Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5
Package of models for fifth generation DHC energy transfer stations
Information
This package contains models for energy transfer stations used in fifth generation district heating and cooling systems.
Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).
Package Content
| Name | Description |
|---|---|
 ChillerBorefield
|
ETS model for 5GDHC systems with heat recovery chiller and optional borefield |
 HeatPumpHeatExchanger
|
Model of a substation with heat pump and compressor-less cooling |
 Controls
|
Package of control blocks for fifth generation DHC ETS |
| Subsystems
|
Package of models for subsystems of fifth generation DHC ETS |
 Examples
|
Example models integrating multiple components |
| Validation
|
Collection of validation models |
 BaseClasses
|
Package with base classes |
Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.ChillerBorefield
ETS model for 5GDHC systems with heat recovery chiller and optional borefield
Information
This model represents an energy transfer station as illustrated in the schematics below.
- The heating and cooling functions are provided by a heat recovery chiller, see Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Subsystems.Chiller for the operating principles and modeling assumptions. The condenser and evaporator loops are equipped with constant speed pumps.
- The supervisory controller ensures the load balancing between the condenser side and the evaporator side of the chiller by controlling in sequence an optional geothermal borefield (priority system), the district heat exchanger (second priority system), and ultimately the chiller, by resetting down the chilled water supply temperature, see Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Controls.Supervisory for a detailed description. The borefield and district heat exchanger loops are equipped with variable speed pumps modulated by the supervisory controller.
Note that the heating and cooling enable signals (uHea and uCoo)
connected to this model should be switched to false when the
building has no corresponding demand (e.g., based on the requests yielded by
the terminal unit controllers, in conjunction with a schedule).
This will significantly improve the system performance as it is a
necessary condition for the chiller to be operated at a lower lift, see
Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Controls.Reset.
Extends from BaseClasses.PartialParallel (Partial ETS model with district heat exchanger and parallel connection of production systems).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumSer | Water | Service side medium | |
| replaceable package MediumSerHea_a | Water | Service side medium at heating inlet | |
| replaceable package MediumBui | Water | Building side medium | |
| Generic | fue[nFue] | Fuel type | |
| ConnectionConfiguration | conCon | EnergyTransferStations.Types... | District connection configuration |
| Integer | nSysHea | 1 | Number of heating systems |
| Integer | nSysCoo | nSysHea | Number of cooling systems |
| Integer | nSouAmb | if have_borFie then 2 else 1 | Number of ambient sources |
| Boolean | have_borFie | false | Set to true in case a borefield is used in addition of the district HX |
| Configuration | |||
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_eleHea | false | Set to true if the ETS has electric heating system |
| Integer | nFue | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | true | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Nominal condition | |||
| HeatFlowRate | QHeaWat_flow_nominal | 0 | Nominal capacity of heating system (>=0) [W] |
| HeatFlowRate | QHotWat_flow_nominal | 0 | Nominal capacity of hot water production system (>=0) [W] |
| HeatFlowRate | QChiWat_flow_nominal | 0 | Nominal capacity of cooling system (<=0) [W] |
| PressureDifference | dpValIso_nominal | 2E3 | Nominal pressure drop of ambient circuit isolation valves [Pa] |
| District heat exchanger | |||
| PressureDifference | dp1Hex_nominal | Nominal pressure drop across heat exchanger on district side [Pa] | |
| PressureDifference | dp2Hex_nominal | Nominal pressure drop across heat exchanger on building side [Pa] | |
| HeatFlowRate | QHex_flow_nominal | Nominal heat flow rate through heat exchanger (from district to building) [W] | |
| Temperature | T_a1Hex_nominal | Nominal water inlet temperature on district side [K] | |
| Temperature | T_b1Hex_nominal | Nominal water outlet temperature on district side [K] | |
| Temperature | T_a2Hex_nominal | Nominal water inlet temperature on building side [K] | |
| Temperature | T_b2Hex_nominal | Nominal water outlet temperature on building side [K] | |
| TemperatureDifference | dT1HexSet[2] | abs(T_b1Hex_nominal - T_a1He... | Primary side deltaT set point schedule (index 1 for heat rejection) [K] |
| Real | spePum1HexMin | 0.1 | Heat exchanger primary pump minimum speed (fractional) [1] |
| Real | yVal1HexMin | 0.1 | Minimum valve opening for temperature measurement (fractional) [1] |
| Real | spePum2HexMin | 0.1 | Heat exchanger secondary pump minimum speed (fractional) [1] |
| Generic | perPum1Hex | redeclare parameter Building... | Record with performance data for primary pump |
| Generic | perPum2Hex | redeclare parameter Building... | Record with performance data for secondary pump |
| Buffer Tank | |||
| Volume | VTanHeaWat | datChi.PLRMin*datChi.mCon_fl... | Heating water tank volume [m3] |
| Length | hTanHeaWat | (VTanHeaWat*16/Modelica.Cons... | Heating water tank height (assuming twice the diameter) [m] |
