Buildings.DHC.Plants.Cooling.Examples

Example models integrating multiple components

Information

This package contains advanced examples illustrating the use of the models in Buildings.DHC.Plants.Cooling.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
ElectricChillerParallel	Example to test the chiller cooling plant
StoragePlantDualSource	Idealised district system model with two sources and three users

Buildings.DHC.Plants.Cooling.Examples.ElectricChillerParallel

Example to test the chiller cooling plant

Buildings.DHC.Plants.Cooling.Examples.ElectricChillerParallel

Information

This model validates the district central cooling plant implemented in Buildings.DHC.Plants.Cooling.ElectricChillerParallel.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
ElectricEIRChiller_York_YT_1055kW_5_96COP_Vanes	perChi	redeclare parameter Building...	Performance data of chiller
MassFlowRate	mCHW_flow_nominal	18.3	Nominal chilled water mass flow rate [kg/s]
MassFlowRate	mCW_flow_nominal	34.7	Nominal condenser water mass flow rate [kg/s]
PressureDifference	dpCHW_nominal	44.8*1000	Nominal chilled water side pressure [Pa]
PressureDifference	dpCW_nominal	46.2*1000	Nominal condenser water side pressure [Pa]
Power	QChi_nominal	mCHW_flow_nominal4200(6.67...	Nominal cooling capaciaty (Negative means cooling) [W]
MassFlowRate	mMin_flow	mCHW_flow_nominal*0.1	Minimum mass flow rate of single chiller [kg/s]
TemperatureDifference	dTApp	3	Approach temperature [K]
Power	PFan_nominal	5000	Fan power [W]
Temperature	TCHWSet	273.15 + 8	Chilled water temperature setpoint [K]
Time	tWai	30	Waiting time [s]
Generic	perCHWPum	perCHWPum(pressure=Buildings...	Performance data for chilled water pumps
Generic	perCWPum	perCWPum(pressure=Buildings....	Performance data for condenser water pumps
Pressure	dpCHWPumVal_nominal	6000	Nominal pressure drop of chilled water pump valve [Pa]
Pressure	dpCWPumVal_nominal	6000	Nominal pressure drop of chilled water pump valve [Pa]
PressureDifference	dpCooTowVal_nominal	6000	Nominal pressure difference of the cooling tower valve [Pa]
ElectricChillerParallel	pla	pla(perChi=perChi, dTApp=dTA...	District cooling plant

