid.Vessels.BaseClasses.HeatTransfer.IdealHeatTransfer,
    energyDynamics=energyDynamics,
    massDynamics=massDynamics,
    substanceDynamics=substanceDynamics,
    traceDynamics=traceDynamics) "Volume for fluid 1";

  replaceable Buildings.Fluid.MixingVolumes.MixingVolume vol2(
    redeclare package Medium = Medium2,
    nPorts = 2,
    V=m2_flow_nominal*tau2/rho2_nominal,
    final use_HeatTransfer=true,
    redeclare model HeatTransfer =
       Modelica.Fluid.Vessels.BaseClasses.HeatTransfer.IdealHeatTransfer(surfaceAreas={1}),
    energyDynamics=energyDynamics,
    massDynamics=massDynamics,
    substanceDynamics=substanceDynamics,
    traceDynamics=traceDynamics) "Volume for fluid 2";

  parameter Modelica.SIunits.Time tau1 = 60 "Time constant at nominal flow";
  parameter Modelica.SIunits.Time tau2 = 60 "Time constant at nominal flow";
  Modelica.SIunits.HeatFlowRate Q1_flow=
     if vol1.use_HeatTransfer then sum(vol1.heatPort.Q_flow) else 0 
    "Heat flow rate into medium 1";
  Modelica.SIunits.HeatFlowRate Q2_flow=
     if vol2.use_HeatTransfer then sum(vol2.heatPort.Q_flow) else 0 
    "Heat flow rate into medium 2";

  // Advanced
  parameter Boolean homotopyInitialization = true "= true, use homotopy method";

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

protected 
  parameter Medium1.ThermodynamicState sta1_nominal=Medium1.setState_pTX(
      T=Medium1.T_default, p=Medium1.p_default, X=Medium1.X_default);
  parameter Modelica.SIunits.Density rho1_nominal=Medium1.density(sta1_nominal) 
    "Density, used to compute fluid volume";
  parameter Medium2.ThermodynamicState sta2_nominal=Medium2.setState_pTX(
      T=Medium2.T_default, p=Medium2.p_default, X=Medium2.X_default);
  parameter Modelica.SIunits.Density rho2_nominal=Medium2.density(sta2_nominal) 
    "Density, used to compute fluid volume";
public 
  FixedResistances.FixedResistanceDpM preDro1(
    redeclare package Medium = Medium1,
    final use_dh=false,
    final m_flow_nominal=m1_flow_nominal,
    final deltaM=deltaM1,
    final allowFlowReversal=allowFlowReversal1,
    final m_flow_small=m1_flow_small,
    final show_T=false,
    final show_V_flow=show_V_flow,
    final from_dp=from_dp1,
    final linearized=linearizeFlowResistance1,
    final homotopyInitialization=homotopyInitialization,
    final dp_nominal=dp1_nominal,
    final dh=1,
    final ReC=4000) "Pressure drop model for fluid 1";

  FixedResistances.FixedResistanceDpM preDro2(
    redeclare package Medium = Medium2,
    final use_dh=false,
    final m_flow_nominal=m2_flow_nominal,
    final deltaM=deltaM2,
    final allowFlowReversal=allowFlowReversal2,
    final m_flow_small=m2_flow_small,
    final show_T=false,
    final show_V_flow=show_V_flow,
    final from_dp=from_dp2,
    final linearized=linearizeFlowResistance2,
    final homotopyInitialization=homotopyInitialization,
    final dp_nominal=dp2_nominal,
    final dh=1,
    final ReC=4000) "Pressure drop model for fluid 2";

equation 
  assert(vol1.use_HeatTransfer == true, "Wrong parameter for vol1.");
  assert(vol2.use_HeatTransfer == true, "Wrong parameter for vol2.");

  connect(vol1.ports[2], port_b1);
  connect(vol2.ports[2], port_b2);
  connect(port_a1, preDro1.port_a);
  connect(preDro1.port_b, vol1.ports[1]);
  connect(port_a2, preDro2.port_a);
  connect(preDro2.port_b, vol2.ports[1]);
end PartialDynamicFourPortTransformer;

Buildings.Fluid.Interfaces.PartialStaticFourPortHeatMassTransfer

Partial model transporting two fluid streams between four ports without storing mass or energy

Buildings.Fluid.Interfaces.PartialStaticFourPortHeatMassTransfer

Information

This component transports two fluid streams between four ports, without storing mass or energy. It is similar to Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer, but it has four ports instead of two. See the documentation of Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer for how to use this partial model.

Parameters

Type Name Default Description

replaceable package Medium1 PartialMedium Medium 1 in the component

replaceable package Medium2 PartialMedium Medium 2 in the component

Boolean sensibleOnly1 Set to true if sensible exchange only for medium 1

Boolean sensibleOnly2 Set to true if sensible exchange only for medium 2

Nominal condition

MassFlowRate m1_flow_nominal Nominal mass flow rate [kg/s]

MassFlowRate m2_flow_nominal Nominal mass flow rate [kg/s]

Pressure dp1_nominal Pressure [Pa]

Pressure dp2_nominal Pressure [Pa]

Initialization

MassFlowRate m1_flow.start 0 Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) [kg/s]

Pressure dp1.start 0 Pressure difference between port_a1 and port_b1 [Pa]

MassFlowRate m2_flow.start 0 Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) [kg/s]

Pressure dp2.start 0 Pressure difference between port_a2 and port_b2 [Pa]

Assumptions

Boolean allowFlowReversal1 system.allowFlowReversal = true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)

Boolean allowFlowReversal2 system.allowFlowReversal = true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)

Initialization

SpecificEnthalpy h_outflow_a1_start Medium1.h_default Start value for enthalpy flowing out of port a1 [J/kg]

SpecificEnthalpy h_outflow_b1_start Medium1.h_default Start value for enthalpy flowing out of port b1 [J/kg]

SpecificEnthalpy h_outflow_a2_start Medium2.h_default Start value for enthalpy flowing out of port a2 [J/kg]

SpecificEnthalpy h_outflow_b2_start Medium2.h_default Start value for enthalpy flowing out of port b2 [J/kg]

