LBL logo

Buildings.Fluid.Sensors

Package with sensor models

Information

Package Sensors consists of idealized sensor components that provide variables of a medium as output signals. These signals can be, e.g., further processed with components of the Modelica.Blocks library.

Extends from Modelica.Icons.SensorsPackage (Icon for packages containing sensors).

Package Content

NameDescription
Buildings.Fluid.Sensors.UsersGuide UsersGuide User's Guide
Buildings.Fluid.Sensors.Conversions Conversions Package with conversions for sensor models
Buildings.Fluid.Sensors.Density Density Ideal one port density sensor
Buildings.Fluid.Sensors.DensityTwoPort DensityTwoPort Ideal two port density sensor
Buildings.Fluid.Sensors.EnthalpyFlowRate EnthalpyFlowRate Ideal enthalphy flow rate sensor
Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate SensibleEnthalpyFlowRate Ideal enthalphy flow rate sensor that outputs the sensible enthalpy flow rate only
Buildings.Fluid.Sensors.LatentEnthalpyFlowRate LatentEnthalpyFlowRate Ideal enthalphy flow rate sensor that outputs the latent enthalpy flow rate only
Buildings.Fluid.Sensors.MassFlowRate MassFlowRate Ideal sensor for mass flow rate
Buildings.Fluid.Sensors.MassFraction MassFraction Ideal one port mass fraction sensor
Buildings.Fluid.Sensors.MassFractionTwoPort MassFractionTwoPort Ideal two port mass fraction sensor
Buildings.Fluid.Sensors.Pressure Pressure Ideal pressure sensor
Buildings.Fluid.Sensors.RelativeHumidity RelativeHumidity Ideal one port relative humidity sensor
Buildings.Fluid.Sensors.RelativeHumidityTwoPort RelativeHumidityTwoPort Ideal two port relative humidity sensor
Buildings.Fluid.Sensors.RelativePressure RelativePressure Ideal relative pressure sensor
Buildings.Fluid.Sensors.RelativeTemperature RelativeTemperature Ideal relative temperature sensor
Buildings.Fluid.Sensors.SpecificEnthalpy SpecificEnthalpy Ideal one port specific enthalpy sensor
Buildings.Fluid.Sensors.SpecificEnthalpyTwoPort SpecificEnthalpyTwoPort Ideal two port sensor for the specific enthalpy
Buildings.Fluid.Sensors.SpecificEntropy SpecificEntropy Ideal one port specific entropy sensor
Buildings.Fluid.Sensors.SpecificEntropyTwoPort SpecificEntropyTwoPort Ideal two port sensor for the specific entropy
Buildings.Fluid.Sensors.Temperature Temperature Ideal one port temperature sensor
Buildings.Fluid.Sensors.TemperatureTwoPort TemperatureTwoPort Ideal two port temperature sensor
Buildings.Fluid.Sensors.TemperatureWetBulbTwoPort TemperatureWetBulbTwoPort Ideal wet bulb temperature sensor
Buildings.Fluid.Sensors.TraceSubstances TraceSubstances Ideal one port trace substances sensor
Buildings.Fluid.Sensors.TraceSubstancesTwoPort TraceSubstancesTwoPort Ideal two port sensor for trace substance
Buildings.Fluid.Sensors.VolumeFlowRate VolumeFlowRate Ideal sensor for volume flow rate
Buildings.Fluid.Sensors.Examples Examples Collection of models that illustrate model use and test models
Buildings.Fluid.Sensors.BaseClasses BaseClasses Package with base classes for Buildings.Fluid.Sensors

Buildings.Fluid.Sensors.Density Buildings.Fluid.Sensors.Density

Ideal one port density sensor

Buildings.Fluid.Sensors.Density

Information

This model outputs the density of the fluid connected to its port. The sensor is ideal, i.e. it does not influence the fluid.

Read the Buildings.Fluid.Sensors.UsersGuide prior to using this model with one fluid port.

Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the sensor

Connectors

TypeNameDescription
FluidPort_aport 
output RealOutputdDensity in port medium [kg/m3]

Modelica definition

model Density "Ideal one port density sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput d(final quantity="Density",
                                          final unit="kg/m3",
                                          min=0) "Density in port medium";

equation 
  d = Medium.density(
       state=Medium.setState_phX(
         p=port.p,
         h=inStream(port.h_outflow),
         X=inStream(port.Xi_outflow)));
end Density;

Buildings.Fluid.Sensors.DensityTwoPort Buildings.Fluid.Sensors.DensityTwoPort

Ideal two port density sensor

Buildings.Fluid.Sensors.DensityTwoPort

Information

This model outputs the density of the fluid flowing from port_a to port_b.

The sensor is ideal, i.e., it does not influence the fluid. If the parameter tau is non-zero, then its output is computed using a first order differential equation. Setting tau=0 is not recommend. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
Timetau1Time constant at nominal flow rate [s]
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)
Densityd_startMedium.density(state=Medium....Initial or guess value of output (=state) [kg/m3]
TemperatureT_startMedium.T_defaultTemperature used to compute d_start [K]
Pressurep_startMedium.p_defaultPressure used to compute d_start [Pa]
MassFractionX_start[Medium.nX]Medium.X_defaultMass fraction used to compute d_start [1]
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
output RealOutputdDensity of the passing fluid [kg/m3]

Modelica definition

model DensityTwoPort "Ideal two port density sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput d(final quantity="Density",
                                          final unit="kg/m3",
                                          min=0) "Density of the passing fluid";
  parameter Medium.Density d_start=
     Medium.density(state=Medium.setState_pTX(
       p=p_start, T=T_start, X=X_start)) 
    "Initial or guess value of output (=state)";
  parameter Modelica.SIunits.Temperature T_start=Medium.T_default 
    "Temperature used to compute d_start";
  parameter Modelica.SIunits.Pressure p_start=Medium.p_default 
    "Pressure used to compute d_start";
  parameter Modelica.SIunits.MassFraction X_start[Medium.nX]=Medium.X_default 
    "Mass fraction used to compute d_start";
protected 
  Medium.Density dMed(start=d_start) 
    "Medium density to which the sensor is exposed";

