Modelica.Fluid.Sensors

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.FirstOrder to model the time constant of the sensor).

For the thermodynamic state variables temperature, specific entalpy, specific entropy and density the fluid library provides two different types of sensors: regular one port and two port sensors.

• The regular one port sensors have the advantage of easy introduction and removal from a model, as no connections have to be broken. A potential drawback is that the obtained value jumps as flow reverts.
• The two port sensors offer the advantages of an adjustable regularized step function around zero flow. Moreover the obtained result is restricted to the value flowing into port_a if allowFlowReversal is false.

Modelica.Fluid.Examples.Explanatory.MeasuringTemperature demonstrates the differences between one- and two-port sensor at hand of a simple example.

Extends from Modelica.Fluid.Icons.VariantLibrary (Icon for a library that contains several variants of one component).

Package Content

Name	Description
Pressure	Ideal pressure sensor
Density	Ideal one port density sensor
DensityTwoPort	Ideal two port density sensor
Temperature	Ideal one port temperature sensor
TemperatureTwoPort	Ideal two port 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
TraceSubstances	Ideal one port trace substances sensor
TraceSubstancesTwoPort	Ideal two port sensor for trace substance
MassFlowRate	Ideal sensor for mass flow rate
VolumeFlowRate	Ideal sensor for volume flow rate
RelativePressure	Ideal relative pressure sensor
RelativeTemperature	Ideal relative temperature sensor
BaseClasses	Base classes used in the Sensors package (only of interest to build new component models)

Modelica.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.

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

Parameters

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]

Modelica definition

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

Modelica.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 please read the Information first.

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

Parameters

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]

Modelica definition

model Density "Ideal one port density sensor"
  extends Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput d(final quantity="Density",
                                          final unit="kg/m3",
                                          displayUnit="g/cm3",
                                          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;

Modelica.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.

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

Parameters

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

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]

Modelica definition

model DensityTwoPort "Ideal two port density sensor"
  extends Sensors.BaseClasses.PartialFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput d(final quantity="Density",
                                          final unit="kg/m3",
                                          displayUnit="g/cm3",
                                          min=0) "Density of the passing fluid";
  parameter Medium.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, density is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";
protected 
  Medium.Density rho_a_inflow "Density of inflowing fluid at port_a";
  Medium.Density rho_b_inflow 
    "Density of inflowing fluid at port_b or rho_a_inflow, if uni-directional flow";
equation 
  if allowFlowReversal then
     rho_a_inflow = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     rho_b_inflow = Medium.density(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     d = Modelica.Fluid.Utilities.regStep(port_a.m_flow, rho_a_inflow, rho_b_inflow, m_flow_small);
  else
     d = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     rho_a_inflow = d;
     rho_b_inflow = d;
  end if;

end DensityTwoPort;

Modelica.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 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

Connectors

Type	Name	Description
FluidPort_a	port
output RealOutput	T	Temperature in port medium [K]

Modelica definition

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

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

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

end Temperature;

Modelica.Fluid.Sensors.TemperatureTwoPort

Information

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

Extends from Sensors.BaseClasses.PartialFlowSensor (Partial component to model sensors that measure flow properties).

Parameters

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

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 Sensors.BaseClasses.PartialFlowSensor;

  Modelica.Blocks.Interfaces.RealOutput T( final quantity="ThermodynamicTemperature",
                                           final unit="K",
                                           min = 0,
                                           displayUnit="degC") 
    "Temperature of the passing fluid";
  parameter Medium.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";

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";
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));
     T = Modelica.Fluid.Utilities.regStep(port_a.m_flow, T_a_inflow, T_b_inflow, m_flow_small);
  else
     T = Medium.temperature(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     T_a_inflow = T;
     T_b_inflow = T;
  end if;

end TemperatureTwoPort;

Modelica.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.

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

Parameters

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]

Modelica definition

model SpecificEnthalpy "Ideal one port specific enthalpy sensor"
  extends 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;

Modelica.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.

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

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	system.m_flow_small	For bi-directional flow, specific enthalpy is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

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 Sensors.BaseClasses.PartialFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput h_out(final quantity="SpecificEnergy",
                                              final unit="J/kg") 
    "Specific enthalpy of the passing fluid";

  parameter Medium.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, specific enthalpy is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";

equation 
  if allowFlowReversal then
     h_out = Modelica.Fluid.Utilities.regStep(port_a.m_flow, port_b.h_outflow, port_a.h_outflow, m_flow_small);
  else
     h_out = port_b.h_outflow;
  end if;

end SpecificEnthalpyTwoPort;

Modelica.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.