Advanced

MassFlowRate m1_flow_small 1E-4*abs(m1_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

MassFlowRate m2_flow_small 1E-4*abs(m2_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Flow resistance

Medium 1

Boolean computeFlowResistance1 (dp1_nominal > Modelica.Cons... =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp1 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance1 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM1 0.1 Fraction of nominal flow rate where flow transitions to laminar

Medium 2

Boolean computeFlowResistance2 (dp2_nominal > Modelica.Cons... =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp2 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance2 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM2 0.1 Fraction of nominal flow rate where flow transitions to laminar

Type	Name	Default	Description
replaceable package Medium1	PartialMedium	Medium 1 in the component
replaceable package Medium2	PartialMedium	Medium 2 in the component
Boolean	sensibleOnly1		Set to true if sensible exchange only for medium 1
Boolean	sensibleOnly2		Set to true if sensible exchange only for medium 2
Nominal condition
MassFlowRate	m1_flow_nominal		Nominal mass flow rate [kg/s]
MassFlowRate	m2_flow_nominal		Nominal mass flow rate [kg/s]
Pressure	dp1_nominal		Pressure [Pa]
Pressure	dp2_nominal		Pressure [Pa]
Initialization
MassFlowRate	m1_flow.start	0	Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) [kg/s]
Pressure	dp1.start	0	Pressure difference between port_a1 and port_b1 [Pa]
MassFlowRate	m2_flow.start	0	Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) [kg/s]
Pressure	dp2.start	0	Pressure difference between port_a2 and port_b2 [Pa]
Assumptions
Boolean	allowFlowReversal1	system.allowFlowReversal	= true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)
Boolean	allowFlowReversal2	system.allowFlowReversal	= true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)
Initialization
SpecificEnthalpy	h_outflow_a1_start	Medium1.h_default	Start value for enthalpy flowing out of port a1 [J/kg]
SpecificEnthalpy	h_outflow_b1_start	Medium1.h_default	Start value for enthalpy flowing out of port b1 [J/kg]
SpecificEnthalpy	h_outflow_a2_start	Medium2.h_default	Start value for enthalpy flowing out of port a2 [J/kg]
SpecificEnthalpy	h_outflow_b2_start	Medium2.h_default	Start value for enthalpy flowing out of port b2 [J/kg]
Advanced
MassFlowRate	m1_flow_small	1E-4*abs(m1_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
MassFlowRate	m2_flow_small	1E-4*abs(m2_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)
Flow resistance
Medium 1
Boolean	computeFlowResistance1	(dp1_nominal > Modelica.Cons...	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp1	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance1	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM1	0.1	Fraction of nominal flow rate where flow transitions to laminar
Medium 2
Boolean	computeFlowResistance2	(dp2_nominal > Modelica.Cons...	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp2	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance2	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM2	0.1	Fraction of nominal flow rate where flow transitions to laminar

Connectors

Type	Name	Description
FluidPort_a	port_a1	Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_b	port_b1	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_a	port_a2	Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_b	port_b2	Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)

Modelica definition

model PartialStaticFourPortHeatMassTransfer 
  "Partial model transporting two fluid streams between four ports without storing mass or energy"
  extends Buildings.Fluid.Interfaces.PartialStaticFourPortInterface;
  extends Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters(
   final computeFlowResistance1=(dp1_nominal > Modelica.Constants.eps),
   final computeFlowResistance2=(dp2_nominal > Modelica.Constants.eps));
  import Modelica.Constants;

  input Modelica.SIunits.HeatFlowRate Q1_flow 
    "Heat transfered into the medium 1";
  input Medium1.MassFlowRate mXi1_flow[Medium1.nXi] 
    "Mass flow rates of independent substances added to the medium 1";
  input Modelica.SIunits.HeatFlowRate Q2_flow 
    "Heat transfered into the medium 2";
  input Medium2.MassFlowRate mXi2_flow[Medium2.nXi] 
    "Mass flow rates of independent substances added to the medium 2";

  constant Boolean sensibleOnly1 
    "Set to true if sensible exchange only for medium 1";
  constant Boolean sensibleOnly2 
    "Set to true if sensible exchange only for medium 2";
protected 
  Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer bal1(
    final sensibleOnly = sensibleOnly1,
    redeclare final package Medium=Medium1,
    final m_flow_nominal = m1_flow_nominal,
    final dp_nominal = dp1_nominal,
    final allowFlowReversal = allowFlowReversal1,
    final m_flow_small = m1_flow_small,
    final homotopyInitialization = homotopyInitialization,
    final show_V_flow = false,
    final show_T = false,
    final from_dp = from_dp1,
    final linearizeFlowResistance = linearizeFlowResistance1,
    final deltaM = deltaM1,
    final Q_flow = Q1_flow,
    final mXi_flow = mXi1_flow) 
    "Model for heat, mass, species, trace substance and pressure balance of stream 1";
  Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer bal2(
    final sensibleOnly = sensibleOnly2,
    redeclare final package Medium=Medium2,
    final m_flow_nominal = m2_flow_nominal,
    final dp_nominal = dp2_nominal,
    final allowFlowReversal = allowFlowReversal2,
    final m_flow_small = m2_flow_small,
    final homotopyInitialization = homotopyInitialization,
    final show_V_flow = false,
    final show_T = false,
    final from_dp = from_dp2,
    final linearizeFlowResistance = linearizeFlowResistance2,
    final deltaM = deltaM2,
    final Q_flow = Q2_flow,
    final mXi_flow = mXi2_flow) 
    "Model for heat, mass, species, trace substance and pressure balance of stream 2";
equation 
  connect(bal1.port_a, port_a1);
  connect(bal1.port_b, port_b1);
  connect(bal2.port_a, port_a2);
  connect(bal2.port_b, port_b2);

end PartialStaticFourPortHeatMassTransfer;

Buildings.Fluid.Interfaces.PartialStaticFourPortInterface

Partial model transporting fluid between two ports without storing mass or energy

Buildings.Fluid.Interfaces.PartialStaticFourPortInterface

Information

This component defines the interface for models that transport two fluid streams between four ports. It is similar to Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface, but it has four ports instead of two.

