Buildings.HeatExchangers.BaseClasses

Package with base classes for heat exchanger models

Package Content

NameDescription
Buildings.HeatExchangers.BaseClasses.DuctManifoldFixedResistance DuctManifoldFixedResistance Manifold for a heat exchanger air duct connection
Buildings.HeatExchangers.BaseClasses.DuctManifoldNoResistance DuctManifoldNoResistance Duct manifold without resistance
Buildings.HeatExchangers.BaseClasses.Examples Examples Collection of models that illustrate model use and test models
Buildings.HeatExchangers.BaseClasses.HASensibleCoil HASensibleCoil Sensible convective heat transfer model for air to water coil
Buildings.HeatExchangers.BaseClasses.HASensibleCoilConstant HASensibleCoilConstant Constant convective heat transfer model
Buildings.HeatExchangers.BaseClasses.PartialDuctManifold PartialDuctManifold Partial manifold for heat exchanger duct connection
Buildings.HeatExchangers.BaseClasses.PartialDuctPipeManifold PartialDuctPipeManifold Partial heat exchanger duct and pipe manifold
Buildings.HeatExchangers.BaseClasses.PartialHA PartialHA Partial model for convective heat transfer coefficients
Buildings.HeatExchangers.BaseClasses.PartialPipeManifold PartialPipeManifold Partial pipe manifold for a heat exchanger
Buildings.HeatExchangers.BaseClasses.PipeManifoldFixedResistance PipeManifoldFixedResistance Pipe manifold for a heat exchanger connection
Buildings.HeatExchangers.BaseClasses.PipeManifoldNoResistance PipeManifoldNoResistance Manifold for heat exchanger register
Buildings.HeatExchangers.BaseClasses.RegisterHeader RegisterHeader Header for a heat exchanger register
Buildings.HeatExchangers.BaseClasses.SensibleCoilRegister SensibleCoilRegister Register for a heat exchanger
Buildings.HeatExchangers.BaseClasses.SensibleHexElement SensibleHexElement Element of a heat exchanger


Buildings.HeatExchangers.BaseClasses.DuctManifoldFixedResistance Buildings.HeatExchangers.BaseClasses.DuctManifoldFixedResistance

Manifold for a heat exchanger air duct connection

Buildings.HeatExchangers.BaseClasses.DuctManifoldFixedResistance

Information


Duct manifold with a fixed flow resistance.

This model causes the flow to be distributed equally into each flow path by using a fixed flow resistance for each flow path.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
IntegernPipSeg Number of pipe segments per register used for discretization
Lengthdh1Hydraulic diameter for duct [m]
RealReC4000Reynolds number where transition to laminar starts
Nominal Condition
MassFlowRatem0_flow Mass flow rate at port_a [kg/s]
Pressuredp0 Pressure [Pa]
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar, nPipSeg]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

model DuctManifoldFixedResistance 
  "Manifold for a heat exchanger air duct connection" 
  extends PartialDuctManifold;
  
  
  parameter Modelica.SIunits.MassFlowRate m0_flow "Mass flow rate at port_a";
  parameter Modelica.SIunits.Pressure dp0(min=0) "Pressure";
  parameter Modelica.SIunits.Length dh=1 "Hydraulic diameter for duct";
  parameter Real ReC=4000 "Reynolds number where transition to laminar starts";
  
  Fluids.FixedResistances.FixedResistanceDpM[nPipPar,nPipSeg] fixRes(
    redeclare each package Medium = Medium,
    each m0_flow=m0_flow/nPipPar/nPipSeg,
    each dp0=dp0,
    each dh=dh/sqrt(nPipPar*nPipSeg),
    each from_dp=true) "Fixed resistance for each duct";
equation 
  for i in 1:nPipPar loop
    for j in 1:nPipSeg loop
     connect(port_a, fixRes[i, j].port_a);
    end for;
  end for;
  
  connect(fixRes.port_b, port_b);
end DuctManifoldFixedResistance;

Buildings.HeatExchangers.BaseClasses.DuctManifoldNoResistance Buildings.HeatExchangers.BaseClasses.DuctManifoldNoResistance

Duct manifold without resistance

Buildings.HeatExchangers.BaseClasses.DuctManifoldNoResistance

Information


Duct manifold without flow resistance.

