modelHEXtubesDefinition

Diagram of HEXtubesDefinitionOpen the diagram

Information

Contains just the definitions of the inner pipe elements needed for the development of the outer flow models. With no equations, in order to allow multiple inheritance of the model without giving too many equations.

Parameters

TypeNameDefaultDescription
Flow data
Modelica.Units.SI.DistanceiElevDiff0inner pipe differential elevation: out elev. - in elev.
Modelica.Units.SI.DistanceoElevDiff0outer flow differential elevation: out elev. - in elev.
RealiNumVelocityHeads2*iNumSerialinner flow number of velocity heads to consider in pressure loss
IntegeriNumUturnsiNumSerial - 1number of U turns in each exchanger
Inner pipe data
BooleaniIsCirculartrueif false, the inner pipe is not circular
Modelica.Units.SI.DistanceiDi0.0inner pipe internal diameter, if circular
Modelica.Units.SI.AreaiSection0inner pipe flow section, if not circular
Modelica.Units.SI.DistanceiPerimeter0inner pipe perimeter, if not circular
Modelica.Units.SI.DistanceiThickness1e-3inner pipe thickness
Modelica.Units.SI.DistanceiRoughness1.5e-005inner pipe roughness. SS:1.5e-5, Steel new:4.6e-5, Steel old:2.0e-4, Concrete:1.5e-3
Modelica.Units.SI.DensityiRhoWall8000inner pipe wall density
Modelica.Units.SI.ThermalConductivityiKwall16inner pipe wall thermal conductivity. Al=210, Cu=390, Steel=50, SS=17
Modelica.Units.SI.DistanceiLTube0stright length of each individual inner pipe
IntegeriNumPipes1number of inner pipes that form a common pass
IntegeriNumParallel1number of parallel inner passes. Normally it is the number of exchangers
IntegeriNumSerial2number of serial inner passes (Each hairpin has two serial passes)
Heat transfer
Modelica.Units.SI.ThermalInsulanceiFoulingF0.0002inner pipe side fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water
Modelica.Units.SI.ThermalInsulanceoFoulingF0.0002outer flow fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water
BooleanuseHTcorrtrueif true, the heat transfer correction factor is used
BooleancounterCurrenttruetrue if flow is counter-current, otherwise it will be considered co-current
Fins data
BooleanuseFinsfalseif true, fins are taken into account in calculations
Modelica.Units.SI.DensityfinRho0fin density. Al=2700, Cu=8930, Steel=7830, SS=8000
Modelica.Units.SI.ThermalConductivityfinK0fin thermal conductivity. Al=210, Cu=390, Steel=50, SS=17
Modelica.Units.SI.DistancefinThickness0.0fin thickness

Connectors

TypeNameDefaultDescription
FreeFluids.Interfaces.FluidPortAIin
FreeFluids.Interfaces.FluidPortBIout
FreeFluids.Interfaces.FluidPortAOin
FreeFluids.Interfaces.FluidPortBOout

Components

TypeNameDefaultDescription
IntegerItotalNumPipestotal number of individual inner pipes
Modelica.Units.SI.DistanceIiPerimeterinner pipe internal wetted perimeter
Modelica.Units.SI.AreaIiSectioninner pipe internal flow section
Modelica.Units.SI.DistanceIDhinternal pipe hydraulic diameter
Modelica.Units.SI.AreaIiAreatotal inner pipes internal heat transfer area
Modelica.Units.SI.DistanceIoPerimeterinner pipe external perimeter
Modelica.Units.SI.AreaIoSectioninner pipe external section
Modelica.Units.SI.AreaIoAreatotal inner pipes external heat transfer area
MediumI.ThermodynamicStateIStateIninner flow inlet state
MediumI.ThermodynamicStateIStateOutinner flow outlet state
Modelica.Units.SI.TemperatureITininner flow inlet temperature
Modelica.Units.SI.TemperatureIToutiiner flow outlet temperature
Modelica.Units.SI.TemperatureITinner pipe average temperature
MediumI.ThermodynamicStateIStateWallinner pipe wall state for correction factors calculation
Modelica.Units.SI.TemperatureITwallinner pipe wall temperature
Modelica.Units.SI.DynamicViscosityIMuWallinner pipe wall dynamic viscosity
RealIPlossCorrinternal pipe pressure loss correction factor
Modelica.Units.SI.AbsolutePressureIPlossinternal pipe pressure loss by friction, without taking into account the nozzles
RealIHTcorrinternal pipe heat transfer correction factor
Modelica.Units.SI.NusseltNumberINuinner pipe Nusselt number
Modelica.Units.SI.CoefficientOfHeatTransferIHinner pipe average heat transfer coefficient
MediumO.ThermodynamicStateOStateInouter flow inlet state
MediumO.ThermodynamicStateOStateOutouter flow outlet state
Modelica.Units.SI.TemperatureOTinouter flow inlet temperature
Modelica.Units.SI.TemperatureOToutouter flow outlet temperature
Modelica.Units.SI.TemperatureOTouter flow average temperature
Modelica.Units.SI.LengthIEquivLengthinternal pipe equivalent length for pressure drop
RealOPlossCorrouter flow pressure loss correction factor
Modelica.Units.SI.AbsolutePressureOPlossouter flow pressure loss by friction
Modelica.Units.SI.AreaOiAreatotal outer flow internal area for heat transfer
FractionOiEfficiencyouter flow internal area efficiency
Modelica.Units.SI.NusseltNumberONuouter flow nusselt number for internal heat transfer
Modelica.Units.SI.CoefficientOfHeatTransferOHiouter flow average heat transfer coefficient to inner pipe
Modelica.Units.SI.ThermalResistanceTRiitotal resitance for the transfer between inner fluid and inner wall
Modelica.Units.SI.ThermalResistanceTRiototal resitance for the transfer between outer fluid and inner wall
Modelica.Units.SI.ThermalResistanceTRitotal resitance for the transfer between inner and outer fluids
Modelica.Units.SI.CoefficientOfHeatTransferUiglobal heat transfer coefficient referenced to total inner flow area
Modelica.Units.SI.TemperatureDifferenceILMTDLMTD between inner and outer fluids
FractionILMTDcorrinternal LMTD correction factor
RealRntu
RealNTU
Modelica.Units.SI.PowerIWheat exchanged between inner and outer fluids. Positive if heat enters the inner fluid
Modelica.Units.SI.AreaIiArea1total inner pipes internal heat transfer area used in first stage transfer
Modelica.Units.SI.ThermalResistanceTRi1total resitance for the transfer between inner and outer fluids in the first stage

Contents

NameDescription
MediumI
MediumO