Modelica definition

model ElectricChillerParallel "Example to test the chiller cooling plant" extends Modelica.Icons.Example; package Medium=Buildings.Media.Water "Medium model for water"; // chiller and cooling tower replaceable parameter Buildings.Fluid.Chillers.Data.ElectricEIR.ElectricEIRChiller_York_YT_1055kW_5_96COP_Vanes perChi "Performance data of chiller"; parameter Modelica.Units.SI.MassFlowRate mCHW_flow_nominal=18.3 "Nominal chilled water mass flow rate"; parameter Modelica.Units.SI.MassFlowRate mCW_flow_nominal=34.7 "Nominal condenser water mass flow rate"; parameter Modelica.Units.SI.PressureDifference dpCHW_nominal=44.8*1000 "Nominal chilled water side pressure"; parameter Modelica.Units.SI.PressureDifference dpCW_nominal=46.2*1000 "Nominal condenser water side pressure"; parameter Modelica.Units.SI.Power QChi_nominal=mCHW_flow_nominal*4200*(6.67 - 18.56) "Nominal cooling capaciaty (Negative means cooling)"; parameter Modelica.Units.SI.MassFlowRate mMin_flow=mCHW_flow_nominal*0.1 "Minimum mass flow rate of single chiller"; parameter Modelica.Units.SI.TemperatureDifference dTApp=3 "Approach temperature"; parameter Modelica.Units.SI.Power PFan_nominal=5000 "Fan power"; // control settings parameter Modelica.Units.SI.Temperature TCHWSet=273.15 + 8 "Chilled water temperature setpoint"; parameter Modelica.Units.SI.Time tWai=30 "Waiting time"; // pumps parameter Buildings.Fluid.Movers.Data.Generic perCHWPum( pressure=Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParameters( V_flow=mCHW_flow_nominal/1000*{0.2,0.6,0.8,1.0}, dp=(dpCHW_nominal+18000+30000)*{1,0.8,0.6,0.2})) "Performance data for chilled water pumps"; parameter Buildings.Fluid.Movers.Data.Generic perCWPum( pressure=Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParameters( V_flow=mCW_flow_nominal/1000*{0.2,0.6,1.0,1.2}, dp=(2*dpCW_nominal+60000+6000)*{1,0.8,0.6,0.2})) "Performance data for condenser water pumps"; parameter Modelica.Units.SI.Pressure dpCHWPumVal_nominal=6000 "Nominal pressure drop of chilled water pump valve"; parameter Modelica.Units.SI.Pressure dpCWPumVal_nominal=6000 "Nominal pressure drop of chilled water pump valve"; parameter Modelica.Units.SI.PressureDifference dpCooTowVal_nominal=6000 "Nominal pressure difference of the cooling tower valve"; replaceable Buildings.DHC.Plants.Cooling.ElectricChillerParallel pla( perChi=perChi, dTApp=dTApp, perCHWPum=perCHWPum, perCWPum=perCWPum, mCHW_flow_nominal=mCHW_flow_nominal, dpCHW_nominal=dpCHW_nominal, QChi_nominal=QChi_nominal, mMin_flow=mMin_flow, mCW_flow_nominal=mCW_flow_nominal, dpCW_nominal=dpCW_nominal, TAirInWB_nominal=298.7, TCW_nominal=308.15, dT_nominal=5.56, TMin=288.15, PFan_nominal=PFan_nominal, dpCooTowVal_nominal=dpCooTowVal_nominal, dpCHWPumVal_nominal=dpCHWPumVal_nominal, dpCWPumVal_nominal=dpCWPumVal_nominal, tWai=tWai, energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial) "District cooling plant"; Buildings.BoundaryConditions.WeatherData.ReaderTMY3 weaDat( final computeWetBulbTemperature=true, filNam=Modelica.Utilities.Files.loadResource( "modelica://Buildings/Resources/weatherdata/USA_CA_San.Francisco.Intl.AP.724940_TMY3.mos")) "Weather data"; Modelica.Blocks.Sources.BooleanConstant on "On signal of the plant"; Modelica.Blocks.Sources.Constant TCHWSupSet( k=TCHWSet) "Chilled water supply temperature setpoint"; Fluid.MixingVolumes.MixingVolume vol( nPorts=2, redeclare package Medium=Medium, m_flow_nominal=pla.numChi*mCHW_flow_nominal, V=0.5, energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial) "Mixing volume"; Modelica.Thermal.HeatTransfer.Sources.PrescribedHeatFlow fixHeaFlo( T_ref=293.15) "Fixed heat flow rate"; Fluid.FixedResistances.PressureDrop res( redeclare package Medium = Medium, m_flow_nominal=pla.numChi*mCHW_flow_nominal, dp_nominal(displayUnit="kPa") = 60000) "Flow resistance"; Modelica.Blocks.Sources.Sine loaVar( amplitude=913865, f=1/126900, offset=913865, startTime(displayUnit="h") = 21600) "Variable demand load"; equation connect(fixHeaFlo.port,vol.heatPort); connect(vol.ports[1], res.port_a); connect(res.port_b, pla.port_aSerCoo); connect(on.y,pla.on); connect(weaDat.weaBus,pla.weaBus); connect(fixHeaFlo.Q_flow,loaVar. y); connect(pla.port_bSerCoo, vol.ports[2]); connect(pla.TCHWSupSet, TCHWSupSet.y); end ElectricChillerParallel;

Buildings.DHC.Plants.Cooling.Examples.StoragePlantDualSource

Idealised district system model with two sources and three users

Buildings.DHC.Plants.Cooling.Examples.StoragePlantDualSource

Information

The modelled system is described in the documentation of Buildings.DHC.Plants.Cooling.StoragePlant.

