modelChillerWSEDesignConditionsGlycol

Validation model that tests the component configurations at design conditions

Extends from Buildings.Applications.DataCenters.LiquidCooled.Examples.ChillerWSE (Example model of a simple liquid cooled data center with chiller and water-side economizer).

Information

Validation model that simulates Buildings.Applications.DataCenters.LiquidCooled.Examples.ChillerWSE at design conditions.

This model verifies the design conditions if the system is designed for full economizer use, and the IT utilization is 100%.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.PowerPRac (from ChillerWSE)1E6Total rack design power
RealfraWSE (from ChillerWSE)0.6Fraction of peak load covered by water side economizer
RealfraChi (from ChillerWSE)1 - fraWSEFraction of peak load covered by chiller
Modelica.Units.SI.TemperatureDifferencedTRac_nominal (from ChillerWSE)-5Temperature difference rack loop
Modelica.Units.SI.TemperatureDifferencedTPla_nominal (from ChillerWSE)-5Temperature difference cooling plant loop
Modelica.Units.SI.TemperatureDifferencedTTow_nominal (from ChillerWSE)dTPla_nominalTemperature difference tower water loop
Modelica.Units.SI.TemperatureTRacSup_nominal (from ChillerWSE)273.15 + 45Supply coolant temperature to rack at design conditions
Modelica.Units.SI.TemperatureTRacRet_nominal (from ChillerWSE)TRacSup_nominal - dTRac_nominalReturn coolant temperature from rack at design conditions
Modelica.Units.SI.TemperatureDifferenceTApp_nominal (from ChillerWSE)3Approach temperature at heat exchangers
Modelica.Units.SI.TemperatureTPlaSup_nominal (from ChillerWSE)TRacSup_nominal - TApp_nominalTemperature from cooling plant to CDU at design conditions
Modelica.Units.SI.TemperatureTPlaRet_nominal (from ChillerWSE)TPlaSup_nominal - dTPla_nominalTemperature from CDU to cooling plant at design conditions
Modelica.Units.SI.TemperatureTTowRet_nominal (from ChillerWSE)TPlaSup_nominal - TApp_nominalReturn temperature from cooling tower
Modelica.Units.SI.TemperatureTTowSup_nominal (from ChillerWSE)TTowRet_nominal - dTTow_nominalSupply temperature to cooling tower
Modelica.Units.SI.TemperatureTDryBul_nominal (from ChillerWSE)273.15 + 36Design dry bulb temperature if WSE is used exclusively (with fraWSE=0.9999)
Modelica.Units.SI.MassFlowRatemRac_flow_nominal (from ChillerWSE)PRac/(TRacRet_nominal - TRacSup_nominal)/MediumRac.cp_constRack mass flow rate at design conditions
Modelica.Units.SI.MassFlowRatemPla_flow_nominal (from ChillerWSE)PRac/(TPlaRet_nominal - TPlaSup_nominal)/cpChi_defaultCooling loop water mass flow rate at design conditions
Modelica.Units.SI.PressureDifferencedpVal_nominal (from ChillerWSE)20000Valve design pressure drop
Modelica.Units.SI.PressureDifferencedpHexChi_nominal (from ChillerWSE)80000Heat exchanger design pressure drop on chiller side
Modelica.Units.SI.PressureDifferencedPRac_nominal (from ChillerWSE)60000Rack design pressure drop
Buildings.Fluid.DataCenterEquipment.Racks.LiquidCooledSinglePhase.Data.OCP_1kW_OAM_PG25datRac (from ChillerWSE)Performance data for IT rack
RealCOPc_nominal (from ChillerWSE)5Chiller COP
RealepsWSE_nominal (from ChillerWSE)QWSE_flow_nominal/(min(mWSEPla_flow_nominal*cpChi_default, mWSETow_flow_nominal*cpTow_default)*(TPlaRet_nominal - TTowRet_nominal))Effectiveness of water side economizer
Modelica.Units.SI.HeatFlowRateQCon_flow_nominal (from ChillerWSE)(1 - fraWSE)*PRac*(1/COPc_nominal + 1)Design heat flow rate of condenser
Modelica.Units.SI.HeatFlowRateQWSE_flow_nominal (from ChillerWSE)fraWSE*PRacDesign heat flow rate of economizer
Modelica.Units.SI.MassFlowRatemEva_flow_nominal (from ChillerWSE)mPla_flow_nominalNominal mass flow rate at condenser water, sized to circulate all water through it to meet set point when trim chiller is needed
Modelica.Units.SI.MassFlowRatemCon_flow_nominal (from ChillerWSE)-QCon_flow_nominal/dTTow_nominal/cpTow_defaultNominal mass flow rate at condenser water
Modelica.Units.SI.MassFlowRatemWSETow_flow_nominal (from ChillerWSE)-QWSE_flow_nominal/dTTow_nominal/cpTow_defaultNominal mass flow rate at WSE on tower side
Modelica.Units.SI.MassFlowRatemWSEPla_flow_nominal (from ChillerWSE)-QWSE_flow_nominal/dTPla_nominal/cpChi_defaultNominal mass flow rate at WSE on chilled water side
Fluid.DataCenterEquipment.CDUs.LiquidToLiquid.Data.Generic_2MWdatCDU (from ChillerWSE)Data record for CDU
Fluid.HeatExchangers.CoolingTowers.Data.DryCooler.GenericdatCooTow (from ChillerWSE)Performance data for cooling tower

