Buildings.Fluid.HeatExchangers.Validation
Collection of models that validate the heat exchanger models
Information
This package contains models that validate the heat exchanger models. The examples plot various outputs, which have been verified against analytical solutions. These model outputs are stored as reference data to allow continuous validation whenever models in the library change.
Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).
Package Content
| Name | Description |
|---|---|
 ConstantEffectiveness
|
Model that demonstrates use of a heat exchanger with constant effectiveness |
| DryCoilEffectivenessNTU
|
Model that demonstrates use of a heat exchanger without condensation that uses the epsilon-NTU relation |
| EvaporatorCondenser
|
Test model for the evaporator or condenser model |
| HeaterCooler_u
|
Model that demonstrates the ideal heater model |
| PrescribedOutlet
|
Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as steady-state |
| PrescribedOutlet_dynamic
|
Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as dynamic |
| WetCoilCounterFlowLowWaterFlowRate
|
Model that tests a heat exchanger with prescribed boundary conditions, in terms of properties of inlet water and inlet air |
| WetCoilDiscretizedInitialization
|
Model that demonstrates use of a finite volume model of a heat exchanger with condensation |
| WetCoilDiscretizedInitializationPerfectGases
|
Model that demonstrates use of a finite volume model of a heat exchanger with condensation |
| WetCoilEffectivenessNTU
|
Model that validates the wet coil effectiveness-NTU model |
| WetCoilEffectivenessNTUCounterFlow
|
Model that validates the wet coil effectiveness-NTU model |
| WetCoilEffectivenessNTUHeating
|
Model that validates the wet coil effectiveness-NTU model in heating conditions |
Buildings.Fluid.HeatExchangers.Validation.ConstantEffectiveness
Model that demonstrates use of a heat exchanger with constant effectiveness
Information
This model tests Buildings.Fluid.HeatExchangers.ConstantEffectiveness for different inlet conditions.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Modelica definition
model ConstantEffectiveness
"Model that demonstrates use of a heat exchanger with constant effectiveness"
extends Modelica.Icons.Example;
package Medium1 = Buildings.Media.Water "Medium model";
package Medium2 = Buildings.Media.Air "Medium model";
Buildings.Fluid.Sources.Boundary_pT sin_2(
redeclare package Medium = Medium2,
use_p_in=true,
nPorts=1,
T=273.15 + 10,
X={0.001,0.999})
"Boundary condition";
Modelica.Blocks.Sources.Ramp PIn(
height=200,
duration=60,
offset=101325,
startTime=50)
"Ramp signal for pressure";
Buildings.Fluid.Sources.Boundary_pT sou_2(
redeclare package Medium = Medium2, T=273.15 + 5,
use_p_in=true,
use_T_in=true,
nPorts=1)
"Boundary condition";
Modelica.Blocks.Sources.Ramp TWat(
height=10,
duration=60,
offset=273.15 + 30,
startTime=60) "Water temperature";
Modelica.Blocks.Sources.Constant TDb(k=293.15) "Drybulb temperature";
Modelica.Blocks.Sources.Constant POut(k=101325) "Pressure";
Buildings.Fluid.Sources.Boundary_pT sin_1(
redeclare package Medium = Medium1,
use_p_in=true,
nPorts=1,
p=300000,
T=273.15 + 25)
"Boundary condition";
Buildings.Fluid.Sources.Boundary_pT sou_1(
redeclare package Medium = Medium1,
p=300000 + 5000,
T=273.15 + 50,
use_T_in=true,
nPorts=1)
"Boundary condition";
Buildings.Fluid.HeatExchangers.ConstantEffectiveness hex(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
show_T=true,
m1_flow_nominal=5,
m2_flow_nominal=5,
dp1_nominal=500,
dp2_nominal=10)
"Heat exchanger";
Modelica.Blocks.Sources.Trapezoid trapezoid(
amplitude=5000,
rising=10,
width=100,
falling=10,
period=3600,
offset=300000)
"Signal for pressure boundary condition";
equation
connect(PIn.y,sou_2. p_in);
connect(TDb.y, sou_2.T_in);
connect(TWat.y, sou_1.T_in);
connect(sou_1.ports[1], hex.port_a1);
connect(hex.port_a2, sou_2.ports[1]);
connect(POut.y, sin_2.p_in);
connect(hex.port_b1, sin_1.ports[1]);
connect(sin_2.ports[1], hex.port_b2);
connect(trapezoid.y, sin_1.p_in);
end ConstantEffectiveness;
Buildings.Fluid.HeatExchangers.Validation.DryCoilEffectivenessNTU
Model that demonstrates use of a heat exchanger without condensation that uses the epsilon-NTU relation
Information
This model tests Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU for different inlet conditions.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| SpecificHeatCapacity | cp1 | Medium1.specificHeatCapacity... | Specific heat capacity of medium 2 [J/(kg.K)] |
| SpecificHeatCapacity | cp2 | Medium2.specificHeatCapacity... | Specific heat capacity of medium 2 [J/(kg.K)] |
| MassFlowRate | m1_flow | 5 | Nominal mass flow rate medium 1 [kg/s] |
| MassFlowRate | m2_flow | m1_flow*cp1/cp2 | Nominal mass flow rate medium 2 [kg/s] |
Modelica definition
model DryCoilEffectivenessNTU
"Model that demonstrates use of a heat exchanger without condensation that uses the epsilon-NTU relation"
extends Modelica.Icons.Example;
package Medium1 = Buildings.Media.Water;
package Medium2 = Buildings.Media.Air;
parameter Modelica.Units.SI.SpecificHeatCapacity cp1=
Medium1.specificHeatCapacityCp(Medium1.setState_pTX(
Medium1.p_default,
Medium1.T_default,
Medium1.X_default)) "Specific heat capacity of medium 2";
parameter Modelica.Units.SI.SpecificHeatCapacity cp2=
Medium2.specificHeatCapacityCp(Medium2.setState_pTX(
Medium2.p_default,
Medium2.T_default,
Medium2.X_default)) "Specific heat capacity of medium 2";
parameter Modelica.Units.SI.MassFlowRate m1_flow=5
"Nominal mass flow rate medium 1";
parameter Modelica.Units.SI.MassFlowRate m2_flow=m1_flow*cp1/cp2
"Nominal mass flow rate medium 2";
Buildings.Fluid.Sources.Boundary_pT sin_2(
redeclare package Medium = Medium2,
use_p_in=true,
nPorts=5,
T=273.15 + 10) "Boundary condition";
Modelica.Blocks.Sources.Ramp PIn(
height=200,
duration=60,
offset=101325,
startTime=100) "Pressure boundary condition";
Buildings.Fluid.Sources.Boundary_pT sou_2(
redeclare package Medium = Medium2,
T=273.15 + 5,
use_p_in=true,
use_T_in=true,
nPorts=5) "Boundary condition";
Modelica.Blocks.Sources.Ramp TWat(
height=10,
duration=60,
offset=273.15 + 30,
startTime=60) "Water temperature";
Modelica.Blocks.Sources.Constant TDb(k=293.15) "Drybulb temperature";