This model connects the flows between the ports without modeling flow friction. The model is used in conjunction with a manifold which contains pressure drop elements and that is added to the other side of the heat exchanger registers.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
IntegernPipSeg Number of pipe segments per register used for discretization
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar, nPipSeg]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

model DuctManifoldNoResistance "Duct manifold without resistance" 
  extends PartialDuctManifold;
  
equation 
  for i in 1:nPipPar loop
    for j in 1:nPipSeg loop
    connect(port_a, port_b[i, j]);
    end for;
  end for;
end DuctManifoldNoResistance;

Buildings.HeatExchangers.BaseClasses.HASensibleCoil Buildings.HeatExchangers.BaseClasses.HASensibleCoil

Sensible convective heat transfer model for air to water coil

Buildings.HeatExchangers.BaseClasses.HASensibleCoil

Information


Model for sensible convective heat transfer coefficients for an air to water coil.

This model computes the convective heat transfer coefficient for an air to water coil. The parameters allow a user to enable or disable, individually for each medium, the mass flow and/or the temperature dependence of the convective heat transfer coefficients. For a detailed explanation of the equation, see the references below.

References


Parameters

TypeNameDefaultDescription
Realr0.5Ratio between air-side and water-side convective heat transfer coefficient
Realn_w0.85Water-side exponent for convective heat transfer coefficient, h~m_flow^n
Realn_a0.8Air-side exponent for convective heat transfer coefficient, h~m_flow^n
Nominal condition
ThermalConductanceUA0 Thermal conductance at nominal flow [W/K]
MassFlowRatem0_flow_w Water mass flow rate [kg/s]
MassFlowRatem0_flow_a Air mass flow rate [kg/s]
ThermalConductancehA0_wUA0*(r + 1)/rWater side convective heat transfer coefficient [W/K]
ThermalConductancehA0_ar*hA0_wAir side convective heat transfer coefficient, including fin resistance [W/K]
TemperatureT0_wModelica.SIunits.Conversions...Water temperature [K]
TemperatureT0_aModelica.SIunits.Conversions...Air temperature [K]
Advanced
Modeling detail
BooleanwaterSideFlowDependenttrueSet to false to make water-side hA independent of mass flow rate
BooleanairSideFlowDependenttrueSet to false to make air-side hA independent of mass flow rate
BooleanwaterSideTemperatureDependenttrueSet to false to make water-side hA independent of temperature
BooleanairSideTemperatureDependenttrueSet to false to make air-side hA independent of temperature

Connectors

TypeNameDescription
RealSignalm_flow_1Mass flow rate medium 1
RealSignalm_flow_2Mass flow rate medium 2
RealSignalhA_1Convective heat transfer medium 1
RealSignalhA_2Convective heat transfer medium 2
RealSignalT_1Temperature medium 1
RealSignalT_2Temperature medium 2

Modelica definition

model HASensibleCoil 
  "Sensible convective heat transfer model for air to water coil" 
  extends PartialHA;
  
