Annex60.Fluid.Chillers.Validation

This package contains models that validate the chiller models. The examples plot various outputs, which have been verified against analytical solutions. These model outputs are stored as reference data to allow continuous validation whenever models in the library change.

Package Content

Name	Description
Carnot_TEva_2ndLaw	Test model to verify that the 2nd law is not violated
Carnot_TEva_HighTemperature	Test model for Carnot_TEva with high evaporator temperature
Carnot_TEva_LimitedCapacity	Test model for Carnot_TEva with limited heating capacity
Carnot_TEva_etaPL	Test model for the part load efficiency curve with evaporator leaving temperature as input signal
Carnot_TEva_reverseFlow	Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal
Carnot_y_etaPL	Test model for the part load efficiency curve with compressor speed as input signal

Annex60.Fluid.Chillers.Validation.Carnot_TEva_2ndLaw

Information

This example verifies that the 2nd law of thermodynamics is not violated despite of a very small temperature lift.

Parameters

Modelica definition

Type	Name	Default	Description
TemperatureDifference	dTEva_nominal	-4	Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal	4	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
HeatFlowRate	QEva_flow_nominal	-100E3	Evaporator heat flow rate [W]

model Carnot_TEva_2ndLaw "Test model to verify that the 2nd law is not violated" extends Modelica.Icons.Example; package Medium = Annex60.Media.Water "Medium model"; parameter Modelica.SIunits.TemperatureDifference dTEva_nominal=-4 "Temperature difference evaporator outlet-inlet"; parameter Modelica.SIunits.TemperatureDifference dTCon_nominal=4 "Temperature difference condenser outlet-inlet"; parameter Real COPc_nominal = 3 "Chiller COP"; parameter Modelica.SIunits.HeatFlowRate QEva_flow_nominal = -100E3 "Evaporator heat flow rate"; final parameter Modelica.SIunits.MassFlowRate m2_flow_nominal= QEva_flow_nominal/dTEva_nominal/4200 "Nominal mass flow rate at chilled water side"; final parameter Modelica.SIunits.MassFlowRate m1_flow_nominal= -m2_flow_nominal/dTCon_nominal*dTEva_nominal "Nominal mass flow rate at condeser water side"; Modelica.Blocks.Sources.Constant TEvaIn(k=273.15 + 20) "Evaporator inlet temperature"; Modelica.Blocks.Sources.Constant dTEva(k=dTEva_nominal) "Temperature difference over evaporator"; Modelica.Blocks.Math.Add TSetEvaLvg "Set point for evaporator leaving temperature"; Modelica.Blocks.Sources.Ramp dTConEva( duration=1, offset=25, height=-25) "Temperature lift condensor inlet minus evaporator outlet"; Modelica.Blocks.Math.Add TConIn "Condensor inlet temperature"; Chiller chi_b( redeclare final package Medium1 = Medium, redeclare final package Medium2 = Medium, final dTEva_nominal=dTEva_nominal, final dTCon_nominal=dTCon_nominal, final QEva_flow_nominal=QEva_flow_nominal, final m2_flow_nominal=m2_flow_nominal, final m1_flow_nominal=m1_flow_nominal) "Chiller model that uses port_b to compute Carnot efficiency"; protected model Chiller "Subsystem model with the chiller" replaceable package Medium1 = Modelica.Media.Interfaces.PartialMedium "Medium model"; replaceable package Medium2 = Modelica.Media.Interfaces.PartialMedium "Medium model"; parameter Modelica.SIunits.TemperatureDifference dTEva_nominal "Temperature difference evaporator outlet-inlet"; parameter Modelica.SIunits.TemperatureDifference dTCon_nominal "Temperature difference condenser outlet-inlet"; parameter Modelica.SIunits.HeatFlowRate QEva_flow_nominal "Evaporator heat flow rate"; parameter Modelica.SIunits.MassFlowRate m1_flow_nominal "Nominal mass flow rate at condeser water side"; parameter Modelica.SIunits.MassFlowRate m2_flow_nominal "Nominal mass flow rate at chilled water side"; Annex60.Fluid.Sources.MassFlowSource_T sou1( redeclare package Medium = Medium1, nPorts=1, use_m_flow_in=false, use_T_in=true, m_flow=m1_flow_nominal) "Mass flow rate source"; Annex60.Fluid.Sources.FixedBoundary sin1(redeclare package Medium = Medium2, nPorts=1) "Pressure source"; Annex60.Fluid.Chillers.Carnot_TEva chi( redeclare package Medium1 = Medium1, redeclare package Medium2 = Medium2, dTEva_nominal=dTEva_nominal, dTCon_nominal=dTCon_nominal, m2_flow_nominal=m2_flow_nominal, show_T=true, QEva_flow_nominal=QEva_flow_nominal, allowFlowReversal1=false, allowFlowReversal2=false, etaCarnot_nominal=0.3, dp1_nominal=0, dp2_nominal=0, energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState, use_eta_Carnot_nominal=true) "Chiller model"; Annex60.Fluid.Sources.MassFlowSource_T sou2( redeclare package Medium = Medium2, m_flow=m2_flow_nominal, use_T_in=true, T=293.15, nPorts=1) "Mass flow rate source"; Annex60.Fluid.Sensors.EntropyFlowRate S_a1( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a2( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a3( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a4( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sources.FixedBoundary sin2(redeclare package Medium = Medium2, nPorts=1) "Pressure source"; Modelica.Blocks.Math.Add SIn_flow "Entropy carried by flow that goes into the chiller"; Modelica.Blocks.Math.Add SOut_flow "Entropy carried by flow that leaves the chiller"; Modelica.Blocks.Math.Add dS_flow(k1=-1) "Change in entropy inflow and outflow"; Modelica.Blocks.Interfaces.RealInput TSetEvaLea(unit="K") "Set point for evaporator leaving temperature"; Modelica.Blocks.Interfaces.RealOutput SGen_flow "Entropy generated"; Modelica.Blocks.Interfaces.RealInput TConIn(final unit="K", displayUnit= "degC") "Condenser inlet temperature"; Modelica.Blocks.Interfaces.RealInput TEvaIn(final unit="K", displayUnit= "degC") "Evaporator inlet temperature"; equation assert(SGen_flow > 0, "Entropy generated is zero or negative, which violates the 2nd law. This is because the model is configured to use the inlet temperatures to compute the Carnot efficiency, which can lead to non-physical results.", level = AssertionLevel.warning); connect(SIn_flow.y, dS_flow.u1); connect(sin1.ports[1],S_a2. port_b); connect(sou1.ports[1],S_a1. port_a); connect(S_a1.port_b,chi. port_a1); connect(chi.port_b1,S_a4. port_a); connect(S_a4.port_b,sin2. ports[1]); connect(S_a3.port_a,sou2. ports[1]); connect(S_a2.port_a,chi. port_b2); connect(S_a3.port_b,chi. port_a2); connect(S_a4.S_flow,SOut_flow. u2); connect(S_a2.S_flow,SOut_flow. u1); connect(S_a3.S_flow,SIn_flow. u2); connect(S_a1.S_flow,SIn_flow. u1); connect(SOut_flow.y,dS_flow. u2); connect(TSetEvaLea, chi.TSet); connect(SGen_flow, dS_flow.y); connect(TConIn, sou1.T_in); connect(TEvaIn, sou2.T_in); end Chiller; equation connect(TSetEvaLvg.u1, TEvaIn.y); connect(dTEva.y, TSetEvaLvg.u2); connect(TSetEvaLvg.y, TConIn.u1); connect(dTConEva.y, TConIn.u2); connect(TEvaIn.y, chi_b.TEvaIn); connect(TSetEvaLvg.y, chi_b.TSetEvaLea); connect(chi_b.TConIn, TConIn.y); end Carnot_TEva_2ndLaw;

Annex60.Fluid.Chillers.Validation.Carnot_TEva_HighTemperature

Information

This example extends from Annex60.Fluid.Chillers.Examples.Carnot_TEva but increases the set point for the leaving evaporator temperature to be above its inlet temperature, in which case the model provides no cooling. Towards the end of the simulation, the inlet temperature of the evaporator is increased to be above the condenser temperature. In this domain, the model requires cooling again. While this is not a meaningful operating point for the model, the example verifies that it robustly simulates this regime.

Extends from Examples.Carnot_TEva (Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal).

Parameters

Modelica definition

Type	Name	Default	Description
TemperatureDifference	dTEva_nominal	-10	Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal	10	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
HeatFlowRate	QEva_flow_nominal	-100E3	Evaporator heat flow rate [W]
MassFlowRate	m2_flow_nominal	QEva_flow_nominal/dTEva_nomi...	Nominal mass flow rate at chilled water side [kg/s]

model Carnot_TEva_HighTemperature "Test model for Carnot_TEva with high evaporator temperature" extends Examples.Carnot_TEva(TEvaLvg(height=34), sou2(use_T_in=true)); Modelica.Blocks.Sources.Ramp TEvaEnt( startTime=3000, height=38, offset=273.15 + 22, duration=60) "Control signal for evaporator entering temperature"; equation connect(TEvaEnt.y, sou2.T_in); end Carnot_TEva_HighTemperature;

Annex60.Fluid.Chillers.Validation.Carnot_TEva_LimitedCapacity

Information

Extends from Examples.Carnot_TEva (Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal).