Modelica.Blocks.Sources.Constant POut(k=101325);
Buildings.Fluid.Sources.Boundary_pT sin_1(
redeclare package Medium = Medium1,
use_p_in=true,
nPorts=5,
p=300000,
T=273.15 + 25)
"Boundary condition";
Buildings.Fluid.Sources.Boundary_pT sou_1(
redeclare package Medium = Medium1,
p=300000 + 5000,
T=273.15 + 50,
use_T_in=true,
nPorts=5)
"Boundary condition";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexPar(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
dp1_nominal=500,
dp2_nominal=10,
m1_flow_nominal=m1_flow,
m2_flow_nominal=m2_flow,
Q_flow_nominal=m2_flow*cp2*(24 - 20),
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.ParallelFlow,
show_T=true,
T_a1_nominal=303.15,
T_a2_nominal=293.15)
"Heat exchanger";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexCou(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
dp1_nominal=500,
dp2_nominal=10,
m1_flow_nominal=m1_flow,
m2_flow_nominal=m2_flow,
Q_flow_nominal=m2_flow*cp2*(24 - 20),
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow,
show_T=true,
T_a1_nominal=303.15,
T_a2_nominal=293.15)
"Heat exchanger";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexCroC1Mix(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
dp1_nominal=500,
dp2_nominal=10,
m1_flow_nominal=m1_flow,
m2_flow_nominal=m2_flow,
Q_flow_nominal=m2_flow*cp2*(24 - 20),
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CrossFlowStream1MixedStream2Unmixed,
show_T=true,
T_a1_nominal=303.15,
T_a2_nominal=293.15)
"Heat exchanger";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexCroC1Unm(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
dp1_nominal=500,
dp2_nominal=10,
m1_flow_nominal=m1_flow,
m2_flow_nominal=m2_flow,
Q_flow_nominal=m2_flow*cp2*(24 - 20),
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CrossFlowStream1UnmixedStream2Mixed,
show_T=true,
T_a1_nominal=303.15,
T_a2_nominal=293.15)
"Heat exchanger";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexCroUnm(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
dp1_nominal=500,
dp2_nominal=10,
m1_flow_nominal=m1_flow,
m2_flow_nominal=m2_flow,
Q_flow_nominal=m2_flow*cp2*(24 - 20),
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CrossFlowUnmixed,
show_T=true,
T_a1_nominal=303.15,
T_a2_nominal=293.15)
"Heat exchanger";
Modelica.Blocks.Sources.Trapezoid trapezoid(
amplitude=5000,
rising=10,
width=100,
falling=10,
period=3600,
offset=300000)
"Pressure boundary condition";
equation
connect(PIn.y,sou_2. p_in);
connect(TDb.y, sou_2.T_in);
connect(TWat.y, sou_1.T_in);
connect(sou_1.ports[1], hexPar.port_a1);
connect(hexPar.port_a2, sou_2.ports[1]);
connect(POut.y, sin_2.p_in);
connect(hexPar.port_b1, sin_1.ports[1]);
connect(sin_2.ports[1], hexPar.port_b2);
connect(hexCou.port_a1, sou_1.ports[2]);
connect(hexCroC1Mix.port_a1, sou_1.ports[3]);
connect(hexCroC1Unm.port_a1, sou_1.ports[4]);
connect(hexCou.port_b2, sin_2.ports[2]);
connect(hexCroC1Mix.port_b2, sin_2.ports[3]);
connect(hexCroC1Unm.port_b2, sin_2.ports[4]);
connect(hexCou.port_b1, sin_1.ports[2]);
connect(hexCroC1Mix.port_b1, sin_1.ports[3]);
connect(hexCroC1Unm.port_b1, sin_1.ports[4]);
connect(hexCou.port_a2, sou_2.ports[2]);
connect(hexCroC1Mix.port_a2, sou_2.ports[3]);
connect(hexCroC1Unm.port_a2, sou_2.ports[4]);
connect(hexCroUnm.port_a1, sou_1.ports[5]);
connect(hexCroUnm.port_b2, sin_2.ports[5]);
connect(hexCroUnm.port_b1, sin_1.ports[5]);
connect(hexCroUnm.port_a2, sou_2.ports[5]);
connect(trapezoid.y, sin_1.p_in);
end DryCoilEffectivenessNTU;
Buildings.Fluid.HeatExchangers.Validation.EvaporatorCondenser
Test model for the evaporator or condenser model
Information
Model that demonstrates the use of the Buildings.Fluid.HeatExchangers.EvaporatorCondenser model.
The fluid flow rate is increased from ṁ = 0.01 kg/s to ṁ = 0.10 kg/s over 100 seconds. As a result, the heat exchanger effectiveness and the fluid temperature difference in the heat exchanger decrease.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 0.01 | Nominal mass flow rate [kg/s] |
Modelica definition
model EvaporatorCondenser "Test model for the evaporator or condenser model"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water "Medium model";
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=0.01
"Nominal mass flow rate";
Buildings.HeatTransfer.Sources.FixedTemperature ref(T=283.15)
"Refrigerant temperature";
Modelica.Thermal.HeatTransfer.Sensors.HeatFlowSensor heaFlo
"Heat flow rate sensor";
Modelica.Fluid.Sources.MassFlowSource_T sou(
nPorts=1,
redeclare package Medium = Medium,
m_flow=0.1,
use_m_flow_in=true,
T=323.15) "Flow source";
Modelica.Fluid.Sources.FixedBoundary sin(
redeclare package Medium = Medium,
p=0,
nPorts=1) "Sink";
Buildings.Fluid.HeatExchangers.EvaporatorCondenser eva(
redeclare package Medium = Medium,
m_flow(start=0.1),
dp(start=10),
UA=100,
dp_nominal=0,
tau=5,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
m_flow_nominal=m_flow_nominal) "Evaporator";
Modelica.Blocks.Sources.Ramp m_flow(
duration=100,
height=9*m_flow_nominal,
offset=m_flow_nominal) "Mass flow rate";
Buildings.Fluid.Sensors.TemperatureTwoPort senTem(
m_flow_nominal=m_flow_nominal,
redeclare package Medium = Medium,
tau=0.01,
initType=Modelica.Blocks.Types.Init.SteadyState) "Temperature sensor";
equation
connect(ref.port, heaFlo.port_a);
connect(heaFlo.port_b, eva.port_ref);
connect(sou.ports[1], eva.port_a);
connect(m_flow.y, sou.m_flow_in);
connect(eva.port_b, senTem.port_a);
connect(senTem.port_b, sin.ports[1]);
end EvaporatorCondenser;
Buildings.Fluid.HeatExchangers.Validation.HeaterCooler_u
Model that demonstrates the ideal heater model
Information
Model that demonstrates the use of an ideal heater. Both heater models are identical, except that one model is configured as a steady-state model, whereas the other is configured as a dynamic model. Both heaters add heat to the medium to track a set-point for the outlet temperature.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 3000/1000/20 | Nominal mass flow rate [kg/s] |
Modelica definition
model HeaterCooler_u "Model that demonstrates the ideal heater model"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Air;
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=3000/1000/20
"Nominal mass flow rate";
Buildings.Fluid.Sources.Boundary_pT sin(