  Medium.Density d_a_inflow "Density of inflowing fluid at port_a";
  Medium.Density d_b_inflow 
    "Density of inflowing fluid at port_b, or rho_a_inflow if uni-directional flow";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(d) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      d = d_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     d_a_inflow = Medium.density(
       state=Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     d_b_inflow = Medium.density(
       state=Medium.setState_phX(p=port_a.p, h=port_a.h_outflow, X=port_a.Xi_outflow));
     dMed = Modelica.Fluid.Utilities.regStep(
       x=port_a.m_flow, y1=d_a_inflow, y2=d_b_inflow, x_small=m_flow_small);
  else
     dMed = Medium.density(
       state=Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     d_a_inflow = dMed;
     d_b_inflow = dMed;
  end if;
  // Output signal of sensor
  if dynamic then
    der(d) = (dMed-d)*k/tau;
  else
    d = dMed;
  end if;
end DensityTwoPort;

Buildings.Fluid.Sensors.EnthalpyFlowRate Buildings.Fluid.Sensors.EnthalpyFlowRate

Ideal enthalphy flow rate sensor

Buildings.Fluid.Sensors.EnthalpyFlowRate

Information

This model outputs the enthalphy flow rate of the medium in the flow between fluid ports. The sensor is ideal, i.e., it does not influence the fluid.

If the parameter tau is non-zero, then the measured specific enthalpy hout that is used to compute the enthalpy flow rate Ḣ = ṁ hout is computed using a first order differential equation. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

For a sensor that measures the latent enthalpy flow rate, use Buildings.Fluid.Sensors.LatentEnthalpyFlowRate.

Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
Timetau1Time constant at nominal flow rate [s]
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpyh_out_startMedium.specificEnthalpy_pTX(...Initial or guess value of measured specific enthalpy [J/kg]
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
output RealOutputH_flowEnthalpy flow rate, positive if from port_a to port_b [W]

Modelica definition

model EnthalpyFlowRate "Ideal enthalphy flow rate sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput H_flow(unit="W") 
    "Enthalpy flow rate, positive if from port_a to port_b";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.specificEnthalpy_pTX(
      p=Medium.p_default,
      T=Medium.T_default,
      X=Medium.X_default) 
    "Initial or guess value of measured specific enthalpy";
protected 
  Modelica.SIunits.SpecificEnthalpy hMed_out(start=h_out_start) 
    "Medium enthalpy to which the sensor is exposed";
  Modelica.SIunits.SpecificEnthalpy h_out(start=h_out_start) 
    "Medium enthalpy that is used to compute the enthalpy flow rate";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(h_out) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      h_out = h_out_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
    hMed_out = Modelica.Fluid.Utilities.regStep(
                 x=port_a.m_flow,
                 y1=port_b.h_outflow,
                 y2=port_a.h_outflow,
                 x_small=m_flow_small);
  else
    hMed_out = port_b.h_outflow;
  end if;
  // Specific enthalpy measured by sensor
  if dynamic then
    der(h_out) = (hMed_out-h_out)*k/tau;
  else
    h_out = hMed_out;
  end if;
  // Sensor output signal
  H_flow = port_a.m_flow * h_out;
end EnthalpyFlowRate;

Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate

Ideal enthalphy flow rate sensor that outputs the sensible enthalpy flow rate only

Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate

Information

This model outputs the sensible enthalphy flow rate of the medium in the flow between its fluid ports. In particular, if the total enthalpy flow rate is

Ḣtot = Ḣsen + Ḣlat,

where Ḣsen = ṁ (1-Xw) cp,air, then this sensor outputs Ḣ = Ḣsen.

If the parameter tau is non-zero, then the measured specific sensible enthalpy hout that is used to compute the sensible enthalpy flow rate Ḣsen = ṁ hout is computed using a first order differential equation. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

For a sensor that measures Ḣtot, use Buildings.Fluid.Sensors.EnthalpyFlowRate.
For a sensor that measures Ḣlat, use Buildings.Fluid.Sensors.LatentEnthalpyFlowRate.

The sensor is ideal, i.e., it does not influence the fluid. The sensor can only be used with medium models that implement the function enthalpyOfNonCondensingGas(T).

Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Buildings.Fluid.BaseClasses.IndexMassFraction (Computes the index of a substance in the mass fraction vector Xi), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
Timetau1Time constant at nominal flow rate [s]
StringsubstanceName"water"Name of species substance
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpyh_out_startMedium.enthalpyOfNonCondensi...Initial or guess value of measured specific sensible enthalpy [J/kg]
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

TypeNameDescription
replaceable package MediumMedium in the component
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
output RealOutputH_flowSensible enthalpy flow rate, positive if from port_a to port_b [W]

Modelica definition

model SensibleEnthalpyFlowRate 
  "Ideal enthalphy flow rate sensor that outputs the sensible enthalpy flow rate only"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor(
    redeclare replaceable package Medium =
        Modelica.Media.Interfaces.PartialCondensingGases);
  extends Buildings.Fluid.BaseClasses.IndexMassFraction(final substanceName="water");
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput H_flow(final unit="W") 
    "Sensible enthalpy flow rate, positive if from port_a to port_b";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.enthalpyOfNonCondensingGas(T=Medium.T_default) 
    "Initial or guess value of measured specific sensible enthalpy";
protected 
  Modelica.SIunits.SpecificEnthalpy hMed_out(start=h_out_start) 
    "Medium sensible enthalpy to which the sensor is exposed";
  Modelica.SIunits.SpecificEnthalpy h_out(start=h_out_start) 
    "Medium sensible enthalpy that is used to compute the enthalpy flow rate";
  Medium.MassFraction XiActual[Medium.nXi] 
    "Medium mass fraction to which sensor is exposed to";
  Medium.SpecificEnthalpy hActual 
    "Medium enthalpy to which sensor is exposed to";
initial equation 
 // Compute initial state
 if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(h_out) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      h_out = h_out_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     XiActual = Modelica.Fluid.Utilities.regStep(
                  x=port_a.m_flow,
                  y1=port_b.Xi_outflow,
                  y2=port_a.Xi_outflow,
                  x_small=m_flow_small);
     hActual = Modelica.Fluid.Utilities.regStep(
                 x=port_a.m_flow,
                 y1=port_b.h_outflow,
                 y2=port_a.h_outflow,
                 x_small=m_flow_small);
  else
     XiActual = port_b.Xi_outflow;
     hActual = port_b.h_outflow;
  end if;
  // Specific enthalpy measured by sensor
  hMed_out = (1-XiActual[i_x]) * Medium.enthalpyOfNonCondensingGas(
      T=Medium.temperature(state=Medium.setState_phX(p=port_a.p, h=hActual, X=XiActual)));
  if dynamic then
    der(h_out) = (hMed_out-h_out)*k/tau;
  else
    h_out = hMed_out;
  end if;
  // Sensor output signal
  H_flow = port_a.m_flow * h_out;
end SensibleEnthalpyFlowRate;