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

Parameters

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)]

Modelica definition

model SpecificEntropy "Ideal one port specific entropy sensor"
  extends 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;

Modelica.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.

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

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	system.m_flow_small	For bi-directional flow, specific entropy is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

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 Sensors.BaseClasses.PartialFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput s(final quantity="SpecificEntropy",
                                          final unit="J/(kg.K)") 
    "Specific entropy of the passing fluid";
  parameter Medium.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, specific entropy is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";

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";
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;

end SpecificEntropyTwoPort;

Modelica.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.

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

Parameters

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

Modelica definition

model TraceSubstances "Ideal one port trace substances sensor"
  extends 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 Integer ind(fixed=false) 
    "Index of species in vector of auxiliary substances";
  Medium.ExtraProperty CVec[Medium.nC](
      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.nC loop
    if ( Modelica.Utilities.Strings.isEqual(Medium.extraPropertiesNames[i], substanceName)) then
      ind := i;
    end if;
  end for;
  assert(ind > 0, "Trace substance '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
equation 
  CVec = inStream(port.C_outflow);
  C = CVec[ind];

end TraceSubstances;

Modelica.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.

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

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
String	substanceName	"CO2"	Name of trace substance
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
MassFlowRate	m_flow_small	system.m_flow_small	For bi-directional flow, trace substance is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required) [kg/s]

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 Sensors.BaseClasses.PartialFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput C 
    "Trace substance of the passing fluid";
  parameter String substanceName = "CO2" "Name of trace substance";
  parameter Medium.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, trace substance is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";

protected 
  parameter Integer ind(fixed=false) 
    "Index of species in vector of auxiliary substances";
initial algorithm 
  ind:= -1;
  for i in 1:Medium.nC loop
    if ( Modelica.Utilities.Strings.isEqual(Medium.extraPropertiesNames[i], substanceName)) then
      ind := i;
    end if;
  end for;
  assert(ind > 0, "Trace substance '" + substanceName + "' is not present in medium '"
         + Medium.mediumName + "'.\n"
         + "Check sensor parameter and medium model.");
equation 
  if allowFlowReversal then
     C = Modelica.Fluid.Utilities.regStep(port_a.m_flow, port_b.C_outflow[ind], port_a.C_outflow[ind], m_flow_small);
  else
     C = port_b.C_outflow[ind];
  end if;

end TraceSubstancesTwoPort;

Modelica.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 Sensors.BaseClasses.PartialFlowSensor (Partial component to model sensors that measure flow properties), Modelica.Icons.RotationalSensor (Icon representing rotational measurement device).

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

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 Sensors.BaseClasses.PartialFlowSensor;
  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;

Modelica.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.

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

Parameters

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

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 Sensors.BaseClasses.PartialFlowSensor;
  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.MassFlowRate m_flow_small(min=0) = system.m_flow_small 
    "For bi-directional flow, density is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";

protected 
  Medium.Density rho_a_inflow "Density of inflowing fluid at port_a";
  Medium.Density rho_b_inflow 
    "Density of inflowing fluid at port_b or rho_a_inflow, if uni-directional flow";
  Medium.Density d "Density of the passing fluid";
equation 
  if allowFlowReversal then
     rho_a_inflow = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     rho_b_inflow = Medium.density(Medium.setState_phX(port_a.p, port_a.h_outflow, port_a.Xi_outflow));
     d = Modelica.Fluid.Utilities.regStep(port_a.m_flow, rho_a_inflow, rho_b_inflow, m_flow_small);
  else
     d = Medium.density(Medium.setState_phX(port_b.p, port_b.h_outflow, port_b.Xi_outflow));
     rho_a_inflow = d;
     rho_b_inflow = d;
  end if;
  V_flow = port_a.m_flow/d;

end VolumeFlowRate;

Modelica.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 translational measurement device).

Connectors

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),
                                redeclare package Medium = Medium);
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                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;

Modelica.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, no flow through the sensor is allowed.

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

Connectors

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),
                                redeclare package Medium = Medium);
  Modelica.Fluid.Interfaces.FluidPort_b port_b(m_flow(min=0),
                                redeclare package Medium = Medium);

  Modelica.Blocks.Interfaces.RealOutput T_rel(final quantity="ThermodynamicTemperature",
                                              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;