Buildings.Fluid.Sensors.BaseClasses
Package with base classes for Buildings.Fluid.Sensors
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 |
 PartialDynamicFlowSensor
|
Partial component to model sensors that measure flow properties using a dynamic model |
 PartialFlowSensor
|
Partial component to model sensors that measure flow properties |
Buildings.Fluid.Sensors.BaseClasses.PartialAbsoluteSensor
Partial component to model a sensor that measures a potential variable
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.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | Modelica.Media.Interfaces.Pa... | Medium in the sensor | |
| Boolean | warnAboutOnePortConnection | true | Set to false to suppress warning about potential numerical issues, see Buildings.Fluid.Sensors.UsersGuide for more information |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package Medium | Medium in the sensor | |
| 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";
parameter Boolean warnAboutOnePortConnection = true
"Set to false to suppress warning about potential numerical issues, see Buildings.Fluid.Sensors.UsersGuide for more information";
Modelica.Fluid.Interfaces.FluidPort_a port(redeclare package Medium=Medium, m_flow(min=0));
protected
parameter String instanceName = getInstanceName() "Name of the instance";
initial equation
assert(not warnAboutOnePortConnection,
"Sensor " + instanceName + " can lead to numerical problems if connected to a scalar fluid port.
Only connect it to a vectorized fluid port, such as used in 'Buildings.Fluid.MixingVolumes`.
See Buildings.Fluid.Sensors.UsersGuide for more information.
To disable this warning, set 'warnAboutOnePortConnection = false' in " + instanceName + ".",
level=AssertionLevel.warning);
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.PartialDynamicFlowSensor
Partial component to model sensors that measure flow properties using a dynamic model
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 sensor computes a gain that is zero at zero mass flow rate. This avoids fast transients if the flow is close to zero, thereby improving the numerical efficiency.
Extends from PartialFlowSensor (Partial component to model sensors that measure flow properties).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Time | tau | 1 | Time constant at nominal flow rate (use tau=0 for steady-state sensor, but see user guide for potential problems) [s] |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal | Nominal mass flow rate, used for regularization near zero flow [kg/s] | |
| Initialization | |||
| Init | initType | Modelica.Blocks.Types.Init.I... | Type of initialization (InitialState and InitialOutput are identical) |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| 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) |
Modelica definition
partial model PartialDynamicFlowSensor
"Partial component to model sensors that measure flow properties using a dynamic model"
extends PartialFlowSensor;
parameter Modelica.Units.SI.Time tau(min=0) = 1
"Time constant at nominal flow rate (use tau=0 for steady-state sensor, but see user guide for potential problems)";
parameter Modelica.Blocks.Types.Init initType = Modelica.Blocks.Types.Init.InitialState
"Type of initialization (InitialState and InitialOutput are identical)";
protected
Real k(start=1)
"Gain to take flow rate into account for sensor time constant";
final parameter Boolean dynamic = tau > 1E-10 or tau < -1E-10
"Flag, true if the sensor is a dynamic sensor";
Real mNor_flow "Normalized mass flow rate";
final parameter Real tauInv(final unit="s-1")= if dynamic then 1/tau else 0
"Inverse of tau";
equation
if dynamic then
mNor_flow = port_a.m_flow/m_flow_nominal;
k = Modelica.Fluid.Utilities.regStep(x=port_a.m_flow,
y1= mNor_flow,
y2=-mNor_flow,
x_small=m_flow_small);
else
mNor_flow = 1;
k = 1;
end if;
end PartialDynamicFlowSensor;
Buildings.Fluid.Sensors.BaseClasses.PartialFlowSensor
Partial component to model sensors that measure flow properties
Information
Partial component to model a sensor. The sensor is ideal. It does not influence mass, energy, species or substance balance, and it has no flow friction.
Extends from Buildings.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] | |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| 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) |
Modelica definition
partial model PartialFlowSensor
"Partial component to model sensors that measure flow properties"
extends Buildings.Fluid.Interfaces.PartialTwoPort;
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal(min=0)
"Nominal mass flow rate, used for regularization near zero flow";
parameter Modelica.Units.SI.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
port_b.m_flow = -port_a.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 = if allowFlowReversal then inStream(port_b.h_outflow) else Medium.h_default;
port_b.h_outflow = inStream(port_a.h_outflow);
port_a.Xi_outflow = if allowFlowReversal then inStream(port_b.Xi_outflow) else Medium.X_default[1:Medium.nXi];
port_b.Xi_outflow = inStream(port_a.Xi_outflow);
port_a.C_outflow = if allowFlowReversal then inStream(port_b.C_outflow) else zeros(Medium.nC);
port_b.C_outflow = inStream(port_a.C_outflow);
end PartialFlowSensor;