Buildings.Fluid.Sensors.LatentEnthalpyFlowRate Buildings.Fluid.Sensors.LatentEnthalpyFlowRate

Ideal enthalphy flow rate sensor that outputs the latent enthalpy flow rate only

Buildings.Fluid.Sensors.LatentEnthalpyFlowRate

Information

This model outputs the latent enthalphy flow rate of the medium in the flow between its fluid ports. In particular, if the total enthalpy flow rate is

Ḣtot = Ḣsen + Ḣlat,

where Ḣsen = ṁ (1-Xw) cp,air, then this sensor outputs Ḣ = Ḣlat.

If the parameter tau is non-zero, then the measured specific latent enthalpy hout that is used to compute the latent enthalpy flow rate Ḣlat = ṁ hout is computed using a first order differential equation. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

For a sensor that measures Ḣtot, use Buildings.Fluid.Sensors.EnthalpyFlowRate.
For a sensor that measures Ḣsen, use Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate.

The sensor is ideal, i.e., it does not influence the fluid. The sensor can only be used with medium models that implement the function enthalpyOfNonCondensingGas(T).

Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Buildings.Fluid.BaseClasses.IndexMassFraction (Computes the index of a substance in the mass fraction vector Xi), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
Timetau1Time constant at nominal flow rate [s]
StringsubstanceName"water"Name of species substance
Nominal condition
MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpyh_out_startMedium.specificEnthalpy_pTX(...Initial or guess value of measured specific latent enthalpy [J/kg]
Assumptions
BooleanallowFlowReversalsystem.allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

TypeNameDescription
replaceable package MediumMedium in the component
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
output RealOutputH_flowLatent enthalpy flow rate, positive if from port_a to port_b [W]

Modelica definition

model LatentEnthalpyFlowRate 
  "Ideal enthalphy flow rate sensor that outputs the latent enthalpy flow rate only"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor(
    redeclare replaceable package Medium =
        Modelica.Media.Interfaces.PartialCondensingGases);
  extends Buildings.Fluid.BaseClasses.IndexMassFraction(final substanceName="water");
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput H_flow(final unit="W") 
    "Latent enthalpy flow rate, positive if from port_a to port_b";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.specificEnthalpy_pTX(
      p=Medium.p_default, T=Medium.T_default, X=Medium.X_default)
    -Medium.enthalpyOfNonCondensingGas(T=Medium.T_default) 
    "Initial or guess value of measured specific latent enthalpy";

protected 
  Modelica.SIunits.SpecificEnthalpy hMed_out(start=h_out_start) 
    "Medium latent enthalpy to which the sensor is exposed";
  Modelica.SIunits.SpecificEnthalpy h_out(start=h_out_start) 
    "Medium latent enthalpy that is used to compute the enthalpy flow rate";

  Medium.MassFraction XiActual[Medium.nXi] 
    "Medium mass fraction to which sensor is exposed to";
  Medium.SpecificEnthalpy hActual 
    "Medium enthalpy to which sensor is exposed to";
initial equation 
 // Compute initial state
 if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(h_out) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      h_out = h_out_start;
    end if;
 end if;
equation 
  if allowFlowReversal then
     XiActual = Modelica.Fluid.Utilities.regStep(
                 x=port_a.m_flow,
                 y1=port_b.Xi_outflow,
                 y2=port_a.Xi_outflow,
                 x_small=m_flow_small);
     hActual = Modelica.Fluid.Utilities.regStep(
                 x=port_a.m_flow,
                 y1=port_b.h_outflow,
                 y2=port_a.h_outflow,
                 x_small=m_flow_small);
  else
     XiActual = port_b.Xi_outflow;
     hActual = port_b.h_outflow;
  end if;
  // Specific enthalpy measured by sensor.
  // Compute H_flow as difference between total enthalpy and enthalpy on non-condensing gas.
  // This is needed to compute the liquid vs. gas fraction of water, using the equations
  // provided by the medium model
  hMed_out = (hActual -
     (1-XiActual[i_x]) * Medium.enthalpyOfNonCondensingGas(
       T=Medium.temperature(Medium.setState_phX(p=port_a.p, h=hActual, X=XiActual))));
  if dynamic then
    der(h_out) = (hMed_out-h_out)*k/tau;
  else
    h_out = hMed_out;
  end if;
  // Sensor output signal
  H_flow = port_a.m_flow * h_out;
end LatentEnthalpyFlowRate;

Buildings.Fluid.Sensors.MassFlowRate Buildings.Fluid.Sensors.MassFlowRate

Ideal sensor for mass flow rate

Buildings.Fluid.Sensors.MassFlowRate

Information

This model outputs the mass flow rate flowing from port_a to port_b. The sensor is ideal, i.e., it does not influence the fluid. 


