modelWellMixedAir
Zone air model assuming perfectly mixed air
Extends from IDEAS.Buildings.Components.ZoneAirModels.BaseClasses.PartialAirModel (Partial for air models).
Information
Perfectly mixed air model.
Main equations
This model computes a single air temperature that is used to evaluate convective heat transfer of all surfaces, components connected to gainCon (e.g. radiators), etc. The air outlet temperature equals the well mixed air temperature.
Assumption and limitations
This model is not valid for buildings where stratification occurs, e.g. when using floor cooling or ceiling heating.
When dry air is used, then the relative humidity output is set to zero.
Typical use and important parameters
The zone air volume Vto determines the thermal mass of the air.
This mass may be artificially increased using mSenFac if desired,
e.g. to take into account the thermal mass of furniture.
Dynamics
This model only contains states to represent the energy and mass dynamics, typically using a temperature and pressure variable. ParametersenergyDynamics and massDynamics
may be used to change the model dynamics.
Validation
See BESTEST.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nSurf (from PartialAirModel) | Number of connected surfaces | |
| Integer | nSeg (from PartialAirModel) | 1 | Number of air segments |
| Integer | nPorts (from PartialAirModel) | Number of fluid port connections to zone air volume | |
| Modelica.Units.SI.Volume | Vtot (from PartialAirModel) | Total zone air volume | |
| Modelica.Units.SI.MassFlowRate | m_flow_nominal (from PartialAirModel) | Nominal flow rate of the ventilation system | |
| StateSelect | stateSelectTVol | if sim.linearise then StateSelect.prefer else StateSelect.default | Set to .prefer to use temperature as a state in mixing volume |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from LumpedVolumeDeclarations) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | substanceDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of independent mass fraction balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | traceDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of trace substance balance: dynamic (3 initialization options) or steady state |
| Advanced › Dynamics | |||
| Modelica.Fluid.Types.Dynamics | massDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_start (from LumpedVolumeDeclarations) | Medium.p_default | Start value of pressure |
| Medium.Temperature | T_start (from LumpedVolumeDeclarations) | Medium.T_default | Start value of temperature |
| Medium.MassFraction[Medium.nX] | X_start (from LumpedVolumeDeclarations) | Medium.X_default | Start value of mass fractions m_i/m |
| Medium.ExtraProperty[Medium.nC] | C_start (from LumpedVolumeDeclarations) | fill(0, Medium.nC) | Start value of trace substances |
| Medium.ExtraProperty[Medium.nC] | C_nominal (from LumpedVolumeDeclarations) | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Dynamics | |||
| Real | mSenFac (from LumpedVolumeDeclarations) | 1 | Factor for scaling the sensible thermal mass of the volume |
| Advanced | |||
| Boolean | allowFlowReversal (from PartialAirModel) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
Connectors
Components
| Type | Name | Default | Description |
|---|---|---|---|
| IDEAS.BoundaryConditions.SimInfoManager | sim (from PartialAirModel) | Simulation information manager for climate data | |
| Real | ACH | (sum(m_flow_pos)*3600/rho_default)/Vtot | Air change rate per hour |
Contents
| Name | Description |
|---|---|
 MixingVolumeNominalprotected | To avoid warning when modifying parameters of protected submodel dynBal of MixingVolumeMoistAir |
Revisions
-
March 21, 2022 by Filip Jorissen:
Disabled latent heat gains when the medium contains no water. #1251. -
November 21, 2020 by Filip Jorissen:
Avoiding warnings for one port sensors. -
December 13, 2019 by Filip Jorissen:
Directly referencingIDEAS.Media.Airinstead ofMediumto avoid warnings in Dymola and errors in OpenModelica. #1097. -
March 29, 2019 by Filip Jorissen:
Added start value for CO2 concentration for #1004. -
February 14, 2019 by Filip Jorissen:
Changed default value ofstateSelectTVol. See #982. -
December 11, 2018 by Filip Jorissen:
Revised mixing volume connection order to avoid triggering flow reversal warnings. See #964. -
August 30, 2018 by Damien Picard:
Added constant StateSelectTVol to be able to select preferred state of mixing volume. See #905. -
July 27, 2018 by Filip Jorissen:
Added nominal values form,mXiandmC. See #864. - Added output for the CO2 concentration. See #868.
-
April 27, 2018 by Filip Jorissen:
CreatedMixingVolumeNominalUsuch thatMixingVolumecan be used without generating a warning. -
April 27, 2018 by Filip Jorissen:
Added nominal value for internal energy of mixing volume. See #797. - Modified model for supporting new interzonal air flow models. Air leakage model and its parameters have been removed. See #796.
-
August 5, 2017 by Filip Jorissen:
Added support for dry air. -
November 15, 2016 by Filip Jorissen:
Revised documentation. -
August 26, 2016 by Filip Jorissen:
Added support for conservation of energy. -
April 30, 2016, by Filip Jorissen:
First implementation.