modelDistribution2PipePlugFlow_v
Model of a two-pipe distribution network using plug flow pipe models in the main lines with hydraulic diameter calculated from nominal velocity
Extends from Buildings.DHC.Networks.BaseClasses.PartialDistribution2Pipe (Partial model for two-pipe distribution network).
Information
This is a model of a two-pipe distribution network using a connection model with a plug flow pipe model (pressure drop, heat transfer, transport delays) in the main lines whose hydraulic diameters are calculated based on nominal velocity at nominal flow rate Buildings.DHC.Networks.Connections.Connection2PipePlugFlow. The same pipe model is also used at the end of the distribution line (after the last connection) only on the supply side.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | show_entFlo (from PartialDistribution2Pipe) | false | Set to true to output enthalpy flow rate difference at each connection |
| Modelica.Units.SI.Length[nCon] | lDis | Length of the distribution pipe before each connection (supply only, not counting return line) | |
| Modelica.Units.SI.Length | lEnd | Length of the end of the distribution line (supply only, not counting return line) | |
| Modelica.Units.SI.Length | dIns | 0.05 | Thickness of pipe insulation, used to compute R |
| Modelica.Units.SI.ThermalConductivity | kIns | 0.028 | Heat conductivity of pipe insulation, used to compute R |
| Modelica.Units.SI.Velocity | v_nominal | 1.5 | Velocity at m_flow_nominal (used to compute default value for hydraulic diameter dh) |
| Modelica.Units.SI.Height | roughness | 2.5e-5 | Average height of surface asperities (default: smooth steel pipe) |
| Modelica.Units.SI.SpecificHeatCapacity | cPip | 2300 | Specific heat of pipe wall material. 2300 for PE, 500 for steel |
| Modelica.Units.SI.Density | rhoPip | 930 | Density of pipe wall material. 930 for PE, 8000 for steel |
| Modelica.Units.SI.Length | thickness | 0.0035 | Pipe wall thickness |
| General | |||
| Integer | nCon (from PartialDistribution2Medium) | Number of connections | |
| Integer | iConDpSen (from PartialDistribution2Pipe) | nCon | Index of the connection where the pressure drop is measured |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialDistribution2Medium) | false | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| General › Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | mDis_flow_nominal (from PartialDistribution2Pipe) | Nominal mass flow rate in the distribution line before the first connection | |
| Modelica.Units.SI.MassFlowRate[nCon] | mCon_flow_nominal (from PartialDistribution2Pipe) | Nominal mass flow rate in each connection line | |
| Modelica.Units.SI.MassFlowRate | mEnd_flow_nominal (from PartialDistribution2Pipe) | mDis_flow_nominal - sum(mCon_flow_nominal) | Nominal mass flow rate in the end of the distribution line |
| Modelica.Units.SI.MassFlowRate[nCon] | mDisCon_flow_nominal (from PartialDistribution2Pipe) | cat(1, {mDis_flow_nominal}, {mDis_flow_nominal - sum(mCon_flow_nominal[1:i]) for i in 1:(nCon - 1)}) | Nominal mass flow rate in the distribution line before each connection |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from PartialDistribution2Pipe) | Modelica.Fluid.Types.Dynamics.FixedInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Dynamics › Nominal condition | |||
| Modelica.Units.SI.Time | tau (from PartialDistribution2Pipe) | 10 | Time constant at nominal flow for dynamic energy and momentum balance |
Connectors
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.DHC.Networks.BaseClasses.PartialConnection2Pipe[nCon] | con (from PartialDistribution2Pipe) | Connection to agent | |
| Model_pipDis | pipEnd (from PartialDistribution2Pipe) | Pipe representing the end of the distribution line (after last connection) | |
| Fluid.Sensors.RelativePressure | senRelPre (from PartialDistribution2Pipe) | Relative pressure sensor |
Revisions
-
March 15, 2024, by David Blum:
Renamed. This is for issue 3712. -
January 27, 2023, by Michael Wetter:
Removed connection to itself. -
January 2, 2023, by Kathryn Hinkelman:
First implementation.