Buildings.Fluid.ZoneEquipment
Package with common configurations of zonal HVAC systems
Information
This package contains models for common configurations of zonal HVAC systems, that are responsible for meeting the zonal heating and cooling loads.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 FourPipe
|
System model for a four-pipe fan coil unit |
Buildings.Fluid.ZoneEquipment.FourPipe
System model for a four-pipe fan coil unit
Information
This is a four-pipe fan coil unit system model. The system consists of the following components:
-
A supply fan
fanof class Buildings.Fluid.Movers.FlowControlled_m_flow. -
Heating coil options for no heating coil, a hot-water heating coil or an electric
heating coil determined by the user selection for parameter
heaCoiTypas follows:-
No heating coil with bypass connector
pipBypof class Buildings.Fluid.FixedResistances.PressureDrop ifheaCoiTypis set toBuildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.None. -
A hot-water heating coil
heaCoiHWof class Buildings.Fluid.HeatExchangers.DryCoilCounterFlow ifheaCoiTypis set toBuildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.WaterBased. -
An electric heating coil
heaCoiEleof class Buildings.Fluid.HeatExchangers.HeaterCooler_u ifheaCoiTypis set toBuildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.Electric.
-
No heating coil with bypass connector
-
A chilled-water cooling coil
cooCoiof class Buildings.Fluid.HeatExchangers.WetCoilCounterFlow.
For examples of how to use the model, refer to Buildings.Examples.FanCoils.FourPipe. The following points are salient when using the model:
- The connected air-loop does not need an additional fan, since the fan in this model generates flow.
- The fluid loop connections for hot-water and chilled-water require an external pressure difference between the inlet and the outlet sufficient to overcome the pressure drop across the two respective coils.
The figure below shows the schematic diagram of the four pipe system when
heaCoiTyp is set to water based using the enumeration
Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumA | Modelica.Media.Interfaces.Pa... | Medium for air | |
| replaceable package MediumHW | Modelica.Media.Interfaces.Pa... | Medium for hot water | |
| replaceable package MediumCHW | Modelica.Media.Interfaces.Pa... | Medium for chilled water | |
| System parameters | |||
| HeatingCoil | heaCoiTyp | Buildings.Controls.OBC.ASHRA... | Heating coil type |
| PressureDifference | dpAir_nominal | Total pressure difference across supply and return ports in air loop [Pa] | |
| MassFlowRate | mAir_flow_nominal | Nominal mass flow rate of supply air [kg/s] | |
| Heating coil parameters | |||
| HeatFlowRate | QHeaCoi_flow_nominal | Nominal heat flow rate of heating coil [W] | |
| Temperature | THeaCoiWatSup_nominal | 333.15 | Design water temperature entering heating coil [K] |
| Temperature | THeaCoiAirEnt_nominal | 293.15 | Design air temperature entering heating coil [K] |
| MassFlowRate | mHeaCoiWat_flow_nominal | Nominal mass flow rate of heating hot water [kg/s] | |
| PressureDifference | dpHeaCoiWat_nominal | Total pressure difference across heating coil (water side) [Pa] | |
| PressureDifference | dpHeaCoiVal_nominal | dpHeaCoiWat_nominal | Design pressure drop of heating water valve [Pa] |
| Cooling coil parameters | |||
| HeatFlowRate | QCooCoi_flow_nominal | Nominal heat flow rate of cooling coil [W] | |
| Temperature | TCooCoiWatEnt_nominal | 279.83 | Design water inlet temperature of cooling coil [K] |
| Temperature | TCooCoiAirEnt_nominal | 296.15 | Design air inlet temperature of cooling coil [K] |
| MassFraction | wCooCoiAirEnt_nominal | 0.012 | Design humidity ratio of inlet air of cooling coil (in kg/kg dry air) [1] |
| MassFlowRate | mCooCoiWat_flow_nominal | Nominal mass flow rate of chilled water [kg/s] | |
| PressureDifference | dpCooCoiWat_nominal | Total pressure difference across cooling coil (water side) [Pa] | |
| PressureDifference | dpCooCoiVal_nominal | dpCooCoiWat_nominal | Design pressure drop of chilled water valve [Pa] |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package MediumA | Medium for air | |
| replaceable package MediumHW | Medium for hot water | |
| replaceable package MediumCHW | Medium for chilled water | |
| input RealInput | uHea | Heating loop control signal [1] |
| input RealInput | uCoo | Cooling loop control signal [1] |