Parameters

Modelica definition

Type	Name	Default	Description
TemperatureDifference	dTEva_nominal	-10	Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal	10	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
HeatFlowRate	QEva_flow_nominal	-100E3	Evaporator heat flow rate [W]
MassFlowRate	m2_flow_nominal	QEva_flow_nominal/dTEva_nomi...	Nominal mass flow rate at chilled water side [kg/s]

model Carnot_TEva_LimitedCapacity "Test model for Carnot_TEva with limited heating capacity" extends Examples.Carnot_TEva( chi(QEva_flow_min=-100000)); end Carnot_TEva_LimitedCapacity;

Annex60.Fluid.Chillers.Validation.Carnot_TEva_etaPL

Test model for the part load efficiency curve with evaporator leaving temperature as input signal

Annex60.Fluid.Chillers.Validation.Carnot_TEva_etaPL

Information

Extends from Examples.Carnot_TEva (Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal).

Parameters

Modelica definition

Type	Name	Default	Description
TemperatureDifference	dTEva_nominal	-10	Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal	10	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
HeatFlowRate	QEva_flow_nominal	-100E3	Evaporator heat flow rate [W]
MassFlowRate	m2_flow_nominal	QEva_flow_nominal/dTEva_nomi...	Nominal mass flow rate at chilled water side [kg/s]

model Carnot_TEva_etaPL "Test model for the part load efficiency curve with evaporator leaving temperature as input signal" extends Examples.Carnot_TEva( chi(a={0.7,0.3}, QEva_flow_min=-100000)); end Carnot_TEva_etaPL;

Annex60.Fluid.Chillers.Validation.Carnot_TEva_reverseFlow

Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal

Annex60.Fluid.Chillers.Validation.Carnot_TEva_reverseFlow

Information

Example that simulates a chiller whose efficiency is scaled based on the Carnot cycle. The chiller takes as an input the evaporator leaving water temperature. The condenser mass flow rate is computed in such a way that it has a temperature difference equal to dTEva_nominal.

Parameters

Modelica definition

Type	Name	Default	Description
TemperatureDifference	dTEva_nominal	-10	Temperature difference evaporator inlet-outlet [K]
TemperatureDifference	dTCon_nominal	10	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
HeatFlowRate	QEva_flow_nominal	-100E3	Evaporator heat flow rate [W]
MassFlowRate	m2_flow_nominal	QEva_flow_nominal/dTEva_nomi...	Nominal mass flow rate at chilled water side [kg/s]
MassFlowRate	m1_flow_nominal	m2_flow_nominal*(COPc_nomina...	Nominal mass flow rate at condenser water wide [kg/s]

