Buildings.Experimental.DHC.EnergyTransferStations.Heating

This package contains models for energy transfer stations used in district heating systems

Information

This package contains models for energy transfer stations used in district heating systems.

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name Description
Buildings.Experimental.DHC.EnergyTransferStations.Heating.Direct Direct Direct cooling ETS model for district energy systems with in-building pumping and deltaT control
Buildings.Experimental.DHC.EnergyTransferStations.Heating.Indirect Indirect Indirect cooling energy transfer station for district energy systems
Buildings.Experimental.DHC.EnergyTransferStations.Heating.Examples Examples  

Buildings.Experimental.DHC.EnergyTransferStations.Heating.Direct Buildings.Experimental.DHC.EnergyTransferStations.Heating.Direct

Direct cooling ETS model for district energy systems with in-building pumping and deltaT control

Buildings.Experimental.DHC.EnergyTransferStations.Heating.Direct

Information

Direct cooling energy transfer station (ETS) model with in-building pumping and deltaT control. The design is based on a typical district cooling ETS described in ASHRAE's District Cooling Guide. As shown in the figure below, the district and building piping are hydronically coupled. The control valve ensures that the return temperature to the district cooling network is at or above the minimum specified value. This configuration naturally results in a fluctuating building supply tempearture.

DC ETS Direct

Reference

American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2019). Chapter 5: End User Interface. In District Cooling Guide, Second Edition and Owner's Guide for Buildings Served by District Cooling.

Extends from Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.PartialDirect (Partial direct ETS model for district energy systems with in-building pumping and deltaT control).

Parameters

TypeNameDefaultDescription
replaceable package MediumSerWaterService side medium
replaceable package MediumSerHea_aWaterService side medium at heating inlet
replaceable package MediumBuiWaterBuilding side medium
Genericfue[nFue] Fuel type
Configuration
DistrictSystemTypetypDHC.Types.DistrictSystemType...Type of district system
Booleanhave_heaWattrueSet to true if the ETS supplies heating water
Booleanhave_chiWatfalseSet to true if the ETS supplies chilled water
Nominal condition
HeatFlowRateQHeaWat_flow_nominal0Nominal capacity of heating system (>=0) [W]
HeatFlowRateQHotWat_flow_nominal0Nominal capacity of hot water production system (>=0) [W]
HeatFlowRateQChiWat_flow_nominal0Nominal capacity of cooling system (<=0) [W]
MassFlowRatemBui_flow_nominal Nominal mass flow rate of building side [kg/s]
PressureDifferencedpConVal_nominal50Nominal pressure drop in the control valve [Pa]
PressureDifferencedpCheVal_nominal6000Nominal pressure drop in the check valve [Pa]
PID controller
SimpleControllercontrollerTypeModelica.Blocks.Types.Simple...Type of controller
Realk0.1Gain of controller [1]
TimeTi60Time constant of integrator block [s]
TimeTd0.1Time constant of derivative block [s]
RealyMax1Upper limit of output
RealyMin0Lower limit of output
Assumptions
BooleanallowFlowReversalSerfalseSet to true to allow flow reversal on service side
BooleanallowFlowReversalBuifalseSet to true to allow flow reversal on building side
Advanced
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
Realbandwidth0.2Bandwidth around reference signal for on/off controller

Connectors

TypeNameDescription
FluidPorts_aports_aHeaWat[nPorts_aHeaWat]Fluid connectors for heating water return (from building)
FluidPorts_bports_bHeaWat[nPorts_bHeaWat]Fluid connectors for heating water supply (to building)
FluidPorts_aports_aChiWat[nPorts_aChiWat]Fluid connectors for chilled water return (from building)
FluidPorts_bports_bChiWat[nPorts_bChiWat]Fluid connectors for chilled water supply (to building)
FluidPort_aport_aSerAmbFluid connector for ambient water service supply line
FluidPort_bport_bSerAmbFluid connector for ambient water service return line
FluidPort_aport_aSerHeaFluid connector for heating service supply line
FluidPort_bport_bSerHeaFluid connector for heating service return line
FluidPort_aport_aSerCooFluid connector for cooling service supply line
FluidPort_bport_bSerCooFluid connector for cooling service return line
output RealOutputPHeaPower drawn by heating system [W]
output RealOutputPCooPower drawn by cooling system [W]
output RealOutputPFanPower drawn by fan motors [W]
output RealOutputPPumPower drawn by pump motors [W]
output RealOutputQFue_flow[nFue]Fuel energy input rate [W]
BusweaBusWeather data bus
input RealInputTSetDisRetSetpoint for the district return temperature (min for cooling, max for heating) [K]
output RealOutputQ_flowMeasured heating demand at the ETS [W]
output RealOutputQMeasured energy consumption at the ETS [J]

Modelica definition

model Direct "Direct cooling ETS model for district energy systems with in-building pumping and deltaT control" extends Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.PartialDirect ( final typ=DHC.Types.DistrictSystemType.HeatingGeneration2to4, final have_chiWat=false, final have_heaWat=true, nPorts_aHeaWat=1, nPorts_bHeaWat=1); equation connect(senTDisRet.port_b, port_bSerHea); connect(port_aSerHea, senTDisSup.port_a); connect(ports_aHeaWat[1], senTBuiRet.port_a); connect(senTBuiSup.port_b, ports_bHeaWat[1]); end Direct;

Buildings.Experimental.DHC.EnergyTransferStations.Heating.Indirect Buildings.Experimental.DHC.EnergyTransferStations.Heating.Indirect

Indirect cooling energy transfer station for district energy systems

Buildings.Experimental.DHC.EnergyTransferStations.Heating.Indirect

Information

Indirect cooling energy transfer station (ETS) model that controls the building chilled water supply temperature by modulating a primary control valve on the district supply side. The design is based on a typical district cooling ETS described in ASHRAE's District Cooling Guide. As shown in the figure below, the building pumping design (constant/variable) is specified on the building side and not within the ETS.

