Buildings.Fluid.Sensors

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Buildings.Fluid.Sensors

Package with sensor models

Information

Package Sensors consists of idealized sensor components that provide variables of a medium model and/or fluid ports as output signals. These signals can be, e.g., further processed with components of the Modelica.Blocks library. Also more realistic sensor models can be built, by further processing (e.g., by attaching block Modelica.Blocks.Continuous.FirstOrder to model the time constant of the sensor).

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

Package Content

Name Description

UsersGuide User's Guide

Conversions Package with conversions for sensor models

Density Ideal one port density sensor

DensityTwoPort Ideal two port density sensor

EnthalpyFlowRate Ideal enthalphy flow rate sensor

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

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

MassFlowRate Ideal sensor for mass flow rate

MassFraction Ideal one port mass fraction sensor

MassFractionTwoPort Ideal two port mass fraction sensor

Pressure Ideal pressure sensor

RelativeHumidity Ideal one port relative humidity sensor

RelativeHumidityTwoPort Ideal two port relative humidity sensor

RelativePressure Ideal relative pressure sensor

RelativeTemperature Ideal relative temperature sensor

SpecificEnthalpy Ideal one port specific enthalpy sensor

SpecificEnthalpyTwoPort Ideal two port sensor for the specific enthalpy

SpecificEntropy Ideal one port specific entropy sensor

SpecificEntropyTwoPort Ideal two port sensor for the specific entropy

Temperature Ideal one port temperature sensor

TemperatureTwoPort Ideal two port temperature sensor

TemperatureWetBulbTwoPort Ideal wet bulb temperature sensor

TraceSubstances Ideal one port trace substances sensor

TraceSubstancesTwoPort Ideal two port sensor for trace substance

VolumeFlowRate Ideal sensor for volume flow rate

Examples Collection of models that illustrate model use and test models

BaseClasses Package with base classes for Buildings.Fluid.Sensors

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

Buildings.Fluid.Sensors.Density

Ideal one port density sensor

Buildings.Fluid.Sensors.Density

Information

This component monitors the density of the fluid passing its port. The sensor is ideal, i.e. it does not influence the fluid.

If using the one port sensor, read the Information first.

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

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput d Density in port medium [kg/m3]

Type	Name	Description
FluidPort_a	port
output RealOutput	d	Density 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(Medium.setState_phX(port.p, inStream(port.h_outflow), inStream(port.Xi_outflow)));
end Density;

Buildings.Fluid.Sensors.DensityTwoPort

Ideal two port density sensor

Buildings.Fluid.Sensors.DensityTwoPort

Information

This component monitors 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

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

Density d_start Medium.density(Medium.setSta... Initial or guess value of output (=state) [kg/m3]

Temperature T_start Medium.T_default Temperature used to compute d_start [K]

Pressure p_start Medium.p_default Pressure used to compute d_start [Pa]

MassFraction X_start[Medium.nX] Medium.X_default Mass fraction used to compute d_start [1]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Density	d_start	Medium.density(Medium.setSta...	Initial or guess value of output (=state) [kg/m3]
Temperature	T_start	Medium.T_default	Temperature used to compute d_start [K]
Pressure	p_start	Medium.p_default	Pressure used to compute d_start [Pa]
MassFraction	X_start[Medium.nX]	Medium.X_default	Mass fraction used to compute d_start [1]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type Name Description

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

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

output RealOutput d Density of the passing fluid [kg/m3]

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)
output RealOutput	d	Density 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(Medium.setState_pTX(p_start, T_start, 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";
  Medium.Density dMed(start=d_start) 
    "Medium temperature to which the sensor is exposed";
protected 
  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(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     d_b_inflow = Medium.density(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     dMed = Modelica.Fluid.Utilities.regStep(port_a.m_flow, d_a_inflow, d_b_inflow, m_flow_small);
  else
     dMed = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, 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