redeclare package Medium = Medium,
use_T_in=false,
p(displayUnit="Pa"),
T=293.15,
nPorts=2)
"Sink";
Buildings.Fluid.HeatExchangers.HeaterCooler_u heaSte(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=6000,
Q_flow_nominal=3000,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Steady-state model of the heater";
Buildings.Fluid.Sensors.TemperatureTwoPort senTem1(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Modelica.Blocks.Sources.TimeTable TSet(table=[0, 273.15 + 20; 120, 273.15
+20; 120, 273.15 + 30; 1200, 273.15 + 30])
"Setpoint";
Buildings.Controls.Continuous.LimPID con1(
Td=1,
k=1,
Ti=10)
"Controller";
Buildings.Fluid.HeatExchangers.HeaterCooler_u heaDyn(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=6000,
Q_flow_nominal=3000,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyStateInitial)
"Dynamic model of the heater";
Buildings.Fluid.Sensors.TemperatureTwoPort senTem2(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Buildings.Controls.Continuous.LimPID con2(
Td=1,
Ti=10,
k=0.1)
"Controller";
Buildings.Fluid.Sources.MassFlowSource_T sou(
redeclare package Medium = Medium,
use_T_in=false,
nPorts=2,
m_flow=2*m_flow_nominal,
T=293.15) "Source";
equation
connect(senTem1.T, con1.u_m);
connect(TSet.y, con1.u_s);
connect(con1.y, heaSte.u);
connect(heaSte.port_b, senTem1.port_a);
connect(senTem2.T, con2.u_m);
connect(TSet.y, con2.u_s);
connect(con2.y, heaDyn.u);
connect(heaDyn.port_b, senTem2.port_a);
connect(heaSte.port_a, sou.ports[1]);
connect(sou.ports[2], heaDyn.port_a);
connect(senTem2.port_b, sin.ports[1]);
connect(senTem1.port_b, sin.ports[2]);
end HeaterCooler_u;
Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet
Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as steady-state
Information
Model that demonstrates the use of an ideal heater and an ideal cooler.
The heater model has a capacity of Q_flow_max = 1.0e4 Watts and
the cooler model has a capacitiy of Q_flow_min = -1000 Watts.
Hence, both only track their set point of the outlet temperature during certain times.
There is also a heater and cooler with unlimited capacity.
At t=1000 second, the flow reverses its direction.
Each flow leg has the same mass flow rate. There are three mass flow sources as using one source only would yield a nonlinear system of equations that needs to be solved to determine the mass flow rate distribution.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 0.1 | Nominal mass flow rate [kg/s] |
Modelica definition
model PrescribedOutlet
"Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as steady-state"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water;
parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=0.1
"Nominal mass flow rate";
Buildings.Fluid.Sources.Boundary_pT sin(
redeclare package Medium = Medium,
use_T_in=false,
p(displayUnit="Pa"),
T=293.15,
nPorts=3) "Sink";
Buildings.Fluid.HeatExchangers.PrescribedOutlet heaHigPow(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=6000,
QMax_flow=1e4,
use_X_wSet=false)
"Steady-state model of the heater with high capacity";
Buildings.Fluid.Sensors.TemperatureTwoPort heaHigPowOut(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Modelica.Blocks.Sources.TimeTable TSetHeat(table=[0,273.15 + 20.0; 120,273.15
+ 20.0; 120,273.15 + 60.0; 500,273.15 + 60.0; 500,273.15 + 30.0; 1200,273.15 + 30.0])
"Setpoint heating";
Buildings.Fluid.Sensors.TemperatureTwoPort cooLimPowOut(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Buildings.Fluid.HeatExchangers.PrescribedOutlet cooLimPow(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=6000,
QMin_flow=-1000,
use_X_wSet=false)
"Steady-state model of the cooler with limited capacity";
Modelica.Blocks.Sources.TimeTable TSetCool(table=[0,273.15 + 20.0; 120,273.15
+ 20.0; 120,273.15 + 15.0; 500,273.15 + 15.0; 500,273.15 + 10.0; 1200,273.15 + 10.0])
"Setpoint cooling";
Buildings.Fluid.HeatExchangers.PrescribedOutlet heaCooUnl(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=6000,
use_X_wSet=false)
"Steady-state model of the heater or cooler with unlimited capacity";
Modelica.Blocks.Sources.TimeTable TSetCoolHeat(table=[0,273.15 + 20.0; 120,273.15
+ 20.0; 120,273.15 + 15.0; 500,273.15 + 15.0; 500,273.15 + 30.0; 1200,273.15
+ 30.0]) "Setpoint cooling";
Buildings.Fluid.Sensors.TemperatureTwoPort heaCooUnlOut(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Modelica.Blocks.Sources.Ramp m_flow(
height=-2*m_flow_nominal,
duration=100,
offset=m_flow_nominal,
startTime=1000) "Mass flow rate";
Buildings.Fluid.Sensors.TemperatureTwoPort heaHigPowIn(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Buildings.Fluid.Sensors.TemperatureTwoPort cooLimPowIn(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Buildings.Fluid.Sensors.TemperatureTwoPort heaCooUnlIn(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal) "Temperature sensor";
Sources.MassFlowSource_T sou1(
redeclare package Medium = Medium,
use_m_flow_in=true,
nPorts=1,
T=293.15) "Flow source";
Sources.MassFlowSource_T sou2(
redeclare package Medium = Medium,
use_m_flow_in=true,
nPorts=1,
T=293.15) "Flow source";
Sources.MassFlowSource_T sou3(
redeclare package Medium = Medium,
use_m_flow_in=true,
nPorts=1,
T=293.15) "Flow source";
equation
connect(heaHigPow.port_b, heaHigPowOut.port_a);
connect(TSetHeat.y, heaHigPow.TSet);
connect(cooLimPow.port_b, cooLimPowOut.port_a);
connect(TSetCool.y, cooLimPow.TSet);
connect(heaCooUnl.port_b, heaCooUnlOut.port_a);
connect(TSetCoolHeat.y, heaCooUnl.TSet);
connect(heaHigPowIn.port_b, heaHigPow.port_a);
connect(cooLimPowIn.port_b, cooLimPow.port_a);
connect(heaCooUnlIn.port_b, heaCooUnl.port_a);
connect(heaCooUnlOut.port_b, sin.ports[1]);
connect(cooLimPowOut.port_b, sin.ports[2]);
connect(heaHigPowOut.port_b, sin.ports[3]);
connect(m_flow.y, sou1.m_flow_in);
connect(sou1.ports[1], heaHigPowIn.port_a);
connect(m_flow.y, sou2.m_flow_in);
connect(m_flow.y, sou3.m_flow_in);
connect(sou2.ports[1], cooLimPowIn.port_a);
connect(sou3.ports[1], heaCooUnlIn.port_a);
end PrescribedOutlet;
Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic
Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as dynamic
Information
Model that demonstrates the use of an ideal heater and an ideal cooler, configured as dynamic models.