The source blocks give the system the following operation schedule during simulation:

At time = 0, the system is all off.
At time = 200, the system is commanded to charge the tank. The chiller is available and charges the tank locally. After some time, the charging stops when the tank status signal returns that the tank is charged.
At time = 1800, load appears at the district network. The storage plant starts producing CHW to the system. Currently the tank is not commanded to charge or discharge, therefore it functions like a common pipe and the CHW is supplied by the chiller.
At time = 3500, the load increases and there is no more overflow through the tank.
At time = 4000, the system is commanded to have the tank take priority for CHW production. After some time, the cooling in the tank is empty and the tank stops producing. Now the chiller takes over.
At time = 7000, there is no longer load in the district system. The system is back to the all-off state.
At time = 7500, the system is once again commanded to charge the tank, but the chiller in the storage plant is not enabled. The tank is therefore charged remotely by the district. This stops once the tank is charged again.

Implementation

The chiller is implemented as an ideal temperature source using Buildings.Fluid.Sources.PropertySource_T. Its outlet temperature is always at the prescribed value.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
MassFlowRate	m_flow_nominal	1	Nominal mass flow rate, slightly larger than needed by one user load [kg/s]
PressureDifference	dp_nominal	300000	Nominal pressure difference [Pa]
Temperature	T_CHWR_nominal	12 + 273.15	Nominal temperature of CHW return [K]
Temperature	T_CHWS_nominal	7 + 273.15	Nominal temperature of CHW supply [K]
Nominal values
MassFlowRate	mTan_flow_nominal	1	Nominal mass flow rate for CHW tank branch [kg/s]
MassFlowRate	mChi_flow_nominal	1	Nominal mass flow rate for CHW chiller branch [kg/s]

