modelBypass
Extends from IBPSA.Fluid.Interfaces.PartialTwoPortInterface (Partial model transporting fluid between two ports without storing mass or energy), IBPSA.Fluid.Interfaces.TwoPortFlowResistanceParameters (Parameters for flow resistance for models with two ports).
Information
This is a model for a generic by-pass that can be used, e.g., in a district heating substation. By-passes are used to avoid waiting times in heat supply and to avoid freezing of return lines in the district heating network. However, their use increases the return temperature and, thus, the losses of the network. The by-pass can be controlled by a thermostat or it can allow a constant flow.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTwoPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Nominal condition | |||
| Modelica.SIunits.MassFlowRate | m_flow_nominal (from PartialTwoPortInterface) | Nominal mass flow rate | |
| Modelica.SIunits.PressureDifference | dp_nominal (from TwoPortFlowResistanceParameters) | Pressure difference | |
| Advanced | |||
| Modelica.SIunits.MassFlowRate | m_flow_small (from PartialTwoPortInterface) | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortInterface) | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | computeFlowResistance (from TwoPortFlowResistanceParameters) | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp (from TwoPortFlowResistanceParameters) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance (from TwoPortFlowResistanceParameters) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM (from TwoPortFlowResistanceParameters) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Control | |||
| Boolean | use_thermostat | false | Use a thermostat to control the bypass valve, otherwise always opened |
| Modelica.SIunits.Temperature | TemSupMinBypass | 50.0 + 273.15 | Minimum supply temperature before bypass valve is opened |
| Modelica.SIunits.TemperatureDifference | TemBandwidthBypass | 3.0 | Temperature bandwidth for bypass activation |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a (from PartialTwoPort) | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b (from PartialTwoPort) | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Blocks.Interfaces.RealInput | T_measurement | Supply temperature measurement |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.SIunits.MassFlowRate | m_flow (from PartialTwoPortInterface) | port_a.m_flow | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) |
| Modelica.SIunits.PressureDifference | dp (from PartialTwoPortInterface) | port_a.p - port_b.p | Pressure difference between port_a and port_b |
| Medium.ThermodynamicState | sta_a (from PartialTwoPortInterface) | Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) | Medium properties in port_a |
| Medium.ThermodynamicState | sta_b (from PartialTwoPortInterface) | Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) | Medium properties in port_b |
| Controls.bypass_control | bypass_control | ||
| DisHeatLib.BaseClasses.FlowUnit | flowUnit |
Revisions
- Feburary 27, 2019, by Benedikt Leitner:
Implementation and added User's guide.