Ideal enthalphy flow rate sensor

Buildings.Fluid.Sensors.EnthalpyFlowRate

Information

This component monitors 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 h_out that is used to compute the enthalpy flow rate Ḣ = ṁ h_out 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 0 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

SpecificEnthalpy h_out_start Medium.specificEnthalpy_pTX(... Initial or guess value of measured specific enthalpy [J/kg]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	0	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpy	h_out_start	Medium.specificEnthalpy_pTX(...	Initial or guess value of measured specific enthalpy [J/kg]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	H_flow	Enthalpy 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(tau=0);
  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(Medium.p_default, Medium.T_default, Medium.X_default) 
    "Initial or guess value of measured specific enthalpy";
  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(port_a.m_flow,
                 port_b.h_outflow,
                 port_a.h_outflow, 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

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

Buildings.Fluid.Sensors.SensibleEnthalpyFlowRate

Information

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

Ḣ_tot = Ḣ_sen + Ḣ_lat,

where Ḣ_sen = ṁ (1-X_w) c_p,air, then this sensor outputs Ḣ = Ḣ_sen.

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

For a sensor that measures Ḣ_tot, use Buildings.Fluid.Sensors.EnthalpyFlowRate.
For a sensor that measures Ḣ_lat, 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(state).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 0 Time constant at nominal flow rate [s]

Integer i_w 1 Index for water substance

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

SpecificEnthalpy h_out_start Medium.enthalpyOfNonCondensi... Initial or guess value of measured specific sensible enthalpy [J/kg]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	0	Time constant at nominal flow rate [s]
Integer	i_w	1	Index for water substance
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpy	h_out_start	Medium.enthalpyOfNonCondensi...	Initial or guess value of measured specific sensible enthalpy [J/kg]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	H_flow	Sensible 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(tau=0);
  extends Modelica.Icons.RotationalSensor;
  // redeclare Medium with a more restricting base class. This improves the error
  // message if a user selects a medium that does not contain the function
  // enthalpyOfLiquid(.)
  replaceable package Medium =
      Modelica.Media.Interfaces.PartialCondensingGases;
  parameter Integer i_w = 1 "Index for water substance";
  Modelica.Blocks.Interfaces.RealOutput H_flow(unit="W") 
    "Sensible enthalpy flow rate, positive if from port_a to port_b";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.enthalpyOfNonCondensingGas(
      Medium.temperature(Medium.setState_phX(
        Medium.p_default, Medium.T_default, Medium.X_default))) 
    "

Initial or guess value of measured specific sensible enthalpy

";
  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";
protected 
  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";
  Medium.ThermodynamicState sta "Medium state to which sensor is exposed to";
  parameter Integer i_w_internal(fixed=false) "Index for water substance";
initial algorithm 
  // Compute index of species vector that carries the water vapor concentration
  i_w_internal :=-1;
    for i in 1:Medium.nXi loop
      if Modelica.Utilities.Strings.isEqual(string1=Medium.substanceNames[i],
                                            string2="Water",
                                            caseSensitive=false) then
        i_w_internal :=i;
      end if;
    end for;
  assert(i_w_internal > 0, "Substance 'water' is not present in medium '"
                  + Medium.mediumName + "'.\n"
                  + "Change medium model to one that has 'water' as a substance.");
  assert(i_w == i_w_internal, "Parameter 'i_w' must be set to '" + String(i_w) + "'.\n");
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(port_a.m_flow,
                 port_b.Xi_outflow,
                 port_a.Xi_outflow, m_flow_small);
     hActual = Modelica.Fluid.Utilities.regStep(port_a.m_flow,
                 port_b.h_outflow,
                 port_a.h_outflow, m_flow_small);
  else
     XiActual = port_b.Xi_outflow;
     hActual = port_b.h_outflow;
  end if;
  // Specific enthalpy measured by sensor
  sta = Medium.setState_phX(port_a.p, hActual, XiActual);
  hMed_out = (1-XiActual[i_w]) * Medium.enthalpyOfNonCondensingGas(
      Medium.temperature(sta));
  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

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

Buildings.Fluid.Sensors.LatentEnthalpyFlowRate

Information

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

Ḣ_tot = Ḣ_sen + Ḣ_lat,

where Ḣ_sen = ṁ (1-X_w) c_p,air, then this sensor outputs Ḣ = Ḣ_lat.