  parameter Real r(min=0, max=1)=0.5 
    "Ratio between air-side and water-side convective heat transfer coefficient";
  parameter Modelica.SIunits.ThermalConductance hA0_w(min=0)=UA0 * (r+1)/r 
    "Water side convective heat transfer coefficient";
  parameter Modelica.SIunits.ThermalConductance hA0_a(min=0)=r * hA0_w 
    "Air side convective heat transfer coefficient, including fin resistance";
  parameter Real n_w(min=0, max=1)=0.85 
    "Water-side exponent for convective heat transfer coefficient, h~m_flow^n";
  parameter Real n_a(min=0, max=1)=0.8 
    "Air-side exponent for convective heat transfer coefficient, h~m_flow^n";
  parameter Modelica.SIunits.Temperature T0_w=
          Modelica.SIunits.Conversions.from_degC(20) "Water temperature";
  parameter Modelica.SIunits.Temperature T0_a=
          Modelica.SIunits.Conversions.from_degC(20) "Air temperature";
  parameter Boolean waterSideFlowDependent = true 
    "Set to false to make water-side hA independent of mass flow rate";
  parameter Boolean airSideFlowDependent = true 
    "Set to false to make air-side hA independent of mass flow rate";
  parameter Boolean waterSideTemperatureDependent = true 
    "Set to false to make water-side hA independent of temperature";
  parameter Boolean airSideTemperatureDependent = true 
    "Set to false to make air-side hA independent of temperature";
protected 
  Real x_a(min=0) 
    "Factor for air side temperature dependent variation of heat transfer coefficient";
  Real x_w(min=0) 
    "Factor for water side temperature dependent variation of heat transfer coefficient";
  Real s_w(min=0, nominal=0.01) 
    "Coefficient for temperature dependence of water side heat transfer coefficient";
  Real fm_w "Fraction of actual to nominal mass flow rate";
  Real fm_a "Fraction of actual to nominal mass flow rate";
equation 
  fm_w = if waterSideFlowDependent then 
              m_flow_1 / m0_flow_w else 1;
  fm_a = if airSideFlowDependent then 
              m_flow_2 / m0_flow_a else 1;
  s_w =  if waterSideTemperatureDependent then 
            0.014/(1+0.014*Modelica.SIunits.Conversions.to_degC(T_1)) else 
              1;
  x_w = if waterSideTemperatureDependent then 
         1 + s_w * (T_1-T0_w) else 
              1;
  x_a = if airSideTemperatureDependent then 
         1 + 4.769E-3 * (T_2-T0_a) else 
              1;
  hA_1 = x_w * Buildings.Utilities.Math.regNonZeroPower(fm_w, n_w, 0.1) * hA0_w;
  hA_2 = x_a * Buildings.Utilities.Math.regNonZeroPower(fm_a, n_a, 0.1) * hA0_a;
end HASensibleCoil;

Buildings.HeatExchangers.BaseClasses.HASensibleCoilConstant Buildings.HeatExchangers.BaseClasses.HASensibleCoilConstant

Constant convective heat transfer model

Buildings.HeatExchangers.BaseClasses.HASensibleCoilConstant

Information


Model for constant sensible convective heat transfer coefficients.


Parameters

TypeNameDefaultDescription
Realr0.5Ratio between air-side and water-side convective heat transfer coefficient
Nominal condition
ThermalConductanceUA0 Thermal conductance at nominal flow [W/K]
MassFlowRatem0_flow_w Water mass flow rate [kg/s]
MassFlowRatem0_flow_a Air mass flow rate [kg/s]
ThermalConductancehA0_wUA0*(r + 1)/rWater side convective heat transfer coefficient [W/K]
ThermalConductancehA0_ar*hA0_wAir side convective heat transfer coefficient, including fin resistance [W/K]

Connectors

TypeNameDescription
RealSignalm_flow_1Mass flow rate medium 1
RealSignalm_flow_2Mass flow rate medium 2
RealSignalhA_1Convective heat transfer medium 1
RealSignalhA_2Convective heat transfer medium 2
RealSignalT_1Temperature medium 1
RealSignalT_2Temperature medium 2

Modelica definition

model HASensibleCoilConstant 
  "Constant convective heat transfer model" 
  extends PartialHA;
  
  parameter Real r(min=0, max=1)=0.5 
    "Ratio between air-side and water-side convective heat transfer coefficient";
  parameter Modelica.SIunits.ThermalConductance hA0_w(min=0)=UA0 * (r+1)/r 
    "Water side convective heat transfer coefficient";
  parameter Modelica.SIunits.ThermalConductance hA0_a(min=0)=r * hA0_w 
    "Air side convective heat transfer coefficient, including fin resistance";
equation 
  hA_1 = hA0_w;
  hA_2 = hA0_a;
end HASensibleCoilConstant;

Buildings.HeatExchangers.BaseClasses.PartialDuctManifold Buildings.HeatExchangers.BaseClasses.PartialDuctManifold

Partial manifold for heat exchanger duct connection

Buildings.HeatExchangers.BaseClasses.PartialDuctManifold

Information


Partial duct manifold for a heat exchanger.

