Buildings.Fluid.HeatExchangers.ThermalWheels.Latent
Package with enthalpy recovery wheels
Information
This package contains component models for enthalpy recovery wheels.
Extends from Modelica.Icons.Package (Icon for standard packages).
Package Content
| Name | Description |
|---|---|
 BypassDampers
|
Enthalpy recovery wheel with bypass dampers |
 SpeedControlled
|
Enthalpy recovery wheel with a variable speed drive |
 Examples
|
Collection of models that illustrate model use and test models |
| Validation
|
Collection of validation models |
 BaseClasses
|
Package with base classes for enthalpy recovery devices |
Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BypassDampers
Enthalpy recovery wheel with bypass dampers
Information
Model of an enthalpy recovery wheel, which consists of a heat exchanger and two dampers to bypass the supply and exhaust airflow.
This model does not require geometric data. The performance is defined by specifying the part load (75% of the nominal supply flow rate) and nominal sensible and latent heat exchanger effectiveness. This operation of the wheel is configured as follows.
-
If the operating signal
uRot=true,- The wheel power consumption is constant and equal to the nominal value.
- The heat exchange in the heat recovery wheel is adjustable via bypassing supply/exhaust air through the heat exchanger. Accordingly, the sensible and latent heat exchanger effectiveness are calculated with Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BaseClasses.Effectiveness.
-
Otherwise,
- The wheel power consumption is 0.
- In addition, there is no sensible or latent heat transfer, i.e., the sensible and latent effectiveness of the heat recovery wheel is 0.
Extends from Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BaseClasses.PartialWheel (Partial model for enthalpy recovery wheel).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Air | |
| Generic | per | Record with performance data | |
| PressureDifference | dpDamper_nominal | 20 | Nominal pressure drop of dampers [Pa] |
| Assumptions | |||
| Boolean | allowFlowReversal1 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Flow resistance | |||
| Medium 1 | |||
| Boolean | from_dp1 | true | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance1 | false | = true, use linear relation between m_flow and dp for any flow rate |
| Medium 2 | |||
| Boolean | from_dp2 | true | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance2 | false | = true, use linear relation between m_flow and dp for any flow rate |
| Dynamics | |||
| Actuator position | |||
| Boolean | use_strokeTime | true | Set to true to continuously open and close valve using strokeTime |
| Time | strokeTime | 120 | Time needed to fully open or close actuator [s] |
| Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization of dampers (no init/steady state/initial state/initial output) |
| Real | yByp_start | 1 | Initial position of bypass actuators |
Connectors
| Type | Name | Description |
|---|---|---|
| output RealOutput | P | Electric power consumption [W] |
| output RealOutput | epsSen | Sensible heat exchanger effectiveness [1] |
| output RealOutput | epsLat | Latent heat exchanger effectiveness [1] |
| FluidPort_a | port_a1 | Fluid connector a1 of the supply air (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_b | port_b2 | Fluid connector b2 of the exhaust air (positive design flow direction is from port_a2 to port_b2) |
| FluidPort_b | port_b1 | Fluid connector b1 of the supply air (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_a | port_a2 | Fluid connector a2 of the exhaust air (positive design flow direction is from port_a2 to port_b2) |
| input RealInput | uBypDamPos | Bypass damper position [1] |
| input BooleanInput | uRot | True when the wheel is operating |
Modelica definition
model BypassDampers
"Enthalpy recovery wheel with bypass dampers"
extends Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BaseClasses.PartialWheel(
from_dp1=true,
from_dp2=true,
hex(final dp1_nominal=0,
final dp2_nominal=0) "Hex dp is lumped in damper");
parameter Modelica.Units.SI.PressureDifference dpDamper_nominal(displayUnit="Pa") = 20
"Nominal pressure drop of dampers";
parameter Boolean use_strokeTime=true
"Set to true to continuously open and close valve using strokeTime";
