Buildings.DHC.ETS.Combined
Package of models for DHC energy transfer stations
Information
This package contains models for energy transfer stations used in 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 for heating, heat pump for domestic hot water, and compressor-less cooling |
 HeatPumpHeatExchangerDHWTank
|
Model of a substation with heat pump for heating, heat pump with storage tank for domestic hot water, 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.DHC.ETS.Combined.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.DHC.ETS.Combined.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.DHC.ETS.Combined.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.DHC.ETS.Combined.Controls.Reset.
Extends from Buildings.DHC.ETS.Combined.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 | Buildings.DHC.ETS.Types.Conn... | 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 |
| Boolean | have_WSE | false | Set to true in case a waterside economizer is used |
| 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] | |
| Real | spePum1HexMin | 0.1 | Heat exchanger primary pump minimum speed (fractional) [1] |
| Real | spePum2HexMin | 0.1 | Heat exchanger secondary pump minimum speed (fractional) [1] |
| 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 |
| Chiller | chi | chi(redeclare final package ... | Chiller |
| Waterside economizer | |||
| PressureDifference | dp1WSE_nominal | 40E3 | Nominal pressure drop across heat exchanger on district side [Pa] |
| PressureDifference | dp2WSE_nominal | 40E3 | Nominal pressure drop across heat exchanger on building side [Pa] |
| HeatFlowRate | QWSE_flow_nominal | 0 | Nominal heat flow rate through heat exchanger (<=0) [W] |
| Temperature | T_a1WSE_nominal | 279.15 | Nominal water inlet temperature on district side [K] |
| Temperature | T_b1WSE_nominal | 284.15 | Nominal water outlet temperature on district side [K] |
| Temperature | T_a2WSE_nominal | 288.15 | Nominal water inlet temperature on building side [K] |
| Temperature | T_b2WSE_nominal | 281.15 | Nominal water outlet temperature on building side [K] |
| Real | y1WSEMin | 0.05 | Minimum pump flow rate or valve opening for temperature measurement (fractional) [1] |
| 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 |
| 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 Buildings.DHC.ETS.Combined.BaseClasses.PartialParallel(
final have_eleCoo=true,
final have_fan=false,
redeclare replaceable Buildings.DHC.ETS.Combined.Controls.Supervisory conSup
constrainedby Buildings.DHC.ETS.Combined.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,
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),
nPorts_bChiWat=1,
nPorts_aHeaWat=1,
nPorts_aChiWat=1,
nPorts_bHeaWat=1);
parameter Boolean have_borFie=false
"Set to true in case a borefield is used in addition of the district HX";
parameter Boolean have_WSE=false
"Set to true in case a waterside economizer is used";
parameter Modelica.Units.SI.PressureDifference dpCon_nominal(displayUnit="Pa")
"Nominal pressure drop accross condenser";
parameter Modelica.Units.SI.PressureDifference dpEva_nominal(displayUnit="Pa")
"Nominal pressure drop accross evaporator";
replaceable parameter Fluid.Chillers.Data.ElectricEIR.Generic datChi
"Chiller performance data";
parameter Modelica.Units.SI.PressureDifference dp1WSE_nominal(displayUnit=
"Pa") = 40E3
"Nominal pressure drop across heat exchanger on district side";
parameter Modelica.Units.SI.PressureDifference dp2WSE_nominal(displayUnit=
"Pa") = 40E3
"Nominal pressure drop across heat exchanger on building side";
parameter Modelica.Units.SI.HeatFlowRate QWSE_flow_nominal=0
"Nominal heat flow rate through heat exchanger (<=0)";
parameter Modelica.Units.SI.Temperature T_a1WSE_nominal=279.15
"Nominal water inlet temperature on district side";
parameter Modelica.Units.SI.Temperature T_b1WSE_nominal=284.15
"Nominal water outlet temperature on district side";
parameter Modelica.Units.SI.Temperature T_a2WSE_nominal=288.15
"Nominal water inlet temperature on building side";
parameter Modelica.Units.SI.Temperature T_b2WSE_nominal=281.15
"Nominal water outlet temperature on building side";
parameter Real y1WSEMin(unit="1")=0.05
"Minimum pump flow rate or valve opening for temperature measurement (fractional)";
final parameter Modelica.Units.SI.MassFlowRate m1WSE_flow_nominal=abs(
QWSE_flow_nominal/4200/(T_b1WSE_nominal - T_a1WSE_nominal))
"WSE primary mass flow rate";
parameter Modelica.Units.SI.Temperature TBorWatEntMax=313.15