| input RealInput | uFan | Fan normalized speed control signal [1] |
| output RealOutput | yFan_actual | Normalized actual fan speed signal [1] |
| output RealOutput | TAirSup | Measured supply air temperature [K] |
| FluidPort_a | port_air_a | Return air port from zone |
| FluidPort_b | port_air_b | Supply air port to the zone |
| FluidPort_a | port_CHW_a | Chilled water supply port |
| FluidPort_b | port_CHW_b | Chilled water return port |
| FluidPort_a | port_HW_a | Hot water supply port |
| FluidPort_b | port_HW_b | Hot water return port |
Modelica definition
model FourPipe "System model for a four-pipe fan coil unit"
replaceable package MediumA = Modelica.Media.Interfaces.PartialMedium
"Medium for air";
replaceable package MediumHW = Modelica.Media.Interfaces.PartialMedium
"Medium for hot water";
replaceable package MediumCHW = Modelica.Media.Interfaces.PartialMedium
"Medium for chilled water";
parameter Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil
heaCoiTyp=Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.WaterBased
"Heating coil type";
parameter Modelica.Units.SI.HeatFlowRate QHeaCoi_flow_nominal(final min=0,
final start=0) "Nominal heat flow rate of heating coil";
parameter Modelica.Units.SI.Temperature THeaCoiWatSup_nominal=333.15
"Design water temperature entering heating coil";
parameter Modelica.Units.SI.Temperature THeaCoiAirEnt_nominal=293.15
"Design air temperature entering heating coil";
parameter Modelica.Units.SI.HeatFlowRate QCooCoi_flow_nominal(final max=0,
final start=0) "Nominal heat flow rate of cooling coil";
parameter Modelica.Units.SI.Temperature TCooCoiWatEnt_nominal=279.83
"Design water inlet temperature of cooling coil";
parameter Modelica.Units.SI.Temperature TCooCoiAirEnt_nominal=296.15
"Design air inlet temperature of cooling coil";
parameter Modelica.Units.SI.MassFraction wCooCoiAirEnt_nominal=0.012
"Design humidity ratio of inlet air of cooling coil (in kg/kg dry air)";
parameter Modelica.Units.SI.MassFlowRate mHeaCoiWat_flow_nominal(final min=0,
final start=0) "Nominal mass flow rate of heating hot water";
parameter Modelica.Units.SI.PressureDifference dpHeaCoiWat_nominal(
displayUnit="Pa", final start=0)
"Total pressure difference across heating coil (water side)";
parameter Modelica.Units.SI.PressureDifference dpHeaCoiVal_nominal(
displayUnit="Pa") =dpHeaCoiWat_nominal
"Design pressure drop of heating water valve";
parameter Modelica.Units.SI.PressureDifference dpAir_nominal(displayUnit="Pa")
"Total pressure difference across supply and return ports in air loop";
parameter Modelica.Units.SI.MassFlowRate mCooCoiWat_flow_nominal
"Nominal mass flow rate of chilled water";
parameter Modelica.Units.SI.PressureDifference dpCooCoiWat_nominal(
displayUnit="Pa")
"Total pressure difference across cooling coil (water side)";
parameter Modelica.Units.SI.PressureDifference dpCooCoiVal_nominal(
displayUnit="Pa") = dpCooCoiWat_nominal
"Design pressure drop of chilled water valve";
parameter Modelica.Units.SI.MassFlowRate mAir_flow_nominal
"Nominal mass flow rate of supply air";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uHea(
final min=0, final max=1, final unit="1") if have_hea
"Heating loop control signal";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uCoo(
final min=0, final max=1, final unit="1")
"Cooling loop control signal";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uFan(
final min=0, final max=1, final unit="1")
"Fan normalized speed control signal";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yFan_actual(
final unit="1",
displayUnit="1")
"Normalized actual fan speed signal";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput TAirSup(
final unit="K",
displayUnit="degC",
final quantity="ThermodynamicTemperature")
"Measured supply air temperature";
Modelica.Fluid.Interfaces.FluidPort_a port_air_a(
redeclare final package Medium = MediumA)
"Return air port from zone";
Modelica.Fluid.Interfaces.FluidPort_b port_air_b(
redeclare final package Medium = MediumA)
"Supply air port to the zone";
Modelica.Fluid.Interfaces.FluidPort_a port_CHW_a(
redeclare package Medium = Buildings.Media.Water)
"Chilled water supply port";
Modelica.Fluid.Interfaces.FluidPort_b port_CHW_b(
redeclare final package Medium = Buildings.Media.Water)
"Chilled water return port";
Modelica.Fluid.Interfaces.FluidPort_a port_HW_a(
redeclare final package Medium = Buildings.Media.Water) if have_hotWat
"Hot water supply port";
