modelPartialWaterCooledDXCoil

Base class for water source DX coils
Diagram of PartialWaterCooledDXCoilOpen the diagram
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Extends from Buildings.BaseClasses.BaseIcon (Base icon), Buildings.Fluid.DXSystems.Cooling.BaseClasses.EssentialParameters (A partial block for essential parameters for cooling DX coils).

Information

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

See Buildings.Fluid.DXSystems.Cooling.UsersGuide for an explanation of the model.

Parameters

TypeNameDefaultDescription
Buildings.Fluid.DXSystems.Cooling.AirSource.Data.Generic.DXCoildatCoi (from EssentialParameters)Performance data
BooleanhomotopyInitializationtrue= true, use homotopy method
BooleancomputeReevaporationtrueSet to true to compute reevaporation of water that accumulated on coil
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
Nominal condition
Modelica.Units.SI.PressureDifferencedpEva_nominalPressure difference over evaporator at nominal flow rate
Modelica.Units.SI.PressureDifferencedpCon_nominalPressure difference over condenser at nominal flow rate
Flow resistance › Evaporator
Booleanfrom_dpEvafalse= true, use m_flow = f(dp) else dp = f(m_flow)
RealnEva2Flow exponent, nEva=1 for laminar, nEva=2 for turbulent
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
Flow resistance › Condenser
Booleanfrom_dpConfalse= true, use m_flow = f(dp) else dp = f(m_flow)
RealnCon2Flow exponent, nCon=1 for laminar, nCon=2 for turbulent
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
Dynamics › Evaporator
Modelica.Units.SI.TimetauEva60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState)
Dynamics › Condenser
Modelica.Units.SI.TimetauCon60Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState)
Initialization › Evaporator
MediumEva.AbsolutePressurepEva_startMediumEva.p_defaultStart value of pressure
MediumEva.TemperatureTEva_startMediumEva.T_defaultStart value of temperature
MediumEva.MassFraction[MediumEva.nX]XEva_startMediumEva.X_defaultStart value of mass fractions m_i/m
MediumEva.ExtraProperty[MediumEva.nC]CEva_startfill(0, MediumEva.nC)Start value of trace substances
MediumEva.ExtraProperty[MediumEva.nC]CEva_nominalfill(1E-2, MediumEva.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Initialization › Condenser
MediumCon.AbsolutePressurepCon_startMediumCon.p_defaultStart value of pressure
MediumCon.TemperatureTCon_startMediumCon.T_defaultStart value of temperature
MediumCon.MassFraction[MediumCon.nX]XCon_startMediumCon.X_defaultStart value of mass fractions m_i/m
MediumCon.ExtraProperty[MediumCon.nC]CCon_startfill(0, MediumCon.nC)Start value of trace substances
MediumCon.ExtraProperty[MediumCon.nC]CCon_nominalfill(1E-2, MediumCon.nC)Nominal value of trace substances. (Set to typical order of magnitude.)
Dynamics › Conservation equations
Modelica.Fluid.Types.DynamicsenergyDynamicsModelica.Fluid.Types.Dynamics.DynamicFreeInitialType of energy balance: dynamic (3 initialization options) or steady state
Advanced › Diagnostics
Booleanshow_Tfalse= true, if actual temperature at port is computed

Connectors

TypeNameDefaultDescription
Modelica.Blocks.Interfaces.RealOutputPElectrical power consumed by the unit
Modelica.Blocks.Interfaces.RealOutputQEvaSen_flowSensible heat flow rate in evaporators
Modelica.Blocks.Interfaces.RealOutputQEvaLat_flowLatent heat flow rate in evaporators
Modelica.Fluid.Interfaces.FluidPort_aport_aFluid connector for evaporator inlet (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_bport_bFluid connector b1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_aportCon_aFluid connector a of condenser (positive design flow direction is from port_a2 to port_b2)
Modelica.Fluid.Interfaces.FluidPort_bportCon_bFluid connector b of condenser (positive design flow direction is from port_a2 to port_b2)

Components

TypeNameDefaultDescription
Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoileva
Buildings.Fluid.HeatExchangers.HeaterCooler_uwatCooConWater source condenser
Modelica.Units.SI.TemperatureTConEntMediumCon.temperature(MediumCon.setState_phX(portCon_a.p, inStream(portCon_a.h_outflow)))Temperature of fluid entering the condenser
MediumEva.ThermodynamicStatesta_a1MediumEva.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow)))Medium properties in port_a1
MediumEva.ThermodynamicStatesta_b1MediumEva.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow)))Medium properties in port_b1
MediumCon.ThermodynamicStatesta_a2MediumCon.setState_phX(portCon_a.p, noEvent(actualStream(portCon_a.h_outflow)), noEvent(actualStream(portCon_a.Xi_outflow)))Medium properties in port_a2
MediumCon.ThermodynamicStatesta_b2MediumCon.setState_phX(portCon_b.p, noEvent(actualStream(portCon_b.h_outflow)), noEvent(actualStream(portCon_b.Xi_outflow)))Medium properties in port_b2

Contents

NameDescription
MediumEvaMedium for evaporator
MediumConMedium for condenser

Revisions

  • June 17, 2026, by Michael Wetter:
    Updated implementation to allow a flow coefficient n that is different from 2. This allows use of the model for not fully turbulent flow.
    This is for Buildings, #4620.
  • November 26, 2025, by Michael Wetter:
    Updated redeclare and replaceable statements.
    This is for issue 4421.
  • April 5 , 2023, by Xing Lu:
    Changed instance name dxCoo in instance eva to dxCoi. Changed baseclass used from PartialDXCoil to PartialDXCoolingCoil.
    Connect statements with references to TConIn changed to TOut.
  • March 3, 2022, by Michael Wetter:
    Moved massDynamics to Advanced tab and added assertion for correct combination of energy and mass dynamics.
    This is for issue 1542.
  • April 14, 2020, by Michael Wetter:
    Changed homotopyInitialization to a constant.
    This is for IBPSA, #1341.
  • March 21, 2017, by Michael Wetter:
    Moved assignment of evaporator data datCoi from the constrainedBy declaration in the base class to the instantiation to work around a limitation of JModelica.
  • March 7, 2017, by Michael Wetter:
    Refactored implementation to avoid code duplication and to propagate parameters.
  • February 16, 2017 by Yangyang Fu:
    First implementation.