modelPipeForcedConvection
Model for pipes with thermal,single phase, flow
Extends from FreeFluids.Pipes.PipeThermalBase (Base model for pipes with thermal flow).
Information
Extends the PipeThermalBase model for forced convection. As an option , you can use twisted tape inserts.If inserts are used, the friction factor is calculated according to Manglik and Bergles (Journal of Thermal Science and Egineering Applications 2013 Vol.5). For laminar flow, the constant power equation is used with a 0.8 factor, in order to allow for lower exchange in constant wall temperature situations. Otherwise the friction factor is calculated as per Churchill's equation.
A correction factor for wall viscosity can be used.
The heat transfer coefficient is calculated according to Manglik and Bergles if tape inserts are used, or according to Gnielinsky and others if not. Interpolation between laminar and turbulent flow is used. A fouling factor and a wall viscosity correction factor can also be used.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Physical data | |||
| Boolean | useTubeLength (from PipePhysical) | true | use the supplied length |
| Modelica.Units.SI.Distance | lTube (from PipePhysical) | 0 | supplied individual tube length |
| Boolean | fixNumTubes (from PipePhysical) | true | if true fixes the number of tubes to numTubes |
| Integer | numTubes (from PipePhysical) | 1 | number of parallel identical paths |
| Boolean | isCircular (from PipePhysical) | true | the pipe is circular in shape |
| Boolean | useDiameter (from PipePhysical) | true | the supplied diameter will be used for calculation of section and perimeter |
| Modelica.Units.SI.Distance | di (from PipePhysical) | 0.0 | supplied internal diameter if path is circular |
| Boolean | useSectionAndPerimeter (from PipePhysical) | false | the supplied section and perimeter will be used |
| Modelica.Units.SI.Area | section (from PipePhysical) | 0 | supplied pipe section if not circular |
| Modelica.Units.SI.Distance | perimeter (from PipePhysical) | 0 | supplied perimeter if not circular |
| Modelica.Units.SI.Distance | thickness (from PipePhysical) | 1e-3 | pipe thickness. Vessel wall thickness for halfcoils |
| Modelica.Units.SI.Distance | roughness (from PipePhysical) | 1.5e-005 | pipe roughness. SS:1.5e-5, Steel new:4.6e-5, Steel old:2.0e-4, Concrete:1.5e-3 |
| Modelica.Units.SI.Distance | thicknessInsul (from PipePhysical) | 0 | insulation thickness |
| Modelica.Units.SI.Density | rhoWall (from PipePhysical) | 8000 | |
| Ports links | |||
| Boolean | useElevDifference (from TwoFluidPorts) | true | introduces, or not, an equation for the ports elevation. Use only in one connector |
| FreeFluids.Types.ElevationOption | elevCalcMethod (from TwoFluidPorts) | FreeFluids.Types.ElevationOption.differential | if useElevDifference==true, selects the equation to use: differential, or absolute for PortB |
| Modelica.Units.SI.Length | elevDifference (from TwoFluidPorts) | 0.0 | used only if previously selected. Positive if PortB higher than PortA |
| Modelica.Units.SI.Length | portBelevation (from TwoFluidPorts) | 0.0 | used only if previously selected. |
| Boolean | calcEnthalpyDifference (from TwoFluidPorts) | true | if true, will calculate the enthalpy difference between ports. Use only in one connector |
| Boolean | passComposition (from TwoFluidPorts) | true | if true, the equation PortA.X=PortB.X will be activated |
| Flow | |||
| Integer | numActiveTubes (from Pipe) | numTubes | number of parallel identical paths used with flow. Default=numTubes |
| Real | pipeComplexity (from Pipe) | 0 | Approx. estimation of equivalent length,0=not used,0.25=supply lines,0.5=long runs, 1=normal,2=valves,4=complex valves |
| Real | equivL_Di (from Pipe) | 0 | Equivalent length of accesories as multiples of Di |
| Real | numVelocityHeads (from Pipe) | 0 | number of velocity heads for pressure loss |
| Modelica.Units.SI.Area | kv (from Pipe) | 0 | This allows for special head loses to be incorporated inside the pipe calculation via Kv |
| Fraction | aperture (from Pipe) | 1 | Fraction of Kv used |
| Boolean | fullBore (from Pipe) | true | true if the full pipe section is used for flow |
| Boolean | isCompressibleFlow (from Pipe) | false | indicates if kinetic energy and momentum are taken into account or not |
| Boolean | twoPhaseFlow (from PipeFlowBase) | false | indicates if there is a two phase flow |