This model defines the duct connection to a heat exchanger. It is extended by other models that model the flow connection between the ports with and without flow friction.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
IntegernPipSeg Number of pipe segments per register used for discretization
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar, nPipSeg]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

partial model PartialDuctManifold 
  "Partial manifold for heat exchanger duct connection" 
  extends PartialDuctPipeManifold;
  parameter Integer nPipSeg(min=1) 
    "Number of pipe segments per register used for discretization";
  
  Modelica_Fluid.Interfaces.FluidPort_b[nPipPar,nPipSeg] port_b(
        redeclare each package Medium = Medium,
        each m_flow(start=0, max=if allowFlowReversal then +Modelica.Constants.inf else 0)) 
    "Fluid connector b for medium (positive design flow direction is from port_a to port_b)";
end PartialDuctManifold;

Buildings.HeatExchangers.BaseClasses.PartialDuctPipeManifold Buildings.HeatExchangers.BaseClasses.PartialDuctPipeManifold

Partial heat exchanger duct and pipe manifold

Buildings.HeatExchangers.BaseClasses.PartialDuctPipeManifold

Information


Partial heat exchanger manifold. This partial model defines ports and parameters that are used for air-side and water-side heat exchanger manifolds.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)

Modelica definition

partial model PartialDuctPipeManifold 
  "Partial heat exchanger duct and pipe manifold" 
  extends Buildings.BaseClasses.BaseIcon;
  extends Buildings.Fluids.Interfaces.PartialSingleFluidParameters;
  
  parameter Integer nPipPar(min=1) "Number of parallel pipes in each register";
  
  Modelica_Fluid.Interfaces.FluidPort_a port_a(
        redeclare package Medium = Medium,
        m_flow(start=0, min=if allowFlowReversal then -Modelica.Constants.inf else 0)) 
    "Fluid connector a for medium (positive design flow direction is from port_a to port_b)";
end PartialDuctPipeManifold;

Buildings.HeatExchangers.BaseClasses.PartialHA Buildings.HeatExchangers.BaseClasses.PartialHA

Partial model for convective heat transfer coefficients

Buildings.HeatExchangers.BaseClasses.PartialHA

Information


Partial model for sensible convective heat transfer coefficients.


Parameters

TypeNameDefaultDescription
Nominal condition
ThermalConductanceUA0 Thermal conductance at nominal flow [W/K]
MassFlowRatem0_flow_w Water mass flow rate [kg/s]
MassFlowRatem0_flow_a Air mass flow rate [kg/s]

Connectors

TypeNameDescription
RealSignalm_flow_1Mass flow rate medium 1
RealSignalm_flow_2Mass flow rate medium 2
RealSignalhA_1Convective heat transfer medium 1
RealSignalhA_2Convective heat transfer medium 2
RealSignalT_1Temperature medium 1
RealSignalT_2Temperature medium 2

Modelica definition

partial model PartialHA 
  "Partial model for convective heat transfer coefficients" 
  extends Buildings.BaseClasses.BaseIcon;
  
  parameter Modelica.SIunits.ThermalConductance UA0(min=0) 
    "Thermal conductance at nominal flow";
  
  parameter Modelica.SIunits.MassFlowRate m0_flow_w "Water mass flow rate";
  parameter Modelica.SIunits.MassFlowRate m0_flow_a "Air mass flow rate";
  
  Modelica.Blocks.Interfaces.RealSignal m_flow_1(redeclare type SignalType = 
        Modelica.SIunits.MassFlowRate) "Mass flow rate medium 1";
  Modelica.Blocks.Interfaces.RealSignal m_flow_2(redeclare type SignalType = 
        Modelica.SIunits.MassFlowRate) "Mass flow rate medium 2";
  Modelica.Blocks.Interfaces.RealSignal hA_1(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Convective heat transfer medium 1";
  Modelica.Blocks.Interfaces.RealSignal hA_2(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Convective heat transfer medium 2";
  Modelica.Blocks.Interfaces.RealSignal T_1(redeclare type SignalType = 
        Modelica.SIunits.Temperature) "Temperature medium 1";
  Modelica.Blocks.Interfaces.RealSignal T_2(redeclare type SignalType = 
        Modelica.SIunits.Temperature) "Temperature medium 2";
end PartialHA;

Buildings.HeatExchangers.BaseClasses.PartialPipeManifold Buildings.HeatExchangers.BaseClasses.PartialPipeManifold

Partial pipe manifold for a heat exchanger

Buildings.HeatExchangers.BaseClasses.PartialPipeManifold

Information


Partial pipe manifold for a heat exchanger.

