modelTable_V_flow
Volume flow(y-axis) vs Pressure(x-axis) cubic spline fit model based on table data, with last two points linearly interpolated
Extends from Buildings.Airflow.Multizone.Table_m_flow (Mass flow(y-axis) vs Pressure(x-axis) cubic spline fit model based from table data, with last two points linearly interpolated).
Information
This model describes the one-directional pressure driven air flow through an opening based on user-provided tabular data describing the relation between volume flow rate and pressure difference over the component.
V̇ = f(Δp),
where V̇ is the volume flow rate and Δp is the pressure difference.
Based on the table input, a cubic hermite spline is constructed between all points except for the two last pairs of points. These point are connected linearly.
The constructed curve is the direct relation between V̇ and Δp.
A similar model is also used in the CONTAM software (Dols and Walton, 2015).
References
- W. S. Dols and B. J. Polidoro,2015. CONTAM User Guide and Program Documentation Version 3.2, National Institute of Standards and Technology, NIST TN 1887, Sep. 2015. doi: 10.6028/NIST.TN.1887.
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.Units.SI.MassFlowRate | m_flow_nominal (from PartialTwoPortInterface) | Nominal mass flow rate | |
| Advanced | |||
| Modelica.Units.SI.MassFlowRate | m_flow_small (from PartialTwoPortInterface) | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Boolean | forceErrorControlOnFlow (from ErrorControl) | true | Flag to force error control on m_flow. Set to true if interested in flow rate |
| Boolean | homotopyInitialization (from PartialOneWayFlowElement) | true | = true, use homotopy method |
| Boolean | useDefaultProperties (from PartialOneWayFlowElement) | true | Set to false to use density and viscosity based on actual medium state, rather than using default values |
| Modelica.Units.SI.PressureDifference | dp_turbulent (from PartialOneWayFlowElement) | 0.1 | Pressure difference where laminar and turbulent flow relation coincide. Recommended = 0.1 |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortInterface) | false | = true, if actual temperature at port is computed |
| Test data | |||
| Modelica.Units.SI.PressureDifference[:] | dpMea_nominal (from Table_m_flow) | Pressure difference of test points | |
| Modelica.Units.SI.MassFlowRate[:] | mMea_flow_nominal (from Table_m_flow) | Mass flow rate of test points | |
| Modelica.Units.SI.VolumeFlowRate[:] | VMea_flow_nominal | Volume flow rate of test points | |
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) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.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.Units.SI.PressureDifference | dp (from PartialTwoPortInterface) | port_a.p - port_b.p | Pressure difference between port_a and port_b |
| Medium.ThermodynamicState | sta_a (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) else Medium.setState_phX(port_a.p, noEvent(inStream(port_a.h_outflow)), noEvent(inStream(port_a.Xi_outflow))) | Medium properties in port_a |
| Medium.ThermodynamicState | sta_b (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) else Medium.setState_phX(port_b.p, noEvent(port_b.h_outflow), noEvent(port_b.Xi_outflow)) | Medium properties in port_b |
| Modelica.Units.SI.VolumeFlowRate | V_flow (from PartialOneWayFlowElement) | m_flow/rho | Volume flow rate through the component |
| Modelica.Units.SI.Density | rho (from PartialOneWayFlowElement) | Fluid density at port_a |
Revisions
-
February 2, 2022, by Michael Wetter:
Revised implementation.
This is for IBPSA, #1436. - Apr 6, 2021, 2020, by Klaas De Jonge:
First implementation.