This example is identical to Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet except that the heater and cooler models are configured to have a time constant of 60 seconds at nominal flow rate. At lower flow rate, the time constant increases proportional to the mass flow rate.
Extends from Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet (Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as steady-state).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 0.1 | Nominal mass flow rate [kg/s] |
Modelica definition
model PrescribedOutlet_dynamic
"Model that demonstrates the ideal heater/cooler model for a prescribed outlet temperature, configured as dynamic"
extends Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet(
heaHigPow(energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial),
cooLimPow(energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial),
heaCooUnl(energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial));
end PrescribedOutlet_dynamic;
Buildings.Fluid.HeatExchangers.Validation.WetCoilCounterFlowLowWaterFlowRate
Model that tests a heat exchanger with prescribed boundary conditions, in terms of properties of inlet water and inlet air
Information
This is a validation case in which the air flow rate is about a third of the design flow rate, and the water mass flow rate is ramped to zero. The validation verifies that the outlet temperatures approach the inlet temperature of the air.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | mWat_flow_nominal | 0.44732114 | Nominal mass flow rate [kg/s] |
| MassFlowRate | mAir_flow_nominal | 0.65844 | Nominal mass flow rate [kg/s] |
Modelica definition
model WetCoilCounterFlowLowWaterFlowRate
"Model that tests a heat exchanger with prescribed boundary conditions, in terms of properties of inlet water and inlet air"
extends Modelica.Icons.Example;
package Medium1 = Buildings.Media.Water
"Medium model for water";
package Medium2 = Buildings.Media.Air
"Medium model for air";
parameter Modelica.Units.SI.MassFlowRate mWat_flow_nominal=0.44732114
"Nominal mass flow rate";
parameter Modelica.Units.SI.MassFlowRate mAir_flow_nominal=0.65844
"Nominal mass flow rate";
Buildings.Fluid.HeatExchangers.WetCoilCounterFlow
hex(
redeclare package Medium1 = Medium1,
redeclare package Medium2 = Medium2,
m1_flow_nominal=mWat_flow_nominal,
m2_flow_nominal=mAir_flow_nominal,
dp2_nominal(displayUnit="Pa") = 200,
dp1_nominal(displayUnit="Pa") = 3000,
UA_nominal=mWat_flow_nominal*4200*10/30,
show_T=true,
nEle=1,
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial)
"Cooling coil";
Buildings.Fluid.Sources.MassFlowSource_T sou_w(
redeclare package Medium = Medium1,
use_Xi_in=false,
m_flow=1E-4*mWat_flow_nominal,
use_T_in=false,
T=282.15,
nPorts=1,
use_m_flow_in=true)
"Source for water";
Buildings.Fluid.Sources.Boundary_pT sin_w(
redeclare package Medium = Medium1,
use_p_in=false,
T=293.15,
nPorts=1)
"sink for water";
Buildings.Fluid.Sources.MassFlowSource_T sou_a(
use_Xi_in=false,
X={0.0086,1 - 0.0086},
m_flow=mAir_flow_nominal,
use_T_in=false,
T=285.15,
nPorts=1,
redeclare package Medium = Medium2,
use_m_flow_in=false)
"Source for air";
Buildings.Fluid.Sources.Boundary_pT sin_a(
redeclare package Medium = Medium2,
use_p_in=false,
T=293.15,
nPorts=1)
"sink for air";
Controls.OBC.CDL.Reals.Sources.Ramp ram(
height=-mWat_flow_nominal,
duration=1800,
offset=mWat_flow_nominal,
startTime=900);
Sensors.TemperatureTwoPort senTemWatIn(
redeclare package Medium = Medium1,
allowFlowReversal=false,
m_flow_nominal=mWat_flow_nominal,
tau=0) "Temperature sensor";
Sensors.TemperatureTwoPort senTemWatOut(
redeclare package Medium = Medium1,
allowFlowReversal=false,
m_flow_nominal=mWat_flow_nominal,
tau=0) "Temperature sensor";
Sensors.TemperatureTwoPort senTemAirIn(
redeclare package Medium = Medium2,
allowFlowReversal=false,
m_flow_nominal=mAir_flow_nominal,
tau=0) "Temperature sensor";
Sensors.TemperatureTwoPort senTemAirOut(
redeclare package Medium = Medium2,
allowFlowReversal=false,
m_flow_nominal=mAir_flow_nominal,
tau=0) "Temperature sensor";
equation
connect(sou_w.m_flow_in, ram.y);
connect(sou_w.ports[1], senTemWatIn.port_a);
connect(senTemWatIn.port_b, hex.port_a1);
connect(sin_w.ports[1], senTemWatOut.port_b);
connect(senTemWatOut.port_a, hex.port_b1);
connect(sou_a.ports[1], senTemAirIn.port_a);
connect(senTemAirIn.port_b, hex.port_a2);
connect(sin_a.ports[1], senTemAirOut.port_b);
connect(senTemAirOut.port_a, hex.port_b2);
end WetCoilCounterFlowLowWaterFlowRate;
Buildings.Fluid.HeatExchangers.Validation.WetCoilDiscretizedInitialization
Model that demonstrates use of a finite volume model of a heat exchanger with condensation
Information
This model is used to test the initialization of the coil model. There are three instances of the coil model, each having different settings for the initial conditions. Each of the coil uses for the medium Buildings.Media.Air.
Extends from Buildings.Fluid.HeatExchangers.Examples.BaseClasses.WetCoilDiscretized (Model that demonstrates use of a finite volume model of a heat exchanger with condensation), Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium2 | PartialMedium | Medium for air-side | |
| Temperature | T_a1_nominal | 5 + 273.15 | Water inlet temperature [K] |
| Temperature | T_b1_nominal | 10 + 273.15 | Water outlet temperature [K] |
| Temperature | T_a2_nominal | 30 + 273.15 | Air inlet temperature [K] |
| Temperature | T_b2_nominal | 10 + 273.15 | Air inlet temperature [K] |
| MassFlowRate | m1_flow_nominal | 5 | Nominal mass flow rate water-side [kg/s] |
| MassFlowRate | m2_flow_nominal | m1_flow_nominal*4200/1000*(T... | Nominal mass flow rate air-side [kg/s] |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package Medium2 | Medium for air-side | |
Modelica definition
model WetCoilDiscretizedInitialization
"Model that demonstrates use of a finite volume model of a heat exchanger with condensation"
extends Buildings.Fluid.HeatExchangers.Examples.BaseClasses.WetCoilDiscretized
(
redeclare package Medium2 =
Buildings.Media.Air);
extends Modelica.Icons.Example;
end WetCoilDiscretizedInitialization;
Buildings.Fluid.HeatExchangers.Validation.WetCoilDiscretizedInitializationPerfectGases
Model that demonstrates use of a finite volume model of a heat exchanger with condensation
Information
This model is used to test the initialization of the coil model. There are three instances of the coil model, each having different settings for the initial conditions. Each of the coil uses for the medium Buildings.Media.Air.