This model defines the pipe connection to a heat exchanger. It is extended by other models that model the flow connection between the ports with and without flow friction.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

partial model PartialPipeManifold 
  "Partial pipe manifold for a heat exchanger" 
  extends PartialDuctPipeManifold;
  Modelica_Fluid.Interfaces.FluidPort_b[nPipPar] port_b(
        redeclare each package Medium = Medium,
        each m_flow(start=0, max=if allowFlowReversal then +Modelica.Constants.inf else 0)) 
    "Fluid connector b for medium (positive design flow direction is from port_a to port_b)";
end PartialPipeManifold;

Buildings.HeatExchangers.BaseClasses.PipeManifoldFixedResistance Buildings.HeatExchangers.BaseClasses.PipeManifoldFixedResistance

Pipe manifold for a heat exchanger connection

Buildings.HeatExchangers.BaseClasses.PipeManifoldFixedResistance

Information


Pipe manifold with a fixed flow resistance.

This model causes the flow to be distributed equally into each flow path by using a fixed flow resistance for each flow path.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
Lengthdh1Hydraulic diameter for each pipe [m]
RealReC4000Reynolds number where transition to laminar starts
Nominal Condition
MassFlowRatem0_flow Mass flow rate at port_a [kg/s]
Pressuredp0 Pressure [Pa]
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

model PipeManifoldFixedResistance 
  "Pipe manifold for a heat exchanger connection" 
  extends PartialPipeManifold;
  
  parameter Modelica.SIunits.MassFlowRate m0_flow "Mass flow rate at port_a";
  parameter Modelica.SIunits.Pressure dp0(min=0) "Pressure";
  parameter Modelica.SIunits.Length dh=1 "Hydraulic diameter for each pipe";
  parameter Real ReC=4000 "Reynolds number where transition to laminar starts";
  
  Fluids.FixedResistances.FixedResistanceDpM[nPipPar] fixRes(
    redeclare each package Medium = Medium,
    each m0_flow=m0_flow/nPipPar,
    each dp0=dp0,
    each dh=dh,
    each from_dp=true) "Fixed resistance for each duct";
equation 
  for i in 1:nPipPar loop
    connect(port_a, fixRes[i].port_a);
    connect(fixRes[i].port_b, port_b[i]);
  end for;
end PipeManifoldFixedResistance;

Buildings.HeatExchangers.BaseClasses.PipeManifoldNoResistance Buildings.HeatExchangers.BaseClasses.PipeManifoldNoResistance

Manifold for heat exchanger register

Buildings.HeatExchangers.BaseClasses.PipeManifoldNoResistance

Information


Pipe manifold without flow resistance.

This model connects the flows between the ports without modeling flow friction. The model is used in conjunction with a manifold which contains pressure drop elements and that is added to the other side of the heat exchanger registers.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

model PipeManifoldNoResistance "Manifold for heat exchanger register" 
  extends PartialPipeManifold;
equation 
  for i in 1:nPipPar loop
    connect(port_a, port_b[i]);
  end for;
end PipeManifoldNoResistance;

Buildings.HeatExchangers.BaseClasses.RegisterHeader Buildings.HeatExchangers.BaseClasses.RegisterHeader

Header for a heat exchanger register

Buildings.HeatExchangers.BaseClasses.RegisterHeader

Information


Header for a heat exchanger register.

This model connects the flow between its ports without modeling flow friction. Currently, the ports are connected without redistributing the flow. In latter versions, the model may be changed to define different flow reroutings in the heat exchanger header.


Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium in the component
IntegernPipPar Number of parallel pipes in each register
Advanced
TempflowDirectionModelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_a[nPipPar]Fluid connector a for medium (positive design flow direction is from port_a to port_b)
FluidPort_bport_b[nPipPar]Fluid connector b for medium (positive design flow direction is from port_a to port_b)

Modelica definition

model RegisterHeader "Header for a heat exchanger register" 
  extends Buildings.BaseClasses.BaseIcon;
  extends Buildings.Fluids.Interfaces.PartialSingleFluidParameters;
  
  parameter Integer nPipPar(min=1) "Number of parallel pipes in each register";
  Modelica_Fluid.Interfaces.FluidPort_a port_a[nPipPar](
        redeclare each final package Medium = Medium,
        each m_flow(start=0, min=if allowFlowReversal then -Modelica.Constants.inf else 0)) 
    "Fluid connector a for medium (positive design flow direction is from port_a to port_b)";
  