Extends from Buildings.Fluid.Sensors.BaseClasses.PartialFlowSensor (Partial component to model sensors that measure flow properties), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Nominal condition


MassFlowRatem_flow_nominal0Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small0For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputm_flowMass flow rate from port_a to port_b [kg/s]




Modelica definition


model MassFlowRate "Ideal sensor for mass flow rate"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialFlowSensor(
    final m_flow_nominal = 0,
    final m_flow_small = 0);
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput m_flow(quantity="MassFlowRate",
                                               final unit="kg/s") 
    "Mass flow rate from port_a to port_b";

equation 
  m_flow = port_a.m_flow;
end MassFlowRate;







Buildings.Fluid.Sensors.MassFraction
Buildings.Fluid.Sensors.MassFraction

Ideal one port mass fraction sensor

Buildings.Fluid.Sensors.MassFraction

Information




This model outputs the mass fraction of the fluid connected to its port. 
The sensor is ideal, i.e., it does not influence the fluid.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Buildings.Fluid.BaseClasses.IndexMassFraction (Computes the index of a substance in the mass fraction vector Xi), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor


StringsubstanceName"water"Name of species substance




Connectors




TypeNameDescription


replaceable package MediumMedium in the sensor


FluidPort_aport 


output RealOutputXMass fraction in port [1]




Modelica definition


model MassFraction "Ideal one port mass fraction sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor(
    redeclare replaceable package Medium =
        Modelica.Media.Interfaces.PartialCondensingGases);
  extends Buildings.Fluid.BaseClasses.IndexMassFraction(substanceName = "water");
  extends Modelica.Icons.RotationalSensor;

  Modelica.Blocks.Interfaces.RealOutput X(min=-1e-3,
                                          max=1.001,
                                          unit="1") "Mass fraction in port";
protected 
  Medium.MassFraction XiVec[Medium.nXi](
      quantity=Medium.extraPropertiesNames) 
    "Mass fraction vector, needed because indexed argument for the operator inStream is not supported";

equation 
  XiVec = inStream(port.Xi_outflow);
  X = if i_x > Medium.nXi then (1-sum(XiVec)) else XiVec[i_x];
end MassFraction;







Buildings.Fluid.Sensors.MassFractionTwoPort
Buildings.Fluid.Sensors.MassFractionTwoPort

Ideal two port mass fraction sensor

Buildings.Fluid.Sensors.MassFractionTwoPort

Information




This model outputs the mass fraction of the passing fluid. 
The sensor is ideal, i.e. it does not influence the fluid.
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Buildings.Fluid.BaseClasses.IndexMassFraction (Computes the index of a substance in the mass fraction vector Xi), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


StringsubstanceName"water"Name of species substance


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


MassFractionX_startMedium.X_default[i_x]Initial or guess value of output (= state) [kg/kg]


Assumptions


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




Connectors




TypeNameDescription


replaceable package MediumMedium in the component


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


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


output RealOutputXMass fraction of the passing fluid [1]




Modelica definition


model MassFractionTwoPort "Ideal two port mass fraction sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor(
    redeclare replaceable package Medium =
        Modelica.Media.Interfaces.PartialCondensingGases);
  extends Buildings.Fluid.BaseClasses.IndexMassFraction(substanceName = "water");
  extends Modelica.Icons.RotationalSensor;

  parameter Medium.MassFraction X_start=Medium.X_default[i_x] 
    "Initial or guess value of output (= state)";

  Modelica.Blocks.Interfaces.RealOutput X(min=-1e-3,
                                          max=1.001,
                                          start=X_start,
                                          unit="1") 
    "Mass fraction of the passing fluid";

protected 
  Medium.MassFraction XMed(start=X_start) 
    "Mass fraction to which the sensor is exposed";
  Medium.MassFraction XiVec[Medium.nXi](
      quantity=Medium.extraPropertiesNames) 
    "Trace substances vector, needed because indexed argument for the operator inStream is not supported";
initial equation 
  // Assign initial conditions
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(X) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      X = X_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
    XiVec = Modelica.Fluid.Utilities.regStep(
              x=port_a.m_flow,
              y1=port_b.Xi_outflow,
              y2=port_a.Xi_outflow,
              x_small=m_flow_small);
  else
    XiVec = port_b.Xi_outflow;
  end if;
  XMed = if i_x > Medium.nXi then (1-sum(XiVec)) else XiVec[i_x];
  // Output signal of sensor
  if dynamic then
    der(X)  = (XMed-X)*k/tau;
  else
    X = XMed;
  end if;
end MassFractionTwoPort;







Buildings.Fluid.Sensors.Pressure
Buildings.Fluid.Sensors.Pressure

Ideal pressure sensor

Buildings.Fluid.Sensors.Pressure

Information




This model outputs the absolute pressure of the fluid connected to its port. 
The sensor is ideal, i.e., it does not influence the fluid.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputpPressure at port [Pa]




Modelica definition


model Pressure "Ideal pressure sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput p(final quantity="Pressure",
                                          final unit="Pa",
                                          min=0) "Pressure at port";
equation 
  p = port.p;
end Pressure;







Buildings.Fluid.Sensors.RelativeHumidity
Buildings.Fluid.Sensors.RelativeHumidity

Ideal one port relative humidity sensor

Buildings.Fluid.Sensors.RelativeHumidity

Information




This model outputs the relative humidity of the fluid connected to its port. 
The sensor is ideal, i.e. it does not influence the fluid.




Note that this sensor can only be used with media that contain the variable phi,
which is typically the case for moist air models.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputphiRelative humidity in port medium [1]




Modelica definition


model RelativeHumidity "Ideal one port relative humidity sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;

  Modelica.Blocks.Interfaces.RealOutput phi(unit="1", min=0) 
    "Relative humidity in port medium";

protected 
  Medium.BaseProperties med "Medium state at dry bulb temperature";

equation 
  med.p = port.p;
  med.h = inStream(port.h_outflow);
  med.Xi = inStream(port.Xi_outflow);
  phi = med.phi;

end RelativeHumidity;







Buildings.Fluid.Sensors.RelativeHumidityTwoPort
Buildings.Fluid.Sensors.RelativeHumidityTwoPort

Ideal two port relative humidity sensor

Buildings.Fluid.Sensors.RelativeHumidityTwoPort

Information




This model outputs the relative humidity of the fluid flowing from 
port_a to port_b. 
The sensor is ideal, i.e., it does not influence the fluid.




Note that this sensor can only be used with media that contain the variable phi,
which is typically the case for moist air models.