Modelica definition

model StoragePlantDualSource "Idealised district system model with two sources and three users" extends Modelica.Icons.Example; package Medium = Buildings.Media.Water "Medium model for CHW"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1 "Nominal mass flow rate, slightly larger than needed by one user load"; parameter Modelica.Units.SI.MassFlowRate mTan_flow_nominal=1 "Nominal mass flow rate for CHW tank branch"; parameter Modelica.Units.SI.MassFlowRate mChi_flow_nominal=1 "Nominal mass flow rate for CHW chiller branch"; parameter Modelica.Units.SI.PressureDifference dp_nominal( final displayUnit="Pa")= 300000 "Nominal pressure difference"; parameter Modelica.Units.SI.Temperature T_CHWR_nominal( final displayUnit="degC")= 12+273.15 "Nominal temperature of CHW return"; parameter Modelica.Units.SI.Temperature T_CHWS_nominal( final displayUnit="degC")= 7+273.15 "Nominal temperature of CHW supply"; // First plant: chiller only Buildings.Fluid.Sources.PropertySource_T chi1( redeclare final package Medium = Medium, final use_T_in=true) "Chiller 1 represented by an ideal temperature source"; Modelica.Blocks.Sources.Constant TSet1(k=T_CHWS_nominal) "Constant CHW leaving temperature"; Buildings.Fluid.Movers.Preconfigured.SpeedControlled_y pumSup1( redeclare final package Medium = Medium, final addPowerToMedium=false, final m_flow_nominal=m_flow_nominal, final dp_nominal=dp_nominal) "CHW supply pump for chi1"; Buildings.Controls.Continuous.LimPID conPI_pumChi1( final controllerType=Modelica.Blocks.Types.SimpleController.PI, k=0.2, Ti=10, final reverseActing=true) "PI controller"; Buildings.DHC.Plants.Cooling.Controls.SelectMin selMin_dp(nin=3) "Min of pressure heads with the signal from storage plant optionally used"; // Second plant: chiller and tank Buildings.DHC.Plants.Cooling.StoragePlant stoPla(redeclare final package Medium = Medium, mTan_flow_nominal=mTan_flow_nominal, mChi_flow_nominal=mChi_flow_nominal, dpPum_nominal=dp_nominal, dpVal_nominal=0.5*dp_nominal, T_CHWS_nominal=T_CHWS_nominal, T_CHWR_nominal=T_CHWR_nominal) "Storage plant"; Buildings.Fluid.Sources.Boundary_pT bou( p(final displayUnit="Pa") = 101325 + dp_nominal, redeclare final package Medium = Medium, nPorts=1) "Pressure boundary"; Buildings.Fluid.Sources.PropertySource_T chi2( redeclare final package Medium = Medium, final use_T_in=true) "Chiller represented by an ideal temperature source"; Modelica.Blocks.Sources.Constant TSet2(final k=T_CHWS_nominal) "Constant CHW leaving temperature"; Modelica.Blocks.Math.Gain gaiStoPla(final k=1/stoPla.dpVal_nominal) "Gain to normalise dp measurement"; // Users Buildings.DHC.Plants.Cooling.BaseClasses.IdealUser ideUse1( redeclare final package Medium = Medium, final m_flow_nominal=0.6*m_flow_nominal, dp_nominal=0.2*dp_nominal, final T_CHWR_nominal=T_CHWR_nominal) "Ideal user"; Buildings.DHC.Plants.Cooling.BaseClasses.IdealUser ideUse2( redeclare final package Medium = Medium, final m_flow_nominal=0.65*m_flow_nominal, dp_nominal=0.2*dp_nominal, final T_CHWR_nominal=T_CHWR_nominal) "Ideal user"; Buildings.DHC.Plants.Cooling.BaseClasses.IdealUser ideUse3( redeclare final package Medium = Medium, final m_flow_nominal=0.65*m_flow_nominal, dp_nominal=0.2*dp_nominal, final T_CHWR_nominal=T_CHWR_nominal) "Ideal user"; Modelica.Blocks.Sources.Constant set_dpUse(final k=1) "Normalized consumer differential pressure setpoint"; Modelica.Blocks.Sources.TimeTable mLoa1_flow(table=[0,0; 1800,0; 1800,ideUse1.m_flow_nominal; 7000,ideUse1.m_flow_nominal; 7000,0; 9000,0]) "Cooling load of user 1 represented by flow rate"; Modelica.Blocks.Sources.TimeTable mLoa2_flow(table=[0,0; 3500,0; 3500,ideUse2.m_flow_nominal; 6500,ideUse2.m_flow_nominal; 6500,0; 9000,0]) "Cooling load of user 2 represented by flow rate"; Modelica.Blocks.Sources.TimeTable mLoa3_flow(table=[0,0; 4500,0; 4500,ideUse3.m_flow_nominal; 6000,ideUse3.m_flow_nominal; 6000,0; 9000,0]) "Cooling load of user 3 represented by flow rate"; Modelica.Blocks.Math.Gain gaiUse1(final k=1/ideUse1.dp_nominal) "Gain to normalise dp measurement"; Modelica.Blocks.Math.Gain gaiUse2(final k=1/ideUse2.dp_nominal) "Gain to normalise dp measurement"; Modelica.Blocks.Math.Gain gaiUse3(final k=1/ideUse3.dp_nominal) "Gain to normalise dp measurement"; // District pipe network