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

For a sensor that measures Ḣ_tot, use Buildings.Fluid.Sensors.EnthalpyFlowRate.
For a sensor that measures Ḣ_sen, 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(state).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 0 Time constant at nominal flow rate [s]

Integer i_w 1 Index for water substance

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

SpecificEnthalpy h_out_start Medium.specificEnthalpy_pTX(... Initial or guess value of measured specific latent enthalpy [J/kg]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	0	Time constant at nominal flow rate [s]
Integer	i_w	1	Index for water substance
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpy	h_out_start	Medium.specificEnthalpy_pTX(...	Initial or guess value of measured specific latent enthalpy [J/kg]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	H_flow	Latent 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(tau=0);
  extends Modelica.Icons.RotationalSensor;
  // redeclare Medium with a more restricting base class. This improves the error
  // message if a user selects a medium that does not contain the function
  // enthalpyOfLiquid(.)
  replaceable package Medium =
      Modelica.Media.Interfaces.PartialCondensingGases;
  parameter Integer i_w = 1 "Index for water substance";
  Modelica.Blocks.Interfaces.RealOutput H_flow(unit="W") 
    "Latent enthalpy flow rate, positive if from port_a to port_b";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.specificEnthalpy_pTX(Medium.p_default, Medium.T_default, Medium.X_default)
    -Medium.enthalpyOfNonCondensingGas(
      Medium.temperature(Medium.setState_phX(
        Medium.p_default, Medium.T_default, Medium.X_default))) 
    "

Initial or guess value of measured specific latent enthalpy

";
  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";
protected 
  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";
  Medium.ThermodynamicState sta "Medium state to which sensor is exposed to";
  parameter Integer i_w_internal(fixed=false) "Index for water substance";
initial algorithm 
  // Compute index of species vector that carries the water vapor concentration
  i_w_internal :=-1;
    for i in 1:Medium.nXi loop
      if Modelica.Utilities.Strings.isEqual(string1=Medium.substanceNames[i],
                                            string2="Water",
                                            caseSensitive=false) then
        i_w_internal :=i;
      end if;
    end for;
  assert(i_w_internal > 0, "Substance 'water' is not present in medium '"
                  + Medium.mediumName + "'.\n"
                  + "Change medium model to one that has 'water' as a substance.");
  assert(i_w == i_w_internal, "Parameter 'i_w' must be set to '" + String(i_w) + "'.\n");
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(port_a.m_flow,
                 port_b.Xi_outflow,
                 port_a.Xi_outflow, m_flow_small);
     hActual = Modelica.Fluid.Utilities.regStep(port_a.m_flow,
                 port_b.h_outflow,
                 port_a.h_outflow, m_flow_small);
  else
     XiActual = port_b.Xi_outflow;
     hActual = port_b.h_outflow;
  end if;
  // Specific enthalpy measured by sensor
  sta = Medium.setState_phX(port_a.p, hActual, XiActual);
  // 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_w]) * Medium.enthalpyOfNonCondensingGas(Medium.temperature(sta)));
  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

Ideal sensor for mass flow rate

Buildings.Fluid.Sensors.MassFlowRate

Information

This component monitors 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

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Nominal condition

MassFlowRate m_flow_nominal 0 Nominal mass flow rate, used for regularization near zero flow [kg/s]

Advanced

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

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Nominal condition
MassFlowRate	m_flow_nominal	0	Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	0	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