If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


Realphi_start0.5Initial or guess value of output (= state) [1]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputphiRelative humidity of the passing fluid [1]




Modelica definition


model RelativeHumidityTwoPort 
  "Ideal two port relative humidity sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput phi(unit="1",
                                            min=0,
                                            start=phi_start) 
    "Relative humidity of the passing fluid";
  parameter Real phi_start(unit="1", min=0, max=1)=0.5 
    "Initial or guess value of output (= state)";

protected 
  Real phiMed(unit="1", min=0, start=phi_start) 
    "Relative humidity to which the sensor is exposed to";
  Medium.BaseProperties med_a_inflow 
    "Medium state of inflowing fluid at port a";
  Medium.BaseProperties med_b_inflow 
    "Medium state of inflowing fluid at port b";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(phi) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      phi = phi_start;
    end if;
  end if;
equation 
  med_a_inflow.p  = port_a.p;
  med_a_inflow.h  = port_b.h_outflow;
  med_a_inflow.Xi = port_b.Xi_outflow;
  med_b_inflow.p  = port_b.p;
  med_b_inflow.h  = port_a.h_outflow;
  med_b_inflow.Xi = port_a.Xi_outflow;
  if allowFlowReversal then
    phiMed = Modelica.Fluid.Utilities.regStep(
               x=port_a.m_flow,
               y1=med_a_inflow.phi,
               y2=med_b_inflow.phi,
               x_small=m_flow_small);
  else
    phiMed = med_a_inflow.phi;
  end if;
  // Output signal of sensor
  if dynamic then
    der(phi) = (phiMed-phi)*k/tau;
  else
    phi = phiMed;
  end if;
end RelativeHumidityTwoPort;







Buildings.Fluid.Sensors.RelativePressure
Buildings.Fluid.Sensors.RelativePressure

Ideal relative pressure sensor

Buildings.Fluid.Sensors.RelativePressure

Information




The relative pressure port_a.p - port_b.p is determined between
the two ports of this component and is provided as output signal. The
sensor should be connected in parallel with other equipment, no flow
through the sensor is allowed.




Extends from Modelica.Icons.TranslationalSensor (Icon representing a linear measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumModelica.Media.Interfaces.Pa...Medium in the sensor




Connectors




TypeNameDescription


replaceable package MediumMedium in the sensor


FluidPort_aport_aFluid connector of stream a


FluidPort_bport_bFluid connector of stream b


output RealOutputp_relRelative pressure of port_a minus port_b [Pa]




Modelica definition


model RelativePressure "Ideal relative pressure sensor"
  extends Modelica.Icons.TranslationalSensor;
  replaceable package Medium =
    Modelica.Media.Interfaces.PartialMedium "Medium in the sensor";

  Modelica.Fluid.Interfaces.FluidPort_a port_a(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium) 
    "Fluid connector of stream a";
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium) 
    "Fluid connector of stream b";

  Modelica.Blocks.Interfaces.RealOutput p_rel(final quantity="Pressure",
                                              final unit="Pa",
                                              displayUnit="Pa") 
    "Relative pressure of port_a minus port_b";
equation 
  // Zero flow equations for connectors
  port_a.m_flow = 0;
  port_b.m_flow = 0;

  // No contribution of specific quantities
  port_a.h_outflow = 0;
  port_b.h_outflow = 0;
  port_a.Xi_outflow = zeros(Medium.nXi);
  port_b.Xi_outflow = zeros(Medium.nXi);
  port_a.C_outflow  = zeros(Medium.nC);
  port_b.C_outflow  = zeros(Medium.nC);

  // Relative pressure
  p_rel = port_a.p - port_b.p;
end RelativePressure;







Buildings.Fluid.Sensors.RelativeTemperature
Buildings.Fluid.Sensors.RelativeTemperature

Ideal relative temperature sensor

Buildings.Fluid.Sensors.RelativeTemperature

Information




The relative temperature T(port_a) - T(port_b) is determined between
the two ports of this component and is provided as output signal. The
sensor should be connected in parallel with other equipment.
There is no flow through the sensor.




Note that this sensor should only be connected to fluid volumes, such as

Buildings.Fluid.MixingVolumes.MixingVolume. Otherwise, numerical
problems may occur if one of the mass flow rates are close to zero.
See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Modelica.Icons.TranslationalSensor (Icon representing a linear measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumModelica.Media.Interfaces.Pa...Medium in the sensor




Connectors




TypeNameDescription


replaceable package MediumMedium in the sensor


FluidPort_aport_aFluid connector of stream a


FluidPort_bport_bFluid connector of stream b


output RealOutputT_relTemperature difference of port_a minus port_b [K]




Modelica definition


model RelativeTemperature "Ideal relative temperature sensor"
  extends Modelica.Icons.TranslationalSensor;
  replaceable package Medium =
    Modelica.Media.Interfaces.PartialMedium "Medium in the sensor";
  Modelica.Fluid.Interfaces.FluidPort_a port_a(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium) 
    "Fluid connector of stream a";
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium) 
    "Fluid connector of stream b";
  Modelica.Blocks.Interfaces.RealOutput T_rel(final unit = "K",
                                              displayUnit = "K") 
    "Temperature difference of port_a minus port_b";
equation 
  // Zero flow equations for connectors
  port_a.m_flow = 0;
  port_b.m_flow = 0;
  // No contribution of specific quantities
  port_a.h_outflow = 0;
  port_b.h_outflow = 0;
  port_a.Xi_outflow = zeros(Medium.nXi);
  port_b.Xi_outflow = zeros(Medium.nXi);
  port_a.C_outflow  = zeros(Medium.nC);
  port_b.C_outflow  = zeros(Medium.nC);
  // Relative temperature
  T_rel = Medium.temperature(state=Medium.setState_phX(
            p=port_a.p, h=inStream(port_a.h_outflow), X=inStream(port_a.Xi_outflow))) -
          Medium.temperature(state=Medium.setState_phX(
            p=port_b.p, h=inStream(port_b.h_outflow), X=inStream(port_b.Xi_outflow)));
end RelativeTemperature;







Buildings.Fluid.Sensors.SpecificEnthalpy
Buildings.Fluid.Sensors.SpecificEnthalpy

Ideal one port specific enthalpy sensor

Buildings.Fluid.Sensors.SpecificEnthalpy

Information




This model outputs the specific enthalpy of the fluid connected to its port. 
The sensor is ideal, i.e. it does not influence the fluid.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputh_outSpecific enthalpy in port medium [J/kg]




Modelica definition


model SpecificEnthalpy "Ideal one port specific enthalpy sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput h_out(final quantity="SpecificEnergy",
                                              final unit="J/kg") 
    "Specific enthalpy in port medium";
equation 
  h_out = inStream(port.h_outflow);
end SpecificEnthalpy;