The model is used by other models in this package that add heat transfer, mass transfer and pressure drop equations.

Extends from Buildings.Fluid.Interfaces.PartialFourPort (Partial model with four ports).

Parameters

Type Name Default Description

replaceable package Medium1 PartialMedium Medium 1 in the component

replaceable package Medium2 PartialMedium Medium 2 in the component

Nominal condition

MassFlowRate m1_flow_nominal Nominal mass flow rate [kg/s]

MassFlowRate m2_flow_nominal Nominal mass flow rate [kg/s]

Assumptions

Boolean allowFlowReversal1 system.allowFlowReversal = true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)

Boolean allowFlowReversal2 system.allowFlowReversal = true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)

Initialization

SpecificEnthalpy h_outflow_a1_start Medium1.h_default Start value for enthalpy flowing out of port a1 [J/kg]

SpecificEnthalpy h_outflow_b1_start Medium1.h_default Start value for enthalpy flowing out of port b1 [J/kg]

SpecificEnthalpy h_outflow_a2_start Medium2.h_default Start value for enthalpy flowing out of port a2 [J/kg]

SpecificEnthalpy h_outflow_b2_start Medium2.h_default Start value for enthalpy flowing out of port b2 [J/kg]

Advanced

MassFlowRate m1_flow_small 1E-4*abs(m1_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

MassFlowRate m2_flow_small 1E-4*abs(m2_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Type	Name	Default	Description
replaceable package Medium1	PartialMedium	Medium 1 in the component
replaceable package Medium2	PartialMedium	Medium 2 in the component
Nominal condition
MassFlowRate	m1_flow_nominal		Nominal mass flow rate [kg/s]
MassFlowRate	m2_flow_nominal		Nominal mass flow rate [kg/s]
Assumptions
Boolean	allowFlowReversal1	system.allowFlowReversal	= true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)
Boolean	allowFlowReversal2	system.allowFlowReversal	= true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)
Initialization
SpecificEnthalpy	h_outflow_a1_start	Medium1.h_default	Start value for enthalpy flowing out of port a1 [J/kg]
SpecificEnthalpy	h_outflow_b1_start	Medium1.h_default	Start value for enthalpy flowing out of port b1 [J/kg]
SpecificEnthalpy	h_outflow_a2_start	Medium2.h_default	Start value for enthalpy flowing out of port a2 [J/kg]
SpecificEnthalpy	h_outflow_b2_start	Medium2.h_default	Start value for enthalpy flowing out of port b2 [J/kg]
Advanced
MassFlowRate	m1_flow_small	1E-4*abs(m1_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
MassFlowRate	m2_flow_small	1E-4*abs(m2_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)

Modelica definition

partial model PartialStaticFourPortInterface 
  "Partial model transporting fluid between two ports without storing mass or energy"
  import Modelica.Constants;
  extends Buildings.Fluid.Interfaces.PartialFourPort(
    port_a1(
      m_flow(min = if allowFlowReversal1 then -Constants.inf else 0)),
    port_b1(
      m_flow(max = if allowFlowReversal1 then +Constants.inf else 0)),
    port_a2(
      m_flow(min = if allowFlowReversal2 then -Constants.inf else 0)),
    port_b2(
      m_flow(max = if allowFlowReversal2 then +Constants.inf else 0)));

  parameter Modelica.SIunits.MassFlowRate m1_flow_nominal(min=0) 
    "Nominal mass flow rate";
  parameter Modelica.SIunits.MassFlowRate m2_flow_nominal(min=0) 
    "Nominal mass flow rate";

  parameter Medium1.MassFlowRate m1_flow_small(min=0) = 1E-4*abs(m1_flow_nominal) 
    "Small mass flow rate for regularization of zero flow";
  parameter Medium2.MassFlowRate m2_flow_small(min=0) = 1E-4*abs(m2_flow_nominal) 
    "Small mass flow rate for regularization of zero flow";
  parameter Boolean homotopyInitialization = true "= true, use homotopy method";

  // Diagnostics
  parameter Boolean show_V_flow = false 
    "= true, if volume flow rate at inflowing port is computed";
  parameter Boolean show_T = false 
    "= true, if actual temperature at port is computed (may lead to events)";

public 
  Modelica.SIunits.VolumeFlowRate V1_flow=m1_flow/Medium.density(sta_a1) if 
        show_V_flow 
    "Volume flow rate at inflowing port (positive when flow from port_a1 to port_b1)";
  Modelica.SIunits.VolumeFlowRate V2_flow=m2_flow/Medium.density(sta_a2) if 
        show_V_flow 
    "Volume flow rate at inflowing port (positive when flow from port_a2 to port_b2)";

  Medium1.MassFlowRate m1_flow(start=0) 
    "Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction)";
  Modelica.SIunits.Pressure dp1(start=0, displayUnit="Pa") 
    "Pressure difference between port_a1 and port_b1";
  Medium2.MassFlowRate m2_flow(start=0) 
    "Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction)";
  Modelica.SIunits.Pressure dp2(start=0, displayUnit="Pa") 
    "Pressure difference between port_a2 and port_b2";

  Medium1.ThermodynamicState sta_a1=if homotopyInitialization then 
      Medium1.setState_phX(port_a1.p,
         homotopy(actual=actualStream(port_a1.h_outflow),
                  simplified=inStream(port_a1.h_outflow)),
         homotopy(actual=actualStream(port_a1.Xi_outflow),
                  simplified=inStream(port_a1.Xi_outflow)))
    else 
      Medium1.setState_phX(port_a1.p,
                           actualStream(port_a1.h_outflow),
                           actualStream(port_a1.Xi_outflow)) if 
         show_T "Medium properties in port_a1";

  Medium1.ThermodynamicState sta_b1=if homotopyInitialization then 
      Medium1.setState_phX(port_b1.p,
          homotopy(actual=actualStream(port_b1.h_outflow),
                   simplified=port_b1.h_outflow),
          homotopy(actual=actualStream(port_b1.Xi_outflow),
                   simplified=port_b1.Xi_outflow))
    else 
      Medium1.setState_phX(port_b1.p,
                           actualStream(port_b1.h_outflow),
                           actualStream(port_b1.Xi_outflow)) if 
         show_T "Medium properties in port_b1";