"Maximum value of borefield water entering temperature";
parameter Real spePumBorMin(unit="1")=0.1
"Borefield pump minimum speed";
parameter Modelica.Units.SI.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";
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.Units.SI.Time TiHot(min=Buildings.Controls.OBC.CDL.Constants.small)
= 300 "Time constant of integrator block on hot side";
parameter Modelica.Units.SI.Time TiCol(min=Buildings.Controls.OBC.CDL.Constants.small)
= 120 "Time constant of integrator block on cold side";
parameter Modelica.Units.SI.Temperature THeaWatSupSetMin(displayUnit="degC")
= datChi.TConEntMin + 5
"Minimum value of heating water supply temperature set point";
parameter Modelica.Units.SI.Temperature TChiWatSupSetMin(displayUnit="degC")
= datChi.TEvaLvgMin
"Minimum value of chilled water supply temperature set point";
replaceable Buildings.DHC.ETS.Combined.Subsystems.Chiller
chi(
redeclare final package Medium = MediumBui,
final dpCon_nominal=dpCon_nominal,
final dpEva_nominal=dpEva_nominal,
final dat=datChi) "Chiller";
replaceable Buildings.DHC.ETS.Combined.Subsystems.Borefield
borFie(
redeclare final package Medium = MediumBui,
final datBorFie=datBorFie,
final TBorWatEntMax=TBorWatEntMax,
final spePumBorMin=spePumBorMin,
final dp_nominal=dpBorFie_nominal) if have_borFie "Borefield";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant zerPPum(
final k=0) if not have_borFie
"Zero power";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant zerPHea(
final k=0)
"Zero power";
Buildings.DHC.Networks.BaseClasses.DifferenceEnthalpyFlowRate dHFloHeaWat(
redeclare final package Medium1 = MediumBui,
final m_flow_nominal=colHeaWat.mDis_flow_nominal)
"Variation of enthalpy flow rate";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput dHHeaWat_flow(final unit="W")
"Heating water distributed energy flow rate";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput dHChiWat_flow(final unit="W")
"Chilled water distributed energy flow rate";
Buildings.DHC.Networks.BaseClasses.DifferenceEnthalpyFlowRate dHFloChiWat(
redeclare final package Medium1 = MediumBui,
final m_flow_nominal=colChiWat.mDis_flow_nominal)
"Variation of enthalpy flow rate";
Buildings.DHC.ETS.Combined.Subsystems.WatersideEconomizer
WSE(
redeclare final package Medium1 = MediumSer,
redeclare final package Medium2 = MediumBui,
final allowFlowReversal1=allowFlowReversalSer,
final allowFlowReversal2=allowFlowReversalBui,
final conCon=conCon,
final dp1Hex_nominal=dp1WSE_nominal,
final dp2Hex_nominal=dp2WSE_nominal,
final Q_flow_nominal=QWSE_flow_nominal,
final T_a1_nominal=T_a1WSE_nominal,
final T_b1_nominal=T_b1WSE_nominal,
final T_a2_nominal=T_a2WSE_nominal,
final T_b2_nominal=T_b2WSE_nominal,
final y1Min=y1WSEMin) if have_WSE "Waterside economizer";
Buildings.DHC.ETS.BaseClasses.Junction splWSE(
redeclare final package Medium = MediumSer,
final m_flow_nominal={
hex.m1_flow_nominal + m1WSE_flow_nominal,
-hex.m1_flow_nominal,
-m1WSE_flow_nominal})
"Flow splitter for WSE";
Buildings.DHC.ETS.BaseClasses.Junction mixWSE(
redeclare final package Medium = MediumSer,
final m_flow_nominal={
hex.m1_flow_nominal,
-hex.m1_flow_nominal - m1WSE_flow_nominal,
m1WSE_flow_nominal})
"Flow mixer for WSE";
equation
if not have_WSE then
connect(tanChiWat.port_aTop, dHFloChiWat.port_b2);
end if;
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);
connect(dHFloHeaWat.dH_flow,dHHeaWat_flow);
connect(dHFloChiWat.dH_flow,dHChiWat_flow);
connect(dHFloChiWat.port_a1, tanChiWat.port_bBot);
connect(dHFloChiWat.port_b1, ports_bChiWat[1]);
connect(tanHeaWat.port_bTop, dHFloHeaWat.port_a1);
connect(tanHeaWat.port_aBot, dHFloHeaWat.port_b2);
connect(dHFloHeaWat.port_a2, ports_aHeaWat[1]);
connect(ports_aChiWat[1], dHFloChiWat.port_a2);
connect(dHFloHeaWat.port_b1, ports_bHeaWat[1]);
connect(splWSE.port_2, hex.port_a1);
connect(dHFloChiWat.port_b2, WSE.port_a2);
connect(WSE.port_b2, tanChiWat.port_aTop);
connect(mixWSE.port_2, port_bSerAmb);
connect(splWSE.port_3, WSE.port_a1);
connect(WSE.port_b1, mixWSE.port_3);
connect(hex.port_b1, mixWSE.port_1);
connect(conSup.yCoo, WSE.uCoo);
connect(valIsoEva.y_actual, WSE.yValIsoEva_actual);
connect(port_aSerAmb, splWSE.port_1);
end ChillerBorefield;
Buildings.DHC.ETS.Combined.HeatPumpHeatExchanger
Model of a substation with heat pump for heating, heat pump for domestic hot water, and compressor-less cooling
Information
This model uses the base energy transfer station defined in Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger.
