Buildings.Experimental.DHC.EnergyTransferStations.Combined.BaseClasses

Package with base classes

Information

This package contains base classes that are used to construct the classes in Buildings.Experimental.DHC.EnergyTransferStations.Combined.

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Package Content

Name	Description
PartialParallel	Partial ETS model with district heat exchanger and parallel connection of production systems

Buildings.Experimental.DHC.EnergyTransferStations.Combined.BaseClasses.PartialParallel

Partial ETS model with district heat exchanger and parallel connection of production systems

Buildings.Experimental.DHC.EnergyTransferStations.Combined.BaseClasses.PartialParallel

Information

This is a base model providing the hydronic configuration for an energy transfer station as described in the schematics below. It is typically used to integrate systems providing both heating water and chilled water, such as heat recovery chillers. Furthermore, it can be connected to an adjustable number (nSouAmb) of systems serving as ambient sources (including the district heat exchanger).

The connection to the district loop is realized with a heat exchanger, according to the operating principles described in Buildings.Experimental.DHC.EnergyTransferStations.Combined.Subsystems.HeatExchanger.
The connection of the heating water and chilled water production systems to the systems serving as ambient sources is realized in parallel.
A replaceable partial class is used to represent a supervisory controller, which must be replaced by a control block providing at least the control signals listed in Buildings.Experimental.DHC.EnergyTransferStations.Combined.Controls.BaseClasses.PartialSupervisory.

Models that extend this base class must

specify the number of systems serving as ambient sources nSouAmb, the number of heating water production systems nSysHea, and the number of chilled water production systems nSysCoo (by default nSysCoo=nSysHea which corresponds to a configuration where both productions are ensured by the same system, such as a heat recovery chiller),
modify the parameter binding with the nominal mass flow rate of each connection to each collector/distributor model, namely the parameter mCon_flow_nominal (array) of the components colChiWat, colHeaWat and colAmbWat. The connection index 1 for the components colChiWat and colHeaWat is reserved for the connection with the ambient source circuit. It increases with the distance from the buffer tank. The connection index 1 for the component colAmbWat is reserved for the connection with the district heat exchanger. Note that the order of the connections has no impact on the flow distribution as the connections are in parallel.

Note that the model includes a pressure boundary condition which is shared between the hot water and chilled water circuits, the two circuits being hydronically connected.

Sequence chart

Extends from Buildings.Experimental.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
ConnectionConfiguration	conCon	Buildings.Experimental.DHC.E...	District connection configuration
Integer	nSysHea		Number of heating systems
Integer	nSysCoo	nSysHea	Number of cooling systems
Integer	nSouAmb	1	Number of ambient sources
PartialSupervisory	conSup	redeclare Buildings.Experime...	Supervisory controller
Configuration
DistrictSystemType	typ	Buildings.Experimental.DHC.T...	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	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	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]
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]
Generic	perPum1Hex	perPum1Hex(motorCooledByFlui...	Record with performance data for primary pump
Generic	perPum2Hex	perPum2Hex(motorCooledByFlui...	Record with performance data for secondary pump
Buffer Tank
Volume	VTanHeaWat		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		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
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]