Buildings.Fluid.Sensors.SpecificEnthalpyTwoPort
Buildings.Fluid.Sensors.SpecificEnthalpyTwoPort

Ideal two port sensor for the specific enthalpy

Buildings.Fluid.Sensors.SpecificEnthalpyTwoPort

Information




This model outputs the specific enthalpy of a passing fluid. 
The sensor is ideal, i.e. it does not influence the fluid.
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


SpecificEnthalpyh_out_startMedium.specificEnthalpy_pTX(...Initial or guess value of output (= state) [J/kg]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputh_outSpecific enthalpy of the passing fluid [J/kg]




Modelica definition


model SpecificEnthalpyTwoPort 
  "Ideal two port sensor for the specific enthalpy"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.specificEnthalpy_pTX(p=Medium.p_default, T=Medium.T_default, X=Medium.X_default) 
    "Initial or guess value of output (= state)";
  Modelica.Blocks.Interfaces.RealOutput h_out(final quantity="SpecificEnergy",
                                              final unit="J/kg",
                                              start=h_out_start) 
    "Specific enthalpy of the passing fluid";
protected 
  Modelica.SIunits.SpecificEnthalpy hMed_out(start=h_out_start) 
    "Medium enthalpy to which the sensor is exposed";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(h_out) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      h_out = h_out_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
    hMed_out = Modelica.Fluid.Utilities.regStep(
                 x=port_a.m_flow,
                 y1=port_b.h_outflow,
                 y2=port_a.h_outflow,
                 x_small=m_flow_small);
  else
    hMed_out = port_b.h_outflow;
  end if;
  // Output signal of sensor
  if dynamic then
    der(h_out) = (hMed_out-h_out)*k/tau;
  else
    h_out = hMed_out;
  end if;
end SpecificEnthalpyTwoPort;







Buildings.Fluid.Sensors.SpecificEntropy
Buildings.Fluid.Sensors.SpecificEntropy

Ideal one port specific entropy sensor

Buildings.Fluid.Sensors.SpecificEntropy

Information




This model outputs the specific entropy of the fluid connected to its port. 
The sensor is ideal, i.e., it does not influence the fluid.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputsSpecific entropy in port medium [J/(kg.K)]




Modelica definition


model SpecificEntropy "Ideal one port specific entropy sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput s(final quantity="SpecificEntropy",
                                          final unit="J/(kg.K)") 
    "Specific entropy in port medium";

equation 
  s = Medium.specificEntropy(state=Medium.setState_phX(
          p=port.p, h=inStream(port.h_outflow), X=inStream(port.Xi_outflow)));
end SpecificEntropy;







Buildings.Fluid.Sensors.SpecificEntropyTwoPort
Buildings.Fluid.Sensors.SpecificEntropyTwoPort

Ideal two port sensor for the specific entropy

Buildings.Fluid.Sensors.SpecificEntropyTwoPort

Information




This model outputs the specific entropy of the passing fluid. 
The sensor is ideal, i.e., it does not influence the fluid.
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


SpecificEntropys_startMedium.specificEntropy_pTX(p...Initial or guess value of output (= state) [J/(kg.K)]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputsSpecific entropy of the passing fluid [J/(kg.K)]




Modelica definition


model SpecificEntropyTwoPort 
  "Ideal two port sensor for the specific entropy"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter Modelica.SIunits.SpecificEntropy s_start=
    Medium.specificEntropy_pTX(p=Medium.p_default, T=Medium.T_default, X=Medium.X_default) 
    "Initial or guess value of output (= state)";
  Modelica.Blocks.Interfaces.RealOutput s(final quantity="SpecificEntropy",
                                          final unit="J/(kg.K)",
                                          start=s_start) 
    "Specific entropy of the passing fluid";
protected 
  Modelica.SIunits.SpecificEntropy sMed(start=s_start) 
    "Medium entropy to which the sensor is exposed";
  Medium.SpecificEntropy s_a_inflow 
    "Specific entropy of inflowing fluid at port_a";
  Medium.SpecificEntropy s_b_inflow 
    "Specific entropy of inflowing fluid at port_b, or s_a_inflow if uni-directional flow";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(s) = 0;
    elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      s = s_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     s_a_inflow = Medium.specificEntropy(state=
                    Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     s_b_inflow = Medium.specificEntropy(state=
                    Medium.setState_phX(p=port_a.p, h=port_a.h_outflow, X=port_a.Xi_outflow));
     sMed = Modelica.Fluid.Utilities.regStep(
           x=port_a.m_flow,
           y1=s_a_inflow,
           y2=s_b_inflow,
           x_small=m_flow_small);
  else
     sMed = Medium.specificEntropy(state=
           Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     s_a_inflow = sMed;
     s_b_inflow = sMed;
  end if;
  // Output signal of sensor
  if dynamic then
    der(s) = (sMed-s)*k/tau;
  else
    s = sMed;
  end if;
end SpecificEntropyTwoPort;







Buildings.Fluid.Sensors.Temperature
Buildings.Fluid.Sensors.Temperature

Ideal one port temperature sensor

Buildings.Fluid.Sensors.Temperature

Information




This model outputs the temperature of the fluid connected to its port. 
The sensor is ideal, i.e., it does not influence the fluid.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputTTemperature in port medium [K]




Modelica definition


model Temperature "Ideal one port temperature sensor"
    extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;

  Modelica.Blocks.Interfaces.RealOutput T(final quantity="ThermodynamicTemperature",
                                          final unit = "K",
                                          min=0,
                                          displayUnit = "degC") 
    "Temperature in port medium";

equation 
  T = Medium.temperature(state=Medium.setState_phX(
        p=port.p, h=inStream(port.h_outflow), X=inStream(port.Xi_outflow)));
end Temperature;







Buildings.Fluid.Sensors.TemperatureTwoPort
Buildings.Fluid.Sensors.TemperatureTwoPort

Ideal two port temperature sensor

Buildings.Fluid.Sensors.TemperatureTwoPort

Information




This model outputs the temperature of the medium in the flow
between its fluid ports. The sensor does not influence the fluid. 
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


TemperatureT_startMedium.T_defaultInitial or guess value of output (= state) [K]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputTTemperature of the passing fluid [K]




