modelVariableSpeed

Variable speed water source DX coils

Extends from Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialWaterCooledDXCoil (Base class for water source DX coils).

Information

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

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

Parameters

Type	Name	Default	Description
Buildings.Fluid.DXSystems.Cooling.AirSource.Data.Generic.DXCoil	datCoi (from EssentialParameters)		Performance data
Boolean	homotopyInitialization (from PartialWaterCooledDXCoil)	true	= true, use homotopy method
Boolean	computeReevaporation (from PartialWaterCooledDXCoil)	true	Set to true to compute reevaporation of water that accumulated on coil
Real	minSpeRat		Minimum speed ratio
Real	speRatDeaBan	0.05	Deadband for minimum speed ratio
Assumptions
Boolean	allowFlowReversalEva (from PartialWaterCooledDXCoil)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for evaporator
Boolean	allowFlowReversalCon (from PartialWaterCooledDXCoil)	true	= false to simplify equations, assuming, but not enforcing, no flow reversal for condenser
Nominal condition
Modelica.Units.SI.PressureDifference	dpEva_nominal (from PartialWaterCooledDXCoil)		Pressure difference over evaporator at nominal flow rate
Modelica.Units.SI.PressureDifference	dpCon_nominal (from PartialWaterCooledDXCoil)		Pressure difference over condenser at nominal flow rate
Flow resistance › Evaporator
Boolean	from_dpEva (from PartialWaterCooledDXCoil)	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Real	nEva (from PartialWaterCooledDXCoil)	2	Flow exponent, nEva=1 for laminar, nEva=2 for turbulent
Boolean	linearizeFlowResistanceEva (from PartialWaterCooledDXCoil)	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaMEva (from PartialWaterCooledDXCoil)	0.1	Fraction of nominal flow rate where flow transitions to laminar
Flow resistance › Condenser
Boolean	from_dpCon (from PartialWaterCooledDXCoil)	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Real	nCon (from PartialWaterCooledDXCoil)	2	Flow exponent, nCon=1 for laminar, nCon=2 for turbulent
Boolean	linearizeFlowResistanceCon (from PartialWaterCooledDXCoil)	false	= true, use linear relation between m_flow and dp for any flow rate
Real	deltaMCon (from PartialWaterCooledDXCoil)	0.1	Fraction of nominal flow rate where flow transitions to laminar
Dynamics › Evaporator
Modelica.Units.SI.Time	tauEva (from PartialWaterCooledDXCoil)	60	Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState)
Dynamics › Condenser
Modelica.Units.SI.Time	tauCon (from PartialWaterCooledDXCoil)	60	Time constant at nominal flow rate (used if energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState)
Initialization › Evaporator
MediumEva.AbsolutePressure	pEva_start (from PartialWaterCooledDXCoil)	MediumEva.p_default	Start value of pressure
MediumEva.Temperature	TEva_start (from PartialWaterCooledDXCoil)	MediumEva.T_default	Start value of temperature
MediumEva.MassFraction[MediumEva.nX]	XEva_start (from PartialWaterCooledDXCoil)	MediumEva.X_default	Start value of mass fractions m_i/m
MediumEva.ExtraProperty[MediumEva.nC]	CEva_start (from PartialWaterCooledDXCoil)	fill(0, MediumEva.nC)	Start value of trace substances
MediumEva.ExtraProperty[MediumEva.nC]	CEva_nominal (from PartialWaterCooledDXCoil)	fill(1E-2, MediumEva.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Initialization › Condenser
MediumCon.AbsolutePressure	pCon_start (from PartialWaterCooledDXCoil)	MediumCon.p_default	Start value of pressure
MediumCon.Temperature	TCon_start (from PartialWaterCooledDXCoil)	MediumCon.T_default	Start value of temperature
MediumCon.MassFraction[MediumCon.nX]	XCon_start (from PartialWaterCooledDXCoil)	MediumCon.X_default	Start value of mass fractions m_i/m
MediumCon.ExtraProperty[MediumCon.nC]	CCon_start (from PartialWaterCooledDXCoil)	fill(0, MediumCon.nC)	Start value of trace substances
MediumCon.ExtraProperty[MediumCon.nC]	CCon_nominal (from PartialWaterCooledDXCoil)	fill(1E-2, MediumCon.nC)	Nominal value of trace substances. (Set to typical order of magnitude.)
Dynamics › Conservation equations
Modelica.Fluid.Types.Dynamics	energyDynamics (from PartialWaterCooledDXCoil)	Modelica.Fluid.Types.Dynamics.DynamicFreeInitial	Type of energy balance: dynamic (3 initialization options) or steady state
Advanced › Diagnostics
Boolean	show_T (from PartialWaterCooledDXCoil)	false	= true, if actual temperature at port is computed