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

Ideal one port mass fraction sensor

Buildings.Fluid.Sensors.MassFraction

Information

This component monitors the mass fraction contained in the fluid passing its port. The sensor is ideal, i.e. it does not influence the fluid.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

String substanceName "water" Name of species substance

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor
String	substanceName	"water"	Name of species substance

Connectors

Type Name Description

FluidPort_a port

output RealOutput X Mass fraction in port medium

Type	Name	Description
FluidPort_a	port
output RealOutput	X	Mass fraction in port medium

Modelica definition

model MassFraction "Ideal one port mass fraction sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter String substanceName = "water" "Name of species substance";

  Modelica.Blocks.Interfaces.RealOutput X(min=0, max=1) 
    "Mass fraction in port medium";

protected 
  parameter Integer ind(fixed=false) 
    "Index of species in vector of auxiliary substances";
  Medium.MassFraction XiVec[Medium.nXi](
      quantity=Medium.extraPropertiesNames) 
    "Trace substances vector, needed because indexed argument for the operator inStream is not supported";
initial algorithm 
  ind:= -1;
  for i in 1:Medium.nX loop
    if ( Modelica.Utilities.Strings.isEqual(string1=Medium.substanceNames[i],
                                            string2=substanceName,
                                            caseSensitive=false)) then
      ind := i;
    end if;
  end for;
  assert(ind > 0, "Species with name '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
equation 
  XiVec = inStream(port.Xi_outflow);
  X = if ind > Medium.nXi then (1-sum(XiVec)) else XiVec[ind];
end MassFraction;

Buildings.Fluid.Sensors.MassFractionTwoPort

Ideal two port mass fraction sensor

Buildings.Fluid.Sensors.MassFractionTwoPort

Information

This component monitors 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

String substanceName "water" Name of species substance

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

MassFraction X_start Medium.X_default[ind] Initial or guess value of output (= state) [kg/kg]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
String	substanceName	"water"	Name of species substance
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
MassFraction	X_start	Medium.X_default[ind]	Initial or guess value of output (= state) [kg/kg]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	X	Mass fraction of the passing fluid

Modelica definition

model MassFractionTwoPort "Ideal two port mass fraction sensor"
  extends Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter String substanceName = "water" "Name of species substance";
  Modelica.Blocks.Interfaces.RealOutput X(min=0, max=1, start=X_start) 
    "Mass fraction of the passing fluid";
  parameter Medium.MassFraction X_start=Medium.X_default[ind] 
    "Initial or guess value of output (= state)";
  Medium.MassFraction XMed(start=X_start) 
    "Mass fraction to which the sensor is exposed";
protected 
  parameter Integer ind(fixed=false) 
    "Index of species in vector of auxiliary substances";
  Medium.MassFraction XiVec[Medium.nXi](
      quantity=Medium.extraPropertiesNames) 
    "Trace substances vector, needed because indexed argument for the operator inStream is not supported";
initial algorithm 
  // Compute the index of the element in the substance vector
  ind:= -1;
  for i in 1:Medium.nX loop
    if ( Modelica.Utilities.Strings.isEqual(string1=Medium.substanceNames[i],
                                            string2=substanceName,
                                            caseSensitive=false)) then
      ind := i;
    end if;
  end for;
  assert(ind > 0, "Species with name '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
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(port_a.m_flow,
         port_b.Xi_outflow, port_a.Xi_outflow, m_flow_small);
  else
    XiVec = port_b.Xi_outflow;
  end if;
  XMed = if ind > Medium.nXi then (1-sum(XiVec)) else XiVec[ind];
  // Output signal of sensor
  if dynamic then
    der(X)  = (XMed-X)*k/tau;
  else
    X = XMed;
  end if;
end MassFractionTwoPort;

Buildings.Fluid.Sensors.Pressure

Ideal pressure sensor

Buildings.Fluid.Sensors.Pressure

Information

This component monitors the absolute pressure at its fluid port. The sensor is ideal, i.e., it does not influence the fluid.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput p Pressure at port [Pa]