  Medium2.ThermodynamicState sta_a2=if homotopyInitialization then 
      Medium2.setState_phX(port_b2.p,
          homotopy(actual=actualStream(port_a2.h_outflow),
                   simplified=inStream(port_a2.h_outflow)),
          homotopy(actual=actualStream(port_a2.Xi_outflow),
                   simplified=inStream(port_a2.Xi_outflow)))
    else 
      Medium2.setState_phX(port_a2.p,
                           actualStream(port_a2.h_outflow),
                           actualStream(port_a2.Xi_outflow)) if 
         show_T "Medium properties in port_a2";

  Medium2.ThermodynamicState sta_b2=if homotopyInitialization then 
      Medium2.setState_phX(port_b2.p,
          homotopy(actual=actualStream(port_b2.h_outflow),
                   simplified=port_b2.h_outflow),
          homotopy(actual=actualStream(port_b2.Xi_outflow),
                   simplified=port_b2.Xi_outflow))
    else 
      Medium2.setState_phX(port_b2.p,
                           actualStream(port_b2.h_outflow),
                           actualStream(port_b2.Xi_outflow)) if 
         show_T "Medium properties in port_b2";

protected 
  Medium1.ThermodynamicState state_a1_inflow=
    Medium1.setState_phX(port_a1.p, inStream(port_a1.h_outflow), inStream(port_a1.Xi_outflow)) 
    "state for medium inflowing through port_a1";
  Medium1.ThermodynamicState state_b1_inflow=
    Medium1.setState_phX(port_b1.p, inStream(port_b1.h_outflow), inStream(port_b1.Xi_outflow)) 
    "state for medium inflowing through port_b1";
  Medium2.ThermodynamicState state_a2_inflow=
    Medium2.setState_phX(port_a2.p, inStream(port_a2.h_outflow), inStream(port_a2.Xi_outflow)) 
    "state for medium inflowing through port_a2";
  Medium2.ThermodynamicState state_b2_inflow=
    Medium2.setState_phX(port_b2.p, inStream(port_b2.h_outflow), inStream(port_b2.Xi_outflow)) 
    "state for medium inflowing through port_b2";

equation 
  // Design direction of mass flow rate
  m1_flow = port_a1.m_flow;
  m2_flow = port_a2.m_flow;

  // Pressure difference between ports
  dp1 = port_a1.p - port_b1.p;
  dp2 = port_a2.p - port_b2.p;

end PartialStaticFourPortInterface;

Buildings.Fluid.Interfaces.PartialFourPort

Partial model with four ports

Buildings.Fluid.Interfaces.PartialFourPort

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.

This partial model is identical to Modelica.Fluid.Interfaces.PartialTwoPort, except that it has four ports.

Parameters

Type Name Default Description

Assumptions

Boolean allowFlowReversal1 system.allowFlowReversal = true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)

Boolean allowFlowReversal2 system.allowFlowReversal = true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)

Initialization

SpecificEnthalpy h_outflow_a1_start Medium1.h_default Start value for enthalpy flowing out of port a1 [J/kg]

SpecificEnthalpy h_outflow_b1_start Medium1.h_default Start value for enthalpy flowing out of port b1 [J/kg]

SpecificEnthalpy h_outflow_a2_start Medium2.h_default Start value for enthalpy flowing out of port a2 [J/kg]

SpecificEnthalpy h_outflow_b2_start Medium2.h_default Start value for enthalpy flowing out of port b2 [J/kg]

Type	Name	Default	Description
Assumptions
Boolean	allowFlowReversal1	system.allowFlowReversal	= true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)
Boolean	allowFlowReversal2	system.allowFlowReversal	= true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)
Initialization
SpecificEnthalpy	h_outflow_a1_start	Medium1.h_default	Start value for enthalpy flowing out of port a1 [J/kg]
SpecificEnthalpy	h_outflow_b1_start	Medium1.h_default	Start value for enthalpy flowing out of port b1 [J/kg]
SpecificEnthalpy	h_outflow_a2_start	Medium2.h_default	Start value for enthalpy flowing out of port a2 [J/kg]
SpecificEnthalpy	h_outflow_b2_start	Medium2.h_default	Start value for enthalpy flowing out of port b2 [J/kg]

Connectors

Type	Name	Description
FluidPort_a	port_a1	Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_b	port_b1	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_a	port_a2	Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_b	port_b2	Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)

Modelica definition

partial model PartialFourPort "Partial model with four ports"
  import Modelica.Constants;
  outer Modelica.Fluid.System system "System wide properties";

  replaceable package Medium1 =
      Modelica.Media.Interfaces.PartialMedium "Medium 1 in the component";
  replaceable package Medium2 =
      Modelica.Media.Interfaces.PartialMedium "Medium 2 in the component";

  parameter Boolean allowFlowReversal1 = system.allowFlowReversal 
    "= true to allow flow reversal in medium 1, false restricts to design direction (port_a -> port_b)";
  parameter Boolean allowFlowReversal2 = system.allowFlowReversal 
    "= true to allow flow reversal in medium 2, false restricts to design direction (port_a -> port_b)";

  parameter Modelica.SIunits.SpecificEnthalpy h_outflow_a1_start = Medium1.h_default 
    "Start value for enthalpy flowing out of port a1";

  parameter Modelica.SIunits.SpecificEnthalpy h_outflow_b1_start = Medium1.h_default 
    "Start value for enthalpy flowing out of port b1";

  parameter Modelica.SIunits.SpecificEnthalpy h_outflow_a2_start = Medium2.h_default 
    "Start value for enthalpy flowing out of port a2";

  parameter Modelica.SIunits.SpecificEnthalpy h_outflow_b2_start = Medium2.h_default 
    "Start value for enthalpy flowing out of port b2";