Connectors

TypeNameDefaultDescription
BoundaryConditions.WeatherData.BusweaBus (from ChillerWSE)Weather data bus

Components

TypeNameDefaultDescription
Controls.OBC.CDL.Reals.Sources.Constantuti (from ChillerWSE)Utilization of hardware
Buildings.Fluid.DataCenterEquipment.Racks.LiquidCooledSinglePhase.ColdPlateR_Prac (from ChillerWSE)Rack with cold plate heat exchangers, modeled for simplicity as one large rack
Buildings.Fluid.Sources.Boundary_pTbou (from ChillerWSE)Pressure boundary condition
Buildings.Fluid.Sensors.TemperatureTwoPortsenTCDU_a (from ChillerWSE)Chilled water supply temperature
Buildings.Fluid.DataCenterEquipment.CDUs.LiquidToLiquid.CDU_epsNTUcdu (from ChillerWSE)CDU, modeled for simplicity as one large CDU
Fluid.Sensors.TemperatureTwoPortsenTCDU_b (from ChillerWSE)Outlet temperature
Fluid.Sensors.TemperatureTwoPortsenTRac_a (from ChillerWSE)Rack inlet temperature
Fluid.Sensors.TemperatureTwoPortsenTRac_b (from ChillerWSE)Rack outlet temperature
Controls.OBC.CDL.Reals.Sources.ConstantdpSet (from ChillerWSE)Set point for head
Controls.OBC.CDL.Reals.Sources.ConstantTSetRacIn (from ChillerWSE)Set point for rack inlet temperature
Fluid.HeatExchangers.ConstantEffectivenesswse (from ChillerWSE)Water side economizer (Heat exchanger)
Fluid.Chillers.Carnot_TEvachi (from ChillerWSE)Chiller
Fluid.HeatExchangers.CoolingTowers.DryCoolercooTow (from ChillerWSE)Cooling tower
BoundaryConditions.WeatherData.ReaderTMY3weaDat (from ChillerWSE)Weather data reader
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_ypumEva (from ChillerWSE)Pump chiller evaporator
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_ypumWSEChi (from ChillerWSE)Pump for water-side economizer
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_ypumTow (from ChillerWSE)Pump for tower loop
Fluid.Sensors.TemperatureTwoPortsenTWSE_b2 (from ChillerWSE)Chilled water outlet temperature of water side economizer
Fluid.Movers.Preconfigured.SpeedControlled_ypumCon (from ChillerWSE)Pump for chiller condenser
Fluid.Sensors.TemperatureTwoPortsenTTow_b (from ChillerWSE)Outlet water temperature of tower
Fluid.FixedResistances.Junctionjun1 (from ChillerWSE)
Fluid.FixedResistances.Junctionjun2 (from ChillerWSE)
Fluid.FixedResistances.Junctionjun3 (from ChillerWSE)
Fluid.Sensors.TemperatureTwoPortsenTEvaIn (from ChillerWSE)Chiller inlet temperature to evaporator
Fluid.FixedResistances.Junctionjun4 (from ChillerWSE)
Fluid.FixedResistances.Junctionjun5 (from ChillerWSE)
Fluid.Sensors.TemperatureTwoPortsenTEvaOut (from ChillerWSE)Chilled water outlet temperature of chiller
Fluid.Sensors.TemperatureTwoPortsenTChi_b1 (from ChillerWSE)Cooling tower water outlet temperature of chiller
Fluid.Sensors.TemperatureTwoPortsenTWSE_b1 (from ChillerWSE)Cooling tower water outlet temperature of water side economizer
Buildings.Fluid.Movers.Preconfigured.SpeedControlled_ypumWSECW (from ChillerWSE)Pump for water side economizer on cooling tower side
Fluid.Movers.Preconfigured.FlowControlled_dppumCDU (from ChillerWSE)Pump chilled water circuit
Fluid.FixedResistances.Junctionjun6 (from ChillerWSE)
Fluid.FixedResistances.Junctionjun7 (from ChillerWSE)
Fluid.FixedResistances.Junctionjun8 (from ChillerWSE)
Controls.OBC.CDL.Reals.PIDconTow (from ChillerWSE)Controller for tower fan and pump
Controls.OBC.CDL.Reals.Sources.ConstantTSetEva (from ChillerWSE)Set point temperature for evaporator outlet temperature
Controls.OBC.CDL.Reals.Sources.ConstantpSetChiWatPum (from ChillerWSE)Pressure setpoint for chilled water pump
Controls.OBC.CDL.Reals.HysteresishysChi (from ChillerWSE)Hysteresis for chiller staging
Controls.OBC.CDL.Conversions.BooleanToRealyPumChi (from ChillerWSE)Control signal for chiller circulation pumps
Fluid.Sources.Boundary_pTbou1 (from ChillerWSE)Pressure boundary condition
Controls.OBC.CDL.Reals.AddParameterTOffSet (from ChillerWSE)Offset for set point