Type	Name	Description
FluidPort_a	port
output RealOutput	p	Pressure 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

Ideal one port relative humidity sensor

Buildings.Fluid.Sensors.RelativeHumidity

Information

This component monitors the relative humidity contained in the fluid passing 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput phi Relative humidity in port medium [1]

Type	Name	Description
FluidPort_a	port
output RealOutput	phi	Relative 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

Ideal two port relative humidity sensor

Buildings.Fluid.Sensors.RelativeHumidityTwoPort

Information

This component monitors 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

Real phi_start 0.5 Initial or guess value of output (= state) [1]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Real	phi_start	0.5	Initial or guess value of output (= state) [1]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	phi	Relative 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)";
  Real phiMed(unit="1", min=0, start=phi_start) 
    "Relative humidity to which the sensor is exposed";
protected 
  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(port_a.m_flow,
            med_a_inflow.phi,
            med_b_inflow.phi, 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

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).

Connectors

Type Name Description

FluidPort_a port_a

FluidPort_b port_b

output RealOutput p_rel Relative pressure signal [Pa]

Type	Name	Description
FluidPort_a	port_a
FluidPort_b	port_b
output RealOutput	p_rel	Relative pressure signal [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);
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium);

  Modelica.Blocks.Interfaces.RealOutput p_rel(final quantity="Pressure",
                                              final unit="Pa",
                                              displayUnit="bar") 
    "Relative pressure signal";
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

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).

Connectors

Type Name Description

FluidPort_a port_a

FluidPort_b port_b

output RealOutput T_rel Relative temperature signal [K]

Type	Name	Description
FluidPort_a	port_a
FluidPort_b	port_b
output RealOutput	T_rel	Relative temperature signal [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);
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                p(start=Medium.p_default),
                                redeclare package Medium = Medium);
  Modelica.Blocks.Interfaces.RealOutput T_rel(final quantity="Temperature",
                                              final unit = "K", displayUnit = "degC", min=0) 
    "Relative temperature signal";
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(Medium.setState_phX(port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow))) -
          Medium.temperature(Medium.setState_phX(port_b.p, inStream(port_b.h_outflow), inStream(port_b.Xi_outflow)));
end RelativeTemperature;

Buildings.Fluid.Sensors.SpecificEnthalpy

Ideal one port specific enthalpy sensor

Buildings.Fluid.Sensors.SpecificEnthalpy

Information

This component monitors the specific enthalpy of the fluid passing its port. The sensor is ideal, i.e. it does not influence the fluid.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput h_out Specific enthalpy in port medium [J/kg]

Type	Name	Description
FluidPort_a	port
output RealOutput	h_out	Specific 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

Ideal two port sensor for the specific enthalpy

Buildings.Fluid.Sensors.SpecificEnthalpyTwoPort

Information

This component monitors 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

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

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
SpecificEnthalpy	h_out_start	Medium.specificEnthalpy_pTX(...	Initial or guess value of output (= state) [J/kg]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	h_out	Specific 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;
  Modelica.Blocks.Interfaces.RealOutput h_out(final quantity="SpecificEnergy",
                                              final unit="J/kg",
                                              start=h_out_start) 
    "Specific enthalpy of the passing fluid";
  parameter Modelica.SIunits.SpecificEnthalpy h_out_start=
    Medium.specificEnthalpy_pTX(Medium.p_default, Medium.T_default, Medium.X_default) 
    "Initial or guess value of output (= state)";
  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(port_a.m_flow,
                 port_b.h_outflow,
                 port_a.h_outflow, 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

Ideal one port specific entropy sensor

Buildings.Fluid.Sensors.SpecificEntropy

Information

This component monitors the specific entropy of the fluid passing its port. The sensor is ideal, i.e. it does not influence the fluid.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput s Specific entropy in port medium [J/(kg.K)]