Buildings.DHC.Plants.Cooling.BaseClasses.ParallelJunctions parJunPla1( redeclare final package Medium = Medium, T1_start=T_CHWS_nominal, T2_start=T_CHWR_nominal, m_flow_nominal = 2*m_flow_nominal) "Parallel junctions for breaking algebraic loops"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelJunctions parJunUse2( redeclare final package Medium = Medium, T1_start=T_CHWR_nominal, T2_start=T_CHWS_nominal, m_flow_nominal = 2*m_flow_nominal) "Parallel junctions for breaking algebraic loops"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelJunctions parJunPla2( redeclare final package Medium = Medium, T1_start=T_CHWS_nominal, T2_start=T_CHWR_nominal, m_flow_nominal = 2*m_flow_nominal) "Parallel junctions for breaking algebraic loops"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelPipes parPipS1U1( redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal, dp_nominal=0.15*dp_nominal) "Parallel pipes"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelPipes parPipS1U2( redeclare package Medium = Medium, m_flow_nominal=2*m_flow_nominal, dp_nominal=0.15*dp_nominal) "Parallel pipes"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelPipes parPipS2U2( redeclare package Medium = Medium, m_flow_nominal=2*m_flow_nominal, dp_nominal=0.15*dp_nominal) "Parallel pipes"; Buildings.DHC.Plants.Cooling.BaseClasses.ParallelPipes parPipS2U3( redeclare package Medium = Medium, m_flow_nominal=m_flow_nominal, dp_nominal=0.15*dp_nominal) "Parallel pipes"; Modelica.Blocks.Routing.Multiplex muxDp(n=3) "Multiplexer block for routing"; Buildings.Controls.OBC.CDL.Reals.MultiMax mulMax_yVal_actual(nin=3) "Position of the most open user control valve"; Modelica.Blocks.Sources.IntegerTable com(table=[0,2; 200,1; 3000,2; 4000,3; 6000,2; 7500,1]) "Command: 1 = charge tank, 2 = no command, 3 = discharge from tank"; Modelica.Blocks.Sources.BooleanTable chiEnaSta(table={0,6000}, startValue= false) "Chiller enable status, true if chiller is enabled"; Buildings.Controls.OBC.CDL.Reals.Hysteresis hys_yVal_actual(uLow=0.05, uHigh=0.5) "Hysteresis for user control valve position"; equation connect(set_dpUse.y,conPI_pumChi1.u_s); connect(mLoa1_flow.y, ideUse1.mPre_flow); connect(mLoa2_flow.y, ideUse2.mPre_flow); connect(mLoa3_flow.y, ideUse3.mPre_flow); connect(ideUse1.dp, gaiUse1.u); connect(ideUse2.dp, gaiUse2.u); connect(ideUse3.dp, gaiUse3.u); connect(parJunUse2.port_c2, ideUse2.port_a); connect(ideUse2.port_b,parJunUse2.port_c1); connect(parPipS1U1.port_b2, parJunPla1.port_a1); connect(parJunPla1.port_b2, parPipS1U1.port_a1); connect(parJunPla1.port_b1, parPipS1U2.port_a2); connect(parPipS1U2.port_b2, parJunUse2.port_a2); connect(parJunUse2.port_b1, parPipS1U2.port_a1); connect(parPipS1U2.port_b1, parJunPla1.port_a2); connect(parJunUse2.port_b2, parPipS2U2.port_a2); connect(parPipS2U2.port_b1, parJunUse2.port_a1); connect(parPipS2U2.port_a1, parJunPla2.port_b2); connect(parJunPla2.port_a1, parPipS2U2.port_b2); connect(parPipS2U3.port_a2, parJunPla2.port_b1); connect(parJunPla2.port_a2, parPipS2U3.port_b1); connect(gaiUse1.y, muxDp.u[1]); connect(gaiUse2.y, muxDp.u[2]); connect(gaiUse3.y, muxDp.u[3]); connect(ideUse1.yVal_actual, mulMax_yVal_actual.u[1]); connect(ideUse2.yVal_actual, mulMax_yVal_actual.u[2]); connect(ideUse3.yVal_actual, mulMax_yVal_actual.u[3]); connect(com.y, stoPla.com); connect(chiEnaSta.y, stoPla.chiEnaSta); connect(hys_yVal_actual.y, stoPla.hasLoa); connect(pumSup1.port_b, parJunPla1.port_c1); connect(conPI_pumChi1.y, pumSup1.y); connect(conPI_pumChi1.y, stoPla.yPum); connect(pumSup1.port_a, chi1.port_b); connect(chi1.port_a, parJunPla1.port_c2); connect(TSet1.y, chi1.T_in); connect(TSet2.y, chi2.T_in); connect(stoPla.port_b1, parJunPla2.port_c1); connect(parJunPla2.port_c2, stoPla.port_a2); connect(stoPla.port_b2, chi2.port_a); connect(chi2.port_b, stoPla.port_a1); connect(bou.ports[1], stoPla.port_a2); connect(parPipS1U1.port_a2, ideUse1.port_a); connect(ideUse1.port_b, parPipS1U1.port_b1); connect(parPipS2U3.port_b2, ideUse3.port_a); connect(parPipS2U3.port_a1, ideUse3.port_b); connect(stoPla.dp, gaiStoPla.u); connect(selMin_dp.y, conPI_pumChi1.u_m); connect(gaiStoPla.y, selMin_dp.dpStoPla); connect(stoPla.isChaRem, selMin_dp.isChaRem); connect(muxDp.y, selMin_dp.dpUse[1:3]); connect(mulMax_yVal_actual.y, hys_yVal_actual.u); end StoragePlantDualSource;