modelDoublePipePair_L2
Information
1. Purpose of model
Usage in simulation of district heating networks with the traditional parallel supply return layout
2. Level of detail, physical effects considered, and physical insight
(no remarks)
3. Limits of validity
(no remarks)
4. Interfaces
(no remarks)
5. Nomenclature
(no remarks)
6. Governing Equations
(no remarks)
7. Remarks for Usage
For bigger simulations deactivate volume - underestimates the thermal delay by heating / cooling of the steel pipes.
Residence time is limited to 10h to improve initialisation with no mass flow present in the system at time = 0.
Pressure loss is linearized for mass flow rates with 5% of the nominal velocity.
8. Validation
(no remarks)
9. References
Heat transfer based on: B. van der Heijde, M. Fuchs, C. Ribas Tugores "Dynamic equation-based thermo-hydraulic pipe model for district heating and cooling systems", 2017
10. Version History
Model created by Philipp Huismann (huismann@gwi-essen.de) on 10.10.2018
Model revised by Philipp Huismann (huismann@gwi-essen.de) on 07.04.2022 | Pressure Loss linearisation for small mass flow rates, Residence Time limitation
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Initialization | |||
| Modelica.Units.SI.Pressure | p_start_supply | 10e5 | Pressure at start of Simulation for the supply pipe |
| Modelica.Units.SI.Temperature | T_start_supply | 120 + 273.1 | Temperature at start of Simulation for the supply pipe |
| Modelica.Units.SI.Pressure | p_start_return | 3e5 | Pressure at start of Simulation for the return pipe |
| Modelica.Units.SI.Temperature | T_start_return | 70 + 273.1 | Temperature at start of Simulation for the return pipe |
| Modelica.Units.SI.MassFlowRate | m_flow_start | 1 | |
| SI.Velocity | v_nom | simCenter.v_nom | Design velocity of pipe. |
| Geometry | |||
| Modelica.Units.SI.Length | length | 10 | Length of the pipes |
| Integer | DN | 20 | Nominal Diameter of the Pipes |
| Modelica.Units.SI.Length | diameter_i | simCenter.DNmat[TransiEnt.Basics.Functions.getIndex(DN, simCenter.dhn_pipe_manufacturer.rowAmount, simCenter.DNmat), 2] | Inner Diameter of the pipe |
| Modelica.Units.SI.Length | diameter_o | simCenter.DNmat[TransiEnt.Basics.Functions.getIndex(DN, simCenter.dhn_pipe_manufacturer.rowAmount, simCenter.DNmat), 3] | Outer Diameter of the pipe |
| Modelica.Units.SI.Length | pipe_wall_thickness | simCenter.DNmat[TransiEnt.Basics.Functions.getIndex(DN, simCenter.dhn_pipe_manufacturer.rowAmount, simCenter.DNmat), 4] | Pipe Wall Thickness |
| Modelica.Units.SI.Length | K | simCenter.K | average height of surface asperities |
| HeatTransfer | |||
| Modelica.Units.SI.ThermalConductivity | lambda_insulation | 0.024 | Heattransfercoefficient of the insulation |
| Boolean | calc_initial_dstrb | simCenter.calc_initial_dstrb | Activates the calculation of a initial temperature distribution inside the pipes |
| Boolean | activate_volumes | simCenter.activate_volumes | Activate / Deactivate volumes to better represent delayed temperatrue changes due to heat capacity effects |
| SI.SpecificHeatCapacity | pipe_wall_capacity | simCenter.pipe_wall_capacity | HeatCapacity of the pipe wall material |
| SI.Density | pipe_wall_d | simCenter.pipe_wall_d | Density of the pipe wall material |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn | waterPortIn_supply | Inlet port | |
| TransiEnt.Basics.Interfaces.Thermal.FluidPortOut | waterPortOut_return | Outlet port | |
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn | waterPortIn_return | Inlet port | |
| TransiEnt.Basics.Interfaces.Thermal.FluidPortOut | waterPortOut_supply | Outlet port | |
| ClaRa.Basics.Interfaces.HeatPort_a | heat_supply | ||
| ClaRa.Basics.Interfaces.HeatPort_a | heat_return |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.SimCenter | simCenter | ||
| Real | Q_loss_specific_supply | heat_supply.Q_flow/length | Specif heat loss per meter of the supply pipe |
| Real | Q_loss_specific_return | heat_return.Q_flow/length | Specif heat loss per meter of the return pipe |
| Real | dp_m_supply | abs(singlePipe_LX_supply.dp_residencetime.dp/length) | Specif pressure loss per meter of the supply pipe |
| Real | dp_m_return | abs(singlePipe_LX_return.dp_residencetime.dp/length) | Specif pressure loss per meter of the return pipe |
| Real | v | singlePipe_LX_supply.dp_residencetime.v_water | Velocity of the heat carrier |
| Real | avrg_dp_m | (dp_m_supply + dp_m_return)/2 | Average Specific pressure loss per meter |
| SinglePipe_L2 | singlePipe_LX_supply | ||
| SinglePipe_L2 | singlePipe_LX_return |
Contents
| Name | Description |
|---|---|
 HeatTransfer |