modelMediumColumnDynamic

Vertical shaft with no friction and storage of heat and mass

Extends from Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes).

Information

This model contains a completely mixed fluid volume and models that take into account the pressure difference of a medium column that is at the same temperature as the fluid volume. It can be used to model the pressure difference caused by a stack effect.

Typical use and important parameters

Set the parameter use_HeatTransfer=true to expose a heatPort. This heatPort can be used to add or subtract heat from the volume. This allows, for example, to use this model in conjunction with a model for heat transfer through walls to model a solar chimney that stores heat.

Dynamics

For a steady-state model, use Buildings.Airflow.Multizone.MediumColumn instead of this model.

In this model, the parameter h must always be positive, and the port port_a must be at the top of the column.

Parameters

Type	Name	Default	Description
Modelica.Units.SI.Length	h	3	Height of shaft
Modelica.Units.SI.Volume	V		Volume in medium shaft
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
Assumptions › Heat transfer
Boolean	use_HeatTransfer	false	= true to use the HeatTransfer model

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
Modelica.Fluid.Interfaces.FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a	heatPort	Heat port to exchange energy with the fluid volume

Components

Type	Name	Description
Buildings.Fluid.MixingVolumes.MixingVolume	vol	Air volume in the shaft
MediumColumn	colTop	Medium column that connects to top port
MediumColumn	colBot	Medium colum that connects to bottom port

Name	Description
Medium	Medium in the component
HeatTransfer

Revisions

February 27, 2024, by Michael Wetter:
Removed wrong annotation that used a non-existent parameter.
This is for #1842.
March 7, 2022, by Michael Wetter:
Set final massDynamics=energyDynamics.
This is for #1542.
January 18, 2019, by Jianjun Hu:
Limited the media choice to moist air only. See #1050.
January 8, 2019, by Michael Wetter:
Changed public parameter m_flow_nominal.
This is for #970.
May 1, 2018, by Filip Jorissen:
Removed declaration of allowFlowReversal and changed default density computation such that it assumes a constant pressure. See #877.
October 6, 2014 by Michael Wetter:
Removed assignment of port_?.p.nominal to avoid a warning in OpenModelica because alias sets have different nominal values.
July 31, 2011 by Michael Wetter:
Changed model to use new base class Buildings.Fluid.Interfaces.LumpedVolumeDeclarations.
May 25, 2011 by Michael Wetter:
Added m_flow_nominal, which is used if component is configured as steady-state.
July 28, 2010 by Michael Wetter:
Released first version.