| Length | dInsTanHeaWat | 0.1 | Heating water tank insulation thickness [m] |
| Volume | VTanChiWat | datChi.PLRMin*datChi.mEva_fl... | Chilled water tank volume [m3] |
| Length | hTanChiWat | (VTanChiWat*16/Modelica.Cons... | Chilled water tank height (without insulation) [m] |
| Length | dInsTanChiWat | 0.1 | Chilled water tank insulation thickness [m] |
| Integer | nSegTan | 3 | Number of volume segments for tanks |
| Chiller | |||
| PressureDifference | dpCon_nominal | Nominal pressure drop accross condenser [Pa] | |
| PressureDifference | dpEva_nominal | Nominal pressure drop accross evaporator [Pa] | |
| Generic | datChi | redeclare parameter Fluid.Ch... | Chiller performance data |
| Generic | perPumCon | perPumCon(motorCooledByFluid... | Record with performance data for condenser pump |
| Generic | perPumEva | perPumEva(motorCooledByFluid... | Record with performance data for evaporator pump |
| Chiller | chi | chi(redeclare final package ... | Chiller |
| Borefield | |||
| Temperature | TBorWatEntMax | 313.15 | Maximum value of borefield water entering temperature [K] |
| Real | spePumBorMin | 0.1 | Borefield pump minimum speed [1] |
| Pressure | dpBorFie_nominal | 5E4 | Pressure losses for the entire borefield (control valve excluded) [Pa] |
| Example | datBorFie | redeclare parameter Fluid.Ge... | Borefield parameters |
| Generic | perPumBorFie | perPumBorFie(motorCooledByFl... | Record with performance data for borefield pump |
| Borefield | borFie | borFie(redeclare final packa... | Borefield |
| Supervisory controller | |||
| SimpleController | controllerType | Buildings.Controls.OBC.CDL.T... | Type of controller |
| Real | kHot | 0.05 | Gain of controller on hot side |
| Real | kCol | 0.1 | Gain of controller on cold side |
| Time | TiHot | 300 | Time constant of integrator block on hot side [s] |
| Time | TiCol | 120 | Time constant of integrator block on cold side [s] |
| Temperature | THeaWatSupSetMin | datChi.TConEntMin + 5 | Minimum value of heating water supply temperature set point [K] |
| Temperature | TChiWatSupSetMin | datChi.TEvaLvgMin | Minimum value of chilled water supply temperature set point [K] |
| Assumptions | |||
| Boolean | allowFlowReversalSer | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui | false | Set to true to allow flow reversal on building side |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPorts_a | ports_aHeaWat[nPorts_aHeaWat] | Fluid connectors for heating water return (from building) |
| FluidPorts_b | ports_bHeaWat[nPorts_bHeaWat] | Fluid connectors for heating water supply (to building) |
| FluidPorts_a | ports_aChiWat[nPorts_aChiWat] | Fluid connectors for chilled water return (from building) |
| FluidPorts_b | ports_bChiWat[nPorts_bChiWat] | Fluid connectors for chilled water supply (to building) |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow[nFue] | Fuel energy input rate [W] |
| Bus | weaBus | Weather data bus |
| input BooleanInput | uHea | Heating enable signal |
| input BooleanInput | uCoo | Cooling enable signal |
| input RealInput | THeaWatSupSet | Heating water supply temperature set point [K] |
| input RealInput | TChiWatSupSet | Chilled water supply temperature set point [K] |
| output RealOutput | dHHeaWat_flow | Heating water distributed energy flow rate [W] |
| output RealOutput | dHChiWat_flow | Chilled water distributed energy flow rate [W] |
Modelica definition
model ChillerBorefield
"ETS model for 5GDHC systems with heat recovery chiller and optional borefield"
extends BaseClasses.PartialParallel(
final have_eleCoo=true,
final have_fan=false,
redeclare replaceable Controls.Supervisory conSup
constrainedby Controls.Supervisory(
final controllerType=controllerType,
final kHot=kHot,
final kCol=kCol,
final TiHot=TiHot,
final TiCol=TiCol,
final THeaWatSupSetMin=THeaWatSupSetMin,
final TChiWatSupSetMin=TChiWatSupSetMin),
nSysHea=1,
nSouAmb=
if have_borFie then
2
else
1,
dT1HexSet=abs(
T_b1Hex_nominal-T_a1Hex_nominal) .* {1+1/datChi.COP_nominal,1},
VTanHeaWat=datChi.PLRMin*datChi.mCon_flow_nominal*5*60/1000,
VTanChiWat=datChi.PLRMin*datChi.mEva_flow_nominal*5*60/1000,
colChiWat(
mCon_flow_nominal={colAmbWat.mDis_flow_nominal,datChi.mEva_flow_nominal}),
colHeaWat(
mCon_flow_nominal={colAmbWat.mDis_flow_nominal,datChi.mCon_flow_nominal}),
colAmbWat(
mCon_flow_nominal=
if have_borFie then
{hex.m2_flow_nominal,datBorFie.conDat.mBorFie_flow_nominal}
else
{hex.m2_flow_nominal}),
totPPum(
nin=3),
totPHea(
nin=1),
totPCoo(
nin=1));
parameter Boolean have_borFie=false
"Set to true in case a borefield is used in addition of the district HX";
parameter Modelica.SIunits.PressureDifference dpCon_nominal(
displayUnit="Pa")
"Nominal pressure drop accross condenser";
parameter Modelica.SIunits.PressureDifference dpEva_nominal(
displayUnit="Pa")
"Nominal pressure drop accross evaporator";
replaceable parameter Fluid.Chillers.Data.ElectricEIR.Generic datChi
"Chiller performance data";
replaceable parameter Buildings.Fluid.Movers.Data.Generic perPumCon(
motorCooledByFluid=false)
constrainedby Buildings.Fluid.Movers.Data.Generic
"Record with performance data for condenser pump";
replaceable parameter Buildings.Fluid.Movers.Data.Generic perPumEva(
motorCooledByFluid=false)
constrainedby Buildings.Fluid.Movers.Data.Generic
"Record with performance data for evaporator pump";
parameter Modelica.SIunits.Temperature TBorWatEntMax=313.15
"Maximum value of borefield water entering temperature";
parameter Real spePumBorMin(
final unit="1")=0.1
"Borefield pump minimum speed";
parameter Modelica.SIunits.Pressure dpBorFie_nominal(
displayUnit="Pa")=5E4
