Buildings.Fluids.Sensors

Information

Package Content

Name	Description
Conversions	Package with conversions for sensor models
DryBulbTemperatureDynamic	Ideal temperature sensor
EnthalpyFlowRate	Ideal enthalphy flow rate sensor
Examples	Collection of models that illustrate model use and test models
MassFraction	Ideal one port mass fraction sensor
WetBulbTemperature	Ideal wet bulb temperature sensor

Buildings.Fluids.Sensors.DryBulbTemperatureDynamic

Information

This component monitors the temperature of the medium in the flow between fluid ports. The sensor does not influence the fluid. Its output is computed using a first order differential equation.

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Time	tau	10	Time constant [s]
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate [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)
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]

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 DryBulbTemperatureDynamic "Ideal temperature sensor"
  extends Modelica_Fluid.Sensors.BaseClasses.PartialFlowSensor;

  parameter Modelica.SIunits.Time tau(min=0) = 10 "Time constant";
  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_nominal(min=0) "Nominal mass flow rate";
  parameter Medium.MassFlowRate m_flow_small(min=0) = 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)";

  parameter Modelica.Blocks.Types.Init initType = Modelica.Blocks.Types.Init.NoInit 
    "Type of initialization (InitialState and InitialOutput are identical)";
  parameter Modelica.SIunits.Temperature T_start=Medium.T_default 
    "Initial or guess value of output (= state)";
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";
  Medium.Temperature TMed "Medium to which sensor is exposed";
initial equation 
  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;
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;
  der(T)  = (TMed-T)/tau;
end DryBulbTemperatureDynamic;

Buildings.Fluids.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.

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	H_flow	Enthalpy flow rate, positive if from port_a to port_b [W]

Modelica definition

model EnthalpyFlowRate "Ideal enthalphy flow rate sensor"
  extends Modelica_Fluid.Sensors.BaseClasses.PartialFlowSensor;
  extends Modelica.Icons.RotationalSensor;
  Modelica.Blocks.Interfaces.RealOutput H_flow(unit="W") 
    "Enthalpy flow rate, positive if from port_a to port_b";


equation 
  if allowFlowReversal then
     H_flow = port_a.m_flow * actualStream(port_a.h_outflow);
  else
     H_flow = port_a.m_flow * port_b.h_outflow;
  end if;
end EnthalpyFlowRate;

Buildings.Fluids.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

Connectors

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 Modelica_Fluid.Sensors.BaseClasses.PartialAbsoluteSensor;
  extends Modelica.Icons.RotationalSensor;
  parameter String substanceName = "water" "Name of species substance";

  Modelica.Blocks.Interfaces.RealOutput X "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(Medium.substanceNames[i], substanceName)) 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.Fluids.Sensors.WetBulbTemperature

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.

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	1e-4	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	T	Wet bulb temperature in port medium [K]

Modelica definition

model WetBulbTemperature "Ideal wet bulb temperature sensor"
  extends Modelica_Fluid.Sensors.BaseClasses.PartialFlowSensor;


  Modelica.Blocks.Interfaces.RealOutput T(
    start=Medium.T_default,
    final quantity="Temperature",
    final unit="K") "Wet bulb temperature in port medium";

  parameter Medium.MassFlowRate m_flow_small(min=0) = 1e-4 
    "For bi-directional flow, specific enthalpy is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)";
  Buildings.Utilities.Psychrometrics.WetBulbTemperature wetBulMod(redeclare 
      package Medium = Medium) "Model for wet bulb temperature";

equation 
  if allowFlowReversal then
    wetBulMod.dryBul.h  = Modelica_Fluid.Utilities.regStep(port_a.m_flow, port_b.h_outflow, port_a.h_outflow, m_flow_small);
    wetBulMod.dryBul.Xi = Modelica_Fluid.Utilities.regStep(port_a.m_flow, port_b.Xi_outflow, port_a.Xi_outflow, m_flow_small);
  else
    wetBulMod.dryBul.h = port_b.h_outflow;
    wetBulMod.dryBul.Xi = port_b.Xi_outflow;
  end if;
  wetBulMod.dryBul.p  = port_a.p;

  // Compute wet bulb temperature
  T = wetBulMod.wetBul.T;

end WetBulbTemperature;