Domestic Hot Water
Domestic hot water is produced using a dedicated water-to-water heat pump on-demand with no storage.
Heating is enabled based on the input signal uSHW
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 enable signal should be computed externally based
on a schedule (to lock out the system during off-hours), ideally in conjunction
with the number of requests or any other signal representative of the load.
When enabled,
- The heat pump and the evaporator and condenser hydronics are controlled based on the principles described in Buildings.DHC.ETS.Combined.Subsystems.HeatPump.
-
The condensor water mass flow rate is computed based on the domestic hot water
heating load (input
QReqHotWat_flow) where the temperature of water is boosted from the domestic cold water temperature (inputTColWat) to the desired domestic hot water distribution temperature (parameterTHotWatSup_nominal), according to the following equation:QReqHotWat_flow= ṁ cp (THotWatSup_nominal-TColWat)
Extends from Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger (Partial model of a substation with heat pump and compressor-less cooling).
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 mass flow rate (ratio to nominal) [1] |
| Configuration | |||
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| 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 | Domestic hot water supply temperature to fixtures [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 | Domestic hot water temperature set point for supply to fixtures [K] |
| input RealInput | TColWat | Cold water temperature [K] |
| input RealInput | QReqHotWat_flow | 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 for heating, heat pump for domestic hot water, and compressor-less cooling"
extends Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger(
volMix_a(nPorts=4),
volMix_b(nPorts=4));
Buildings.DHC.ETS.Combined.Subsystems.HeatPump proHotWat(
redeclare final package Medium1 = MediumBui,
redeclare final package Medium2 = MediumSer,
final COP_nominal=COPHotWat_nominal,
final TCon_nominal=THotWatSup_nominal,
final TEva_nominal=TDisWatMin - dT_nominal,
dT_nominal=dT_nominal,
final Q1_flow_nominal=QHotWat_flow_nominal,
final allowFlowReversal1=allowFlowReversalBui,
final allowFlowReversal2=allowFlowReversalSer,
final dp1_nominal=dp_nominal,
final dp2_nominal=dp_nominal) if have_hotWat
"Subsystem for hot water production";
Buildings.Fluid.Sources.Boundary_pT souColWat(
redeclare final package Medium = MediumBui,
use_T_in=true,
nPorts=1) if have_hotWat
"Source for cold water";
Buildings.Fluid.Sources.Boundary_pT sinSHW(redeclare final package Medium = MediumBui,
nPorts=1)
if have_hotWat
"Sink for service hot water";
Buildings.Controls.OBC.CDL.Reals.Divide div1 if have_hotWat
"Compute mass flow rate from load";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai(final k=
cpBui_default) if have_hotWat "Times Cp";
Buildings.Controls.OBC.CDL.Reals.Subtract delT if have_hotWat
"Compute DeltaT needed on condenser side";
equation
connect(souColWat.ports[1], proHotWat.port_a1);
connect(sinSHW.ports[1], proHotWat.port_b1);
connect(THotWatSupSet, proHotWat.TSupSet);
connect(enaSHW.y, proHotWat.uEna);
connect(proHotWat.PPum, PPumHeaTot.u[2]);
connect(proHotWat.mEva_flow, masFloHeaTot.u[2]);
connect(proHotWat.mEva_flow, masFloHea.u2);
connect(proHotWat.PHea, PHeaTot.u[2]);
connect(TColWat, souColWat.T_in);
connect(proHotWat.port_a2, volMix_a.ports[4]);
connect(proHotWat.port_b2, volMix_b.ports[4]);
connect(gai.y,div1. u2);
connect(QReqHotWat_flow,div1. u1);
connect(delT.y,gai. u);
connect(TColWat,delT. u2);
connect(THotWatSupSet,delT. u1);
connect(div1.y, proHotWat.m1_flow);
end HeatPumpHeatExchanger;
Buildings.DHC.ETS.Combined.HeatPumpHeatExchangerDHWTank
Model of a substation with heat pump for heating, heat pump with storage tank for domestic hot water, and compressor-less cooling
Information
This model uses the base energy transfer station defined in Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger.