Modelica definition


model TemperatureTwoPort "Ideal two port temperature sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  Modelica.Blocks.Interfaces.RealOutput T(final quantity="ThermodynamicTemperature",
                                          final unit="K",
                                          displayUnit = "degC",
                                          min = 0,
                                          start=T_start) 
    "Temperature of the passing fluid";
  parameter Modelica.SIunits.Temperature T_start=Medium.T_default 
    "Initial or guess value of output (= state)";

protected 
  Medium.Temperature TMed(start=T_start) 
    "Medium temperature to which the sensor is exposed";
  Medium.Temperature T_a_inflow "Temperature of inflowing fluid at port_a";
  Medium.Temperature T_b_inflow 
    "Temperature of inflowing fluid at port_b, or T_a_inflow if uni-directional flow";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(T) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      T = T_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     T_a_inflow = Medium.temperature(state=
                    Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     T_b_inflow = Medium.temperature(state=
                    Medium.setState_phX(p=port_a.p, h=port_a.h_outflow, X=port_a.Xi_outflow));
     TMed = Modelica.Fluid.Utilities.regStep(
              x=port_a.m_flow,
              y1=T_a_inflow,
              y2=T_b_inflow,
              x_small=m_flow_small);
  else
     TMed = Medium.temperature(state=
              Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     T_a_inflow = TMed;
     T_b_inflow = TMed;
  end if;
  // Output signal of sensor
  if dynamic then
    der(T) = (TMed-T)*k/tau;
  else
    T = TMed;
  end if;
end TemperatureTwoPort;







Buildings.Fluid.Sensors.TemperatureWetBulbTwoPort
Buildings.Fluid.Sensors.TemperatureWetBulbTwoPort

Ideal wet bulb temperature sensor

Buildings.Fluid.Sensors.TemperatureWetBulbTwoPort

Information




This sensor outputs the wet bulb temperature of the medium in the flow
between its fluid ports. The sensor is ideal, i.e., it does not influence the fluid.
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


TemperatureTWetBul_startMedium.T_defaultInitial or guess value of wet bulb temperature (used to compute initial output signal)) [K]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputTWet bulb temperature in port medium [K]




Modelica definition


model TemperatureWetBulbTwoPort "Ideal wet bulb temperature sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  Modelica.Blocks.Interfaces.RealOutput T(
    start=TWetBul_start,
    final quantity="ThermodynamicTemperature",
    final unit="K",
    displayUnit = "degC") "Wet bulb temperature in port medium";
  parameter Modelica.SIunits.Temperature TWetBul_start = Medium.T_default 
    "Initial or guess value of wet bulb temperature (used to compute initial output signal))";

protected 
  Medium.Temperature TMedWetBul(start=TWetBul_start) 
    "Medium wet bulb temperature to which the sensor is exposed";
  Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulMod(
    redeclare package Medium = Medium,
    TWetBul(start=TWetBul_start)) "Block for wet bulb temperature";
  Modelica.SIunits.SpecificEnthalpy h "Specific enthalpy";
  Medium.MassFraction Xi[Medium.nXi] 
    "Species vector, needed because indexed argument for the operator inStream is not supported";
initial equation 
  // Initialization of wet bulb temperature
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(T) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
            initType == Modelica.Blocks.Types.Init.InitialOutput then
      T = TWetBul_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
    h  = Modelica.Fluid.Utilities.regStep(
           x=port_a.m_flow,
           y1=port_b.h_outflow,
           y2=port_a.h_outflow,
           x_small=m_flow_small);
    Xi = Modelica.Fluid.Utilities.regStep(
           x=port_a.m_flow,
           y1=port_b.Xi_outflow,
           y2=port_a.Xi_outflow,
           x_small=m_flow_small);
  else
    h = port_b.h_outflow;
    Xi = port_b.Xi_outflow;
  end if;
  // Compute wet bulb temperature
  wetBulMod.TDryBul = Medium.T_phX(p=port_a.p, h=h, X=cat(1,Xi,{1-sum(Xi)}));
  wetBulMod.Xi = Xi;
  wetBulMod.p  = port_a.p;
  TMedWetBul = wetBulMod.TWetBul;
  // Output signal of sensor
  if dynamic then
    der(T) = (TMedWetBul-T)*k/tau;
  else
    T = TMedWetBul;
  end if;
end TemperatureWetBulbTwoPort;







Buildings.Fluid.Sensors.TraceSubstances
Buildings.Fluid.Sensors.TraceSubstances

Ideal one port trace substances sensor

Buildings.Fluid.Sensors.TraceSubstances

Information




This model outputs the trace substances contained in the fluid connected to its port. 
The sensor is ideal, i.e., it does not influence the fluid.




Read the 

Buildings.Fluid.Sensors.UsersGuide
prior to using this model with one fluid port.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor (Partial component to model a sensor that measures a potential variable), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the sensor


StringsubstanceName"CO2"Name of trace substance




Connectors




TypeNameDescription


FluidPort_aport 


output RealOutputCTrace substance in port medium




Modelica definition


model TraceSubstances "Ideal one port trace substances sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter String substanceName = "CO2" "Name of trace substance";

  Modelica.Blocks.Interfaces.RealOutput C(min=0) 
    "Trace substance in port medium";

protected 
  parameter Real s[Medium.nC](each fixed=false) 
    "Vector with zero everywhere except where species is";
initial algorithm 
  for i in 1:Medium.nC loop
    if ( Modelica.Utilities.Strings.isEqual(string1=Medium.extraPropertiesNames[i],
                                            string2=substanceName,
                                            caseSensitive=false)) then
      s[i] :=1;
    else
      s[i] :=0;
    end if;
  end for;
  assert(abs(1-sum(s)) < 1E-4, "Trace substance '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
equation 
  // We obtain the species concentration with a vector multiplication
  // because Dymola 7.3 cannot find the derivative in the model
  // Buildings.Examples.VAVSystemCTControl.mo
  // if we set C = CVec[ind];
  C = s*inStream(port.C_outflow);
end TraceSubstances;







Buildings.Fluid.Sensors.TraceSubstancesTwoPort
Buildings.Fluid.Sensors.TraceSubstancesTwoPort