parameter Modelica.Units.SI.Time strokeTime=120
"Time needed to fully open or close actuator";
parameter Modelica.Blocks.Types.Init init=Modelica.Blocks.Types.Init.InitialOutput
"Type of initialization of dampers (no init/steady state/initial state/initial output)";
parameter Real yByp_start=1 "Initial position of bypass actuators";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uBypDamPos(
final unit="1",
final min=0,
final max=1)
"Bypass damper position";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uRot
"True when the wheel is operating";
Buildings.Fluid.Actuators.Dampers.Exponential bypDamSup(
redeclare package Medium = Medium,
final allowFlowReversal=allowFlowReversal1,
final m_flow_nominal=per.mSup_flow_nominal,
final from_dp=from_dp1,
final linearized=linearizeFlowResistance1,
final use_strokeTime=use_strokeTime,
final strokeTime=strokeTime,
final init=init,
final y_start=yByp_start,
final dpDamper_nominal=dpDamper_nominal)
"Supply air bypass damper";
Buildings.Fluid.Actuators.Dampers.Exponential damSup(
redeclare package Medium = Medium,
final allowFlowReversal=allowFlowReversal1,
final m_flow_nominal=per.mSup_flow_nominal,
final from_dp=from_dp1,
final linearized=linearizeFlowResistance1,
final use_strokeTime=use_strokeTime,
final strokeTime=strokeTime,
final init=init,
y_start=1-yByp_start,
final dpDamper_nominal=dpDamper_nominal,
final dpFixed_nominal=per.dpSup_nominal)
"Supply air damper";
Buildings.Fluid.Actuators.Dampers.Exponential damExh(
redeclare package Medium = Medium,
final allowFlowReversal=allowFlowReversal2,
final m_flow_nominal=per.mExh_flow_nominal,
final from_dp=from_dp2,
final linearized=linearizeFlowResistance2,
final use_strokeTime=use_strokeTime,
final strokeTime=strokeTime,
final init=init,
y_start=1-yByp_start,
final dpDamper_nominal=dpDamper_nominal,
final dpFixed_nominal=per.dpExh_nominal)
"Exhaust air damper";
Buildings.Fluid.Actuators.Dampers.Exponential bypDamExh(
redeclare package Medium = Medium,
final allowFlowReversal=allowFlowReversal2,
final m_flow_nominal=per.mExh_flow_nominal,
final from_dp=from_dp2,
final linearized=linearizeFlowResistance2,
final use_strokeTime=use_strokeTime,
final strokeTime=strokeTime,
final init=init,
final y_start=yByp_start,
final dpDamper_nominal=dpDamper_nominal)
"Exhaust air bypass damper";
Buildings.Controls.OBC.CDL.Reals.Switch swiEpsSen
"Switch the sensible heat exchanger effectiveness based on the wheel operation status";
Buildings.Controls.OBC.CDL.Reals.Switch swiEpsLat
"Switch the latent heat exchanger effectiveness based on the wheel operation status";
protected
Modelica.Blocks.Sources.Constant uni(
final k=1)
"Unity signal";
Buildings.Controls.OBC.CDL.Reals.Subtract sub
"Difference of the two inputs";
Modelica.Blocks.Math.BooleanToReal PEle(
final realTrue=per.P_nominal,
final realFalse=0)
"Electric power consumption for motor";
Modelica.Blocks.Sources.Constant zero(final k=0)
"Zero signal";
initial equation
assert(not per.have_varSpe,
"In " + getInstanceName() + ": The performance data record
is wrong, the variable speed flag must be false",
level=AssertionLevel.error)
"Check if the performance data record is correct";
equation
connect(sub.y, damSup.y);
connect(damExh.y,sub. y);
connect(bypDamSup.y, uBypDamPos);
connect(damSup.port_b, hex.port_a1);
connect(bypDamExh.y, uBypDamPos);
connect(sub.u2, uBypDamPos);
connect(uni.y, sub.u1);
connect(PEle.y, P);
connect(damSup.port_a, port_a1);
connect(damExh.port_b, hex.port_a2);
connect(bypDamExh.port_b, port_b2);
connect(damExh.port_a, port_a2);
connect(bypDamExh.port_a, port_a2);
connect(bypDamSup.port_b, port_b1);
connect(bypDamSup.port_a, port_a1);
connect(zero.y,swiEpsSen. u3);
connect(swiEpsLat.u3, zero.y);
connect(effCal.epsSen,swiEpsSen. u1);
connect(effCal.epsLat,swiEpsLat. u1);
connect(swiEpsSen.u2, uRot);
connect(swiEpsLat.u2, uRot);
connect(swiEpsSen.y, hex.epsSen);
connect(swiEpsLat.y, hex.epsLat);
connect(swiEpsSen.y, epsSen);
connect(swiEpsLat.y, epsLat);
connect(PEle.u, uRot);
end BypassDampers;
Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.SpeedControlled
Enthalpy recovery wheel with a variable speed drive
Information
Model of an enthalpy recovery wheel, which has the wheel speed as the input to control the heat recovery.