  Modelica_Fluid.Interfaces.FluidPort_b port_b[nPipPar](
        redeclare each final package Medium = Medium,
        each m_flow(start=0, max=if allowFlowReversal then +Modelica.Constants.inf else 0)) 
    "Fluid connector b for medium (positive design flow direction is from port_a to port_b)";
  
equation 
  connect(port_a, port_b);
end RegisterHeader;

Buildings.HeatExchangers.BaseClasses.SensibleCoilRegister Buildings.HeatExchangers.BaseClasses.SensibleCoilRegister

Register for a heat exchanger

Buildings.HeatExchangers.BaseClasses.SensibleCoilRegister

Information


Register of a heat exchanger with dynamics on the fluids and the solid. The register represents one array of pipes that are perpendicular to the air stream. The hA value for both fluids is an input. The driving force for the heat transfer is the temperature difference between the fluid volumes and the solid in each heat exchanger element.


Parameters

TypeNameDefaultDescription
BooleanallowFlowReversal_1flowDirection_1 == Modelica_...= false, if flow only from port_a to port_b, otherwise reversing flow allowed
BooleanallowFlowReversal_2flowDirection_2 == Modelica_...= false, if flow only from port_a to port_b, otherwise reversing flow allowed
IntegernPipPar2Number of parallel pipes in each register
IntegernPipSeg3Number of pipe segments per register used for discretization
Fluid 1
replaceable package Medium_1PartialMediumFluid 1
Fluid 2
replaceable package Medium_2PartialMediumFluid 2
Nominal condition
HeatFlowRateUA0 Thermal conductance at nominal flow, used to compute time constant [W]
MassFlowRatem0_flow_1 Mass flow rate medim 1 [kg/s]
MassFlowRatem0_flow_2 Mass flow rate medium 2 [kg/s]
Timetau_160Time constant at nominal flow for medium 1 [s]
Timetau_260Time constant at nominal flow for medium 2 [s]
Timetau_m60Time constant of metal at nominal UA value [s]
Advanced
TempflowDirection_1Modelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component
TempflowDirection_2Modelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_a1[nPipPar]Fluid connector a for medium 1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_bport_b1[nPipPar]Fluid connector b for medium 1 (positive design flow direction is from port_a to port_b)
FluidPort_aport_a2[nPipPar, nPipSeg]Fluid connector a for medium 2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_bport_b2[nPipPar, nPipSeg]Fluid connector b for medium 2 (positive design flow direction is from port_a to port_b)
input RealInputGc_2Signal representing the convective thermal conductance medium 2 in [W/K]
input RealInputGc_1Signal representing the convective thermal conductance medium 1 in [W/K]

Modelica definition

model SensibleCoilRegister "Register for a heat exchanger" 
  extends Buildings.BaseClasses.BaseIcon;
  extends Buildings.Fluids.Interfaces.PartialDoubleFluidParameters;
  import Modelica.Constants;
  
  
  parameter Integer nPipPar(min=1)=2 
    "Number of parallel pipes in each register";
  parameter Integer nPipSeg(min=1)=3 
    "Number of pipe segments per register used for discretization";
  final parameter Integer nEle = nPipPar * nPipSeg 
    "Number of heat exchanger elements";
  
  Buildings.HeatExchangers.BaseClasses.SensibleHexElement[
                      nPipPar, nPipSeg] ele(
    redeclare each package Medium_1 = Medium_1,
    redeclare each package Medium_2 = Medium_2,
    each flowDirection_1=flowDirection_1,
    each flowDirection_2=flowDirection_2,
    each tau_1=tau_1/nPipSeg,
    each m0_flow_1=m0_flow_1/nPipPar,
    each tau_2=tau_2,
    each m0_flow_2=m0_flow_2/nPipPar/nPipSeg,
    each tau_m=tau_m,
    each UA0=UA0/nPipPar/nPipSeg) "Element of a heat exchanger";
  
