Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled

Waterr-cooled DX package unit

Information

This package contains water-cooled DX coil models, including single-speed, multi-speed, and variable-speed DX coil models.

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

Package Content

Name Description
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.MultiStage MultiStage Multi speed water-cooled DX coils
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.SingleSpeed SingleSpeed Single speed water-cooled DX coils
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.VariableSpeed VariableSpeed Variable speed water-cooled DX coils
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Data Data Package with performance data for water-cooled DX coils
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Examples Examples Package with example of water-cooled DX cooling coil models
Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Validation Validation Collection of validation models

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.MultiStage Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.MultiStage

Multi speed water-cooled DX coils

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.MultiStage

Information

This model can be used to simulate a water-cooled DX cooling coil with multiple operating stages. Depending on the used performance curves, each stage could be a different compressor speed, or a different mode of operation, such as with or without hot gas reheat.

See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.

Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil (Base class for water-cooled DX coils).

Parameters

TypeNameDefaultDescription
DXCoildatCoiredeclare Buildings.Fluid.He...Performance data
replaceable package MediumEvaPartialMediumMedium for evaporator
replaceable package MediumConPartialMediumMedium for condenser
BooleancomputeReevaporationtrueSet to true to compute reevaporation of water that accumulated on coil
Nominal condition
PressureDifferencedpEva_nominal Pressure difference over evaporator at nominal flow rate [Pa]
PressureDifferencedpCon_nominal Pressure difference over condenser at nominal flow rate [Pa]
Assumptions
BooleanallowFlowReversalEvatrue= false to simplify equations, assuming, but not enforcing, no flow reversal for evaporator
BooleanallowFlowReversalContrue= false to simplify equations, assuming, but not enforcing, no flow reversal for condenser
Advanced
BooleanhomotopyInitializationtrue= true, use homotopy method
Diagnostics
Booleanshow_Tfalse= true, if actual temperature at port is computed
Flow resistance
Condenser
Booleanfrom_dpEvafalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceEvafalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMEva0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Evaporator
Booleanfrom_dpConfalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceConfalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMCon0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Dynamics
Condenser
TimetauEva60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Evaporator
TimetauCon60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
DynamicsmassDynamicsenergyDynamicsType of mass balance: dynamic (3 initialization options) or steady state
Initialization
Medium 1
AbsolutePressurepEva_startMediumEva.p_defaultStart value of pressure [Pa]
TemperatureTEva_startMediumEva.T_defaultStart value of temperature [K]
MassFractionXEva_start[MediumEva.nX]MediumEva.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCEva_start[MediumEva.nC]fill(0, MediumEva.nC)Start value of trace substances
ExtraPropertyCEva_nominal[MediumEva.nC]fill(1E-2, MediumEva.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Medium 2
AbsolutePressurepCon_startMediumCon.p_defaultStart value of pressure [Pa]
TemperatureTCon_startMediumCon.T_defaultStart value of temperature [K]
MassFractionXCon_start[MediumCon.nX]MediumCon.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCCon_start[MediumCon.nC]fill(0, MediumCon.nC)Start value of trace substances
ExtraPropertyCCon_nominal[MediumCon.nC]fill(1E-2, MediumCon.nC)Nominal value of trace substances. (Set to typical order of magnitude.)

Connectors

TypeNameDescription
output RealOutputPElectrical power consumed by the unit [W]
output RealOutputQEvaSen_flowSensible heat flow rate in evaporators [W]
output RealOutputQEvaLat_flowLatent heat flow rate in evaporators [W]
FluidPort_aport_aFluid connector for evaporator inlet (positive design flow direction is from port_a1 to port_b1)
FluidPort_bport_bFluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_aportCon_aFluid connector a of condenser (positive design flow direction is from port_a2 to port_b2)
FluidPort_bportCon_bFluid connector b of condenser (positive design flow direction is from port_a2 to port_b2)
input IntegerInputstageStage of cooling coil (0: off, 1: first stage, 2: second stage...)

Modelica definition

model MultiStage "Multi speed water-cooled DX coils" extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil ( redeclare final Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.MultiStage eva( redeclare final Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Data.Generic.DXCoil datCoi=datCoi)); Modelica.Blocks.Interfaces.IntegerInput stage "Stage of cooling coil (0: off, 1: first stage, 2: second stage...)"; equation connect(eva.stage, stage); end MultiStage;

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.SingleSpeed Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.SingleSpeed

Single speed water-cooled DX coils

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.SingleSpeed

Information

This model can be used to simulate a water-cooled DX cooling coil with single speed compressor.

