modelGenericHumidifier_u
Steam or adiabatic humidifier with relative mass flow rate as input
Extends from AixLib.Fluid.Interfaces.TwoPortHeatMassExchanger (Partial model transporting one fluid stream with storing mass or energy).
Information
Model for an air humidifier.
This model adds moisture to the air stream. The moisture can be either liquid (adiabatic) or steam. If steam is chosen, the vaporization temperature can be fixed or calculated from the pressure.
The amount of added moisture is equal to
ṁwat = u ṁwat,nom,
where u is the control input signal and
ṁwat,nom is equal to the parameter
mWat_flow_nominal. The parameter
mWat_flow_nominal must be positive.
Twater_in is used to calculate the thermal power for the vaporization (sensible and latent heat) of the steam humidifier and to calculate the enthalpy for the liquid in the adiabatic case.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization (from TwoPortHeatMassExchanger) | true | = true, use homotopy method |
| Modelica.Units.SI.MassFlowRate | mWat_flow_nominal | Water mass flow rate at u=1, positive for humidification | |
| Modelica.Units.SI.Temperature | TLiqWat_in | Temperature of liquid water that is vaporized | |
| Boolean | steamHumidifier | true | True: steam humidifier, false: adiabatic (water) humidifier |
| 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 | |
| Modelica.Units.SI.PressureDifference | dp_nominal (from TwoPortFlowResistanceParameters) | Pressure difference | |
| 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 |
| 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 |
| Dynamics › Nominal condition | |||
| Modelica.Units.SI.Time | tau (from TwoPortHeatMassExchanger) | 30 | Time constant at nominal flow (if energyDynamics <> SteadyState) |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from TwoPortHeatMassExchanger) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_start (from TwoPortHeatMassExchanger) | Medium.p_default | Start value of pressure |
| Medium.Temperature | T_start (from TwoPortHeatMassExchanger) | Medium.T_default | Start value of temperature |
| Medium.MassFraction[Medium.nX] | X_start (from TwoPortHeatMassExchanger) | Medium.X_default | Start value of mass fractions m_i/m |
| Medium.ExtraProperty[Medium.nC] | C_start (from TwoPortHeatMassExchanger) | fill(0, Medium.nC) | Start value of trace substances |
| Advanced › Vaporization | |||
| Boolean | TVapFixed | true | True: fixed vaporization temperature, false: vaporization temperature from pressure |
| Modelica.Units.SI.Temperature | TVap | 373.15 | Vaporization temperature of steam |
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 | u | Control input | |
| Modelica.Blocks.Interfaces.RealOutput | mWat_flow | Water added to the fluid | |
| Modelica.Blocks.Interfaces.RealOutput | powerEva | Consumed power for evaporization |
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 |
| AixLib.Fluid.MixingVolumes.MixingVolume | vol (from TwoPortHeatMassExchanger) | ||
| AixLib.Fluid.FixedResistances.PressureDrop | preDro (from TwoPortHeatMassExchanger) | Flow resistance | |
| Modelica.Blocks.Sources.RealExpression | steamEnthalpyFlow | ||
| Modelica.Blocks.Sources.RealExpression | waterEnthalpyFlow | ||
| Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow | prescribedHeatFlow | ||
| Modelica.Blocks.Sources.RealExpression | TVapPoint | ||
| Modelica.Blocks.Sources.RealExpression | TVapPointFix | ||
| Modelica.Blocks.Routing.RealPassThrough | Tsteam | ||
| Modelica.Blocks.Sources.RealExpression | realExpression | ||
| Modelica.Blocks.Math.Product | product |
Revisions
- December 06, 2022, by EBC-Modelica group:
Fixes to increase compatability to OpenModelica #1378. - October 22, 2019, by Alexander Kümpel:
First implementation.