| Boolean | usePLossWallCorr | true | |
| Heat transfer | |||
| FreeFluids.Types.ThermalType | thermalType (from PipeFlowBase) | FreeFluids.Types.ThermalType.detailed | Alternatives: detailed, isenthalpic, adiabatic, isothermal, fixed W, fixed deltaT. If detailed, W calculation must be supplied |
| Modelica.Units.SI.HeatFlowRate | fixedW (from PipeFlowBase) | 0 | Heat exchange if thermaltype = fixedPower. Positive if heat enters the tube |
| Modelica.Units.SI.TemperatureDifference | fixedDeltaT (from PipeFlowBase) | 0 | fixed T diff. between ports if thermalType = fixedDeltaT. Positive if Tb > Ta |
| Modelica.Units.SI.ThermalConductivity | kWall (from PipeThermalBase) | 16 | Wall thermal conductivity. typical value for SS=16.7 |
| Modelica.Units.SI.ThermalConductivity | kInsul (from PipeThermalBase) | 0.04 | Insulation thermal conductivity. Typical value for glass fiber=0.04 W/(K·m) |
| Modelica.Units.SI.ThermalInsulance | foulingF (from PipeThermalBase) | 0.0002 | Tube side fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water |
| Boolean | useWallsResistance (from PipeThermalBase) | false | if true, will calculate Twall-Tsurf according to wall conduction, otherwise Twall=Tsurf |
| Real | emissionCoef (from PipeThermalBase) | 0.26 | emission coefficient of surface typical values: Aluminium:0.1, SS:0.15, dirty metal: 0.45, non-metallic:0.94 |
| Boolean | fullHTperimeter (from PipeThermalBase) | true | indicates if all active perimeter is used in heat transfer. It is false for halfpipes |
| Boolean | fullHTlength (from PipeThermalBase) | true | indicates if all tube length is used in heat transfer. For partial immersion or condensation |
| Boolean | useThermalConnector (from PipeThermalBase) | true | if true, the thermal connector will be used for heat transfer. Otherwise a specific calculation must be coded |
| Boolean | useHTWallCorrFactor | true | |
| Boolean | useTwistedTapeInserts | false | |
| Modelica.Units.SI.Length | tapeWidth | di | only if twisted tape inserts are used |
| Modelica.Units.SI.Length | tapeThickness | thickness | only if twisted tape inserts are used |
| Real | twistRatio | 6 | Length of a 180 degrees twist divided by Di, if twisted tape inserts are used |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FreeFluids.Interfaces.FluidPortA | PortA (from TwoFluidPorts) | ||
| FreeFluids.Interfaces.FluidPortB | PortB (from TwoFluidPorts) | ||
| FreeFluids.Interfaces.HeatPortB | PortH (from PipeThermalBase) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Diameter | Di (from PipePhysical) | pipe internal diameter only if circular, otherwise four times Section/Perimeter | |
| Modelica.Units.SI.Area | PathSection (from PipePhysical) | Internal section of the tube. But not the flow section if double pipe | |
| Modelica.Units.SI.Distance | PathPerimeter (from PipePhysical) | Internal perimeter of the tube. But not the flow perimeter if double pipe | |
| Modelica.Units.SI.Distance | Ltotal (from PipePhysical) | total pipe length, as necessary for obtainning its total weight | |
| Modelica.Units.SI.Distance | Ltube (from PipePhysical) | pipe path length, as necessary for obtainning friction loss | |
| Integer | NumTubes (from PipePhysical) | number of parallel identical paths | |
| Modelica.Units.SI.Area | SiTube (from PipePhysical) | each tube internal surface | |
| Modelica.Units.SI.Area | SiTotal (from PipePhysical) | total pipe internal surface | |
| Modelica.Units.SI.Volume | ViTube (from PipePhysical) | each tube internal volume | |
| Modelica.Units.SI.Volume | ViTotal (from PipePhysical) | total pipe internal volume | |
| Modelica.Units.SI.Diameter | Do (from PipePhysical) | pipe external diameter | |
| Modelica.Units.SI.Diameter | Dinsul (from PipePhysical) | pipe diameter with insulation | |
| Modelica.Units.SI.Area | SoTube (from PipePhysical) | each tube external surface | |
| Modelica.Units.SI.Area | SoTotal (from PipePhysical) | total pipe external surface | |
| Modelica.Units.SI.Volume | VoTube (from PipePhysical) | each tube external volume | |
| Modelica.Units.SI.Volume | VoTotal (from PipePhysical) | total pipe external volume | |
| Modelica.Units.SI.Area | SinsulTube (from PipePhysical) | each tube insulation surface | |
| Modelica.Units.SI.Area | SinsulTotal (from PipePhysical) | total pipe insulation surface | |
| Modelica.Units.SI.Mass | MassPipeTotal (from PipePhysical) | total mass of the pipe | |