  Modelica.Fluid.Interfaces.FluidPort_a port_a1(
                                redeclare package Medium = Medium1,
                     m_flow(min=if allowFlowReversal1 then -Constants.inf else 0),
                     h_outflow(nominal=1E5, start=h_outflow_a1_start),
                     Xi_outflow(nominal=0.01)) 
    "Fluid connector a1 (positive design flow direction is from port_a1 to port_b1)";
  Modelica.Fluid.Interfaces.FluidPort_b port_b1(
                                redeclare package Medium = Medium1,
                     m_flow(max=if allowFlowReversal1 then +Constants.inf else 0),
                     h_outflow(nominal=1E5, start=h_outflow_b1_start),
                     Xi_outflow(nominal=0.01)) 
    "Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)";

  Modelica.Fluid.Interfaces.FluidPort_a port_a2(
                                redeclare package Medium = Medium2,
                     m_flow(min=if allowFlowReversal2 then -Constants.inf else 0),
                     h_outflow(nominal=1E5,start=h_outflow_a2_start),
                     Xi_outflow(nominal=0.01)) 
    "Fluid connector a2 (positive design flow direction is from port_a2 to port_b2)";
  Modelica.Fluid.Interfaces.FluidPort_b port_b2(
                                redeclare package Medium = Medium2,
                     m_flow(max=if allowFlowReversal2 then +Constants.inf else 0),
                     h_outflow(nominal=1E5, start=h_outflow_b2_start),
                     Xi_outflow(nominal=0.01)) 
    "Fluid connector b2 (positive design flow direction is from port_a2 to port_b2)";

end PartialFourPort;

Buildings.Fluid.Interfaces.FourPortFlowResistanceParameters

Parameters for flow resistance for models with four ports

Information

This class contains parameters that are used to compute the pressure drop in components that have two fluid streams. Note that the nominal mass flow rate is not declared here because the model PartialStaticFourPortInterface already declares it.

Parameters

Type Name Default Description

Nominal condition

Pressure dp1_nominal Pressure [Pa]

Pressure dp2_nominal Pressure [Pa]

Flow resistance

Medium 1

Boolean computeFlowResistance1 true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp1 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance1 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM1 0.1 Fraction of nominal flow rate where flow transitions to laminar

Medium 2

Boolean computeFlowResistance2 true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp2 false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance2 false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM2 0.1 Fraction of nominal flow rate where flow transitions to laminar

Type	Name	Default	Description
Nominal condition
Pressure	dp1_nominal		Pressure [Pa]
Pressure	dp2_nominal		Pressure [Pa]
Flow resistance
Medium 1
Boolean	computeFlowResistance1	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp1	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance1	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM1	0.1	Fraction of nominal flow rate where flow transitions to laminar
Medium 2
Boolean	computeFlowResistance2	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp2	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance2	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM2	0.1	Fraction of nominal flow rate where flow transitions to laminar

Modelica definition

record FourPortFlowResistanceParameters 
  "Parameters for flow resistance for models with four ports"

  parameter Boolean computeFlowResistance1 = true 
    "=true, compute flow resistance. Set to false to assume no friction";

  parameter Boolean from_dp1 = false 
    "= true, use m_flow = f(dp) else dp = f(m_flow)";
  parameter Modelica.SIunits.Pressure dp1_nominal(min=0, displayUnit="Pa") 
    "Pressure";
  parameter Boolean linearizeFlowResistance1 = false 
    "= true, use linear relation between m_flow and dp for any flow rate";
  parameter Real deltaM1 = 0.1 
    "Fraction of nominal flow rate where flow transitions to laminar";
  parameter Boolean computeFlowResistance2 = true 
    "=true, compute flow resistance. Set to false to assume no friction";

  parameter Boolean from_dp2 = false 
    "= true, use m_flow = f(dp) else dp = f(m_flow)";
  parameter Modelica.SIunits.Pressure dp2_nominal(min=0, displayUnit="Pa") 
    "Pressure";
  parameter Boolean linearizeFlowResistance2 = false 
    "= true, use linear relation between m_flow and dp for any flow rate";
  parameter Real deltaM2 = 0.1 
    "Fraction of nominal flow rate where flow transitions to laminar";
end FourPortFlowResistanceParameters;

Buildings.Fluid.Interfaces.PartialDynamicTwoPortTransformer

Partial model transporting one fluid stream with storing mass or energy

Buildings.Fluid.Interfaces.PartialDynamicTwoPortTransformer

Information

This component transports one fluid stream. It provides the basic model for implementing a dynamic heater such as a boiler. It is used by Buildings.Fluid.Boilers.BoilerPolynomial. The variable names follow the conventions used in Modelica.Fluid.HeatExchangers.BasicHX.

Extends from Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface (Partial model transporting fluid between two ports without storing mass or energy), Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters (Parameters for flow resistance for models with two ports).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Pressure dp_nominal Pressure [Pa]

Time tau 300 Time constant at nominal flow [s]

Initialization

MassFlowRate m_flow.start 0 Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]

Pressure dp.start 0 Pressure difference between port_a and port_b [Pa]

Assumptions

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

Dynamics

Dynamics energyDynamics system.energyDynamics Formulation of energy balance

Dynamics massDynamics energyDynamics Formulation of mass balance

Advanced

MassFlowRate m_flow_small 1E-4*abs(m_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Flow resistance

Boolean computeFlowResistance true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM 0.1 Fraction of nominal flow rate where flow transitions to laminar

Initialization

AbsolutePressure p_start Medium.p_default 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
replaceable package Medium	PartialMedium	Medium in the component
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Pressure	dp_nominal		Pressure [Pa]
Time	tau	300	Time constant at nominal flow [s]
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Dynamics
Dynamics	energyDynamics	system.energyDynamics	Formulation of energy balance
Dynamics	massDynamics	energyDynamics	Formulation of mass balance
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)
Flow resistance
Boolean	computeFlowResistance	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar
Initialization
AbsolutePressure	p_start	Medium.p_default	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

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 PartialDynamicTwoPortTransformer 
  "Partial model transporting one fluid stream with storing mass or energy"
  extends Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface;
  extends Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters(
    final computeFlowResistance=true);
  import Modelica.Constants;