See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.

Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil (Base class for water-cooled DX coils).

Parameters

TypeNameDefaultDescription
DXCoildatCoiredeclare Buildings.Fluid.He...Performance data
replaceable package MediumEvaPartialMediumMedium for evaporator
replaceable package MediumConPartialMediumMedium for condenser
BooleancomputeReevaporationtrueSet to true to compute reevaporation of water that accumulated on coil
Nominal condition
PressureDifferencedpEva_nominal Pressure difference over evaporator at nominal flow rate [Pa]
PressureDifferencedpCon_nominal Pressure difference over condenser at nominal flow rate [Pa]
Assumptions
BooleanallowFlowReversalEvatrue= false to simplify equations, assuming, but not enforcing, no flow reversal for evaporator
BooleanallowFlowReversalContrue= false to simplify equations, assuming, but not enforcing, no flow reversal for condenser
Advanced
BooleanhomotopyInitializationtrue= true, use homotopy method
Diagnostics
Booleanshow_Tfalse= true, if actual temperature at port is computed
Flow resistance
Condenser
Booleanfrom_dpEvafalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceEvafalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMEva0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Evaporator
Booleanfrom_dpConfalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceConfalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMCon0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Dynamics
Condenser
TimetauEva60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Evaporator
TimetauCon60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
DynamicsmassDynamicsenergyDynamicsType of mass balance: dynamic (3 initialization options) or steady state
Initialization
Medium 1
AbsolutePressurepEva_startMediumEva.p_defaultStart value of pressure [Pa]
TemperatureTEva_startMediumEva.T_defaultStart value of temperature [K]
MassFractionXEva_start[MediumEva.nX]MediumEva.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCEva_start[MediumEva.nC]fill(0, MediumEva.nC)Start value of trace substances
ExtraPropertyCEva_nominal[MediumEva.nC]fill(1E-2, MediumEva.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Medium 2
AbsolutePressurepCon_startMediumCon.p_defaultStart value of pressure [Pa]
TemperatureTCon_startMediumCon.T_defaultStart value of temperature [K]
MassFractionXCon_start[MediumCon.nX]MediumCon.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCCon_start[MediumCon.nC]fill(0, MediumCon.nC)Start value of trace substances
ExtraPropertyCCon_nominal[MediumCon.nC]fill(1E-2, MediumCon.nC)Nominal value of trace substances. (Set to typical order of magnitude.)

Connectors

TypeNameDescription
output RealOutputPElectrical power consumed by the unit [W]
output RealOutputQEvaSen_flowSensible heat flow rate in evaporators [W]
output RealOutputQEvaLat_flowLatent heat flow rate in evaporators [W]
FluidPort_aport_aFluid connector for evaporator inlet (positive design flow direction is from port_a1 to port_b1)
FluidPort_bport_bFluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_aportCon_aFluid connector a of condenser (positive design flow direction is from port_a2 to port_b2)
FluidPort_bportCon_bFluid connector b of condenser (positive design flow direction is from port_a2 to port_b2)
input BooleanInputonSet to true to enable compressor, or false to disable compressor

Modelica definition

model SingleSpeed "Single speed water-cooled DX coils" extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil ( redeclare Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.SingleSpeed eva( redeclare final Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Data.Generic.DXCoil datCoi=datCoi)); Modelica.Blocks.Interfaces.BooleanInput on "Set to true to enable compressor, or false to disable compressor"; equation connect(eva.on, on); end SingleSpeed;

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.VariableSpeed Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.VariableSpeed

Variable speed water-cooled DX coils

Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.VariableSpeed

Information

This model can be used to simulate a water-cooled DX cooling coil with variable speed compressor.

See Buildings.Fluid.HeatExchangers.DXCoils.UsersGuide for an explanation of the model.

Extends from Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil (Base class for water-cooled DX coils).