model Carnot_TEva_reverseFlow "Test model for chiller based on Carnot efficiency and evaporator outlet temperature control signal" extends Modelica.Icons.Example; package Medium1 = Annex60.Media.Water "Medium model"; package Medium2 = Annex60.Media.Water "Medium model"; parameter Modelica.SIunits.TemperatureDifference dTEva_nominal=-10 "Temperature difference evaporator inlet-outlet"; parameter Modelica.SIunits.TemperatureDifference dTCon_nominal=10 "Temperature difference condenser outlet-inlet"; parameter Real COPc_nominal = 3 "Chiller COP"; parameter Modelica.SIunits.HeatFlowRate QEva_flow_nominal = -100E3 "Evaporator heat flow rate"; parameter Modelica.SIunits.MassFlowRate m2_flow_nominal= QEva_flow_nominal/dTEva_nominal/4200 "Nominal mass flow rate at chilled water side"; parameter Modelica.SIunits.MassFlowRate m1_flow_nominal= m2_flow_nominal*(COPc_nominal+1)/COPc_nominal "Nominal mass flow rate at condenser water wide"; Annex60.Fluid.Chillers.Carnot_TEva chi( redeclare package Medium1 = Medium1, redeclare package Medium2 = Medium2, dTEva_nominal=dTEva_nominal, dTCon_nominal=dTCon_nominal, use_eta_Carnot_nominal=true, etaCarnot_nominal=0.3, m1_flow_nominal=m1_flow_nominal, m2_flow_nominal=m2_flow_nominal, show_T=true, QEva_flow_nominal=QEva_flow_nominal, allowFlowReversal1=true, allowFlowReversal2=true, dp1_nominal=6000, dp2_nominal=6000) "Chiller model"; Annex60.Fluid.Sources.MassFlowSource_T sou1(nPorts=1, redeclare package Medium = Medium1, m_flow=m1_flow_nominal, use_T_in=false, use_m_flow_in=true, T=298.15); Annex60.Fluid.Sources.MassFlowSource_T sou2(nPorts=1, redeclare package Medium = Medium2, m_flow=m2_flow_nominal, use_T_in=false, use_m_flow_in=true, T=295.15); Annex60.Fluid.Sources.FixedBoundary sin1( redeclare package Medium = Medium1, nPorts=1); Annex60.Fluid.Sources.FixedBoundary sin2(nPorts=1, redeclare package Medium = Medium2); Modelica.Blocks.Sources.Constant TEvaLvg(k=273.15 + 10) "Control signal for evaporator leaving temperature"; Modelica.Blocks.Math.Gain mCon_flow(k=-1/cp1_default/dTEva_nominal) "Condenser mass flow rate"; Modelica.Blocks.Math.Add QCon_flow(k2=-1) "Condenser heat flow rate"; final parameter Modelica.SIunits.SpecificHeatCapacity cp1_default= Medium1.specificHeatCapacityCp(Medium1.setState_pTX( Medium1.p_default, Medium1.T_default, Medium1.X_default)) "Specific heat capacity of medium 1 at default medium state"; Modelica.Blocks.Sources.Ramp mEva_flow( duration=60, startTime=1800, height=-2*m2_flow_nominal, offset=m2_flow_nominal) "Mass flow rate for evaporater"; equation connect(sou1.ports[1], chi.port_a1); connect(sou2.ports[1], chi.port_a2); connect(sin2.ports[1], chi.port_b2); connect(TEvaLvg.y, chi.TSet); connect(chi.P, QCon_flow.u1); connect(chi.QEva_flow, QCon_flow.u2); connect(QCon_flow.y, mCon_flow.u); connect(mCon_flow.y, sou1.m_flow_in); connect(chi.port_b1, sin1.ports[1]); connect(mEva_flow.y, sou2.m_flow_in); end Carnot_TEva_reverseFlow;

Annex60.Fluid.Chillers.Validation.Carnot_y_etaPL

Test model for the part load efficiency curve with compressor speed as input signal

Annex60.Fluid.Chillers.Validation.Carnot_y_etaPL

Information

Extends from Examples.Carnot_y (Test model for chiller based on Carnot_y efficiency).

Parameters

Modelica definition

Type	Name	Default	Description
Power	P_nominal	10E3	Nominal compressor power (at y=1) [W]
TemperatureDifference	dTEva_nominal	-10	Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal	10	Temperature difference condenser outlet-inlet [K]
Real	COPc_nominal	3	Chiller COP
MassFlowRate	m2_flow_nominal	-P_nominal*COPc_nominal/dTEv...	Nominal mass flow rate at chilled water side [kg/s]
MassFlowRate	m1_flow_nominal	m2_flow_nominal*(COPc_nomina...	Nominal mass flow rate at condenser water wide [kg/s]

model Carnot_y_etaPL "Test model for the part load efficiency curve with compressor speed as input signal" extends Examples.Carnot_y(chi(a={0.7,0.3})); end Carnot_y_etaPL;

Annex60.Fluid.Chillers.Validation.Carnot_TEva_2ndLaw.Chiller

Parameters

Connectors

Modelica definition

Type	Name	Default	Description
replaceable package Medium1	Modelica.Media.Interfaces.Pa...	Medium model
replaceable package Medium2	Modelica.Media.Interfaces.Pa...	Medium model
TemperatureDifference	dTEva_nominal		Temperature difference evaporator outlet-inlet [K]
TemperatureDifference	dTCon_nominal		Temperature difference condenser outlet-inlet [K]
HeatFlowRate	QEva_flow_nominal		Evaporator heat flow rate [W]
MassFlowRate	m1_flow_nominal		Nominal mass flow rate at condeser water side [kg/s]
MassFlowRate	m2_flow_nominal		Nominal mass flow rate at chilled water side [kg/s]