  Buildings.Fluid.MixingVolumes.MixingVolume vol(
    redeclare package Medium = Medium,
    nPorts = 2,
    V=m_flow_nominal*tau/rho_nominal,
    final use_HeatTransfer=true,
    redeclare model HeatTransfer =
        Modelica.Fluid.Vessels.BaseClasses.HeatTransfer.IdealHeatTransfer,
    final energyDynamics=energyDynamics,
    final massDynamics=massDynamics,
    final p_start=p_start,
    final use_T_start=use_T_start,
    final T_start=T_start,
    final h_start=h_start,
    final X_start=X_start,
    final C_start=C_start) "Volume for fluid stream";

  parameter Modelica.SIunits.Time tau = 300 "Time constant at nominal flow";

  // Advanced
  parameter Boolean homotopyInitialization = true "= true, use homotopy method";

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

  // Initialization
  parameter Medium.AbsolutePressure p_start = Medium.p_default 
    "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";

  Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor temSen(
    T(final quantity="Temperature",
      final unit = "K", displayUnit = "degC", min=0)) 
    "Temperature sensor of metal";

protected 
  parameter Medium.ThermodynamicState sta_nominal=Medium.setState_pTX(
      T=Medium.T_default, p=Medium.p_default, X=Medium.X_default);
  parameter Modelica.SIunits.Density rho_nominal=Medium.density(sta_nominal) 
    "Density, used to compute fluid volume";
public 
  Buildings.Fluid.FixedResistances.FixedResistanceDpM preDro(
    redeclare package Medium = Medium,
    final use_dh=false,
    final m_flow_nominal=m_flow_nominal,
    final deltaM=deltaM,
    final allowFlowReversal=allowFlowReversal,
    final m_flow_small=m_flow_small,
    final show_T=false,
    final show_V_flow=show_V_flow,
    final from_dp=from_dp,
    final linearized=linearizeFlowResistance,
    final homotopyInitialization=homotopyInitialization,
    final dp_nominal=dp_nominal) "Pressure drop model";
equation 
  assert(vol.use_HeatTransfer == true, "Wrong parameter for vol.");

  connect(temSen.port, vol.heatPort);
  connect(vol.ports[2], port_b);
  connect(port_a, preDro.port_a);
  connect(preDro.port_b, vol.ports[1]);
end PartialDynamicTwoPortTransformer;

Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer

Partial model transporting fluid between two ports without storing mass or energy

Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer

Information

This component transports fluid between its two ports, without storing mass or energy. It is based on Modelica.Fluid.Interfaces.PartialTwoPortTransport but it does use a different implementation for handling reverse flow because in this component, mass flow rate can be added or removed from the medium.

Depending on the parameter settings, this component computes pressure drop due to flow friction. The pressure drop is defined by a quadratic function that goes through the point (m_flow_nominal, dp_nominal). At |m_flow| < deltaM * m_flow_nominal, the pressure drop vs. flow relation is linearized. If the parameter linearizeFlowResistance is set to true, then the whole pressure drop vs. flow resistance curve is linearized.

When using this partial component, an equation for the energy and mass balances need to be added, such as

  mWat_flow = u * m_flow_nominal;
  Q_flow = Medium.enthalpyOfLiquid(TWat) * mWat_flow;
  for i in 1:Medium.nXi loop
     mXi_flow[i] = if ( i == Medium.Water) then  mWat_flow else 0;
  end for;

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Boolean sensibleOnly Set to true if sensible exchange only

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Pressure dp_nominal Pressure [Pa]

Initialization

MassFlowRate m_flow.start 0 Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]

Pressure dp.start 0 Pressure difference between port_a and port_b [Pa]

Assumptions

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

Advanced

MassFlowRate m_flow_small 1E-4*abs(m_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Flow resistance

Boolean computeFlowResistance (dp_nominal > Modelica.Const... =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM 0.1 Fraction of nominal flow rate where flow transitions to laminar

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Boolean	sensibleOnly		Set to true if sensible exchange only
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Pressure	dp_nominal		Pressure [Pa]
Initialization
MassFlowRate	m_flow.start	0	Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) [kg/s]
Pressure	dp.start	0	Pressure difference between port_a and port_b [Pa]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)
Flow resistance
Boolean	computeFlowResistance	(dp_nominal > Modelica.Const...	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar

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

model PartialStaticTwoPortHeatMassTransfer 
  "Partial model transporting fluid between two ports without storing mass or energy"
  extends Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface(
  showDesignFlowDirection = false);
  extends Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters(
    final computeFlowResistance=(dp_nominal > Modelica.Constants.eps));
  import Modelica.Constants;

  input Modelica.SIunits.HeatFlowRate Q_flow "Heat transfered into the medium";
  input Medium.MassFlowRate mXi_flow[Medium.nXi] 
    "Mass flow rates of independent substances added to the medium";
  constant Boolean sensibleOnly "Set to true if sensible exchange only";
protected 
  Real m_flowInv(unit="s/kg") "Regularization of 1/m_flow";
equation 
  // Regularization of m_flow around the origin to avoid a division by zero
/*  m_flowInv = smooth(2, if (abs(port_a.m_flow) > m_flow_small/1E3) then 
      1/port_a.m_flow
      else 
      Buildings.Utilities.Math.Functions.inverseXRegularized(x=port_a.m_flow, delta=m_flow_small/1E3));
 */
 m_flowInv = Buildings.Utilities.Math.Functions.inverseXRegularized(x=port_a.m_flow, delta=m_flow_small/1E3);
  //////////////////////////////////////////////////////////////////////////////////////////
  // Energy balance and mass balance
  if sensibleOnly then
    // Mass balance
    port_a.m_flow = -port_b.m_flow;
    // Energy balance
    port_b.h_outflow = inStream(port_a.h_outflow) + Q_flow * m_flowInv;
    port_a.h_outflow = inStream(port_b.h_outflow) - Q_flow * m_flowInv;

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

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

  else
    // Mass balance (no storage)
    port_a.m_flow + port_b.m_flow = -sum(mXi_flow);