Ideal two port sensor for trace substance

Buildings.Fluid.Sensors.TraceSubstancesTwoPort

Information




This model outputs the trace substance of the passing fluid. 
The sensor is ideal, i.e., it does not influence the fluid.
If the parameter tau is non-zero, then its output
is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


StringsubstanceName"CO2"Name of trace substance


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


RealC_start0Initial or guess value of output (= state)


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputCTrace substance of the passing fluid




Modelica definition


model TraceSubstancesTwoPort 
  "Ideal two port sensor for trace substance"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput C(min=0,
                                          start=C_start) 
    "Trace substance of the passing fluid";
  parameter String substanceName = "CO2" "Name of trace substance";
  parameter Real C_start(min=0) = 0 
    "Initial or guess value of output (= state)";

protected 
  Real CMed(min=0, start=C_start, nominal=sum(Medium.C_nominal)) 
    "Medium trace substance to which the sensor is exposed";
  parameter Real s[Medium.nC](each fixed=false) 
    "Vector with zero everywhere except where the trace substance is";
initial algorithm 
  for i in 1:Medium.nC loop
    if ( Modelica.Utilities.Strings.isEqual(string1=Medium.extraPropertiesNames[i],
                                            string2=substanceName,
                                            caseSensitive=false)) then
      s[i] :=1;
    else
      s[i] :=0;
    end if;
  end for;
  assert(abs(1-sum(s))<1E-4, "Trace substance '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(C) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      C = C_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     CMed = Modelica.Fluid.Utilities.regStep(
              x=port_a.m_flow,
              y1=s*port_b.C_outflow,
              y2=s*port_a.C_outflow,
              x_small=m_flow_small);
  else
     CMed = s*inStream(port_b.C_outflow);
  end if;
  // Output signal of sensor
  if dynamic then
    der(C) = (CMed-C)*k/tau;
  else
    C = CMed;
  end if;
end TraceSubstancesTwoPort;







Buildings.Fluid.Sensors.VolumeFlowRate
Buildings.Fluid.Sensors.VolumeFlowRate

Ideal sensor for volume flow rate

Buildings.Fluid.Sensors.VolumeFlowRate

Information




This model outputs the volume flow rate flowing from 
port_a to port_b. 
The sensor is ideal, i.e., it does not influence the fluid.
If the parameter tau is non-zero, then the measured
density that is used to convert the mass flow rate into
volumetric flow rate is computed using a first order differential equation. 
Setting tau=0 is not recommend. See

Buildings.Fluid.Sensors.UsersGuide for an explanation.




Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model), Modelica.Icons.RotationalSensor (Icon representing a round measurement device).

Parameters




TypeNameDefaultDescription


replaceable package MediumPartialMediumMedium in the component


Timetau1Time constant at nominal flow rate [s]


Nominal condition


MassFlowRatem_flow_nominal Nominal mass flow rate, used for regularization near zero flow [kg/s]


Advanced


MassFlowRatem_flow_small1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]


Initialization


InitinitTypeModelica.Blocks.Types.Init.I...Type of initialization (InitialState and InitialOutput are identical)


Densityd_startMedium.density(Medium.setSta...Initial or guess value of density [kg/m3]


TemperatureT_startMedium.T_defaultTemperature used to compute d_start [K]


Pressurep_startMedium.p_defaultPressure used to compute d_start [Pa]


MassFractionX_start[Medium.nX]Medium.X_defaultMass fraction used to compute d_start [1]


Assumptions


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




Connectors




TypeNameDescription


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


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


output RealOutputV_flowVolume flow rate from port_a to port_b [m3/s]




Modelica definition


model VolumeFlowRate "Ideal sensor for volume flow rate"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter Medium.Density
    d_start=Medium.density(Medium.setState_pTX(p_start, T_start, X_start)) 
    "Initial or guess value of density";
  parameter Modelica.SIunits.Temperature T_start=Medium.T_default 
    "Temperature used to compute d_start";
  parameter Modelica.SIunits.Pressure p_start=Medium.p_default 
    "Pressure used to compute d_start";
  parameter Modelica.SIunits.MassFraction X_start[Medium.nX]=Medium.X_default 
    "Mass fraction used to compute d_start";
  Modelica.Blocks.Interfaces.RealOutput V_flow(final quantity="VolumeFlowRate",
                                               final unit="m3/s") 
    "Volume flow rate from port_a to port_b";
protected 
  Medium.Density dMed(start=d_start) 
    "Medium temperature to which the sensor is exposed";

  Medium.Density d_a_inflow(start=d_start) 
    "Density of inflowing fluid at port_a";
  Medium.Density d_b_inflow(start=d_start) 
    "Density of inflowing fluid at port_b, or rho_a_inflow if uni-directional flow";
  Medium.Density d(start=d_start) "Density of the passing fluid";
initial equation 
  if dynamic then
    if initType == Modelica.Blocks.Types.Init.SteadyState then
      der(d) = 0;
     elseif initType == Modelica.Blocks.Types.Init.InitialState or 
           initType == Modelica.Blocks.Types.Init.InitialOutput then
      d = d_start;
    end if;
  end if;
equation 
  if allowFlowReversal then
     d_a_inflow = Medium.density(state=
                    Medium.setState_phX(p=port_b.p, h=port_b.h_outflow, X=port_b.Xi_outflow));
     d_b_inflow = Medium.density(state=
                    Medium.setState_phX(p=port_a.p, h=port_a.h_outflow, X=port_a.Xi_outflow));
     dMed = Modelica.Fluid.Utilities.regStep(
              x=port_a.m_flow,
              y1=d_a_inflow,
              y2=d_b_inflow,
              x_small=m_flow_small);
  else
     dMed = Medium.density(state=Medium.setState_phX(
              p=port_b.p,
              h=port_b.h_outflow,
              X=port_b.Xi_outflow));
     d_a_inflow = dMed;
     d_b_inflow = dMed;
  end if;
  // Output signal of density sensor that is used to compute
  // the volume flow rate
  if dynamic then
    der(d) = (dMed-d)*k/tau;
  else
    d = dMed;
  end if;
  // Volume flow rate
  V_flow = port_a.m_flow/d;
end VolumeFlowRate;





Automatically generated Wed Feb 12 08:16:53 2014.