Connectors

Type	Name	Description
Modelica.Blocks.Interfaces.RealOutput	P (from PartialWaterCooledDXCoil)	Electrical power consumed by the unit
Modelica.Blocks.Interfaces.RealOutput	QEvaSen_flow (from PartialWaterCooledDXCoil)	Sensible heat flow rate in evaporators
Modelica.Blocks.Interfaces.RealOutput	QEvaLat_flow (from PartialWaterCooledDXCoil)	Latent heat flow rate in evaporators
Modelica.Fluid.Interfaces.FluidPort_a	port_a (from PartialWaterCooledDXCoil)	Fluid connector for evaporator inlet (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_b	port_b (from PartialWaterCooledDXCoil)	Fluid connector b1 (positive design flow direction is from port_a1 to port_b1)
Modelica.Fluid.Interfaces.FluidPort_a	portCon_a (from PartialWaterCooledDXCoil)	Fluid connector a of condenser (positive design flow direction is from port_a2 to port_b2)
Modelica.Fluid.Interfaces.FluidPort_b	portCon_b (from PartialWaterCooledDXCoil)	Fluid connector b of condenser (positive design flow direction is from port_a2 to port_b2)
Modelica.Blocks.Interfaces.RealInput	speRat	Speed ratio

Components

Type	Name	Default	Description
Buildings.Fluid.DXSystems.Cooling.BaseClasses.PartialDXCoolingCoil	eva (from PartialWaterCooledDXCoil)
Buildings.Fluid.HeatExchangers.HeaterCooler_u	watCooCon (from PartialWaterCooledDXCoil)		Water source condenser
Modelica.Units.SI.Temperature	TConEnt (from PartialWaterCooledDXCoil)	MediumCon.temperature(MediumCon.setState_phX(portCon_a.p, inStream(portCon_a.h_outflow)))	Temperature of fluid entering the condenser
MediumEva.ThermodynamicState	sta_a1 (from PartialWaterCooledDXCoil)	MediumEva.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow)))	Medium properties in port_a1
MediumEva.ThermodynamicState	sta_b1 (from PartialWaterCooledDXCoil)	MediumEva.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow)))	Medium properties in port_b1
MediumCon.ThermodynamicState	sta_a2 (from PartialWaterCooledDXCoil)	MediumCon.setState_phX(portCon_a.p, noEvent(actualStream(portCon_a.h_outflow)), noEvent(actualStream(portCon_a.Xi_outflow)))	Medium properties in port_a2
MediumCon.ThermodynamicState	sta_b2 (from PartialWaterCooledDXCoil)	MediumCon.setState_phX(portCon_b.p, noEvent(actualStream(portCon_b.h_outflow)), noEvent(actualStream(portCon_b.Xi_outflow)))	Medium properties in port_b2

Revisions

April 5, 2023, by Xing Lu:
Updated air-source cooling coil class being extended from VariableSpeed to Buildings.Fluid.DXSystems.Cooling.AirSource.VariableSpeed.
March 7, 2022, by Michael Wetter:
Set final massDynamics=energyDynamics.
This is for #1542.
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.