modeldp_residencetime
Information
1. Purpose of model
Calculates pressure drop and thermal delay of temperature changes with respect to flow velocity and pipe length
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
See Reference
7. Remarks for Usage
Pressure loss is linearized for mass flow rates below 5% of the nominal velocity.
Residence time is limited to 10h to improve initialisation with no mass flow present in the system at time = 0.
8. Validation
(no remarks)
9. References
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 |
|---|---|---|---|
| SI.Pressure | p_start | pipe_parameter.p_start | Pressure at start of simulation |
| SI.Temperature | T_start | pipe_parameter.T_start | Temperature at start of simulation |
| SI.Temperature | T_start_out | pipe_parameter.T_start_out | |
| SI.MassFlowRate | m_flow_start | 0.005 | Start Massflow |
| SI.MassFlowRate | m_flow_small_local | 0.05*Modelica.Constants.pi/4*diameter_i*diameter_i*rho*v_nom | For linearization of pressure drop at mass flow below 5% of nominal velocity |
| SI.Length | diameter_i | pipe_parameter.diameter_i | Inner Diameter of the Pipe |
| SI.Height | z_in | pipe_parameter.z_in | Inlet Height of the pipe |
| SI.Height | z_out | pipe_parameter.z_out | Outlet Height of the pipe |
| SI.Height | dz | z_in - z_out | Height difference between inlet and outlet |
| SI.Length | length | pipe_parameter.length | Length of the pipe |
| SI.Length | K | pipe_parameter.K | average height of surface asperities |
| SI.Velocity | v_nom | simCenter.v_nom | Design Velocity of the pipe. Typically smaller than 2 m/s |
| SI.SpecificEnthalpy | h_start | pipe_parameter.h_start | |
| SI.SpecificEnthalpy | h_start_out | pipe_parameter.h_start_out | |
| SI.SpecificHeatCapacity | cp_w | pipe_parameter.cp_w | |
| SI.Density | rho | pipe_parameter.rho | |
| SI.DynamicViscosity | dyn_vis | pipe_parameter.dyn_vis | |
| HeatTransfer | |||
| Boolean | calc_initial_dstrb | true | Activates the calculation of a initial temperature distribution inside the pipes |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn | waterPortIn | Inlet port | |
| TransiEnt.Basics.Interfaces.Thermal.FluidPortOut | waterPortOut | Outlet port | |
| Modelica.Blocks.Interfaces.RealOutput | residence_time_nom | ||
| Modelica.Blocks.Interfaces.RealOutput | residence_time_reversed |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.SimCenter | simCenter | ||
| TransiEnt.Components.Heat.VolumesValvesFittings.Pipes.Base.pipe_parameters | pipe_parameter | ||
| SI.SpecificEnthalpy | h_in | waterPortIn.h_outflow | Inlet enthalpy |
| SI.SpecificEnthalpy | h_out | waterPortOut.h_outflow | Outlet enthalpy |
| SI.Pressure | dp | Pressure difference between inlet and outlet by friction | |
| SI.Pressure | dp_h | Pressure difference between inlet and outlet due to geostatic height difference | |
| SI.PressureDifference | dp_small | ||
| Real | time_flow | ||
| Real | time_reversed | ||
| SI.Velocity | v_water | Velocity of the fluid | |
| Real | x | Coordinate for spatialDistribution | |
| Modelica.Fluid.Dissipation.PressureLoss.StraightPipe.dp_overall_IN_con | inCon | ||
| Modelica.Fluid.Dissipation.PressureLoss.StraightPipe.dp_overall_IN_var | inVar |