Modelica.Blocks.Sources.RealExpressionPFan (from ChillerWSE)Power consumption of tower fans
Modelica.Blocks.Sources.RealExpressionPPum (from ChillerWSE)Power consumption of pumps
Modelica.Blocks.Sources.RealExpressionPChi (from ChillerWSE)Power consumption of chiller
Modelica.Blocks.Sources.RealExpressionPIT (from ChillerWSE)Power consumption of IT
BaseClasses.ElectricalEnergyMeterEFan (from ChillerWSE)Energy meter
BaseClasses.ElectricalEnergyMeterEPum (from ChillerWSE)Energy meter
BaseClasses.ElectricalEnergyMeterEChi (from ChillerWSE)Energy meter
BaseClasses.ElectricalEnergyMeterEPIT (from ChillerWSE)Energy meter
Modelica.Blocks.Math.MultiSumEFac (from ChillerWSE)Electricity for facility
Modelica.Blocks.Math.DivisionPUE (from ChillerWSE)Power use effectiveness (not taking into account electrical losses)
Fluid.Sensors.TemperatureTwoPortsenTWSEMix (from ChillerWSE)Water temperature cooling tower loop after WSE
Fluid.Actuators.Valves.TwoWayLinearvalByp (from ChillerWSE)Valve for condenser loop bypass
Fluid.Actuators.Valves.TwoWayLinearvalThr (from ChillerWSE)Valve for condenser loop from cooling tower
Fluid.FixedResistances.Junctionjun9 (from ChillerWSE)Junction at condenser loop
Fluid.FixedResistances.Junctionjun10 (from ChillerWSE)Junction at condenser loop[
Buildings.Fluid.Sensors.TemperatureTwoPortsenTChi_a1 (from ChillerWSE)Cooling tower water inlet temperature of chiller
Controls.OBC.CDL.Reals.PIDWithResetconPIDCon (from ChillerWSE)Controller for minimum chiller lift
Controls.OBC.CDL.Reals.AddParameterTLifMin (from ChillerWSE)Minimum lift of chiller
Controls.OBC.CDL.Reals.MultiplyByParameterinvValSig (from ChillerWSE)Invert valve signal
Controls.OBC.CDL.Reals.AddParameterinvValSig2 (from ChillerWSE)Invert valve control signal
Fluid.Sensors.TemperatureTwoPortsenTTow_a (from ChillerWSE)Inlet water temperature of tower
Controls.OBC.CDL.Reals.AddParameterTOffSetWSE (from ChillerWSE)Offset for set point for WSE control
Fluid.Sensors.MassFlowRatesenMasFloByEco (from ChillerWSE)Mass flow rate sensor in economizer bypass
Controls.OBC.CDL.Reals.PIDconEcoPla (from ChillerWSE)Controller for economizer pump on facility level
Controls.OBC.CDL.Reals.Sources.Constantzer (from ChillerWSE)Zero as a set point
Fluid.Sensors.MassFlowRatesenMasFlo3 (from ChillerWSE)Mass flow rate sensor
Controls.OBC.CDL.Reals.LimiteryPumTow (from ChillerWSE)Pump control signal
Controls.OBC.CDL.Reals.Sources.Constantzer1 (from ChillerWSE)Zero as a set point
Controls.OBC.CDL.Reals.PIDconEcoTow (from ChillerWSE)Controller for economizer pump on tower loop
Controls.OBC.CDL.Reals.Sources.ConstantTSetTowRet (from ChillerWSE)Set point temperature for tower return temperature
Controls.OBC.CDL.Reals.PIDconPumTow (from ChillerWSE)Controller for tower pump
Controls.OBC.CDL.Reals.SubtracterrTFre (from ChillerWSE)Temperature error after free cooling
Controls.OBC.CDL.Reals.LimiteryFanTow (from ChillerWSE)Tower fan control signal based on economizer leaving temperature
Controls.OBC.CDL.Reals.MaxyTowFan (from ChillerWSE)Fan control signal
Fluid.Actuators.Valves.TwoWayLinearvalRac (from ChillerWSE)Valve for rack flow control
Controls.OBC.CDL.Reals.Sources.ConstantTSetRacOut (from ChillerWSE)Set point for rack outlet temperature
Controls.OBC.CDL.Reals.PIDconVal (from ChillerWSE)Controller for valve
Modelica.Blocks.Math.GainPITIn (from ChillerWSE)Power consumption by the IT equipment
PipepipTowIn (from ChillerWSE)Pipe at tower inlet
PipepipTowOut (from ChillerWSE)Pipe at tower outlet
PipepipCDUIn (from ChillerWSE)Pipe at CDU inlet
PipepipCDUOut (from ChillerWSE)Pipe at CDU outlet
PipepipRacIn (from ChillerWSE)Pipe at rack inlet
PipepipRacOut (from ChillerWSE)Pipe at rack outlet
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTDryBulConDesign dry bulb temperature

Revisions

  • June 24, 2026, by Michael Wetter:
    First implementation.