Extends from Buildings.Fluid.HeatExchangers.Examples.BaseClasses.WetCoilDiscretized (Model that demonstrates use of a finite volume model of a heat exchanger with condensation), Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium2 | PartialMedium | Medium for air-side | |
| Temperature | T_a1_nominal | 5 + 273.15 | Water inlet temperature [K] |
| Temperature | T_b1_nominal | 10 + 273.15 | Water outlet temperature [K] |
| Temperature | T_a2_nominal | 30 + 273.15 | Air inlet temperature [K] |
| Temperature | T_b2_nominal | 10 + 273.15 | Air inlet temperature [K] |
| MassFlowRate | m1_flow_nominal | 5 | Nominal mass flow rate water-side [kg/s] |
| MassFlowRate | m2_flow_nominal | m1_flow_nominal*4200/1000*(T... | Nominal mass flow rate air-side [kg/s] |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package Medium2 | Medium for air-side | |
Modelica definition
model WetCoilDiscretizedInitializationPerfectGases
"Model that demonstrates use of a finite volume model of a heat exchanger with condensation"
extends Buildings.Fluid.HeatExchangers.Examples.BaseClasses.WetCoilDiscretized
(
redeclare package Medium2 =
Buildings.Media.Air);
extends Modelica.Icons.Example;
end WetCoilDiscretizedInitializationPerfectGases;
Buildings.Fluid.HeatExchangers.Validation.WetCoilEffectivenessNTU
Model that validates the wet coil effectiveness-NTU model
Information
This model duplicates an example from Mitchell and Braun 2012, example SM-2-1 (Mitchell and Braun 2012) to validate a single case for the Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU model.
Validation
The example simulates a wet coil with constant air and water inlet temperature and mass flow rate, and an increasing air inlet humidity which triggers the transition from a fully-dry to a fully-wet regime. The reference used for validation is the published experimental data.
Note that the outlet air relative humidity may slightly exceed 100% when using the epsilon-NTU model.
References
Mitchell, John W., and James E. Braun. 2012. "Supplementary Material Chapter 2: Heat Exchangers for Cooling Applications". Excerpt from Principles of heating, ventilation, and air conditioning in buildings. Hoboken, N.J.: Wiley. Available online: http://bcs.wiley.com/he-bcs/Books?action=index&itemId=0470624574&bcsId=7185
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | T_a1_nominal | Modelica.Units.Conversions.f... | Inlet water temperature [K] |
| Temperature | T_a2_nominal | Modelica.Units.Conversions.f... | Inlet air temperature [K] |
| Temperature | T_b1_nominal | 273.15 + 11.0678 | Outlet water temperature in fully wet conditions [K] |
| Temperature | T_b2_nominal | 273.15 + 13.5805 | Outlet air temperature in fully wet conditions [K] |
| Real | X_w_a2_nominal | 0.0173 | Inlet water mass fraction in fully wet conditions |
| ThermalConductance | UA_nominal | 4748 | Total thermal conductance at nominal flow, from textbook [W/K] |
| MassFlowRate | m1_flow_nominal | 3.78 | Nominal mass flow rate of water [kg/s] |
| MassFlowRate | m2_flow_nominal | 2.646 | Nominal mass flow rate of air [kg/s] |
| HeatExchangerConfiguration | hexCon | Types.HeatExchangerConfigura... | Heat exchanger configuration |
Modelica definition
model WetCoilEffectivenessNTU
"Model that validates the wet coil effectiveness-NTU model"
extends Modelica.Icons.Example;
package Medium_W = Buildings.Media.Water;
package Medium_A = Buildings.Media.Air;
constant Modelica.Units.SI.AbsolutePressure pAtm=101325
"Atmospheric pressure";
parameter Modelica.Units.SI.Temperature T_a1_nominal=
Modelica.Units.Conversions.from_degF(42) "Inlet water temperature";
parameter Modelica.Units.SI.Temperature T_a2_nominal=
Modelica.Units.Conversions.from_degF(80) "Inlet air temperature";
parameter Modelica.Units.SI.Temperature T_b1_nominal=273.15 + 11.0678
"Outlet water temperature in fully wet conditions";
parameter Modelica.Units.SI.Temperature T_b2_nominal=273.15 + 13.5805
"Outlet air temperature in fully wet conditions";
final parameter Modelica.Units.SI.HeatFlowRate Q_flow_nominal=m1_flow_nominal
*4186*(T_a1_nominal - T_b1_nominal);
parameter Real X_w_a2_nominal = 0.0173
"Inlet water mass fraction in fully wet conditions";
parameter Modelica.Units.SI.ThermalConductance UA_nominal=4748
"Total thermal conductance at nominal flow, from textbook";
parameter Modelica.Units.SI.MassFlowRate m1_flow_nominal=3.78
"Nominal mass flow rate of water";
parameter Modelica.Units.SI.MassFlowRate m2_flow_nominal=2.646
"Nominal mass flow rate of air";
parameter Types.HeatExchangerConfiguration hexCon=
Types.HeatExchangerConfiguration.CounterFlow
"Heat exchanger configuration";
Buildings.Fluid.Sources.Boundary_pT sinAir(
redeclare package Medium = Medium_A,
use_p_in=false,
nPorts=2)
"Air sink";
Sources.MassFlowSource_T souAir(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
T=T_a2_nominal,
use_Xi_in=true,
nPorts=1)
"Air source";
Buildings.Fluid.Sources.Boundary_pT sinWat(
redeclare package Medium = Medium_W,
nPorts=2)
"Sink for water";
Buildings.Utilities.Psychrometrics.ToTotalAir conversion;
Sensors.RelativeHumidityTwoPort relHumIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet relative humidity";
Sensors.TemperatureTwoPort TDryBulIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet dry bulb temperature";
Modelica.Blocks.Sources.RealExpression pAir(y=pAtm) "Air pressure";
Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulIn(redeclare
package Medium = Medium_A) "Computation of wet bulb temperature";
Sensors.MassFractionTwoPort senMasFraIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of entering air";
