modelHexElementLatent
Element of a heat exchanger with humidity condensation of fluid 2
Extends from Buildings.Fluid.HeatExchangers.BaseClasses.PartialHexElement (Element of a heat exchanger 2).
Information
Element of a heat exchanger with humidity condensation of fluid 2 and with dynamics of the fluids and the solid.
See
Buildings.Fluid.HeatExchangers.BaseClasses.PartialHexElement
for a description of the physics of the sensible heat exchange.
For the latent heat exchange, this model removes water vapor from the air stream, as
computed by the instance masExc, and deposits it on the coil.
Hence, the latent heat is treated such that it transfers to the coil surface.
The latent heat is removed from the air stream using heat flow source heaConVapAir
and deposited on the coil surface using heat flow source heaConVapCoi.
Note that the driving potential for latent heat transfer is the temperature of the instance mas.
This is an approximation as it neglects the thermal resistance of the water film that builds up on the coil.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization (from FourPortHeatMassExchanger) | true | = true, use homotopy method |
| Modelica.Units.SI.HeatCapacity | C (from PartialHexElement) | 2*UA_nominal*tau_m | Heat capacity of metal (= cp*m) |
| Boolean | simplify_mWat_flow | true | Set to true to cause port_a.m_flow + port_b.m_flow = 0 even if mWat_flow is non-zero. Used only if Medium.nX > 1 |
| Assumptions | |||
| Boolean | allowFlowReversal1 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m1_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.PressureDifference | dp1_nominal (from FourPortFlowResistanceParameters) | Pressure difference | |
| Modelica.Units.SI.PressureDifference | dp2_nominal (from FourPortFlowResistanceParameters) | Pressure difference | |
| Modelica.Units.SI.ThermalConductance | UA_nominal (from PartialHexElement) | Thermal conductance at nominal flow, used to compute time constant | |
| Advanced | |||
| Medium1.MassFlowRate | m1_flow_small (from PartialFourPortInterface) | 1E-4*abs(m1_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Medium2.MassFlowRate | m2_flow_small (from PartialFourPortInterface) | 1E-4*abs(m2_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Boolean | initialize_p1 (from PartialHexElement) | not Medium1.singleState | Set to true to initialize the pressure of volume 1 |
| Boolean | initialize_p2 (from PartialHexElement) | not Medium2.singleState | Set to true to initialize the pressure of volume 2 |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialFourPortInterface) | false | = true, if actual temperature at port is computed |
| Flow resistance › Medium 1 | |||
| Boolean | computeFlowResistance1 (from FourPortFlowResistanceParameters) | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp1 (from FourPortFlowResistanceParameters) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Real | n1 (from FourPortFlowResistanceParameters) | 2 | Flow exponent for side 1, n=1 for laminar, n=2 for turbulent |
| Boolean | linearizeFlowResistance1 (from FourPortFlowResistanceParameters) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM1 (from FourPortFlowResistanceParameters) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Flow resistance › Medium 2 | |||
| Boolean | computeFlowResistance2 (from FourPortFlowResistanceParameters) | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp2 (from FourPortFlowResistanceParameters) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Real | n2 (from FourPortFlowResistanceParameters) | 2 | Flow exponent for side 2, n=1 for laminar, n=2 for turbulent |
| Boolean | linearizeFlowResistance2 (from FourPortFlowResistanceParameters) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM2 (from FourPortFlowResistanceParameters) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics › Nominal condition | |||
| Modelica.Units.SI.Time | tau1 (from FourPortHeatMassExchanger) | 30 | Time constant at nominal flow |
| Modelica.Units.SI.Time | tau2 (from FourPortHeatMassExchanger) | 30 | Time constant at nominal flow |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from FourPortHeatMassExchanger) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Initialization › Medium 1 | |||
| Medium1.AbsolutePressure | p1_start (from FourPortHeatMassExchanger) | Medium1.p_default | Start value of pressure |
| Medium1.Temperature | T1_start (from FourPortHeatMassExchanger) | Medium1.T_default | Start value of temperature |
| Medium1.MassFraction[Medium1.nX] | X1_start (from FourPortHeatMassExchanger) | Medium1.X_default | Start value of mass fractions m_i/m |
| Medium1.ExtraProperty[Medium1.nC] | C1_start (from FourPortHeatMassExchanger) | fill(0, Medium1.nC) | Start value of trace substances |
| Medium1.ExtraProperty[Medium1.nC] | C1_nominal (from FourPortHeatMassExchanger) | fill(1E-2, Medium1.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Initialization › Medium 2 | |||
| Medium2.AbsolutePressure | p2_start (from FourPortHeatMassExchanger) | Medium2.p_default | Start value of pressure |
| Medium2.Temperature | T2_start (from FourPortHeatMassExchanger) | Medium2.T_default | Start value of temperature |
| Medium2.MassFraction[Medium2.nX] | X2_start (from FourPortHeatMassExchanger) | Medium2.X_default | Start value of mass fractions m_i/m |
