modelDC_Example
Example of a simple district heating grid of active producer and direct consumer
Extends from dhcSim.DHC.Networks.BaseClasses.BaseGrid (Base class for grid module).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nLev (from LumpedMultiVolumeDeclarations) | 2 | Number of grid levels |
| Medium.SpecificEnthalpy | h_start (from LumpedMultiVolumeDeclarations) | Medium.specificEnthalpy(state = Medium.setState_pTX(p = p_start, T = T_start, X = X_start)) | |
| Integer | nMix (from BaseGrid) | Number of mixing connection points | |
| Integer | nPip (from BaseGrid) | Number of pipes | |
| Modelica.SIunits.Pressure | pAbs (from BaseGrid) | p_start[1] | Absolute pressure level of grid in pressure point |
| Integer | nSeg (from BaseGrid) | fill(1, nPip) | Number of volume segments |
| Modelica.SIunits.Length | diameter (from BaseGrid) | fill(0.1, nPip, nLev) | Pipe diameter |
| Modelica.SIunits.Length | length (from BaseGrid) | fill(10, nPip) | Length of the pipe |
| Modelica.SIunits.Velocity | v_nominal_pip (from BaseGrid) | fill(2, nPip, nLev) | Velocity at m_flow_nominal (used to compute default diameter) |
| Modelica.SIunits.PressureDifference | dp_fixed_nominal_pip (from BaseGrid) | zeros(nPip, nLev) | Additional nominal pressure drop of pipes |
| Modelica.SIunits.Length | roughness (from BaseGrid) | 2.5e-5 | Absolute roughness of pipe, with a default for a smooth steel pipe (dummy if use_roughness = false) |
| Modelica.SIunits.PressureDifference | dp_nominal_pip (from BaseGrid) | fill(10, nPip, nLev) | Pressure difference |
| Modelica.SIunits.MassFlowRate | m_flow_nominal_pip (from BaseGrid) | fill(1, nPip, nLev) | Pressure difference |
| Integer[nMix] | MixNPrt (from BaseGrid) | ones(nMix) | Number of connection ports for each mixing volume |
| Modelica.SIunits.MassFlowRate | m_flow_nominal_conPoi (from BaseGrid) | 1 | Nominal mass flow rate for connection points |
| Modelica.SIunits.Time | tau (from BaseGrid) | 10 | Time constant at nominal flow for dynamic energy and momentum balance |
| Integer | nPro | 1 | Number of producer |
| Integer | nCon | 5 | Number of consumer |
| String | fileNameCon | fill(gp("modelica://dhcSim/Resources/LoadProf/default/consumerNom.txt"), nCon) | |
| Dynamics › Equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from LumpedMultiVolumeDeclarations) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | massDynamics (from LumpedMultiVolumeDeclarations) | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | substanceDynamics (from LumpedMultiVolumeDeclarations) | energyDynamics | Type of independent mass fraction balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | traceDynamics (from LumpedMultiVolumeDeclarations) | energyDynamics | Type of trace substance balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Modelica.SIunits.AbsolutePressure | p_start (from LumpedMultiVolumeDeclarations) | fill(Medium.p_default, nLev) | Start value of pressure |
| Modelica.SIunits.Temperature | T_start (from LumpedMultiVolumeDeclarations) | fill(Medium.T_default, nLev) | Start value of temperature |
| Medium.MassFraction | X_start (from LumpedMultiVolumeDeclarations) | fill(Medium.X_default, nLev) | Start value of mass fractions m_i/m |
| Medium.ExtraProperty | C_start (from LumpedMultiVolumeDeclarations) | fill(0, nLev, Medium.nC) | Start value of trace substances |
| Medium.ExtraProperty | C_nominal (from LumpedMultiVolumeDeclarations) | fill(1E-2, nLev, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Dynamics | |||
| Real | mSenFac (from LumpedMultiVolumeDeclarations) | 1 | Factor for scaling the sensible thermal mass of the volume |
| Pressure drop | |||
| dhcSim.DHC.Submodules.TwoPortModules.Pipe.Types.dpTypes | dpType (from BaseGrid) | dhcSim.DHC.Submodules.TwoPortModules.Pipe.Types.dpTypes.dp_nominal | Define pressure drop calculation |
| Assumptions | |||
| Boolean | allowFlowReversal (from BaseGrid) | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| Advanced | |||
| Medium.MassFlowRate | m_flow_small_pip (from BaseGrid) | 1E-4.*abs(m_flow_nominal_pip) | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from BaseGrid) | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Real | ReC (from BaseGrid) | 4000 | Reynolds number where transition to turbulent starts |
| Boolean | from_dp (from BaseGrid) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance (from BaseGrid) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM (from BaseGrid) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Heat losses | |||
| Modelica.SIunits.Length | disPip (from BaseGrid) | 10 | Fictive pipe distance, used to calculate fictive Resistance |
| Modelica.SIunits.Length | uniWidth (from BaseGrid) | 1 | Universal width |
| Initialization › Heat losses | |||
| Modelica.SIunits.Temperature | T_surf_a_start (from BaseGrid) | 293.15 | Initial temperature at surf_a, used if steadyStateInitial = false |
| Modelica.SIunits.Temperature | T_surf_b_start (from BaseGrid) | 283.15 | Initial temperature at surf_b, used if steadyStateInitial = false |