"Pressure losses for the entire borefield (control valve excluded)";
replaceable parameter Fluid.Geothermal.Borefields.Data.Borefield.Example datBorFie
constrainedby Fluid.Geothermal.Borefields.Data.Borefield.Template
"Borefield parameters";
replaceable parameter Buildings.Fluid.Movers.Data.Generic perPumBorFie(
motorCooledByFluid=false)
constrainedby Buildings.Fluid.Movers.Data.Generic
"Record with performance data for borefield pump";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Type of controller";
parameter Real kHot(
min=0)=0.05
"Gain of controller on hot side";
parameter Real kCol(
min=0)=0.1
"Gain of controller on cold side";
parameter Modelica.SIunits.Time TiHot(
min=Buildings.Controls.OBC.CDL.Constants.small)=300
"Time constant of integrator block on hot side";
parameter Modelica.SIunits.Time TiCol(
min=Buildings.Controls.OBC.CDL.Constants.small)=120
"Time constant of integrator block on cold side";
parameter Modelica.SIunits.Temperature THeaWatSupSetMin(
displayUnit="degC")=datChi.TConEntMin+5
"Minimum value of heating water supply temperature set point";
parameter Modelica.SIunits.Temperature TChiWatSupSetMin(
displayUnit="degC")=datChi.TEvaLvgMin
"Minimum value of chilled water supply temperature set point";
replaceable Subsystems.Chiller chi(
redeclare final package Medium=MediumBui,
final perPumCon=perPumCon,
final perPumEva=perPumEva,
final dpCon_nominal=dpCon_nominal,
final dpEva_nominal=dpEva_nominal,
final dat=datChi)
"Chiller";
replaceable Subsystems.Borefield borFie(
redeclare final package Medium=MediumBui,
final datBorFie=datBorFie,
final perPum=perPumBorFie,
final TBorWatEntMax=TBorWatEntMax,
final spePumBorMin=spePumBorMin,
final dp_nominal=dpBorFie_nominal) if have_borFie
"Borefield";
Buildings.Controls.OBC.CDL.Continuous.Sources.Constant zerPPum(
final k=0) if not have_borFie
"Zero power";
Buildings.Controls.OBC.CDL.Continuous.Sources.Constant zerPHea(
final k=0)
"Zero power";
equation
connect(chi.port_bHeaWat,colHeaWat.ports_aCon[2]);
connect(chi.port_aHeaWat,colHeaWat.ports_bCon[2]);
connect(chi.port_bChiWat,colChiWat.ports_aCon[2]);
connect(colChiWat.ports_bCon[2],chi.port_aChiWat);
connect(conSup.TChiWatSupSet,chi.TChiWatSupSet);
connect(chi.PPum,totPPum.u[2]);
connect(colAmbWat.ports_aCon[2],borFie.port_b);
connect(colAmbWat.ports_bCon[2],borFie.port_a);
connect(conSup.yAmb[1],borFie.u);
connect(valIsoCon.y_actual,borFie.yValIso_actual[1]);
connect(valIsoEva.y_actual,borFie.yValIso_actual[2]);
connect(borFie.PPum,totPPum.u[3]);
connect(zerPPum.y,totPPum.u[3]);
connect(zerPHea.y,totPHea.u[1]);
connect(chi.PChi,totPCoo.u[1]);
connect(uHea,conSup.uHea);
connect(conSup.yHea,chi.uHea);
connect(conSup.yCoo,chi.uCoo);
connect(valIsoCon.y_actual,conSup.yValIsoCon_actual);
connect(valIsoEva.y_actual,conSup.yValIsoEva_actual);
end ChillerBorefield;
Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.HeatPumpHeatExchanger
Model of a substation with heat pump and compressor-less cooling
Information
This model represents an energy transfer station as described in Sommer (2020).
- The cooling function is provided in a compressor-less mode by a heat exchanger connected to the service line. The chilled water is typically produced at high temperature and distributed to radiant cooling systems, for instance at 19°C.
-
The heating functions are provided by water-to-water heat pumps.
-
By default the condenser and evaporator loops are operated
with variable mass flow rate, with a lower limit specified by the ratio
ratFloMin. The model can also represent constant flow condenser and evaporator loops by settinghave_varFloConandhave_varFloEvatofalse. - The evaporator water is supplied by mixing the flow rate from the direct connection to the service line to the flow rate from the primary side of the cooling heat exchanger. The hydronic arrangement modeled in Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Subsystems.SwitchBox ensures that the resulting fluid stream in the service line always flows in the same direction.
- The heating hot water is typically produced at low temperature, for instance 40°C.
-
By default the condenser and evaporator loops are operated
with variable mass flow rate, with a lower limit specified by the ratio
Controls
Heating (resp. cooling) is enabled based on the input signal uHea
(resp. uCoo) which is held for 15 minutes, meaning that,
when enabled, the mode remains active for at least 15 minutes and,
when disabled, the mode cannot be enabled again for at least 15 minutes.
The heating and cooling enable signals should be computed externally based
on a schedule (to lock out the system during off-hours), ideally in conjunction
with the number of requests yielded by the terminal unit controllers, or any
other signal representative of the load.
When enabled,
- the heat pumps and the evaporator and condenser water pumps are controlled based on the principles described in Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Subsystems.HeatPump. The evaporator and condenser water mass flow rates are computed based on the logic described in Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Controls.PrimaryVariableFlow.
- the cooling heat exchanger primary pump is modulated based on a PI control loop tracking the chilled water supply temperature at the outlet of the heat exchanger secondary side.
Modeling considerations
There is a control volume at each of the two fluid ports that serve as inlet and outlet of the heating and cooling systems. These approximate the dynamics of the substation, and they also generally avoid nonlinear systems of equations if multiple substations are connected to each other.