Parameters

TypeNameDefaultDescription
DXCoildatCoiredeclare Buildings.Fluid.He...Performance data
replaceable package MediumEvaPartialMediumMedium for evaporator
replaceable package MediumConPartialMediumMedium for condenser
BooleancomputeReevaporationtrueSet to true to compute reevaporation of water that accumulated on coil
RealminSpeRatminSpeRat( ...Minimum speed ratio
RealspeRatDeaBan0.05Deadband for minimum speed ratio
Nominal condition
PressureDifferencedpEva_nominal Pressure difference over evaporator at nominal flow rate [Pa]
PressureDifferencedpCon_nominal Pressure difference over condenser at nominal flow rate [Pa]
Assumptions
BooleanallowFlowReversalEvatrue= false to simplify equations, assuming, but not enforcing, no flow reversal for evaporator
BooleanallowFlowReversalContrue= false to simplify equations, assuming, but not enforcing, no flow reversal for condenser
Advanced
BooleanhomotopyInitializationtrue= true, use homotopy method
Diagnostics
Booleanshow_Tfalse= true, if actual temperature at port is computed
Flow resistance
Condenser
Booleanfrom_dpEvafalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceEvafalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMEva0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Evaporator
Booleanfrom_dpConfalse= true, use m_flow = f(dp) else dp = f(m_flow)
BooleanlinearizeFlowResistanceConfalse= true, use linear relation between m_flow and dp for any flow rate
RealdeltaMCon0.1Fraction of nominal flow rate where flow transitions to laminar [1]
Dynamics
Condenser
TimetauEva60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Evaporator
TimetauCon60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState) [s]
Equations
DynamicsenergyDynamicsModelica.Fluid.Types.Dynamic...Type of energy balance: dynamic (3 initialization options) or steady state
DynamicsmassDynamicsenergyDynamicsType of mass balance: dynamic (3 initialization options) or steady state
Initialization
Medium 1
AbsolutePressurepEva_startMediumEva.p_defaultStart value of pressure [Pa]
TemperatureTEva_startMediumEva.T_defaultStart value of temperature [K]
MassFractionXEva_start[MediumEva.nX]MediumEva.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCEva_start[MediumEva.nC]fill(0, MediumEva.nC)Start value of trace substances
ExtraPropertyCEva_nominal[MediumEva.nC]fill(1E-2, MediumEva.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Medium 2
AbsolutePressurepCon_startMediumCon.p_defaultStart value of pressure [Pa]
TemperatureTCon_startMediumCon.T_defaultStart value of temperature [K]
MassFractionXCon_start[MediumCon.nX]MediumCon.X_defaultStart value of mass fractions m_i/m [kg/kg]
ExtraPropertyCCon_start[MediumCon.nC]fill(0, MediumCon.nC)Start value of trace substances
ExtraPropertyCCon_nominal[MediumCon.nC]fill(1E-2, MediumCon.nC)Nominal value of trace substances. (Set to typical order of magnitude.)

Connectors

TypeNameDescription
output RealOutputPElectrical power consumed by the unit [W]
output RealOutputQEvaSen_flowSensible heat flow rate in evaporators [W]
output RealOutputQEvaLat_flowLatent heat flow rate in evaporators [W]
FluidPort_aport_aFluid connector for evaporator inlet (positive design flow direction is from port_a1 to port_b1)
FluidPort_bport_bFluid connector b1 (positive design flow direction is from port_a1 to port_b1)
FluidPort_aportCon_aFluid connector a of condenser (positive design flow direction is from port_a2 to port_b2)
FluidPort_bportCon_bFluid connector b of condenser (positive design flow direction is from port_a2 to port_b2)
input RealInputspeRatSpeed ratio

Modelica definition

model VariableSpeed "Variable speed water-cooled DX coils" extends Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.PartialWaterCooledDXCoil ( redeclare final Buildings.Fluid.HeatExchangers.DXCoils.AirCooled.VariableSpeed eva( redeclare final Buildings.Fluid.HeatExchangers.DXCoils.WaterCooled.Data.Generic.DXCoil datCoi=datCoi, final minSpeRat = minSpeRat, final speRatDeaBan = speRatDeaBan)); parameter Real minSpeRat(min=0,max=1) "Minimum speed ratio"; parameter Real speRatDeaBan= 0.05 "Deadband for minimum speed ratio"; Modelica.Blocks.Interfaces.RealInput speRat "Speed ratio"; equation connect(speRat, eva.speRat); end VariableSpeed;