Package with delay models
This package contains components models for transport delays in piping networks.
The model Buildings.Fluid.Delays.DelayFirstOrder approximates transport delays using a first order differential equation.
For a discretized model of a pipe or duct, see Buildings.Fluid.FixedResistances.Pipe.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
| Name | Description |
|---|---|
 DelayFirstOrder
|
Delay element, approximated by a first order differential equation |
 Examples
|
Collection of models that illustrate model use and test models |
Buildings.Fluid.Delays.DelayFirstOrder
Delay element, approximated by a first order differential equation
This model approximates a transport delay using a first order differential equations.
The model consists of a mixing volume with two ports. The size of the
mixing volume is such that at the nominal mass flow rate
m_flow_nominal,
the time constant of the volume is equal to the parameter tau.
The heat flux connector is optional, it need not be connnected.
Extends from Buildings.Fluid.MixingVolumes.MixingVolume (Mixing volume with inlet and outlet ports (flow reversal is allowed)).
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Volume | V | V_nominal | Volume [m3] |
| Nominal condition | |||
| MassFlowRate | m_flow_nominal | Nominal mass flow rate [kg/s] | |
| Dynamics | |||
| Equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance |
| Dynamics | massDynamics | energyDynamics | Formulation of mass balance |
| Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume |
| Nominal condition | |||
| Time | tau | 60 | Time constant at nominal flow [s] |
| 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.) |
| Advanced | |||
| MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = true to allow flow reversal in medium, false restricts to design direction (ports[1] -> ports[2]). Used only if model has two ports. |
| Heat transfer | |||
| Boolean | prescribedHeatFlowRate | false | Set to true if the model has a prescribed heat flow at its heatPort. If the heat flow rate at the heatPort is only based on temperature difference, then set to false. |
| Type | Name | Description |
|---|---|---|
| VesselFluidPorts_b | ports[nPorts] | Fluid inlets and outlets |
| HeatPort_a | heatPort | Heat port for sensible heat input |