References
Sommer T., Sulzer M., Wetter M., Sotnikov A., Mennel S., Stettler C. The reservoir network: A new network topology for district heating and cooling. Energy, Volume 199, 15 May 2020, 117418.
Extends from DHC.EnergyTransferStations.BaseClasses.PartialETS (Partial class for modeling an energy transfer station).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package MediumSer | Water | Service side medium | |
| replaceable package MediumSerHea_a | Water | Service side medium at heating inlet | |
| replaceable package MediumBui | Water | Building side medium | |
| Generic | fue[nFue] | Fuel type | |
| Boolean | have_varFloCon | true | Set to true for heat pumps with variable condenser flow |
| Boolean | have_varFloEva | true | Set to true for heat pumps with variable evaporator flow |
| Real | ratFloMin | 0.3 | Minimum condenser or evaporator mass flow rate (ratio to nominal) [1] |
| Configuration | |||
| DistrictSystemType | typ | DHC.Types.DistrictSystemType... | Type of district system |
| Boolean | have_heaWat | true | Set to true if the ETS supplies heating water |
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| Boolean | have_chiWat | true | Set to true if the ETS supplies chilled water |
| Boolean | have_fan | false | Set to true if fan power is computed |
| Boolean | have_pum | true | Set to true if pump power is computed |
| Boolean | have_eleHea | true | Set to true if the ETS has electric heating system |
| Integer | nFue | 0 | Number of fuel types (0 means no combustion system) |
| Boolean | have_eleCoo | false | Set to true if the ETS has electric cooling system |
| Boolean | have_weaBus | false | Set to true to use a weather bus |
| Nominal condition | |||
| HeatFlowRate | QHeaWat_flow_nominal | 0 | Nominal capacity of heating system (>=0) [W] |
| HeatFlowRate | QHotWat_flow_nominal | 0 | Nominal capacity of hot water production system (>=0) [W] |
| HeatFlowRate | QChiWat_flow_nominal | 0 | Nominal capacity of cooling system (<=0) [W] |
| TemperatureDifference | dT_nominal | 5 | Water temperature drop/increase accross load and source-side HX (always positive) [K] |
| Temperature | THeaWatSup_nominal | 313.15 | Heating water supply temperature [K] |
| Temperature | THotWatSup_nominal | 336.15 | Hot water supply temperature [K] |
| Temperature | TColWat_nominal | 288.15 | Cold water temperature (for hot water production) [K] |
| Pressure | dp_nominal | 50000 | Pressure difference at nominal flow rate (for each flow leg) [Pa] |
| Real | COPHeaWat_nominal | COP of heat pump for heating water production [1] | |
| Real | COPHotWat_nominal | COP of heat pump for hot water production [1] | |
| DHC system | |||
| Temperature | TDisWatMin | District water minimum temperature [K] | |
| Temperature | TDisWatMax | District water maximum temperature [K] | |
| Nominal conditions | |||
| Temperature | TChiWatSup_nominal | 291.15 | Chilled water supply temperature [K] |
| Assumptions | |||
| Boolean | allowFlowReversalSer | false | Set to true to allow flow reversal on service side |
| Boolean | allowFlowReversalBui | false | Set to true to allow flow reversal on building side |
| Dynamics | |||
| Dynamics | mixingVolumeEnergyDynamics | Modelica.Fluid.Types.Dynamic... | Formulation of energy balance for mixing volume at inlet and outlet |
Connectors
| Type | Name | Description |
|---|---|---|
| FluidPorts_a | ports_aHeaWat[nPorts_aHeaWat] | Fluid connectors for heating water return (from building) |
| FluidPorts_b | ports_bHeaWat[nPorts_bHeaWat] | Fluid connectors for heating water supply (to building) |
| FluidPorts_a | ports_aChiWat[nPorts_aChiWat] | Fluid connectors for chilled water return (from building) |
| FluidPorts_b | ports_bChiWat[nPorts_bChiWat] | Fluid connectors for chilled water supply (to building) |
| FluidPort_a | port_aSerAmb | Fluid connector for ambient water service supply line |
| FluidPort_b | port_bSerAmb | Fluid connector for ambient water service return line |
| FluidPort_a | port_aSerHea | Fluid connector for heating service supply line |
| FluidPort_b | port_bSerHea | Fluid connector for heating service return line |
| FluidPort_a | port_aSerCoo | Fluid connector for cooling service supply line |
| FluidPort_b | port_bSerCoo | Fluid connector for cooling service return line |
| output RealOutput | PHea | Power drawn by heating system [W] |
| output RealOutput | PCoo | Power drawn by cooling system [W] |
| output RealOutput | PFan | Power drawn by fan motors [W] |
| output RealOutput | PPum | Power drawn by pump motors [W] |
| output RealOutput | QFue_flow[nFue] | Fuel energy input rate [W] |
| Bus | weaBus | Weather data bus |