Domestic Hot Water
Domestic hot water is produced using a dedicated water-to-water heat pump with storage tank.
Heating is enabled based on the input signal uSHW
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 enable signal should be computed externally based
on a schedule (to lock out the system during off-hours), ideally in conjunction
with the number of requests or any other signal representative of the load.
When enabled,
- The heat pump and the evaporator and condenser hydronics are controlled based on the principles described in Buildings.DHC.ETS.Combined.Subsystems.HeatPumpDHWTank.
-
The mass flow rate of water leaving the domestic hot water heat exchanger is computed based on the domestic hot water
heating load (input
QReqHotWat_flow) combined with the operation of a thermostatic mixing valve used to mix down the temperature of hot water leaving the domestic hot water heat exchanger to the temperature distributed to fixtures (parameterTHotWatSup_nominal) using domestic cold water at the cold water temperature (inputTColWat). The desired water flow rate leaving the thermostatic mixing valve is determined according to the following equation:QReqHotWat_flow= ṁ cp (THotWatSup_nominal-TColWat)
Extends from Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger (Partial model of a substation with heat pump and compressor-less cooling).
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 mass flow rate (ratio to nominal) [1] |
| GenericDomesticHotWaterWithHeatExchanger | datWatHea | Performance data | |
| Configuration | |||
| Boolean | have_hotWat | false | Set to true if the ETS supplies hot water |
| 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 | Domestic hot water supply temperature to fixtures [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 | Domestic hot water temperature set point for supply to fixtures [K] |
| input RealInput | TColWat | Cold water temperature [K] |
| input RealInput | QReqHotWat_flow | 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 HeatPumpHeatExchangerDHWTank
"Model of a substation with heat pump for heating, heat pump with storage tank for domestic hot water, and compressor-less cooling"
extends Buildings.DHC.ETS.Combined.BaseClasses.PartialHeatPumpHeatExchanger(
volMix_b(nPorts=4),
volMix_a(nPorts=4));
Buildings.Fluid.Sources.Boundary_pT souDCW(
redeclare final package Medium = MediumBui,
use_T_in=true,
nPorts=1) if have_hotWat "Source for domestic cold water";
Buildings.DHC.ETS.Combined.Subsystems.HeatPumpDHWTank proHotWat(
redeclare final package Medium1 = MediumBui,
redeclare final package Medium2 = MediumSer,
final COP_nominal=COPHotWat_nominal,
TCon_nominal=THotWatSup_nominal,
TEva_nominal=TDisWatMin - dT_nominal,
QHotWat_flow_nominal=QHotWat_flow_nominal,
dT_nominal=dT_nominal,
final allowFlowReversal1=allowFlowReversalBui,
final allowFlowReversal2=allowFlowReversalSer,
dp1_nominal=6000,
dp2_nominal=6000,
datWatHea=datWatHea) if have_hotWat
"Subsystem for hot water production";
parameter Buildings.DHC.Loads.HotWater.Data.GenericDomesticHotWaterWithHeatExchanger
datWatHea "Performance data";
Buildings.DHC.Loads.HotWater.ThermostaticMixingValve theMixVal(
redeclare package Medium = MediumBui,
mMix_flow_nominal=QHotWat_flow_nominal/cpBui_default/(THotWatSup_nominal - TColWat_nominal))
if have_hotWat
"Thermostatic mixing valve";
Buildings.DHC.ETS.BaseClasses.Junction dcwSpl(
redeclare final package Medium = MediumBui, final m_flow_nominal=
datWatHea.mDom_flow_nominal*{1,-1,-1})
"Splitter for domestic cold water";
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai(
k=1/QHotWat_flow_nominal) if have_hotWat;
equation
connect(proHotWat.port_b2, volMix_b.ports[4]);
connect(proHotWat.PHea, PHeaTot.u[2]);
connect(proHotWat.PPum, PPumHeaTot.u[2]);
connect(proHotWat.mEva_flow, masFloHeaTot.u[2]);
connect(proHotWat.mEva_flow, masFloHea.u2);
connect(proHotWat.port_a2, volMix_a.ports[4]);
connect(souDCW.ports[1], dcwSpl.port_1);
connect(dcwSpl.port_3, proHotWat.port_a1);
connect(dcwSpl.port_2, theMixVal.port_col);
connect(proHotWat.port_b1, theMixVal.port_hot);
connect(souDCW.T_in, TColWat);
connect(THotWatSupSet, theMixVal.TMixSet);
connect(QReqHotWat_flow, gai.u);
connect(gai.y, theMixVal.yMixSet);
connect(enaSHW.y, proHotWat.uEna);
end HeatPumpHeatExchangerDHWTank;