Sensors.MassFractionTwoPort senMasFraOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of leaving air";
Sensors.TemperatureTwoPort TDryBulOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Dry bulb temperature of leaving air";
Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulOut(redeclare
package Medium = Medium_A) "Computation of wet bulb temperature";
Modelica.Blocks.Sources.RealExpression pAir1(y=pAtm) "Air pressure";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNTU(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
UA_nominal=UA_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true) "Effectiveness-NTU coil model (parameterized with nominal UA)";
Sources.MassFlowSource_T souWat1(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
Sensors.RelativeHumidityTwoPort relHumOut_eps(redeclare package Medium =
Medium_A, m_flow_nominal=m2_flow_nominal) "Outlet relative humidity";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNTU_TX(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
use_Q_flow_nominal=true,
Q_flow_nominal=Q_flow_nominal,
T_a2_nominal=T_a2_nominal,
w_a2_nominal=X_w_a2_nominal/(1 - X_w_a2_nominal),
T_a1_nominal=T_a1_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true)
"Effectiveness-NTU coil model (parameterized with nominal T and X)";
Sources.MassFlowSource_T souAir1(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
T=T_a2_nominal,
use_Xi_in=true,
nPorts=1)
"Air source";
Sources.MassFlowSource_T souWat2(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
Modelica.Blocks.Sources.CombiTimeTable w_a2(table=[0,0.0035383; 1,0.01765],
timeScale=1000)
"Absolute humidity of entering air";
equation
connect(pAir.y, wetBulIn.p);
connect(pAir1.y, wetBulOut.p);
connect(senMasFraOut.port_b, sinAir.ports[1]);
connect(TDryBulOut.T, wetBulOut.TDryBul);
connect(senMasFraOut.X, wetBulOut.Xi[1]);
connect(souAir.ports[1], senMasFraIn.port_a);
connect(senMasFraIn.port_b, TDryBulIn.port_a);
connect(senMasFraIn.X, wetBulIn.Xi[1]);
connect(TDryBulIn.T, wetBulIn.TDryBul);
connect(TDryBulIn.port_b, relHumIn.port_a);
connect(souWat1.ports[1], hexWetNTU.port_a1);
connect(hexWetNTU.port_b1, sinWat.ports[1]);
connect(hexWetNTU.port_b2, TDryBulOut.port_a);
connect(hexWetNTU.port_a2, relHumIn.port_b);
connect(TDryBulOut.port_b, relHumOut_eps.port_a);
connect(relHumOut_eps.port_b, senMasFraOut.port_a);
connect(hexWetNTU_TX.port_b1, sinWat.ports[2]);
connect(souAir1.ports[1], hexWetNTU_TX.port_a2);
connect(sinAir.ports[2], hexWetNTU_TX.port_b2);
connect(souWat2.ports[1], hexWetNTU_TX.port_a1);
connect(w_a2.y[1], conversion.XiDry);
connect(conversion.XiTotalAir, souAir.Xi_in[1]);
connect(conversion.XiTotalAir, souAir1.Xi_in[1]);
end WetCoilEffectivenessNTU;
Buildings.Fluid.HeatExchangers.Validation.WetCoilEffectivenessNTUCounterFlow
Model that validates the wet coil effectiveness-NTU model
Information
This model is similar to Buildings.Fluid.HeatExchangers.Validation.WetCoilEffectivenessNTU, except that a discretized wet coil model is also simulated for comparison. To provide an accurate reference, the latter model is configured with 30 elements. Under steady-state modeling assumptions, this creates a large system of non-linear equations. To alleviate this effect, dynamics are considered but the simulation time is increased to 1000 s to reproduce quasi steady-state conditions.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | T_a1_nominal | Modelica.Units.Conversions.f... | Inlet water temperature [K] |
| Temperature | T_a2_nominal | Modelica.Units.Conversions.f... | Inlet air temperature [K] |
| Temperature | T_b1_nominal | 273.15 + 11.0678 | Outlet water temperature in fully wet conditions [K] |
| Temperature | T_b2_nominal | 273.15 + 13.5805 | Outlet air temperature in fully wet conditions [K] |
| Real | X_w_a2_nominal | 0.0173 | Inlet water mass fraction in fully wet conditions |
| ThermalConductance | UA_nominal | 4748 | Total thermal conductance at nominal flow, from textbook [W/K] |
| MassFlowRate | m1_flow_nominal | 3.78 | Nominal mass flow rate of water [kg/s] |
| MassFlowRate | m2_flow_nominal | 2.646 | Nominal mass flow rate of air [kg/s] |
| HeatExchangerConfiguration | hexCon | Types.HeatExchangerConfigura... | Heat exchanger configuration |
Modelica definition
model WetCoilEffectivenessNTUCounterFlow
"Model that validates the wet coil effectiveness-NTU model"
extends Modelica.Icons.Example;
package Medium_W = Buildings.Media.Water;
package Medium_A = Buildings.Media.Air;
constant Modelica.Units.SI.AbsolutePressure pAtm=101325
"Atmospheric pressure";
parameter Modelica.Units.SI.Temperature T_a1_nominal=
Modelica.Units.Conversions.from_degF(42) "Inlet water temperature";
parameter Modelica.Units.SI.Temperature T_a2_nominal=
Modelica.Units.Conversions.from_degF(80) "Inlet air temperature";
parameter Modelica.Units.SI.Temperature T_b1_nominal=273.15 + 11.0678
"Outlet water temperature in fully wet conditions";
parameter Modelica.Units.SI.Temperature T_b2_nominal=273.15 + 13.5805
"Outlet air temperature in fully wet conditions";
final parameter Modelica.Units.SI.HeatFlowRate Q_flow_nominal=m1_flow_nominal
*4186*(T_a1_nominal - T_b1_nominal);
parameter Real X_w_a2_nominal = 0.0173
"Inlet water mass fraction in fully wet conditions";
parameter Modelica.Units.SI.ThermalConductance UA_nominal=4748
"Total thermal conductance at nominal flow, from textbook";
parameter Modelica.Units.SI.MassFlowRate m1_flow_nominal=3.78
"Nominal mass flow rate of water";
parameter Modelica.Units.SI.MassFlowRate m2_flow_nominal=2.646