| input BooleanInput | uCoo | Cooling enable signal |
| input BooleanInput | uHea | Heating enable signal |
| input BooleanInput | uSHW | SHW production enable signal |
| input RealInput | THeaWatSupSet | Heating water supply temperature set point [K] |
| input RealInput | THotWatSupSet | Service hot water supply temperature set point [K] |
| input RealInput | TColWat | Cold water temperature [K] |
| input RealInput | loaSHW | Service hot water load [W] |
| input RealInput | TChiWatSupSet | Chilled water supply temperature set point [K] |
| output RealOutput | mHea_flow | District water mass flow rate used for heating service [kg/s] |
| output RealOutput | mCoo_flow | District water mass flow rate used for cooling service [kg/s] |
Modelica definition
model HeatPumpHeatExchanger
"Model of a substation with heat pump and compressor-less cooling"
extends DHC.EnergyTransferStations.BaseClasses.PartialETS(
final typ=DHC.Types.DistrictSystemType.CombinedGeneration5,
final have_weaBus=false,
final have_chiWat=true,
final have_heaWat=true,
have_hotWat=false,
final have_eleHea=true,
final nFue=0,
final have_eleCoo=false,
final have_pum=true,
final have_fan=false,
nPorts_aHeaWat=1,
nPorts_aChiWat=1);
// SYSTEM GENERAL
parameter Boolean have_varFloCon = true
"Set to true for heat pumps with variable condenser flow";
parameter Boolean have_varFloEva = true
"Set to true for heat pumps with variable evaporator flow";
parameter Real ratFloMin(
final unit="1",
final min=0,
final max=1)=0.3
"Minimum condenser or evaporator mass flow rate (ratio to nominal)";
parameter Modelica.SIunits.Temperature TDisWatMin
"District water minimum temperature";
parameter Modelica.SIunits.Temperature TDisWatMax
"District water maximum temperature";
parameter Modelica.SIunits.TemperatureDifference dT_nominal(min=0) = 5
"Water temperature drop/increase accross load and source-side HX (always positive)";
parameter Modelica.SIunits.Temperature TChiWatSup_nominal=291.15
"Chilled water supply temperature";
final parameter Modelica.SIunits.Temperature TChiWatRet_nominal=
TChiWatSup_nominal + dT_nominal
"Chilled water return temperature";
parameter Modelica.SIunits.Temperature THeaWatSup_nominal=313.15
"Heating water supply temperature";
final parameter Modelica.SIunits.Temperature THeaWatRet_nominal=
THeaWatSup_nominal - dT_nominal
"Heating water return temperature";
parameter Modelica.SIunits.Temperature THotWatSup_nominal=336.15
"Hot water supply temperature";
parameter Modelica.SIunits.Temperature TColWat_nominal=288.15
"Cold water temperature (for hot water production)";
parameter Modelica.SIunits.Pressure dp_nominal(displayUnit="Pa") = 50000
"Pressure difference at nominal flow rate (for each flow leg)";
final parameter Modelica.SIunits.MassFlowRate mHeaWat_flow_nominal(min=0)=
abs(QHeaWat_flow_nominal / cpBui_default / (THeaWatSup_nominal - THeaWatRet_nominal))
"Heating water mass flow rate";
final parameter Modelica.SIunits.MassFlowRate mChiWat_flow_nominal(min=0)=
abs(QChiWat_flow_nominal / cpBui_default / (TChiWatSup_nominal - TChiWatRet_nominal))
"Chilled water mass flow rate";
final parameter Modelica.SIunits.MassFlowRate mEvaHotWat_flow_nominal(min=0)=
QHotWat_flow_nominal * (COPHotWat_nominal - 1) / COPHotWat_nominal /
cpSer_default / dT_nominal
"Evaporator water mass flow rate of heat pump for hot water production";
final parameter Modelica.SIunits.MassFlowRate mDisWat_flow_nominal(min=0)=
max(proHeaWat.m2_flow_nominal + mEvaHotWat_flow_nominal, hexChi.m1_flow_nominal)
"District water mass flow rate";
constant Modelica.SIunits.SpecificHeatCapacity cpBui_default=
MediumBui.specificHeatCapacityCp(MediumBui.setState_pTX(
p = MediumBui.p_default,
T = MediumBui.T_default))
"Specific heat capacity of the fluid";
constant Modelica.SIunits.SpecificHeatCapacity cpSer_default=
MediumBui.specificHeatCapacityCp(MediumSer.setState_pTX(
p = MediumSer.p_default,
T = MediumSer.T_default))
"Specific heat capacity of the fluid";
// Heat pump for heating water production
parameter Real COPHeaWat_nominal(final unit="1")
"COP of heat pump for heating water production";
// Heat pump for hot water production
parameter Real COPHotWat_nominal(final unit="1")
"COP of heat pump for hot water production";
// District HX
final parameter Modelica.SIunits.MassFlowRate m1HexChi_flow_nominal(min=0)=
abs(QChiWat_flow_nominal / cpSer_default / dT_nominal)
"CHW HX primary mass flow rate";
final parameter Modelica.SIunits.MassFlowRate m2HexChi_flow_nominal(min=0)=
abs(QChiWat_flow_nominal / cpSer_default / (THeaWatSup_nominal - THeaWatRet_nominal))
"CHW HX secondary mass flow rate";
// Dynamics
parameter Modelica.Fluid.Types.Dynamics mixingVolumeEnergyDynamics=