This model does not require geometric data. The performance is defined by specifying the part load (75% of the nominal supply flow rate) and nominal sensible and latent heat exchanger effectiveness.
The operation of the heat recovery wheel is adjustable by modulating the wheel speed. See details about the impacts of the wheel speed in Buildings.Fluid.HeatExchangers.ThermalWheels.BaseClasses.SpeedCorrectionLatent.
Extends from Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BaseClasses.PartialWheel (Partial model for enthalpy recovery wheel).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialCondensingGases | Air | |
| Generic | per | Record with performance data | |
| Assumptions | |||
| Boolean | allowFlowReversal1 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Flow resistance | |||
| Medium 1 | |||
| Boolean | from_dp1 | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance1 | false | = true, use linear relation between m_flow and dp for any flow rate |
| Medium 2 | |||
| Boolean | from_dp2 | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearizeFlowResistance2 | false | = true, use linear relation between m_flow and dp for any flow rate |
Connectors
| Type | Name | Description |
|---|---|---|
| output RealOutput | P | Electric power consumption [W] |
| output RealOutput | epsSen | Sensible heat exchanger effectiveness [1] |
| output RealOutput | epsLat | Latent heat exchanger effectiveness [1] |
| FluidPort_a | port_a1 | Fluid connector a1 of the supply air (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_b | port_b2 | Fluid connector b2 of the exhaust air (positive design flow direction is from port_a2 to port_b2) |
| FluidPort_b | port_b1 | Fluid connector b1 of the supply air (positive design flow direction is from port_a1 to port_b1) |
| FluidPort_a | port_a2 | Fluid connector a2 of the exhaust air (positive design flow direction is from port_a2 to port_b2) |
| input RealInput | uSpe | Wheel speed ratio [1] |
Modelica definition
model SpeedControlled
"Enthalpy recovery wheel with a variable speed drive"
extends Buildings.Fluid.HeatExchangers.ThermalWheels.Latent.BaseClasses.PartialWheel(
hex(
final dp1_nominal=per.dpSup_nominal,
final dp2_nominal=per.dpExh_nominal));
Buildings.Controls.OBC.CDL.Interfaces.RealInput uSpe(
final unit="1",
final max=1)
"Wheel speed ratio";
Buildings.Fluid.HeatExchangers.ThermalWheels.BaseClasses.SpeedCorrectionLatent
speCor(
final per=per)
"Correct the wheel performance based on the wheel speed";
Buildings.Controls.OBC.CDL.Reals.Multiply mulSen
"Correct the sensible heat exchanger effectiveness";
Buildings.Controls.OBC.CDL.Reals.Multiply mulLat
"Correct the latent heat exchanger effectiveness";
initial equation
assert(per.have_varSpe,
"In " + getInstanceName() + ": The performance data record
is wrong, the variable speed flag must be true",
level=AssertionLevel.error)
"Check if the performance data record is correct";
equation
connect(hex.port_a2, port_a2);
connect(hex.port_a1, port_a1);
connect(speCor.epsSenCor, mulSen.u1);
connect(speCor.epsLatCor, mulLat.u1);
connect(effCal.epsSen, mulSen.u2);
connect(effCal.epsLat, mulLat.u2);
connect(mulSen.y, hex.epsSen);
connect(hex.epsLat, mulLat.y);
connect(mulSen.y, epsSen);
connect(mulLat.y, epsLat);
connect(speCor.P, P);
connect(speCor.uSpe, uSpe);
end SpeedControlled;