modelAirDuct
model of the air duct
Extends from Interfaces.PartialTwoPortInterface, AixLib.Fluid.Interfaces.TwoPortFlowResistanceParameters.
Information
This model provides the definition of the air duct in a parallel membrane enthalpy exchanger. It is based on the PartialTwoPortInterface model.
This model defines the geometry of the air duct, as well as the convective heat and mass transfer processes in the air duct. The model can be discretized in flow direction using finite volumes.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | nNodes | 2 | number of discrete volumes (over length) in the air duct |
| Integer | nParallel | 2 | number of parallel air ducts |
| Integer | nWidth | 1 | number of segments in width direction |
| Geometry | |||
| Modelica.Units.SI.Length | lengthDuct | length in flow direction of duct | |
| Modelica.Units.SI.Length | widthDuct | width of duct | |
| Modelica.Units.SI.Length | heightDuct | height of duct | |
| Boolean | couFloArr | true | true: counter-flow arrangement; false: quasi-counter-flow arrangement |
| Heat and Mass transfer | |||
| Boolean | uniWalTem | true if uniform wall temperature, else uniform wall heat flux | |
| Boolean | local | true if local Nusselt/Sherwood number, else average | |
| Boolean | recDuct | true if rectangular duct is used for Nusselt/Sherwood number calculation, else flat gap is used. | |
| Advanced | |||
| Boolean | homotopyInitialization | true | = true, use homotopy method |
| Dynamics › Equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_a_start | Medium.p_default | Start value of pressure at port a |
| Medium.AbsolutePressure | p_b_start | p_a_start | Start value of pressure at port b |
| Medium.AbsolutePressure | p_start | Medium.p_default | Start value of pressure |
| Medium.Temperature | T_start | Medium.T_default | Start value of temperature |
| Medium.MassFraction[Medium.nX] | X_start | Medium.X_default | Start value of mass fractions m_i/m |
| Medium.ExtraProperty[Medium.nC] | C_start | fill(0, Medium.nC) | Start value of trace substances |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Length | lengths | {i*(lengthDuct/((nNodes + 1)*nNodes/2)) for i in 1:nNodes} | length of segements in flow direction |
| Modelica.Units.SI.Area | croSecs | fill(heightDuct*widthDuct, nNodes) | cross section of duct segments |
| Modelica.Units.SI.Velocity | vs | {port_a.m_flow/Medium.density(states[i])/croSecs[i] for i in 1:nNodes}/nParallel | velocity in air duct segments |
| Modelica.Units.SI.PartialPressure | ps | {vol[i].p*vol[i].X_w*(Ms[i]/M_steam) for i in 1:nNodes} | |
| Modelica.Units.SI.MolarMass | Ms | {1/(vol[i].X_w/M_steam + (1 - vol[i].X_w)/M_air) for i in 1:nNodes} | |
| Medium.ThermodynamicState | states | {Medium.setState_pTX(vol[i].p, vol[i].T, vol[i].Xi) for i in 1:nNodes} | |
| Modelica.Units.SI.SpecificEnthalpy | dhAds | adsorptionEnthalpy.dhAds | adsorption enthalpy |
| Modelica.Blocks.Interfaces.RealInput | coeCroCouSens | coefficient for heat transfer reduction due to cross-flow portion | |
| Modelica.Blocks.Interfaces.RealInput | coeCroCouLats | coefficient for mass transfer reduction due to cross-flow portion | |
| HeatTransfer | heatTransfer | ||
| MassTransfer | massTransfer | ||
| AixLib.Fluid.MixingVolumes.MixingVolumeMoistAir[nNodes] | vol | Volume for fluid stream | |
| AixLib.Fluid.FixedResistances.PressureDrop | preDro | Flow resistance | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a[nNodes] | heatPorts | ||
| Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow[nNodes] | prescribedHeatFlow | ||
| Utilities.MassTransfer.MassPort[nNodes] | massPorts | ||
| Modelica.Blocks.Sources.RealExpression[nNodes] | Q_flow | ||
| Modelica.Blocks.Sources.RealExpression[nNodes] | mWat_flow |
Contents
| Name | Description |
|---|---|
| HeatTransfer | |
| MassTransfer |
Revisions
- November 23, 2018, by Martin Kremer:
Changing adsorption enthalpy dhAds from parameter to input for usage of adsorption enthalpy model. - August 21, 2018, by Martin Kremer:
First Implementation