"Nominal mass flow rate of air";
parameter Types.HeatExchangerConfiguration hexCon=
Types.HeatExchangerConfiguration.CounterFlow
"Heat exchanger configuration";
Buildings.Fluid.Sources.Boundary_pT sinAir(
redeclare package Medium = Medium_A,
use_p_in=false,
nPorts=3)
"Air sink";
Sources.MassFlowSource_T souAir(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
T=T_a2_nominal,
use_Xi_in=true,
nPorts=1)
"Air source";
Buildings.Fluid.Sources.Boundary_pT sinWat(
redeclare package Medium = Medium_W,
nPorts=3)
"Sink for water";
Buildings.Utilities.Psychrometrics.ToTotalAir conversion;
Sensors.RelativeHumidityTwoPort relHumIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet relative humidity";
Sensors.TemperatureTwoPort TDryBulIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet dry bulb temperature";
Modelica.Blocks.Sources.RealExpression pAir(y=pAtm) "Air pressure";
Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulIn(redeclare
package Medium = Medium_A) "Computation of wet bulb temperature";
Sensors.MassFractionTwoPort senMasFraIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of entering air";
Sensors.MassFractionTwoPort senMasFraOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of leaving air";
Sensors.TemperatureTwoPort TDryBulOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Dry bulb temperature of leaving air";
Buildings.Utilities.Psychrometrics.TWetBul_TDryBulXi wetBulOut(redeclare
package Medium = Medium_A) "Computation of wet bulb temperature";
Modelica.Blocks.Sources.RealExpression pAir1(y=pAtm) "Air pressure";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNTU(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
UA_nominal=UA_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true) "Effectiveness-NTU coil model (parameterized with nominal UA)";
Sources.MassFlowSource_T souWat1(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
WetCoilCounterFlow hexDis(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
allowFlowReversal1=false,
allowFlowReversal2=false,
dp1_nominal=0,
UA_nominal=UA_nominal,
show_T=true,
nEle=30,
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
tau1=0.1,
tau2=0.1,
tau_m=0.1)
"Discretized coil model";
Sources.MassFlowSource_T souWat(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1) "Source for water";
Sources.MassFlowSource_T souAir2(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
T=T_a2_nominal,
use_Xi_in=true,
nPorts=1)
"Air source";
Sensors.MassFractionTwoPort senMasFraOut1(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of leaving air";
Sensors.TemperatureTwoPort TDryBulOut1(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Dry bulb temperature of leaving air";
Sensors.RelativeHumidityTwoPort relHumOut_eps(redeclare package Medium =
Medium_A, m_flow_nominal=m2_flow_nominal) "Outlet relative humidity";
Sensors.RelativeHumidityTwoPort relHumOut_dis(redeclare package Medium =
Medium_A, m_flow_nominal=m2_flow_nominal) "Outlet relative humidity";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNTU_TX(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
use_Q_flow_nominal=true,
Q_flow_nominal=Q_flow_nominal,
T_a2_nominal=T_a2_nominal,
w_a2_nominal=X_w_a2_nominal/(1 - X_w_a2_nominal),
T_a1_nominal=T_a1_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true)
"Effectiveness-NTU coil model (parameterized with nominal T and X)";
Sources.MassFlowSource_T souAir1(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
T=T_a2_nominal,
use_Xi_in=true,
nPorts=1)
"Air source";
Sources.MassFlowSource_T souWat2(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
Modelica.Blocks.Sources.CombiTimeTable w_a2(table=[0,0.0035383; 1,0.01765],
timeScale=1000)
"Absolute humidity of entering air";
equation
connect(pAir.y, wetBulIn.p);
connect(pAir1.y, wetBulOut.p);
connect(senMasFraOut.port_b, sinAir.ports[1]);
connect(TDryBulOut.T, wetBulOut.TDryBul);
connect(senMasFraOut.X, wetBulOut.Xi[1]);
connect(souAir.ports[1], senMasFraIn.port_a);
connect(senMasFraIn.port_b, TDryBulIn.port_a);
connect(senMasFraIn.X, wetBulIn.Xi[1]);
connect(TDryBulIn.T, wetBulIn.TDryBul);
connect(TDryBulIn.port_b, relHumIn.port_a);
connect(souWat1.ports[1], hexWetNTU.port_a1);
connect(hexWetNTU.port_b1, sinWat.ports[1]);
connect(souWat.ports[1], hexDis.port_a1);
connect(hexDis.port_b1, sinWat.ports[2]);
connect(souAir2.ports[1], hexDis.port_a2);
connect(hexWetNTU.port_b2, TDryBulOut.port_a);
connect(hexWetNTU.port_a2, relHumIn.port_b);
connect(hexDis.port_b2, TDryBulOut1.port_a);
connect(senMasFraOut1.port_b, sinAir.ports[2]);
connect(TDryBulOut.port_b, relHumOut_eps.port_a);
connect(relHumOut_eps.port_b, senMasFraOut.port_a);
connect(TDryBulOut1.port_b, relHumOut_dis.port_a);
connect(relHumOut_dis.port_b, senMasFraOut1.port_a);
connect(hexWetNTU_TX.port_b1, sinWat.ports[3]);
connect(souAir1.ports[1], hexWetNTU_TX.port_a2);
connect(sinAir.ports[3], hexWetNTU_TX.port_b2);
connect(souWat2.ports[1], hexWetNTU_TX.port_a1);
connect(w_a2.y[1], conversion.XiDry);
connect(conversion.XiTotalAir, souAir.Xi_in[1]);
connect(conversion.XiTotalAir, souAir1.Xi_in[1]);
connect(conversion.XiTotalAir, souAir2.Xi_in[1]);
end WetCoilEffectivenessNTUCounterFlow;
Buildings.Fluid.HeatExchangers.Validation.WetCoilEffectivenessNTUHeating
Model that validates the wet coil effectiveness-NTU model in heating conditions
Information
This model simulates various coil models in heating conditions, with
- on the water-side: constant inlet temperature and mass flow rate,
- on the air-side: constant inlet humidity ratio and mass flow rate, and an increasing inlet temperature.