Type	Name	Description
FluidPort_a	port
output RealOutput	s	Specific 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(Medium.setState_phX(port.p,
          inStream(port.h_outflow), inStream(port.Xi_outflow)));
end SpecificEntropy;

Buildings.Fluid.Sensors.SpecificEntropyTwoPort

Ideal two port sensor for the specific entropy

Buildings.Fluid.Sensors.SpecificEntropyTwoPort

Information

This component monitors 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

SpecificEntropy s_start Medium.specificEntropy_pTX(M... Initial or guess value of output (= state) [J/(kg.K)]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
SpecificEntropy	s_start	Medium.specificEntropy_pTX(M...	Initial or guess value of output (= state) [J/(kg.K)]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	s	Specific 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;
  Modelica.Blocks.Interfaces.RealOutput s(final quantity="SpecificEntropy",
                                          final unit="J/(kg.K)",
                                          start=s_start) 
    "Specific entropy of the passing fluid";
  parameter Modelica.SIunits.SpecificEntropy s_start=
    Medium.specificEntropy_pTX(Medium.p_default, Medium.T_default, Medium.X_default) 
    "Initial or guess value of output (= state)";
  Modelica.SIunits.SpecificEntropy sMed(start=s_start) 
    "Medium entropy to which the sensor is exposed";
protected 
  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(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     s_b_inflow = Medium.specificEntropy(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     s = Modelica.Fluid.Utilities.regStep(port_a.m_flow, s_a_inflow, s_b_inflow, m_flow_small);
  else
     s = Medium.specificEntropy(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     s_a_inflow = s;
     s_b_inflow = s;
  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

Ideal one port temperature sensor

Buildings.Fluid.Sensors.Temperature

Information

This component monitors the temperature of the fluid passing 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).

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor

Connectors

Type Name Description

FluidPort_a port

output RealOutput T Temperature in port medium [K]

Type	Name	Description
FluidPort_a	port
output RealOutput	T	Temperature 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="Temperature",
                                          final unit = "K", min=0,
                                          displayUnit = "degC") 
    "Temperature in port medium";

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

Buildings.Fluid.Sensors.TemperatureTwoPort

Ideal two port temperature sensor

Buildings.Fluid.Sensors.TemperatureTwoPort

Information

This component monitors the temperature of the medium in the flow between 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

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

Temperature T_start Medium.T_default Initial or guess value of output (= state) [K]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Temperature	T_start	Medium.T_default	Initial or guess value of output (= state) [K]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	T	Temperature 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="Temperature",
                                          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)";
  Medium.Temperature TMed(start=T_start) 
    "Medium temperature to which the sensor is exposed";
protected 
  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(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     T_b_inflow = Medium.temperature(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     TMed = Modelica.Fluid.Utilities.regStep(port_a.m_flow, T_a_inflow, T_b_inflow, m_flow_small);
  else
     TMed = Medium.temperature(Medium.setState_phX(port_b.p, port_b.h_outflow, 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

Ideal wet bulb temperature sensor

Buildings.Fluid.Sensors.TemperatureWetBulbTwoPort

Information

This component monitors the wet bulb temperature 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 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

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

Temperature TWetBul_start Medium.T_default Initial or guess value of wet bulb temperature (used to compute initial output signal)) [K]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Temperature	TWetBul_start	Medium.T_default	Initial or guess value of wet bulb temperature (used to compute initial output signal)) [K]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	T	Wet 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="Temperature",
    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))

";
  Medium.Temperature TMedWetBul(start=TWetBul_start) 
    "Medium wet bulb temperature to which the sensor is exposed";
protected 
  Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulMod(
    redeclare package Medium = Medium) "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(port_a.m_flow, port_b.h_outflow,  port_a.h_outflow,  m_flow_small);
    Xi = Modelica.Fluid.Utilities.regStep(port_a.m_flow, port_b.Xi_outflow, port_a.Xi_outflow, 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(port_a.p, h, 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