DHC.ETS.Indirect

Reference

American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2019). Chapter 5: End User Interface. In District Cooling Guide, Second Edition and Owner's Guide for Buildings Served by District Cooling.

Extends from Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.PartialIndirect (Partial indirect energy transfer station for district energy systems).

Parameters

TypeNameDefaultDescription
replaceable package MediumSerWaterService side medium
replaceable package MediumSerHea_aWaterService side medium at heating inlet
replaceable package MediumBuiWaterBuilding side medium
Genericfue[nFue] Fuel type
Configuration
DistrictSystemTypetypDHC.Types.DistrictSystemType...Type of district system
Booleanhave_heaWattrueSet to true if the ETS supplies heating water
Booleanhave_chiWatfalseSet to true if the ETS supplies chilled water
Nominal condition
HeatFlowRateQHeaWat_flow_nominalQ_flow_nominalNominal capacity of heating system (>=0) [W]
HeatFlowRateQHotWat_flow_nominal0Nominal capacity of hot water production system (>=0) [W]
HeatFlowRateQChiWat_flow_nominal0Nominal capacity of cooling system (<=0) [W]
MassFlowRatemDis_flow_nominal Nominal mass flow rate of district side [kg/s]
MassFlowRatemBui_flow_nominal Nominal mass flow rate of building side [kg/s]
PressureDifferencedpConVal_nominal6000Nominal pressure drop of fully open control valve [Pa]
Heat exchanger
PressureDifferencedp1_nominal Nominal pressure difference on primary side [Pa]
PressureDifferencedp2_nominal Nominal pressure difference on secondary side [Pa]
Booleanuse_Q_flow_nominaltrueSet to true to specify Q_flow_nominal and temeratures, or to false to specify effectiveness
TemperatureT_a1_nominal Nominal temperature at port a1 (district supply) [K]
TemperatureT_a2_nominal Nominal temperature at port a2 (building return) [K]
Efficiencyeta0.8Constant effectiveness [1]
PID controller
SimpleControllercontrollerTypeModelica.Blocks.Types.Simple...Type of controller
Realk1Gain of controller [1]
TimeTi120Time constant of integrator block [s]
TimeTd0.1Time constant of derivative block [s]
RealyMax1Upper limit of output
RealyMin0.01Lower limit of output
Assumptions
BooleanallowFlowReversalSerfalseSet to true to allow flow reversal on service side
BooleanallowFlowReversalBuifalseSet to true to allow flow reversal on building side

Connectors

TypeNameDescription
FluidPorts_aports_aHeaWat[nPorts_aHeaWat]Fluid connectors for heating water return (from building)
FluidPorts_bports_bHeaWat[nPorts_bHeaWat]Fluid connectors for heating water supply (to building)
FluidPorts_aports_aChiWat[nPorts_aChiWat]Fluid connectors for chilled water return (from building)
FluidPorts_bports_bChiWat[nPorts_bChiWat]Fluid connectors for chilled water supply (to building)
FluidPort_aport_aSerAmbFluid connector for ambient water service supply line
FluidPort_bport_bSerAmbFluid connector for ambient water service return line
FluidPort_aport_aSerHeaFluid connector for heating service supply line
FluidPort_bport_bSerHeaFluid connector for heating service return line
FluidPort_aport_aSerCooFluid connector for cooling service supply line
FluidPort_bport_bSerCooFluid connector for cooling service return line
output RealOutputPHeaPower drawn by heating system [W]
output RealOutputPCooPower drawn by cooling system [W]
output RealOutputPFanPower drawn by fan motors [W]
output RealOutputPPumPower drawn by pump motors [W]
output RealOutputQFue_flow[nFue]Fuel energy input rate [W]
BusweaBusWeather data bus
input RealInputTSetBuiSupSetpoint temperature for building supply
output RealOutputQ_flowMeasured heating demand at the ETS [W]
output RealOutputQMeasured energy consumption at the ETS [J]

Modelica definition

model Indirect "Indirect cooling energy transfer station for district energy systems" extends Buildings.Experimental.DHC.EnergyTransferStations.BaseClasses.PartialIndirect ( QHeaWat_flow_nominal=Q_flow_nominal, final typ=DHC.Types.DistrictSystemType.HeatingGeneration2to4, final have_chiWat=false, final have_heaWat=true, Q_flow_nominal(min=0), nPorts_aHeaWat=1, nPorts_bHeaWat=1); equation connect(ports_aHeaWat[1], senTBuiRet.port_a); connect(port_aSerHea, senTDisSup.port_a); connect(senTBuiSup.port_b, ports_bHeaWat[1]); connect(senTDisRet.port_b, port_bSerHea); end Indirect;