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... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Dynamics | massDynamics | energyDynamics | Type of mass 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 | 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 | |||
| Boolean | use_C_flow | false | Set to true to enable input connector for trace substance |
| 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. |
| Type | Name | Description |
|---|---|---|
| VesselFluidPorts_b | ports[nPorts] | Fluid inlets and outlets |
| HeatPort_a | heatPort | Heat port for sensible heat input |
| output RealOutput | U | Internal energy of the component [J] |
| output RealOutput | m | Mass of the component [kg] |
| output RealOutput | mXi[Medium.nXi] | Species mass of the component [kg] |
| output RealOutput | mC[Medium.nC] | Trace substance mass of the component [kg] |
| input RealInput | C_flow[Medium.nC] | Trace substance mass flow rate added to the medium |