    // Energy balance.
    // This equation is approximate since m_flow = port_a.m_flow is used for the mass flow rate
    // at both ports. Since mXi_flow << m_flow, the error is small.
    port_b.h_outflow = inStream(port_a.h_outflow) + Q_flow * m_flowInv;
    port_a.h_outflow = inStream(port_b.h_outflow) - Q_flow * m_flowInv;

    // Transport of species
    for i in 1:Medium.nXi loop
      port_b.Xi_outflow[i] = inStream(port_a.Xi_outflow[i]) + mXi_flow[i] * m_flowInv;
      port_a.Xi_outflow[i] = inStream(port_b.Xi_outflow[i]) - mXi_flow[i] * m_flowInv;
    end for;
    // Transport of trace substances
    for i in 1:Medium.nC loop
      port_a.m_flow*port_a.C_outflow[i] = -port_b.m_flow*inStream(port_b.C_outflow[i]);
      port_b.m_flow*port_b.C_outflow[i] = -port_a.m_flow*inStream(port_a.C_outflow[i]);
    end for;
  end if; // sensibleOnly
  //////////////////////////////////////////////////////////////////////////////////////////
  // Pressure drop calculation
  if computeFlowResistance then
    if homotopyInitialization then
      if from_dp then
        m_flow = homotopy(actual=Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp(
                                    dp=dp,
                                    k=m_flow_nominal/sqrt(dp_nominal),
                                    m_flow_turbulent=deltaM * m_flow_nominal,
                                    linearized=linearizeFlowResistance),
                          simplified=m_flow_nominal*dp/dp_nominal);
      else
        dp = homotopy(actual=Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow(
                                    m_flow=m_flow,
                                    k=m_flow_nominal/sqrt(dp_nominal),
                                    m_flow_turbulent=deltaM * m_flow_nominal,
                                    linearized=linearizeFlowResistance),
                      simplified=dp_nominal*m_flow/m_flow_nominal);
      end if;
    else // do not use homotopy
      if from_dp then
        m_flow = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp(
                                    dp=dp,
                                    k=m_flow_nominal/sqrt(dp_nominal),
                                    m_flow_turbulent=deltaM * m_flow_nominal,
                                    linearized=linearizeFlowResistance);
      else
        dp = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow(
                                    m_flow=m_flow,
                                    k=m_flow_nominal/sqrt(dp_nominal),
                                    m_flow_turbulent=deltaM * m_flow_nominal,
                                    linearized=linearizeFlowResistance);
      end if;
    end if; // homotopyInitialization
  else // do not compute flow resistance
    dp = 0;
  end if; // computeFlowResistance

end PartialStaticTwoPortHeatMassTransfer;

Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface

Partial model transporting fluid between two ports without storing mass or energy

Buildings.Fluid.Interfaces.PartialStaticTwoPortInterface

Information

This component defines the interface for models that transports a fluid between two ports. It is similar to Modelica.Fluid.Interfaces.PartialTwoPortTransport, but it does not include the species balance

  port_b.Xi_outflow = inStream(port_a.Xi_outflow);

Thus, it can be used as a base class for a heat and mass transfer component

The model is used by other models in this package that add heat transfer, mass transfer and pressure drop equations. See for example Buildings.Fluid.Interfaces.PartialStaticTwoPortHeatMassTransfer.

Extends from Modelica.Fluid.Interfaces.PartialTwoPort (Partial component with two ports).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Nominal condition

MassFlowRate m_flow_nominal Nominal mass flow rate [kg/s]

Assumptions

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

Advanced

MassFlowRate m_flow_small 1E-4*abs(m_flow_nominal) Small mass flow rate for regularization of zero flow [kg/s]

Boolean homotopyInitialization true = true, use homotopy method

Diagnostics

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

Boolean show_T false = true, if actual temperature at port is computed (may lead to events)

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [kg/s]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	1E-4*abs(m_flow_nominal)	Small mass flow rate for regularization of zero flow [kg/s]
Boolean	homotopyInitialization	true	= true, use homotopy method
Diagnostics
Boolean	show_V_flow	false	= true, if volume flow rate at inflowing port is computed
Boolean	show_T	false	= true, if actual temperature at port is computed (may lead to events)

Modelica definition

partial model PartialStaticTwoPortInterface 
  "Partial model transporting fluid between two ports without storing mass or energy"
  import Modelica.Constants;
  extends Modelica.Fluid.Interfaces.PartialTwoPort(
    port_a(p(start=Medium.p_default,
             nominal=Medium.p_default)),
    port_b(p(start=Medium.p_default,
           nominal=Medium.p_default)));

  parameter Medium.MassFlowRate m_flow_nominal "Nominal mass flow rate";
  parameter Medium.MassFlowRate m_flow_small(min=0) = 1E-4*abs(m_flow_nominal) 
    "Small mass flow rate for regularization of zero flow";
  parameter Boolean homotopyInitialization = true "= true, use homotopy method";

  // Diagnostics
   parameter Boolean show_V_flow = false 
    "= true, if volume flow rate at inflowing port is computed";
   parameter Boolean show_T = false 
    "= true, if actual temperature at port is computed (may lead to events)";

  Modelica.SIunits.VolumeFlowRate V_flow=
      m_flow/Medium.density(sta_a) if show_V_flow 
    "Volume flow rate at inflowing port (positive when flow from port_a to port_b)";

  Medium.MassFlowRate m_flow(start=0) 
    "Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction)";
  Modelica.SIunits.Pressure dp(start=0, displayUnit="Pa") 
    "Pressure difference between port_a and port_b";

  Medium.ThermodynamicState sta_a=if homotopyInitialization then 
      Medium.setState_phX(port_a.p,
                          homotopy(actual=actualStream(port_a.h_outflow),
                                   simplified=inStream(port_a.h_outflow)),
                          homotopy(actual=actualStream(port_a.Xi_outflow),
                                   simplified=inStream(port_a.Xi_outflow)))
    else 
      Medium.setState_phX(port_a.p,
                          actualStream(port_a.h_outflow),
                          actualStream(port_a.Xi_outflow)) if 
         show_T or show_V_flow "Medium properties in port_a";
  Medium.ThermodynamicState sta_b=if homotopyInitialization then 
      Medium.setState_phX(port_b.p,
                          homotopy(actual=actualStream(port_b.h_outflow),
                                   simplified=port_b.h_outflow),
                          homotopy(actual=actualStream(port_b.Xi_outflow),
                            simplified=port_b.Xi_outflow))
    else 
      Medium.setState_phX(port_b.p,
                          actualStream(port_b.h_outflow),
                          actualStream(port_b.Xi_outflow)) if 
          show_T "Medium properties in port_b";

equation 
  // Design direction of mass flow rate
  m_flow = port_a.m_flow;