Modelica.Fluid.Types.Dynamics.FixedInitial
"Formulation of energy balance for mixing volume at inlet and outlet";
// IO CONNECTORS
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uCoo
"Cooling enable signal";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uHea
"Heating enable signal";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uSHW if have_hotWat
"SHW production enable signal";
Buildings.Controls.OBC.CDL.Interfaces.RealInput THeaWatSupSet(
final unit="K",
displayUnit="degC")
"Heating water supply temperature set point";
Buildings.Controls.OBC.CDL.Interfaces.RealInput THotWatSupSet(
final unit="K",
displayUnit="degC") if have_hotWat
"Service hot water supply temperature set point";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TColWat(
final unit="K",
displayUnit="degC") if have_hotWat
"Cold water temperature";
Buildings.Controls.OBC.CDL.Interfaces.RealInput loaSHW(
final unit="W") if have_hotWat "Service hot water load";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TChiWatSupSet(final unit="K",
displayUnit="degC")
"Chilled water supply temperature set point";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput mHea_flow(final unit="kg/s")
"District water mass flow rate used for heating service";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput mCoo_flow(final unit="kg/s")
"District water mass flow rate used for cooling service";
// COMPONENTS
Buildings.Fluid.Delays.DelayFirstOrder volMix_a(
redeclare final package Medium = MediumSer,
final nPorts=if have_hotWat then 4 else 3,
final m_flow_nominal=mDisWat_flow_nominal,
tau=600,
final energyDynamics=mixingVolumeEnergyDynamics)
"Mixing volume to break algebraic loops and to emulate the delay of the substation";
Buildings.Fluid.Delays.DelayFirstOrder volMix_b(
redeclare final package Medium = MediumSer,
final nPorts=if have_hotWat then 4 else 3,
final m_flow_nominal=mDisWat_flow_nominal,
tau=600,
final energyDynamics=mixingVolumeEnergyDynamics)
"Mixing volume to break algebraic loops and to emulate the delay of the substation";
DHC.EnergyTransferStations.BaseClasses.Pump_m_flow pum1HexChi(
redeclare final package Medium = MediumSer,
final m_flow_nominal=m1HexChi_flow_nominal,
final allowFlowReversal=allowFlowReversalSer)
"Chilled water HX primary pump";
Buildings.Fluid.HeatExchangers.DryCoilEffectivenessNTU hexChi(
redeclare final package Medium1 = MediumSer,
redeclare final package Medium2 = MediumBui,
final m1_flow_nominal=m1HexChi_flow_nominal,
final m2_flow_nominal=m2HexChi_flow_nominal,
final dp1_nominal=dp_nominal/2,
final dp2_nominal=dp_nominal/2,
configuration=Buildings.Fluid.Types.HeatExchangerConfiguration.CounterFlow,
final Q_flow_nominal=QChiWat_flow_nominal,
final T_a1_nominal=TDisWatMax,
final T_a2_nominal=TChiWatRet_nominal,
final allowFlowReversal1=allowFlowReversalSer,
final allowFlowReversal2=allowFlowReversalBui)
"Chilled water HX";
Buildings.Fluid.Delays.DelayFirstOrder volHeaWatRet(
redeclare final package Medium = MediumBui,
final m_flow_nominal=proHeaWat.m1_flow_nominal,
tau=60,
final energyDynamics=mixingVolumeEnergyDynamics,
T_start=THeaWatSup_nominal,
nPorts=3) "Mixing volume representing building HHW primary";
Buildings.Fluid.Sensors.MassFlowRate senMasFloHeaWat(
redeclare final package Medium = MediumBui,
final allowFlowReversal=allowFlowReversalBui)
"Heating water mass flow rate";
Buildings.Fluid.Delays.DelayFirstOrder volChiWat(
redeclare final package Medium = MediumBui,
final m_flow_nominal=m1HexChi_flow_nominal,
tau=60,
final energyDynamics=mixingVolumeEnergyDynamics,
T_start=TChiWatSup_nominal,
nPorts=3) "Mixing volume representing building CHW primary";
Buildings.Fluid.Sensors.MassFlowRate senMasFloChiWat(
redeclare final package Medium = MediumBui,
final allowFlowReversal=allowFlowReversalBui)
"Chilled water mass flow rate";
Buildings.Controls.OBC.CDL.Continuous.Gain gai2(
final k=m1HexChi_flow_nominal);
DHC.EnergyTransferStations.Combined.Generation5.Controls.PIDWithEnable conTChiWat(
k=0.05,
Ti=120,
yMax=1,
controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.PI,
reverseActing=false,
yMin=0) "PI controller for district HX primary side";
Buildings.Controls.OBC.CDL.Continuous.MultiSum PPumHeaTot(final nin=2)
"Total pump power for heating applications";
Buildings.Fluid.Sources.Boundary_pT bouHeaWat(
redeclare final package Medium = MediumBui,
nPorts=1)
"Pressure boundary condition representing the expansion vessel";
Buildings.Fluid.Sources.Boundary_pT bouChiWat(
redeclare final package Medium = MediumBui,
nPorts=1)
"Pressure boundary condition representing the expansion vessel";
Buildings.Controls.OBC.CDL.Continuous.MultiSum PPumCooTot(nin=1)
"Total pump power for space cooling";