Type	Name	Description
replaceable package Medium1	Medium model
replaceable package Medium2	Medium model
input RealInput	TSetEvaLea	Set point for evaporator leaving temperature [K]
output RealOutput	SGen_flow	Entropy generated
input RealInput	TConIn	Condenser inlet temperature [K]
input RealInput	TEvaIn	Evaporator inlet temperature [K]

model Chiller "Subsystem model with the chiller" replaceable package Medium1 = Modelica.Media.Interfaces.PartialMedium "Medium model"; replaceable package Medium2 = Modelica.Media.Interfaces.PartialMedium "Medium model"; parameter Modelica.SIunits.TemperatureDifference dTEva_nominal "Temperature difference evaporator outlet-inlet"; parameter Modelica.SIunits.TemperatureDifference dTCon_nominal "Temperature difference condenser outlet-inlet"; parameter Modelica.SIunits.HeatFlowRate QEva_flow_nominal "Evaporator heat flow rate"; parameter Modelica.SIunits.MassFlowRate m1_flow_nominal "Nominal mass flow rate at condeser water side"; parameter Modelica.SIunits.MassFlowRate m2_flow_nominal "Nominal mass flow rate at chilled water side"; Annex60.Fluid.Sources.MassFlowSource_T sou1( redeclare package Medium = Medium1, nPorts=1, use_m_flow_in=false, use_T_in=true, m_flow=m1_flow_nominal) "Mass flow rate source"; Annex60.Fluid.Sources.FixedBoundary sin1(redeclare package Medium = Medium2, nPorts=1) "Pressure source"; Annex60.Fluid.Chillers.Carnot_TEva chi( redeclare package Medium1 = Medium1, redeclare package Medium2 = Medium2, dTEva_nominal=dTEva_nominal, dTCon_nominal=dTCon_nominal, m2_flow_nominal=m2_flow_nominal, show_T=true, QEva_flow_nominal=QEva_flow_nominal, allowFlowReversal1=false, allowFlowReversal2=false, etaCarnot_nominal=0.3, dp1_nominal=0, dp2_nominal=0, energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState, use_eta_Carnot_nominal=true) "Chiller model"; Annex60.Fluid.Sources.MassFlowSource_T sou2( redeclare package Medium = Medium2, m_flow=m2_flow_nominal, use_T_in=true, T=293.15, nPorts=1) "Mass flow rate source"; Annex60.Fluid.Sensors.EntropyFlowRate S_a1( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a2( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a3( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sensors.EntropyFlowRate S_a4( redeclare package Medium = Medium1, m_flow_nominal=m1_flow_nominal, tau=0) "Entropy flow rate sensor"; Annex60.Fluid.Sources.FixedBoundary sin2(redeclare package Medium = Medium2, nPorts=1) "Pressure source"; Modelica.Blocks.Math.Add SIn_flow "Entropy carried by flow that goes into the chiller"; Modelica.Blocks.Math.Add SOut_flow "Entropy carried by flow that leaves the chiller"; Modelica.Blocks.Math.Add dS_flow(k1=-1) "Change in entropy inflow and outflow"; Modelica.Blocks.Interfaces.RealInput TSetEvaLea(unit="K") "Set point for evaporator leaving temperature"; Modelica.Blocks.Interfaces.RealOutput SGen_flow "Entropy generated"; Modelica.Blocks.Interfaces.RealInput TConIn(final unit="K", displayUnit= "degC") "Condenser inlet temperature"; Modelica.Blocks.Interfaces.RealInput TEvaIn(final unit="K", displayUnit= "degC") "Evaporator inlet temperature"; equation assert(SGen_flow > 0, "Entropy generated is zero or negative, which violates the 2nd law. This is because the model is configured to use the inlet temperatures to compute the Carnot efficiency, which can lead to non-physical results.", level = AssertionLevel.warning); connect(SIn_flow.y, dS_flow.u1); connect(sin1.ports[1],S_a2. port_b); connect(sou1.ports[1],S_a1. port_a); connect(S_a1.port_b,chi. port_a1); connect(chi.port_b1,S_a4. port_a); connect(S_a4.port_b,sin2. ports[1]); connect(S_a3.port_a,sou2. ports[1]); connect(S_a2.port_a,chi. port_b2); connect(S_a3.port_b,chi. port_a2); connect(S_a4.S_flow,SOut_flow. u2); connect(S_a2.S_flow,SOut_flow. u1); connect(S_a3.S_flow,SIn_flow. u2); connect(S_a1.S_flow,SIn_flow. u1); connect(SOut_flow.y,dS_flow. u2); connect(TSetEvaLea, chi.TSet); connect(SGen_flow, dS_flow.y); connect(TConIn, sou1.T_in); connect(TEvaIn, sou2.T_in); end Chiller;