To provide an accurate reference, the instance of Buildings.Fluid.HeatExchangers.DryCoilCounterFlow is configured with 30 elements. Under steady-state modeling assumptions, this creates a large system of non-linear equations. To alleviate this effect, dynamics are considered but the simulation time is increased to 1000 s to reproduce quasi steady-state conditions.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Temperature | T_a1_nominal | 50 + 273.15 | Inlet water temperature [K] |
| Temperature | T_b1_nominal | 45 + 273.15 | Outlet water temperature [K] |
| Temperature | T_a2_nominal | 273.15 | Inlet air temperature [K] |
| ThermalConductance | UA_nominal | Buildings.Fluid.HeatExchange... | Total thermal conductance at nominal flow [W/K] |
| MassFlowRate | m1_flow_nominal | 3.78 | Nominal mass flow rate of water [kg/s] |
| MassFlowRate | m2_flow_nominal | 2.646 | Nominal mass flow rate of air [kg/s] |
| HeatExchangerConfiguration | hexCon | Types.HeatExchangerConfigura... | Heat exchanger configuration |
Modelica definition
model WetCoilEffectivenessNTUHeating
"Model that validates the wet coil effectiveness-NTU model in heating conditions"
extends Modelica.Icons.Example;
package Medium_W = Buildings.Media.Water;
package Medium_A = Buildings.Media.Air;
constant Modelica.Units.SI.AbsolutePressure pAtm=101325
"Atmospheric pressure";
parameter Modelica.Units.SI.Temperature T_a1_nominal=50 + 273.15
"Inlet water temperature";
parameter Modelica.Units.SI.Temperature T_b1_nominal=45 + 273.15
"Outlet water temperature";
parameter Modelica.Units.SI.Temperature T_a2_nominal=273.15
"Inlet air temperature";
final parameter Modelica.Units.SI.Temperature T_b2_nominal=T_a2_nominal +
Q_flow_nominal/m2_flow_nominal/1010 "Outlet air temperature";
final parameter Modelica.Units.SI.ThermalConductance CMin_flow_nominal=min(
m1_flow_nominal*4186, m2_flow_nominal*1010)
"Minimal capacity flow rate at nominal condition";
final parameter Modelica.Units.SI.ThermalConductance CMax_flow_nominal=max(
m1_flow_nominal*4186, m2_flow_nominal*1010)
"Minimal capacity flow rate at nominal condition";
final parameter Modelica.Units.SI.HeatFlowRate Q_flow_nominal=m1_flow_nominal
*4186*(T_a1_nominal - T_b1_nominal);
final parameter Real eps_nominal=
abs(Q_flow_nominal/((T_a1_nominal - T_a2_nominal) * CMin_flow_nominal))
"Nominal effectiveness";
parameter Modelica.Units.SI.ThermalConductance UA_nominal=
Buildings.Fluid.HeatExchangers.BaseClasses.ntu_epsilonZ(
eps=eps_nominal,
Z=CMin_flow_nominal/CMax_flow_nominal,
flowRegime=Integer(hexCon))*CMin_flow_nominal
"Total thermal conductance at nominal flow";
parameter Modelica.Units.SI.MassFlowRate m1_flow_nominal=3.78
"Nominal mass flow rate of water";
parameter Modelica.Units.SI.MassFlowRate m2_flow_nominal=2.646
"Nominal mass flow rate of air";
parameter Types.HeatExchangerConfiguration hexCon=
Types.HeatExchangerConfiguration.CounterFlow
"Heat exchanger configuration";
Buildings.Fluid.Sources.Boundary_pT sinAir(
redeclare package Medium = Medium_A,
use_p_in=false,
nPorts=3)
"Air sink";
Sources.MassFlowSource_T souAir(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
use_T_in=true,
T=T_a2_nominal,
nPorts=1)
"Air source";
Buildings.Fluid.Sources.Boundary_pT sinWat(
redeclare package Medium = Medium_W,
nPorts=3)
"Sink for water";
Sensors.RelativeHumidityTwoPort relHumIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet relative humidity";
Sensors.TemperatureTwoPort TDryBulIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Inlet dry bulb temperature";
Sensors.MassFractionTwoPort senMasFraIn(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of entering air";
Sensors.MassFractionTwoPort senMasFraOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of leaving air";
Sensors.TemperatureTwoPort TDryBulOut(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Dry bulb temperature of leaving air";
Sources.MassFlowSource_T souWat1(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
DryCoilCounterFlow hexDis(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
allowFlowReversal1=false,
allowFlowReversal2=false,
dp1_nominal=0,
UA_nominal=UA_nominal,
show_T=true,
nEle=30,
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
tau1=0.1,
tau2=0.1,
tau_m=0.1)
"Discretized coil model";
Sources.MassFlowSource_T souWat(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1) "Source for water";
Sources.MassFlowSource_T souAir2(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
use_T_in=true,
T=T_a2_nominal,
nPorts=1)
"Air source";
Sensors.MassFractionTwoPort senMasFraOut1(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Water mass fraction of leaving air";
Sensors.TemperatureTwoPort TDryBulOut1(redeclare package Medium = Medium_A,
m_flow_nominal=m2_flow_nominal) "Dry bulb temperature of leaving air";
Sensors.RelativeHumidityTwoPort relHumOut_eps(redeclare package Medium =
Medium_A, m_flow_nominal=m2_flow_nominal) "Outlet relative humidity";
Sensors.RelativeHumidityTwoPort relHumOut_dis(redeclare package Medium =
Medium_A, m_flow_nominal=m2_flow_nominal) "Outlet relative humidity";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexDryNTU_T(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
Q_flow_nominal=Q_flow_nominal,
T_a2_nominal=T_a2_nominal,
T_a1_nominal=T_a1_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true)
"Effectiveness-NTU coil model (parameterized with nominal T and X)";
Sources.MassFlowSource_T souAir1(
redeclare package Medium = Medium_A,
m_flow=m2_flow_nominal,
use_T_in=true,
T=T_a2_nominal,
nPorts=1)
"Air source";
Sources.MassFlowSource_T souWat2(
redeclare package Medium = Medium_W,
m_flow=m1_flow_nominal,
T=T_a1_nominal,
nPorts=1)
"Source for water";
Controls.OBC.CDL.Reals.Sources.Ramp T_a2(
height=15,
duration=1000,
offset=273.15) "Air inlet temperature";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNTU_TX(
redeclare package Medium1 = Medium_W,
redeclare package Medium2 = Medium_A,
use_Q_flow_nominal=true,
Q_flow_nominal=Q_flow_nominal,
T_a2_nominal=T_a2_nominal,
w_a2_nominal=0.001,
T_a1_nominal=T_a1_nominal,
m1_flow_nominal=m1_flow_nominal,
m2_flow_nominal=m2_flow_nominal,
dp2_nominal=0,
dp1_nominal=0,
configuration=hexCon,
show_T=true)
"Effectiveness-NTU coil model (parameterized with nominal T and X)";
equation
connect(senMasFraOut.port_b, sinAir.ports[1]);
connect(souAir.ports[1], senMasFraIn.port_a);
connect(senMasFraIn.port_b, TDryBulIn.port_a);
connect(TDryBulIn.port_b, relHumIn.port_a);
connect(souWat.ports[1], hexDis.port_a1);
connect(hexDis.port_b1, sinWat.ports[1]);
connect(souAir2.ports[1], hexDis.port_a2);
connect(hexDis.port_b2, TDryBulOut1.port_a);
connect(senMasFraOut1.port_b, sinAir.ports[2]);
connect(TDryBulOut.port_b, relHumOut_eps.port_a);
connect(relHumOut_eps.port_b, senMasFraOut.port_a);
connect(TDryBulOut1.port_b, relHumOut_dis.port_a);
connect(relHumOut_dis.port_b, senMasFraOut1.port_a);
connect(hexDryNTU_T.port_b1, sinWat.ports[2]);
connect(souAir1.ports[1], hexDryNTU_T.port_a2);
connect(sinAir.ports[3], hexDryNTU_T.port_b2);
connect(souWat2.ports[1], hexDryNTU_T.port_a1);
connect(T_a2.y, souAir2.T_in);
connect(T_a2.y, souAir.T_in);
connect(T_a2.y, souAir1.T_in);
connect(souWat1.ports[1], hexWetNTU_TX.port_a1);
connect(hexWetNTU_TX.port_b1, sinWat.ports[3]);
connect(relHumIn.port_b, hexWetNTU_TX.port_a2);
connect(hexWetNTU_TX.port_b2, TDryBulOut.port_a);
end WetCoilEffectivenessNTUHeating;