Buildings.Obsolete.Fluid.Movers.BaseClasses
Package with base classes for Buildings.Obsolete.Fluid.Movers
Information
This package contains base classes that are used to construct the models in Buildings.Obsolete.Fluid.Movers.
Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).
Package Content
Name | Description |
---|---|
PartialFlowMachine | Partial model to interface fan or pump models with the medium |
Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine
Partial model to interface fan or pump models with the medium
Information
This is the base model for fans and pumps. It provides an interface between the equations that compute head and power consumption, and the implementation of the energy and pressure balance of the fluid.
Optionally, the fluid volume is computed using a dynamic balance or a steady-state balance.
The parameter addPowerToMedium
determines whether
any power is added to the fluid. The default is addPowerToMedium=true
,
and hence the outlet enthalpy is higher than the inlet enthalpy if the
flow device is operating.
The setting addPowerToMedium=false
is physically incorrect
(since the flow work, the flow friction and the fan heat do not increase
the enthalpy of the medium), but this setting does in some cases lead to simpler equations
and more robust simulation, in particular if the mass flow is equal to zero.
In the previous implementation, this model extends from
Buildings.Fluid.Interfaces.PartialTwoPortInterface.
Now it copies much of the code instead.
This is to resolve a potential circular parameter binding that occurs when
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y
extends from
Buildings.Fluid.Movers.SpeedControlled_y.
The former uses the nominal flow rate provided by user to construct
the pressure curve, whilst the latter uses the user-provided pressure curve
to determine the nominal flow rate. The new implementation removes the
original declaration of nominal flow rate from
Buildings.Fluid.Interfaces.PartialTwoPortInterface
and hides it (protected _m_flow_nominal
) from the user.
This way, A higher-level model (e.g.
Buildings.Fluid.Movers.FlowControlled_dp),
can still provide a default but not the other way around.
See discussions in
#1705.
Extends from Buildings.Obsolete.BaseClasses.ObsoleteModel (Icon for classes that are obsolete and will be removed in later versions), Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes), Buildings.Fluid.Interfaces.PartialTwoPort (Partial component with two ports).
Parameters
Type | Name | Default | Description |
---|---|---|---|
replaceable package Medium | PartialMedium | Medium in the component | |
Generic | per | redeclare parameter Building... | Record with performance data |
Boolean | computePowerUsingSimilarityLaws | = true, compute power exactly, using similarity laws. Otherwise approximate. | |
Boolean | addPowerToMedium | true | Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations) |
Boolean | nominalValuesDefineDefaultPressureCurve | false | Set to true to avoid warning if m_flow_nominal and dp_nominal are used to construct the default pressure curve |
Control | |||
InputType | inputType | Buildings.Fluid.Types.InputT... | Control input type |
Real | constInput | 0 | Constant input set point |
Real | stageInputs[:] | Vector of input set points corresponding to stages | |
Dynamics | |||
Conservation equations | |||
Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume |
Nominal condition | |||
Time | tau | 1 | Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic [s] |
Filtered speed | |||
Boolean | use_inputFilter | true | = true, if speed is filtered with a 2nd order CriticalDamping filter |
Time | riseTime | 30 | Rise time of the filter (time to reach 99.6 % of the speed) [s] |
Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
Advanced | |||
Dynamics | |||
Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state |
MassFlowRate | m_flow_small | 1E-4*abs(_m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
Diagnostics | |||
Boolean | show_T | false | = true, if actual temperature at port is computed |
Initialization | |||
AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
Temperature | T_start | Medium.T_default | Start value of temperature [K] |
MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg] |
ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances |
ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
Assumptions | |||
Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
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) |
input IntegerInput | stage | Stage input signal for the pressure head |
output RealOutput | y_actual | Actual normalised fan or pump speed that is used for computations [1] |
output RealOutput | P | Electrical power consumed [W] |
HeatPort_a | heatPort | Heat dissipation to environment |
Modelica definition
Buildings.Obsolete.Fluid.Movers.BaseClasses.PartialFlowMachine.Extractor
Extract scalar signal out of signal vector dependent on IntegerRealInput index
Information
Extends from Modelica.Blocks.Interfaces.MISO (Multiple Input Single Output continuous control block).
Parameters
Type | Name | Default | Description |
---|---|---|---|
Integer | nin | 1 | Number of inputs |
Connectors
Type | Name | Description |
---|---|---|
input RealInput | u[nin] | Connector of Real input signals |
output RealOutput | y | Connector of Real output signal |
input IntegerInput | index | Integer input for control input |