| Medium2.ExtraProperty[Medium2.nC] | C2_start (from FourPortHeatMassExchanger) | fill(0, Medium2.nC) | Start value of trace substances |
| Medium2.ExtraProperty[Medium2.nC] | C2_nominal (from FourPortHeatMassExchanger) | fill(1E-2, Medium2.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| General › Nominal condition | |||
| Modelica.Units.SI.Time | tau_m (from PartialHexElement) | 60 | Time constant of metal at nominal UA value |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a1 (from PartialFourPort) | Fluid connector a1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b1 (from PartialFourPort) | Fluid connector b1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_a2 (from PartialFourPort) | Fluid connector a2 (positive design flow direction is from port_a2 to port_b2) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b2 (from PartialFourPort) | Fluid connector b2 (positive design flow direction is from port_a2 to port_b2) | |
| Modelica.Blocks.Interfaces.RealInput | Gc_1 (from PartialHexElement) | Signal representing the convective thermal conductance medium 1 in [W/K] | |
| Modelica.Blocks.Interfaces.RealInput | Gc_2 (from PartialHexElement) | Signal representing the convective thermal conductance medium 2 in [W/K] | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | heaPor1 (from PartialHexElement) | Heat port for heat exchange with the control volume 1 | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | heaPor2 (from PartialHexElement) | Heat port for heat exchange with the control volume 2 |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium1.MassFlowRate | m1_flow (from PartialFourPortInterface) | port_a1.m_flow | Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp1 (from PartialFourPortInterface) | port_a1.p - port_b1.p | Pressure difference between port_a1 and port_b1 |
| Medium2.MassFlowRate | m2_flow (from PartialFourPortInterface) | port_a2.m_flow | Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp2 (from PartialFourPortInterface) | port_a2.p - port_b2.p | Pressure difference between port_a2 and port_b2 |
| Medium1.ThermodynamicState | sta_a1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_a1.p, noEvent(actualStream(port_a1.h_outflow)), noEvent(actualStream(port_a1.Xi_outflow))) else Medium1.setState_phX(port_a1.p, inStream(port_a1.h_outflow), inStream(port_a1.Xi_outflow)) | Medium properties in port_a1 |
| Medium1.ThermodynamicState | sta_b1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_b1.p, noEvent(actualStream(port_b1.h_outflow)), noEvent(actualStream(port_b1.Xi_outflow))) else Medium1.setState_phX(port_b1.p, port_b1.h_outflow, port_b1.Xi_outflow) | Medium properties in port_b1 |
| Medium2.ThermodynamicState | sta_a2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_a2.p, noEvent(actualStream(port_a2.h_outflow)), noEvent(actualStream(port_a2.Xi_outflow))) else Medium2.setState_phX(port_a2.p, inStream(port_a2.h_outflow), inStream(port_a2.Xi_outflow)) | Medium properties in port_a2 |
| Medium2.ThermodynamicState | sta_b2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_b2.p, noEvent(actualStream(port_b2.h_outflow)), noEvent(actualStream(port_b2.Xi_outflow))) else Medium2.setState_phX(port_b2.p, port_b2.h_outflow, port_b2.Xi_outflow) | Medium properties in port_b2 |
| Modelica.Units.SI.HeatFlowRate | Q1_flow (from FourPortHeatMassExchanger) | vol1.heatPort.Q_flow | Heat flow rate into medium 1 |
| Modelica.Units.SI.HeatFlowRate | Q2_flow (from FourPortHeatMassExchanger) | vol2.heatPort.Q_flow | Heat flow rate into medium 2 |
| Buildings.Fluid.MixingVolumes.BaseClasses.MixingVolumeHeatPort | vol1 (from FourPortHeatMassExchanger) | ||
| Buildings.Fluid.MixingVolumes.MixingVolume | vol2 (from FourPortHeatMassExchanger) | ||
| Buildings.Fluid.FixedResistances.PressureDrop | preDro1 (from FourPortHeatMassExchanger) | Flow resistance of fluid 1 | |
| Buildings.Fluid.FixedResistances.PressureDrop | preDro2 (from FourPortHeatMassExchanger) | Flow resistance of fluid 2 | |
| Modelica.Thermal.HeatTransfer.Components.HeatCapacitor | mas (from PartialHexElement) | Mass of metal | |
| Modelica.Thermal.HeatTransfer.Components.Convection | con1 (from PartialHexElement) | Convection (and conduction) on fluid side 1 | |
| Modelica.Thermal.HeatTransfer.Components.Convection | con2 (from PartialHexElement) | Convection (and conduction) on fluid side 2 | |
| MassExchange | masExc | Model for mass exchange | |
| Modelica.Blocks.Math.Gain | gain | Change sign |
Revisions
-
July 5, 2022, by Antoine Gautier:
Restored the addition of heat tomas.T.
This is for #3065. -
May 26, 2022, by Michael Wetter:
Removed addition of heat tomas.T.
This is for #3027. -
March 11, 2021, by Michael Wetter:
Changed constantsimplify_mWat_flowfrom protected to public because it is assigned by Buildings.Fluid.HeatExchangers.WetCoilCounterFlow.
This is for #2387. -
May 1, 2020, by Michael Wetter:
Added constantsimplify_mWat_flow.
This is for #1920. -
April 14, 2017, by David Blum:
Added heat of condensation to coil surface heat balance and removed it from the air stream.
This is for issue Buildings #711. -
April 12, 2017, by Michael Wetter:
Removed temperature that is no longer needed.
This is for issue Buildings #704. -
June 18, 2014, by Michael Wetter:
Added initialization formasto avoid a warning during translation. -
September 11, 2013, by Michael Latentter:
First implementation.