Modelica definition

model PartialParallel "Partial ETS model with district heat exchanger and parallel connection of production systems" extends Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.PartialETS ( final typ=Buildings.Experimental.DHC.Types.DistrictSystemType.CombinedGeneration5, final have_heaWat=true, final have_chiWat=true, final have_pum=true, have_hotWat=false, have_eleHea=false, have_weaBus=false); parameter Buildings.Experimental.DHC.EnergyTransferStations.Types.ConnectionConfiguration conCon= Buildings.Experimental.DHC.EnergyTransferStations.Types.ConnectionConfiguration.Pump "District connection configuration"; parameter Integer nSysHea "Number of heating systems"; parameter Integer nSysCoo=nSysHea "Number of cooling systems"; parameter Integer nSouAmb=1 "Number of ambient sources"; parameter Modelica.Units.SI.PressureDifference dpValIso_nominal(displayUnit= "Pa") = 2E3 "Nominal pressure drop of ambient circuit isolation valves"; parameter Modelica.Units.SI.PressureDifference dp1Hex_nominal(displayUnit= "Pa") "Nominal pressure drop across heat exchanger on district side"; parameter Modelica.Units.SI.PressureDifference dp2Hex_nominal(displayUnit= "Pa") "Nominal pressure drop across heat exchanger on building side"; parameter Modelica.Units.SI.HeatFlowRate QHex_flow_nominal "Nominal heat flow rate through heat exchanger (from district to building)"; parameter Modelica.Units.SI.Temperature T_a1Hex_nominal "Nominal water inlet temperature on district side"; parameter Modelica.Units.SI.Temperature T_b1Hex_nominal "Nominal water outlet temperature on district side"; parameter Modelica.Units.SI.Temperature T_a2Hex_nominal "Nominal water inlet temperature on building side"; parameter Modelica.Units.SI.Temperature T_b2Hex_nominal "Nominal water outlet temperature on building side"; parameter Real spePum1HexMin( final unit="1", min=0)=0.1 "Heat exchanger primary pump minimum speed (fractional)"; parameter Real spePum2HexMin( final unit="1", min=0.01)=0.1 "Heat exchanger secondary pump minimum speed (fractional)"; replaceable parameter Buildings.Fluid.Movers.Data.Generic perPum1Hex( motorCooledByFluid=false) constrainedby Buildings.Fluid.Movers.Data.Generic "Record with performance data for primary pump"; replaceable parameter Buildings.Fluid.Movers.Data.Generic perPum2Hex( motorCooledByFluid=false) constrainedby Buildings.Fluid.Movers.Data.Generic "Record with performance data for secondary pump"; parameter Modelica.Units.SI.Volume VTanHeaWat "Heating water tank volume"; parameter Modelica.Units.SI.Length hTanHeaWat=(VTanHeaWat*16/Modelica.Constants.pi) ^(1/3) "Heating water tank height (assuming twice the diameter)"; parameter Modelica.Units.SI.Length dInsTanHeaWat=0.1 "Heating water tank insulation thickness"; parameter Modelica.Units.SI.Volume VTanChiWat "Chilled water tank volume"; parameter Modelica.Units.SI.Length hTanChiWat=(VTanChiWat*16/Modelica.Constants.pi) ^(1/3) "Chilled water tank height (without insulation)"; parameter Modelica.Units.SI.Length dInsTanChiWat=0.1 "Chilled water tank insulation thickness"; parameter Integer nSegTan=3 "Number of volume segments for tanks"; // IO VARIABLES Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uHea "Heating enable signal"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uCoo "Cooling 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 TChiWatSupSet( final unit="K", displayUnit="degC") "Chilled water supply temperature set point"; // COMPONENTS replaceable Buildings.Experimental.DHC.EnergyTransferStations.Combined.Controls.BaseClasses.PartialSupervisory conSup constrainedby Buildings.Experimental.DHC.EnergyTransferStations.Combined.Controls.BaseClasses.PartialSupervisory ( final nSouAmb=nSouAmb) "Supervisory controller"; Buildings.Fluid.Actuators.Valves.TwoWayLinear valIsoEva( redeclare final package Medium = MediumBui, final dpValve_nominal=dpValIso_nominal, final m_flow_nominal=colAmbWat.mDis_flow_nominal, use_inputFilter=false) "Evaporator to ambient loop isolation valve"; Buildings.Fluid.Actuators.Valves.TwoWayLinear valIsoCon( redeclare