Buildings.Controls.OBC.CDL.Continuous.MultiSum PPumTot(nin=2)
"Total pump power";
Buildings.Fluid.Sensors.TemperatureTwoPort senTHeaWatSup(
redeclare final package Medium=MediumBui,
final allowFlowReversal=allowFlowReversalBui,
final m_flow_nominal=mHeaWat_flow_nominal)
"Heating water supply temperature";
Buildings.Fluid.Sensors.TemperatureTwoPort senTChiWatSup(
redeclare final package Medium=MediumBui,
final allowFlowReversal=allowFlowReversalBui,
final m_flow_nominal=mChiWat_flow_nominal)
"Chilled water supply temperature";
Buildings.Experimental.DHC.EnergyTransferStations.Combined.Generation5.Subsystems.SwitchBox
swiFlo(
redeclare final package Medium = MediumSer,
final m_flow_nominal=mDisWat_flow_nominal) "Flow switch box";
DHC.EnergyTransferStations.BaseClasses.Junction bypHeaWatSup(redeclare final
package Medium = MediumBui, final m_flow_nominal=proHeaWat.m1_flow_nominal
*{1,-1,-1}) "Bypass heating water (supply)";
DHC.EnergyTransferStations.BaseClasses.Junction bypHeaWatRet(
redeclare final package Medium = MediumBui,
final m_flow_nominal=proHeaWat.m1_flow_nominal*{1,-1,1})
"Bypass heating water (return)";
Buildings.Controls.OBC.CDL.Logical.TrueFalseHold enaHea(
trueHoldDuration=15*60) "Enable heating";
Subsystems.HeatPump proHeaWat(
redeclare final package Medium1 = MediumBui,
redeclare final package Medium2 = MediumSer,
final have_varFloCon=have_varFloCon,
final have_varFloEva=have_varFloEva,
final COP_nominal=COPHeaWat_nominal,
final TCon_nominal=THeaWatSup_nominal,
final TEva_nominal=TDisWatMin-dT_nominal,
final Q1_flow_nominal=QHeaWat_flow_nominal,
final allowFlowReversal1=allowFlowReversalBui,
final allowFlowReversal2=allowFlowReversalSer,
final dT1_nominal=dT_nominal,
final dT2_nominal=-dT_nominal,
final dp1_nominal=dp_nominal,
final dp2_nominal=dp_nominal) "Subsystem for heating water production";
Subsystems.HeatPump proHotWat(
redeclare final package Medium1 = MediumBui,
redeclare final package Medium2 = MediumSer,
final have_pumCon=false,
final have_varFloEva=have_varFloEva,
final COP_nominal=COPHotWat_nominal,
final TCon_nominal=THotWatSup_nominal,
final TEva_nominal=TDisWatMin-dT_nominal,
final Q1_flow_nominal=QHotWat_flow_nominal,
final allowFlowReversal1=allowFlowReversalBui,
final allowFlowReversal2=allowFlowReversalSer,
final dT1_nominal=THotWatSup_nominal - TColWat_nominal,
final dT2_nominal=-dT_nominal,
final dp1_nominal=dp_nominal,
final dp2_nominal=dp_nominal) if have_hotWat
"Subsystem for hot water production";
Fluid.Sources.Boundary_pT sinSHW(
redeclare final package Medium = MediumBui,
nPorts=1) if have_hotWat
"Sink for service hot water";
Fluid.Sources.MassFlowSource_T souColWat(
redeclare final package Medium = MediumBui,
use_m_flow_in=true,
use_T_in=true,
nPorts=1) if have_hotWat
"Source for cold water";
Buildings.Controls.OBC.CDL.Continuous.Division div1 if have_hotWat
"Compute mass flow rate from load";
Buildings.Controls.OBC.CDL.Continuous.Gain gai(final k=cpBui_default)
if have_hotWat "Times Cp";
Buildings.Controls.OBC.CDL.Continuous.MultiSum masFloHeaTot(final nin=2)
"Compute district water mass flow rate used for heating service";
Modelica.Blocks.Sources.Constant zer(final k=0) if not have_hotWat
"Replacement variable";
Fluid.Sensors.TemperatureTwoPort senTHeaWatRet(
redeclare final package Medium = MediumBui,
final allowFlowReversal=allowFlowReversalBui,
final m_flow_nominal=mHeaWat_flow_nominal)
"Heating water return temperature";
Fluid.Sensors.TemperatureTwoPort senTChiWatRet(
redeclare final package Medium = MediumBui,
final allowFlowReversal=allowFlowReversalBui,
final m_flow_nominal=mChiWat_flow_nominal)
"Chilled water return temperature";
Buildings.Controls.OBC.CDL.Continuous.Add delT(final k2=-1) if have_hotWat
"Compute DeltaT needed on condenser side";
Fluid.Sensors.MassFlowRate senMasFloHeaWatPri(redeclare final package Medium =
MediumBui, final allowFlowReversal=allowFlowReversalBui)
"Primary heating water mass flow rate";
Buildings.Controls.OBC.CDL.Logical.TrueFalseHold enaSHW(trueHoldDuration=15*
60) if have_hotWat "Enable SHW production";
Modelica.Blocks.Sources.Constant zer1(k=0) if not have_hotWat
"Replacement variable";
Buildings.Controls.OBC.CDL.Continuous.Add masFloHea
"Service water mass flow rate for heating applications";
Buildings.Controls.OBC.CDL.Continuous.MultiSum PHeaTot(final nin=2)
"Total power used for heating and hot water production";
Buildings.Controls.OBC.CDL.Continuous.Add heaFloEvaSHW if have_hotWat and have_varFloEva
"Heat flow rate at evaporator";
Buildings.Controls.OBC.CDL.Continuous.Add dTHHW(k2=-1) if have_hotWat and have_varFloEva
"Heating hot water DeltaT";
Buildings.Controls.OBC.CDL.Continuous.Gain capFloHHW(