Ideal one port trace substances sensor

Buildings.Fluid.Sensors.TraceSubstances

Information

This component monitors the trace substances contained in the fluid passing its port. The sensor is ideal, i.e. it does not influence the fluid.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the sensor

String substanceName "CO2" Name of trace substance

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the sensor
String	substanceName	"CO2"	Name of trace substance

Connectors

Type Name Description

FluidPort_a port

output RealOutput C Trace substance in port medium

Type	Name	Description
FluidPort_a	port
output RealOutput	C	Trace 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 "Trace substance in port medium";

protected 
  parameter Real s[Medium.nC](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

Ideal two port sensor for trace substance

Buildings.Fluid.Sensors.TraceSubstancesTwoPort

Information

This component monitors 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.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 1 Time constant at nominal flow rate [s]

String substanceName "CO2" Name of trace substance

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

Real C_start Initial or guess value of output (= state)

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	1	Time constant at nominal flow rate [s]
String	substanceName	"CO2"	Name of trace substance
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Real	C_start		Initial or guess value of output (= state)
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	C	Trace 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,
                                          nominal=Medium.C_nominal,
                                          start=C_start) 
    "Trace substance of the passing fluid";
  parameter String substanceName = "CO2" "Name of trace substance";
  parameter Real C_start(min=0) "Initial or guess value of output (= state)";
  Real CMed(min=0, start=C_start, nominal=Medium.C_nominal) 
    "Medium trace substance to which the sensor is exposed";
protected 
  parameter Real s[Medium.nC](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.");
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(port_a.m_flow, s*port_b.C_outflow, s*port_a.C_outflow, 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

Ideal sensor for volume flow rate

Buildings.Fluid.Sensors.VolumeFlowRate

Information

This component monitors 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. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

Parameters

Type Name Default Description

replaceable package Medium PartialMedium Medium in the component

Time tau 0 Time constant at nominal flow rate [s]

Nominal condition

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

Advanced

MassFlowRate m_flow_small 1E-4*m_flow_nominal For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

Initialization

Init initType Modelica.Blocks.Types.Init.N... Type of initialization (InitialState and InitialOutput are identical)

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

Temperature T_start Medium.T_default Temperature used to compute d_start [K]

Pressure p_start Medium.p_default Pressure used to compute d_start [Pa]

MassFraction X_start[Medium.nX] Medium.X_default Mass fraction used to compute d_start [1]

Assumptions

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

Type	Name	Default	Description
replaceable package Medium	PartialMedium	Medium in the component
Time	tau	0	Time constant at nominal flow rate [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, used for regularization near zero flow [kg/s]
Advanced
MassFlowRate	m_flow_small	1E-4*m_flow_nominal	For bi-directional flow, temperature is regularized in the region \|m_flow\| < m_flow_small (m_flow_small > 0 required) [kg/s]
Initialization
Init	initType	Modelica.Blocks.Types.Init.N...	Type of initialization (InitialState and InitialOutput are identical)
Density	d_start	Medium.density(Medium.setSta...	Initial or guess value of density [kg/m3]
Temperature	T_start	Medium.T_default	Temperature used to compute d_start [K]
Pressure	p_start	Medium.p_default	Pressure used to compute d_start [Pa]
MassFraction	X_start[Medium.nX]	Medium.X_default	Mass fraction used to compute d_start [1]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
output RealOutput	V_flow	Volume 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(tau=0);
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput V_flow(final quantity="VolumeFlowRate",
                                               final unit="m3/s") 
    "Volume flow rate from port_a to port_b";
  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";
  Medium.Density dMed(start=d_start) 
    "Medium temperature to which the sensor is exposed";
protected 
  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(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     d_b_inflow = Medium.density(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     dMed = Modelica.Fluid.Utilities.regStep(port_a.m_flow, d_a_inflow, d_b_inflow, m_flow_small);
  else
     dMed = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, 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 Thu Jul 26 10:21:32 2012.