final package Medium = MediumBui, final dpValve_nominal=dpValIso_nominal, final m_flow_nominal=colAmbWat.mDis_flow_nominal, use_inputFilter=false) "Condenser to ambient loop isolation valve"; Buildings.Experimental.DHC.EnergyTransferStations.Combined.Subsystems.HeatExchanger hex( redeclare final package Medium1=MediumSer, redeclare final package Medium2=MediumBui, final perPum1=perPum1Hex, final perPum2=perPum2Hex, final allowFlowReversal1=allowFlowReversalSer, final allowFlowReversal2=allowFlowReversalBui, final conCon=conCon, final dp1Hex_nominal=dp1Hex_nominal, final dp2Hex_nominal=dp2Hex_nominal, final Q_flow_nominal=QHex_flow_nominal, final T_a1_nominal=T_a1Hex_nominal, final T_b1_nominal=T_b1Hex_nominal, final T_a2_nominal=T_a2Hex_nominal, final T_b2_nominal=T_b2Hex_nominal, final spePum1Min=spePum1HexMin, final spePum2Min=spePum2HexMin) "District heat exchanger"; Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.StratifiedTank tanChiWat( redeclare final package Medium = MediumBui, final m_flow_nominal=colChiWat.mDis_flow_nominal, final VTan=VTanChiWat, final hTan=hTanChiWat, final dIns=dInsTanChiWat, final nSeg=nSegTan) "Chilled water tank"; Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.StratifiedTank tanHeaWat( redeclare final package Medium = MediumBui, final m_flow_nominal=colHeaWat.mDis_flow_nominal, final VTan=VTanHeaWat, final hTan=hTanHeaWat, final dIns=dInsTanHeaWat, final nSeg=nSegTan) "Heating water tank"; Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.CollectorDistributor colChiWat( redeclare final package Medium = MediumBui, final nCon=1 + nSysCoo, mCon_flow_nominal={colAmbWat.mDis_flow_nominal}) "Collector/distributor for chilled water"; Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.CollectorDistributor colHeaWat( redeclare final package Medium = MediumBui, final nCon=1 + nSysHea, mCon_flow_nominal={colAmbWat.mDis_flow_nominal}) "Collector/distributor for heating water"; Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.CollectorDistributor colAmbWat( redeclare final package Medium = MediumBui, final nCon=nSouAmb, mCon_flow_nominal={hex.m2_flow_nominal}) "Collector/distributor for ambient water"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPPum( nin=1) "Total pump power"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPHea( nin=1) "Total power drawn by heating system"; Buildings.Controls.OBC.CDL.Reals.MultiSum totPCoo( nin=1) "Total power drawn by cooling system"; Buildings.Fluid.Sources.Boundary_pT bou(redeclare final package Medium = MediumBui, nPorts=1) "Pressure boundary condition representing expansion vessel (common to HHW and CHW)"; protected parameter Boolean have_val1Hex= conCon == DHC.EnergyTransferStations.Types.ConnectionConfiguration.TwoWayValve "True in case of control valve on district side, false in case of a pump"; equation connect(hex.PPum,totPPum.u[1]); connect(THeaWatSupSet,conSup.THeaWatSupPreSet); connect(tanHeaWat.TTop,conSup.THeaWatTop); connect(tanChiWat.TBot,conSup.TChiWatBot); connect(hex.port_b2,colAmbWat.ports_aCon[1]); connect(hex.port_a2,colAmbWat.ports_bCon[1]); connect(totPPum.y,PPum); connect(hex.yValIso_actual[1],valIsoCon.y_actual); connect(hex.yValIso_actual[2],valIsoEva.y_actual); connect(valIsoEva.port_b,colAmbWat.port_bDisSup); connect(valIsoCon.port_b,colAmbWat.port_aDisSup); connect(TChiWatSupSet,conSup.TChiWatSupPreSet); connect(uCoo,conSup.uCoo); connect(uHea,conSup.uHea); connect(valIsoEva.port_a,colChiWat.ports_aCon[1]); connect(colAmbWat.port_aDisRet,colChiWat.ports_bCon[1]); connect(conSup.yValIsoEva,valIsoEva.y); connect(conSup.yValIsoCon,valIsoCon.y); connect(conSup.yAmb[nSouAmb],hex.u); connect(colChiWat.port_bDisRet,tanChiWat.port_aBot); connect(colChiWat.port_aDisSup,tanChiWat.port_bTop); connect(colHeaWat.port_bDisRet,tanHeaWat.port_aTop); connect(tanHeaWat.port_bBot,colHeaWat.port_aDisSup); connect(valIsoCon.port_a,colHeaWat.ports_aCon[1]); connect(colAmbWat.port_bDisRet,colHeaWat.ports_bCon[1]); connect(totPHea.y,PHea); connect(totPCoo.y,PCoo); connect(bou.ports[1], colChiWat.port_aDisSup); end PartialParallel;