| Modelica.Units.SI.SpecificEnthalpy | Hdiff (from TwoFluidPorts) | specific enthalpy difference: Port B - Port A | |
| Modelica.Units.SI.PressureDifference | Pdiff (from TwoFluidPorts) | pressure difference: Port B - Port A | |
| Integer | NumActiveTubes (from Pipe) | number of parallel identical paths used with flow. | |
| Real | Slope (from Pipe) | pipe slope as (PortB.Elevation-PortA.Elevation)/Ltube | |
| Modelica.Units.SI.Area | SiActive (from Pipe) | active pipe internal surface | |
| Modelica.Units.SI.Volume | ViActive (from Pipe) | active pipe internal volume | |
| Modelica.Units.SI.Area | SoActive (from Pipe) | active pipe external surface | |
| Modelica.Units.SI.Volume | VoActive (from Pipe) | active pipe external volume | |
| Modelica.Units.SI.Area | SinsulActive (from Pipe) | active pipe external surface | |
| Modelica.Units.SI.Distance | LeTube (from Pipe) | equivalent length of the pipe for pressure loss | |
| Modelica.Units.SI.Area | PathSectionActive (from Pipe) | section of each tube used for flow calculation | |
| Modelica.Units.SI.Distance | PathPerimeterActive (from Pipe) | perimeter of each tube used for flow calculation | |
| Modelica.Units.SI.Diameter | Dh (from Pipe) | four time the hydraulic radius | |
| Modelica.Units.SI.Mass | MassProductTotal (from Pipe) | Mass of product inside all the tubes | |
| Modelica.Units.SI.Pressure | PLossFriction (from Pipe) | friction head loss | |
| Modelica.Units.SI.Velocity | Va (from PipeFlowBase) | ||
| Modelica.Units.SI.Velocity | Vb (from PipeFlowBase) | ||
| Medium.Density | RhoA (from PipeFlowBase) | density at Port A | |
| Medium.Density | RhoB (from PipeFlowBase) | density at PortB | |
| Medium.ThermodynamicState | StateA (from PipeFlowBase) | state at PortA | |
| Medium.ThermodynamicState | StateB (from PipeFlowBase) | state at PortB | |
| Modelica.Units.SI.VolumeFlowRate | Qa (from PipeFlowBase) | volume flow rate at PortA | |
| Modelica.Units.SI.VolumeFlowRate | Qb (from PipeFlowBase) | volume flow rate at PortB | |
| Medium.Temperature | Ta (from PipeFlowBase) | ||
| Medium.Temperature | Tb (from PipeFlowBase) | ||
| Modelica.Units.SI.Power | W (from PipeFlowBase) | heat transfer between fluid and wall. Positive if fluid inputs heat | |
| Medium.Temperature | Twall (from PipeThermalBase) | average wall temperature (tube inside) | |
| Medium.Temperature | Tsurf (from PipeThermalBase) | average superficial temperature (tube outside) | |
| Modelica.Units.SI.TemperatureDifference | LMTD (from PipeThermalBase) | Logarithmic mean temperature difference, referenced to Tsurf | |
| Modelica.Units.SI.Area | SactiveHT (from PipeThermalBase) | internal surface potentially active for heat transfer, due to partial perimeter usage | |
| Modelica.Units.SI.Area | SusedHT (from PipeThermalBase) | internal surface used for heat transfer, due to partial perimeter or partial length usage. Probably to be deprecated | |
| Modelica.Units.SI.CoefficientOfHeatTransfer | H (from PipeThermalBase) | average heat transfer coefficient of unique or main mechanism | |
| Medium.ThermodynamicState | StateAvg | average state for physical properties calculation | |
| Modelica.Units.SI.Density | Rho | average density used in calculations | |
| Medium.DynamicViscosity | Mu | average dynamic viscosity used in calculations | |
| Modelica.Units.SI.ReynoldsNumber | Re | Reynolds number at average conditions | |
| Real | Fl | laminar Darcy's friction factor at average conditions | |
| Real | Ft | turbulent Darcy's friction factor at average conditions | |
| Real | F | Darcy's friction factor at average conditions | |
| Modelica.Units.SI.VolumeFlowRate | Q | volume flow rate in each active tube at average conditions | |
| Modelica.Units.SI.Velocity | V | velocity at average conditions. Normally between 0.9 and 3.0 m/s for liquids | |
| Modelica.Units.SI.HeatCapacity | Cp | ||
| Modelica.Units.SI.ThermalConductivity | K | ||
| Modelica.Units.SI.PrandtlNumber | Pr | ||
| Real | PLossWallCorr | ||
| Medium.ThermodynamicState | StateW | Thermodynamic state at wall | |
| Medium.Temperature | T | absolute temperature used for physical properties calc. | |
| Medium.DynamicViscosity | MuWall | average wall viscosity | |
| Real | Fsmooth | smooth pipe friction factor | |
| Real | HTWallCorrFactor | ||
| Modelica.Units.SI.RayleighNumber | Ra | Rayleigh number | |
| Real | Sw | Swirl number | |
| Modelica.Units.SI.NusseltNumber | Nu |