  Modelica_Fluid.Interfaces.FluidPort_a[nPipPar] port_a1(
        redeclare each package Medium = Medium_1,
        each m_flow(start=0, min=if allowFlowReversal_1 then -Constants.inf else 0)) 
    "Fluid connector a for medium 1 (positive design flow direction is from port_a1 to port_b1)";
  Modelica_Fluid.Interfaces.FluidPort_b[nPipPar] port_b1(
        redeclare each package Medium = Medium_1,
        each m_flow(start=0, max=if allowFlowReversal_1 then +Constants.inf else 0)) 
    "Fluid connector b for medium 1 (positive design flow direction is from port_a to port_b)";
  Modelica_Fluid.Interfaces.FluidPort_a[nPipPar,nPipSeg] port_a2(
        redeclare each package Medium = Medium_2,
        each m_flow(start=0, min=if allowFlowReversal_2 then -Constants.inf else 0)) 
    "Fluid connector a for medium 2 (positive design flow direction is from port_a2 to port_b2)";
  Modelica_Fluid.Interfaces.FluidPort_b[nPipPar,nPipSeg] port_b2(
        redeclare each package Medium = Medium_2,
        each m_flow(start=0, max=if allowFlowReversal_2 then +Constants.inf else 0)) 
    "Fluid connector b for medium 2 (positive design flow direction is from port_a to port_b)";
  
  parameter Modelica.SIunits.HeatFlowRate UA0 
    "Thermal conductance at nominal flow, used to compute time constant";
  
  parameter Modelica.SIunits.MassFlowRate m0_flow_1 "Mass flow rate medim 1";
  parameter Modelica.SIunits.MassFlowRate m0_flow_2 "Mass flow rate medium 2";
  
  parameter Modelica.SIunits.Time tau_1=60 
    "Time constant at nominal flow for medium 1";
  parameter Modelica.SIunits.Time tau_2=60 
    "Time constant at nominal flow for medium 2";
  Modelica.SIunits.HeatFlowRate Q_flow_1 
    "Heat transfered from solid into medium 1";
  Modelica.SIunits.HeatFlowRate Q_flow_2 
    "Heat transfered from solid into medium 2";
  parameter Modelica.SIunits.Time tau_m=60 
    "Time constant of metal at nominal UA value";
  Modelica.Blocks.Interfaces.RealInput Gc_2(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Signal representing the convective thermal conductance medium 2 in [W/K]";
  Modelica.Blocks.Interfaces.RealInput Gc_1(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Signal representing the convective thermal conductance medium 1 in [W/K]";
protected 
  Modelica.Blocks.Math.Gain gai_1(k=1/nEle) 
    "Gain medium-side 1 to take discretization into account";
  Modelica.Blocks.Math.Gain gai_2(k=1/nEle) 
    "Gain medium-side 2 to take discretization into account";
equation 
  Q_flow_1 = sum(ele[i,j].Q_flow_1 for i in 1:nPipPar, j in 1:nPipSeg);
  Q_flow_2 = sum(ele[i,j].Q_flow_2 for i in 1:nPipPar, j in 1:nPipSeg);
  for i in 1:nPipPar loop
    // liquid side (pipes)
    connect(ele[i,1].port_a1,       port_a1[i]);
    connect(ele[i,nPipSeg].port_b1, port_b1[i]);
    for j in 1:nPipSeg-1 loop
      connect(ele[i,j].port_b1, ele[i,j+1].port_a1);
    end for;
    // gas side (duct)                                                                                      //water connections
    for j in 1:nPipSeg loop
      connect(ele[i,j].port_a2, port_a2[i,j]);
      connect(ele[i,j].port_b2, port_b2[i,j]);
    end for;
  end for;
  
  connect(Gc_1, gai_1.u);
  connect(Gc_2, gai_2.u);
  
  for i in 1:nPipPar loop
     for j in 1:nPipSeg loop
      connect(gai_1.y, ele[i,j].Gc_1);
      connect(gai_2.y, ele[i,j].Gc_2);
     end for;
  end for;
  
end SensibleCoilRegister;

Buildings.HeatExchangers.BaseClasses.SensibleHexElement Buildings.HeatExchangers.BaseClasses.SensibleHexElement

Element of a heat exchanger

Buildings.HeatExchangers.BaseClasses.SensibleHexElement

Information


Element of a heat exchanger with dynamics on the fluids and the solid. The hA value for both fluids is an input. The driving force for the heat transfer is the temperature difference between the fluid volumes and the solid.

