Buildings.Fluid.Sensors.BaseClasses

Information

This package contains base classes that are used to construct the models in Buildings.Fluid.Sensors.

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Package Content

Name	Description
PartialAbsoluteSensor	Partial component to model a sensor that measures a potential variable
PartialFlowSensor	Partial component to model sensors that measure flow properties

Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor

Information

Partial component to model an absolute sensor. The component can be used for pressure sensor models. Use for other properties such as temperature or density is discouraged, because the enthalpy at the connector can have different meanings, depending on the connection topology. For these properties, use Buildings.Fluid.Sensors.BaseClasses.PartialFlowSensor.

Connectors

Type	Name	Description
FluidPort_a	port

Modelica definition

partial model PartialAbsoluteSensor 
  "Partial component to model a sensor that measures a potential variable"

  replaceable package Medium=Modelica.Media.Interfaces.PartialMedium 
    "Medium in the sensor";

  Modelica.Fluid.Interfaces.FluidPort_a port(redeclare package Medium=Medium, m_flow(min=0));

equation 
  port.m_flow = 0;
  port.h_outflow = 0;
  port.Xi_outflow = zeros(Medium.nXi);
  port.C_outflow = zeros(Medium.nC);
end PartialAbsoluteSensor;

Buildings.Fluid.Sensors.BaseClasses.PartialFlowSensor

Information

Partial component to model a sensor that measures any intensive properties of a flow, e.g., to get temperature or density in the flow between fluid connectors.

The model includes zero-volume balance equations. Sensor models inheriting from this partial class should add a medium instance to calculate the measured property.

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

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Nominal condition
MassFlowRate	m_flow_nominal		Nominal mass flow rate, 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]
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)

Modelica definition

partial model PartialFlowSensor 
  "Partial component to model sensors that measure flow properties"
  extends Modelica.Fluid.Interfaces.PartialTwoPort;

  parameter Medium.MassFlowRate m_flow_nominal(min=0) 
    "Nominal mass flow rate, used for regularization near zero flow";
  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)";

equation 
  // mass balance
  0 = port_a.m_flow + port_b.m_flow;

  // momentum equation (no pressure loss)
  port_a.p = port_b.p;

  // isenthalpic state transformation (no storage and no loss of energy)
  port_a.h_outflow = inStream(port_b.h_outflow);
  port_b.h_outflow = inStream(port_a.h_outflow);

  port_a.Xi_outflow = inStream(port_b.Xi_outflow);
  port_b.Xi_outflow = inStream(port_a.Xi_outflow);

  port_a.C_outflow = inStream(port_b.C_outflow);
  port_b.C_outflow = inStream(port_a.C_outflow);
end PartialFlowSensor;