Modelica.Fluid.Interfaces.FluidPort_b port_HW_b(
redeclare final package Medium = Buildings.Media.Water) if have_hotWat
"Hot water return port";
Buildings.Fluid.Sensors.TemperatureTwoPort TAirHea(
redeclare final package Medium = MediumA,
final m_flow_nominal=mAir_flow_nominal)
"Heating coil discharge air temperature sensor";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hex(
redeclare final package Medium1 = MediumHW,
redeclare final package Medium2 = MediumA,
final m1_flow_nominal=mHeaCoiWat_flow_nominal,
final m2_flow_nominal=mAir_flow_nominal,
show_T=true,
final dp1_nominal=0,
final dp2_nominal=0,
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow,
use_Q_flow_nominal=true,
final Q_flow_nominal=QHeaCoi_flow_nominal,
final T_a1_nominal=THeaCoiWatSup_nominal,
final T_a2_nominal=THeaCoiAirEnt_nominal) if have_hotWat
"Hot water heating coil";
Buildings.Fluid.Actuators.Valves.TwoWayLinear valHW(
redeclare final package Medium = MediumHW,
final m_flow_nominal=mHeaCoiWat_flow_nominal,
final dpValve_nominal=dpHeaCoiVal_nominal,
dpFixed_nominal=dpHeaCoiWat_nominal) if have_hotWat
"Hot water flow control valve";
Buildings.Fluid.HeatExchangers.WetCoilEffectivenessNTU hexWetNtu(
redeclare final package Medium1 = MediumCHW,
redeclare final package Medium2 = MediumA,
final m1_flow_nominal=mCooCoiWat_flow_nominal,
final m2_flow_nominal=mAir_flow_nominal,
show_T=true,
final dp1_nominal=0,
final dp2_nominal=0,
use_Q_flow_nominal=true,
final Q_flow_nominal=QCooCoi_flow_nominal,
final T_a1_nominal=TCooCoiWatEnt_nominal,
final T_a2_nominal=TCooCoiAirEnt_nominal,
final w_a2_nominal=wCooCoiAirEnt_nominal,
final energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial)
"Chilled-water cooling coil";
Buildings.Fluid.Actuators.Valves.TwoWayLinear valCHW(
redeclare final package Medium = MediumCHW,
final m_flow_nominal=mCooCoiWat_flow_nominal,
final dpValve_nominal=dpCooCoiVal_nominal,
dpFixed_nominal=dpCooCoiWat_nominal) "Chilled-water flow control valve";
Buildings.Fluid.Sensors.TemperatureTwoPort TAirLvg(
redeclare final package Medium = MediumA,
final m_flow_nominal=mAir_flow_nominal)
"Supply air temperature sensor";
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y fan(
redeclare final package Medium = MediumA,
final energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
addPowerToMedium=true,
final m_flow_nominal=mAir_flow_nominal,
final dp_nominal=dpAir_nominal)
"Supply fan";
Buildings.Fluid.FixedResistances.PressureDrop totResAir(
redeclare final package Medium = MediumA,
final m_flow_nominal = mAir_flow_nominal,
final dp_nominal = dpAir_nominal,
final allowFlowReversal = true)
"Total resistance of air path";
Buildings.Fluid.HeatExchangers.HeaterCooler_u heaCoiEle(
redeclare final package Medium = MediumA,
final m_flow_nominal=mAir_flow_nominal,
show_T=true,
final dp_nominal=0,
final Q_flow_nominal=QHeaCoi_flow_nominal,
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial)
if have_heaEle
"Electric heating coil";
protected
final parameter Boolean have_hotWat=(heaCoiTyp ==Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.WaterBased)
"True if a hot water heating coil exists";
final parameter Boolean have_heaEle=(heaCoiTyp ==Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.Electric)
"True if an electric heating coil exists";
final parameter Boolean have_hea=have_hotWat or have_heaEle
"True if a heating coil exists";
Buildings.Fluid.FixedResistances.LosslessPipe pipByp(
redeclare final package Medium = MediumA,
final m_flow_nominal=mAir_flow_nominal,
final allowFlowReversal=true) if not have_hea
"Bypass when heating coil is absent";
equation
connect(valHW.port_a, hex.port_b1);
connect(hex.port_b2, TAirHea.port_a);
connect(uHea, valHW.y);
connect(valCHW.port_a, hexWetNtu.port_b1);
connect(TAirHea.port_b, hexWetNtu.port_a2);
connect(fan.port_b, TAirLvg.port_a);
connect(uCoo, valCHW.y);
connect(hexWetNtu.port_b2, totResAir.port_a);
connect(heaCoiEle.port_b, TAirHea.port_a);
connect(uHea, heaCoiEle.u);
connect(TAirLvg.T, TAirSup);
connect(totResAir.port_b, fan.port_a);
connect(pipByp.port_b, TAirHea.port_a);
connect(uFan, fan.y);
connect(fan.y_actual, yFan_actual);
connect(hex.port_a1, port_HW_a);
connect(valHW.port_b, port_HW_b);
connect(hexWetNtu.port_a1, port_CHW_a);
connect(valCHW.port_b, port_CHW_b);
connect(port_air_a, pipByp.port_a);
connect(port_air_a, heaCoiEle.port_a);
connect(port_air_a, hex.port_a2);
connect(TAirLvg.port_b, port_air_b);
end FourPipe;