The heat capacity C of the metal is assigned as follows. Suppose the metal temperature is governed by

     dT
  C ---- = hA_1 (T_1 - T) + hA_2 (T_2 - T)
     dt
where hA are the convective heat transfer coefficients that also take into account heat conduction in the heat exchanger fins and T_1 and T_2 are the medium temperatures. Assuming hA_1=hA_2, this equation can be rewritten as
  C       dT
 ------  ---- = (T_1 - T) + (T_2 - T)
 2 UA0    dt
where UA0 is the UA value at nominal condition. Hence we set the heat capacity of the metal to C = 2 * UA0 * tau_m.


Parameters

TypeNameDefaultDescription
BooleanallowFlowReversal_1flowDirection_1 == Modelica_...= false, if flow only from port_a to port_b, otherwise reversing flow allowed
BooleanallowFlowReversal_2flowDirection_2 == Modelica_...= false, if flow only from port_a to port_b, otherwise reversing flow allowed
Fluid 1
replaceable package Medium_1PartialMediumFluid 1
Fluid 2
replaceable package Medium_2PartialMediumFluid 2
Initialization
MassFlowRatem_flow_1 Mass flow rate from port_a1 to port_b1 (m_flow_1 > 0 is design flow direction) [kg/s]
MassFlowRatem_flow_2 Mass flow rate from port_a2 to port_b2 (m_flow_2 > 0 is design flow direction) [kg/s]
Pressuredp_1 Pressure difference between port_a1 and port_b1 [Pa]
Pressuredp_2 Pressure difference between port_a2 and port_b2 [Pa]
Nominal condition
Timetau_160Time constant at nominal flow [s]
MassFlowRatem0_flow_1 Mass flow rate [kg/s]
Timetau_260Time constant at nominal flow [s]
MassFlowRatem0_flow_2 Mass flow rate [kg/s]
HeatFlowRateUA0 Thermal conductance at nominal flow, used to compute time constant [W]
Timetau_m60Time constant of metal at nominal UA value [s]
Advanced
TempflowDirection_1Modelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component
TempflowDirection_2Modelica_Fluid.Types.FlowDir...Unidirectional (port_a -> port_b) or bidirectional flow component

Connectors

TypeNameDescription
FluidPort_aport_a1Fluid connector a for medium 1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_bport_b1Fluid connector b for medium 1 (positive design flow direction is from port_a to port_b)
FluidPort_aport_a2Fluid connector a for medium 2 (positive design flow direction is from port_a2 to port_b2)
FluidPort_bport_b2Fluid connector b for medium 2 (positive design flow direction is from port_a to port_b)
input RealInputGc_1Signal representing the convective thermal conductance medium 1 in [W/K]
input RealInputGc_2Signal representing the convective thermal conductance medium 2 in [W/K]

Modelica definition

model SensibleHexElement "Element of a heat exchanger" 
  extends Fluids.Interfaces.PartialDynamicFourPortTransformer(final C=2*UA0*tau_m,
    mas(steadyStateStart=true),
    vol_1(use_T_start=true, initType=Modelica_Fluid.Types.Init.SteadyState),
    vol_2(use_T_start=true, initType=Modelica_Fluid.Types.Init.SteadyState));
  extends Buildings.BaseClasses.BaseIcon;
  
  parameter Modelica.SIunits.HeatFlowRate UA0 
    "Thermal conductance at nominal flow, used to compute time constant";
  parameter Modelica.SIunits.Time tau_m(min=0) = 60 
    "Time constant of metal at nominal UA value";
  Modelica.Blocks.Interfaces.RealInput Gc_1(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Signal representing the convective thermal conductance medium 1 in [W/K]";
  Modelica.Blocks.Interfaces.RealInput Gc_2(redeclare type SignalType = 
        Modelica.SIunits.ThermalConductance) 
    "Signal representing the convective thermal conductance medium 2 in [W/K]";
equation 
  connect(Gc_1, con1.Gc);
  connect(Gc_2, con2.Gc);
end SensibleHexElement;

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