final k=cpBui_default) if have_varFloEva or have_varFloCon
"Capacity flow rate";
Buildings.Controls.OBC.CDL.Continuous.Add heaFloEvaHHW if have_varFloEva
"Heat flow rate at evaporator";
Controls.PrimaryVariableFlow conFloEvaSHW(
final Q_flow_nominal=-QHotWat_flow_nominal*(1 + 1/COPHotWat_nominal),
final dT_nominal=-dT_nominal,
final ratFloMin=ratFloMin,
final cp=cpSer_default) if have_hotWat and have_varFloEva
"Mass flow rate control";
Controls.PrimaryVariableFlow conFloConHHW(
final Q_flow_nominal=QHeaWat_flow_nominal,
final dT_nominal=dT_nominal,
final ratFloMin=ratFloMin,
final cp=cpBui_default) if have_varFloCon
"Mass flow rate control";
Controls.PrimaryVariableFlow conFloEvaHHW(
final Q_flow_nominal=-QHeaWat_flow_nominal*(1 + 1/COPHeaWat_nominal),
final dT_nominal=-dT_nominal,
final ratFloMin=ratFloMin,
final cp=cpSer_default) if have_varFloEva
"Mass flow rate control";
Buildings.Controls.OBC.CDL.Continuous.Max priOve "Ensure primary overflow";
Buildings.Controls.OBC.CDL.Continuous.Product loaHHW "Heating load";
equation
connect(TChiWatSupSet, conTChiWat.u_s);
connect(pum1HexChi.P, PPumCooTot.u[1]);
connect(PPumHeaTot.y, PPumTot.u[1]);
connect(PPumCooTot.y, PPumTot.u[2]);
connect(pum1HexChi.port_b, hexChi.port_a1);
connect(pum1HexChi.m_flow_actual, mCoo_flow);
connect(volMix_a.ports[1], swiFlo.port_bSup);
connect(swiFlo.port_aRet, volMix_b.ports[1]);
connect(volMix_b.ports[2], pum1HexChi.port_a);
connect(hexChi.port_b1, volMix_a.ports[2]);
connect(pum1HexChi.m_flow_actual, swiFlo.mRev_flow);
connect(gai2.y, pum1HexChi.m_flow_in);
connect(PPumTot.y, PPum);
connect(ports_aHeaWat[1], senMasFloHeaWat.port_a);
connect(bypHeaWatSup.port_2, senTHeaWatSup.port_a);
connect(senTHeaWatSup.port_b, ports_bHeaWat[1]);
connect(bypHeaWatRet.port_2, volHeaWatRet.ports[1]);
connect(bouHeaWat.ports[1], volHeaWatRet.ports[2]);
connect(ports_aChiWat[1], senMasFloChiWat.port_a);
connect(senTChiWatSup.port_b, ports_bChiWat[1]);
connect(bypHeaWatRet.port_3, bypHeaWatSup.port_3);
connect(volHeaWatRet.ports[3], proHeaWat.port_a1);
connect(proHeaWat.port_b2, volMix_b.ports[3]);
connect(volMix_a.ports[3], proHeaWat.port_a2);
connect(enaHea.y, proHeaWat.uEna);
connect(THeaWatSupSet, proHeaWat.TSupSet);
connect(proHeaWat.PPum, PPumHeaTot.u[1]);
connect(volMix_a.ports[4], proHotWat.port_a2);
connect(proHotWat.port_b2, volMix_b.ports[4]);
connect(THotWatSupSet, proHotWat.TSupSet);
connect(sinSHW.ports[1], proHotWat.port_b1);
connect(TColWat, souColWat.T_in);
connect(gai.y, div1.u2);
connect(loaSHW, div1.u1);
connect(masFloHeaTot.y, mHea_flow);
connect(proHotWat.mEva_flow, masFloHeaTot.u[2]);
connect(zer.y, masFloHeaTot.u[2]);
connect(proHotWat.PPum, PPumHeaTot.u[2]);
connect(proHeaWat.mEva_flow, masFloHeaTot.u[1]);
connect(zer.y, PPumHeaTot.u[2]);
connect(senMasFloHeaWat.port_b, senTHeaWatRet.port_a);
connect(senTHeaWatRet.port_b, bypHeaWatRet.port_1);
connect(senMasFloChiWat.port_b, senTChiWatRet.port_a);
connect(souColWat.ports[1], proHotWat.port_a1);
connect(delT.y, gai.u);
connect(TColWat, delT.u2);
connect(THotWatSupSet, delT.u1);
connect(proHeaWat.port_b1, senMasFloHeaWatPri.port_a);
connect(senMasFloHeaWatPri.port_b, bypHeaWatSup.port_1);
connect(port_aSerAmb, swiFlo.port_aSup);
connect(swiFlo.port_bRet, port_bSerAmb);
connect(uHea, enaHea.u);
connect(conTChiWat.y, gai2.u);
connect(uCoo, conTChiWat.uEna);
connect(uSHW, enaSHW.u);
connect(enaSHW.y, proHotWat.uEna);
connect(div1.y, souColWat.m_flow_in);
connect(senTChiWatRet.port_b, volChiWat.ports[1]);
connect(volChiWat.ports[2], hexChi.port_a2);
connect(hexChi.port_b2, senTChiWatSup.port_a);
connect(bouChiWat.ports[1], volChiWat.ports[3]);
connect(senTChiWatSup.T, conTChiWat.u_m);
connect(zer1.y, masFloHea.u2);
connect(proHotWat.mEva_flow, masFloHea.u2);
connect(proHeaWat.mEva_flow, masFloHea.u1);
connect(masFloHea.y, swiFlo.mPos_flow);
connect(proHeaWat.PHea, PHeaTot.u[1]);
connect(proHotWat.PHea, PHeaTot.u[2]);
connect(zer.y, PHeaTot.u[2]);
connect(PHeaTot.y, PHea);
connect(loaSHW, heaFloEvaSHW.u1);
connect(proHotWat.PHea, heaFloEvaSHW.u2);
connect(senTHeaWatRet.T, dTHHW.u2);
connect(senTHeaWatSup.T, dTHHW.u1);
connect(senMasFloHeaWat.m_flow, capFloHHW.u);
connect(proHeaWat.PHea, heaFloEvaHHW.u2);
connect(conFloEvaSHW.m_flow, proHotWat.m2_flow);
connect(conFloEvaHHW.m_flow, proHeaWat.m2_flow);
connect(senMasFloHeaWat.m_flow, priOve.u1);
connect(conFloConHHW.m_flow, priOve.u2);
connect(priOve.y, proHeaWat.m1_flow);
connect(heaFloEvaSHW.y, conFloEvaSHW.loa);
connect(heaFloEvaHHW.y, conFloEvaHHW.loa);
connect(capFloHHW.y, loaHHW.u2);
connect(dTHHW.y, loaHHW.u1);
connect(loaHHW.y, conFloConHHW.loa);
connect(loaHHW.y, heaFloEvaHHW.u1);
end HeatPumpHeatExchanger;