  // Pressure difference between ports
  dp = port_a.p - port_b.p;

end PartialStaticTwoPortInterface;

Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters

Parameters for flow resistance for models with two ports

Information

This class contains parameters that are used to compute the pressure drop in models that have one fluid stream. Note that the nominal mass flow rate is not declared here because the model PartialStaticTwoPortInterface already declares it.

Parameters

Type Name Default Description

Nominal condition

Pressure dp_nominal Pressure [Pa]

Flow resistance

Boolean computeFlowResistance true =true, compute flow resistance. Set to false to assume no friction

Boolean from_dp false = true, use m_flow = f(dp) else dp = f(m_flow)

Boolean linearizeFlowResistance false = true, use linear relation between m_flow and dp for any flow rate

Real deltaM 0.1 Fraction of nominal flow rate where flow transitions to laminar

Type	Name	Default	Description
Nominal condition
Pressure	dp_nominal		Pressure [Pa]
Flow resistance
Boolean	computeFlowResistance	true	=true, compute flow resistance. Set to false to assume no friction
Boolean	from_dp	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Boolean	linearizeFlowResistance	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaM	0.1	Fraction of nominal flow rate where flow transitions to laminar

Modelica definition

record TwoPortFlowResistanceParameters 
  "Parameters for flow resistance for models with two ports"

  parameter Boolean computeFlowResistance = true 
    "=true, compute flow resistance. Set to false to assume no friction";

  parameter Boolean from_dp = false 
    "= true, use m_flow = f(dp) else dp = f(m_flow)";
  parameter Modelica.SIunits.Pressure dp_nominal(min=0, displayUnit="Pa") 
    "Pressure";
  parameter Boolean linearizeFlowResistance = false 
    "= true, use linear relation between m_flow and dp for any flow rate";
  parameter Real deltaM = 0.1 
    "Fraction of nominal flow rate where flow transitions to laminar";

end TwoPortFlowResistanceParameters;

Buildings.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. An extending class must specify an equation for Qb_flow, e.g. convective or latent heat flow rate across the boundary.

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.

Note: This model is similar to Modelica.Fluid.Interfaces.PartialLumpedVolume, except for

the assert statement, which has been removed in this model
the final keyword for the declaration of the the substance and trace substance balance.

These modifications have been made to allow modeling the air humidity using a differential equation, while modeling the total mass balance as a steady-state equation.

Parameters

Type Name Default Description

Assumptions

Dynamics

Dynamics energyDynamics system.energyDynamics Formulation of energy balance

Dynamics massDynamics system.massDynamics Formulation of mass balance

Dynamics substanceDynamics massDynamics Formulation of substance balance

Dynamics traceDynamics massDynamics Formulation of trace substance balance

Initialization

AbsolutePressure p_start Medium.p_default 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

ExtraProperty C_nominal[Medium.nC] fill(1E-2, Medium.nC) Nominal value of trace substances. (Set to typical order of magnitude.)

Type	Name	Default	Description
Assumptions
Dynamics
Dynamics	energyDynamics	system.energyDynamics	Formulation of energy balance
Dynamics	massDynamics	system.massDynamics	Formulation of mass balance
Dynamics	substanceDynamics	massDynamics	Formulation of substance balance
Dynamics	traceDynamics	massDynamics	Formulation of trace substance balance
Initialization
AbsolutePressure	p_start	Medium.p_default	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
ExtraProperty	C_nominal[Medium.nC]	fill(1E-2, Medium.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)

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 Modelica.SIunits.Volume fluidVolume "Volume";

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

  // Initialization
  parameter Medium.AbsolutePressure p_start = Medium.p_default 
    "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";
  parameter Medium.ExtraProperty C_nominal[Medium.nC](
       quantity=Medium.extraPropertiesNames) = fill(1E-2, Medium.nC) 
    "Nominal value of trace substances. (Set to typical order of magnitude.)";
  // Set nominal attributes where literal values can be used.
  Medium.BaseProperties medium(
    preferredMediumStates=true,
    p(start=p_start, nominal=Medium.p_default),
    h(start=h_start),
    T(start=T_start, nominal=Medium.T_default),
    Xi(start=X_start[1:Medium.nXi], nominal=Medium.X_default[1:Medium.nXi])) 
    "Medium properties";

  Modelica.SIunits.Energy U "Internal energy of fluid";
  Modelica.SIunits.Mass m "Mass of fluid";
  Modelica.SIunits.Mass[Medium.nXi] mXi 
    "Masses of independent components in the fluid";
  Modelica.SIunits.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](nominal=C_nominal) 
    "Trace substance mixture content";

  // variables that need to be defined by an extending class
  Modelica.SIunits.MassFlowRate mb_flow "Mass flows across boundaries";
  Modelica.SIunits.MassFlowRate[Medium.nXi] mbXi_flow 
    "Substance mass flows across boundaries";
  Medium.ExtraPropertyFlowRate[Medium.nC] mbC_flow 
    "Trace substance mass flows across boundaries";
  Modelica.SIunits.EnthalpyFlowRate Hb_flow 
    "Enthalpy flow across boundaries or energy source/sink";
  Modelica.SIunits.HeatFlowRate Qb_flow 
    "Heat flow across boundaries or energy source/sink";
protected 
  parameter Boolean initialize_p = not Medium.singleState 
    "= true to set up initial equations for pressure";
equation 
/* statement from original model  
   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;
  else
    der(U) = Hb_flow + Qb_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;

Automatically generated Fri May 06 14:12:57 2011.