modelPipeThermalBase
Base model for pipes with thermal flow
Extends from PipeFlowBase (Base model for a single medium pipe.).
Information
Extends the PipeFlowBase model, adding the variables needed for heat exchange calculation in forced convection and in falling film situations.An external surface temperature is introduced, and the LMTD is calculated in reference to this temperature. It is necessary to take into account that, except if we can grant really an unique surface temperature, the objetive of this calculation is not to obtain the exchanged heat, but to obtain a surface temperature for introducing corrections in the calculation, once the heat transfer is known. In this case the heat transfer is calculated using information from both sides.
It adds also an optional heat port, in order to allow the connection of the pipe to other thermal elements. As the connector gives only one temperature and one heat flow, the use is limited.
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 |
| 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 | 16 | Wall thermal conductivity. typical value for SS=16.7 |
| Modelica.Units.SI.ThermalConductivity | kInsul | 0.04 | Insulation thermal conductivity. Typical value for glass fiber=0.04 W/(K·m) |
| Modelica.Units.SI.ThermalInsulance | foulingF | 0.0002 | Tube side fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water |
| Boolean | useWallsResistance | false | if true, will calculate Twall-Tsurf according to wall conduction, otherwise Twall=Tsurf |
| Real | emissionCoef | 0.26 | emission coefficient of surface typical values: Aluminium:0.1, SS:0.15, dirty metal: 0.45, non-metallic:0.94 |
| Boolean | fullHTperimeter | true | indicates if all active perimeter is used in heat transfer. It is false for halfpipes |
| Boolean | fullHTlength | true | indicates if all tube length is used in heat transfer. For partial immersion or condensation |
| Boolean | useThermalConnector | true | if true, the thermal connector will be used for heat transfer. Otherwise a specific calculation must be coded |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FreeFluids.Interfaces.FluidPortA | PortA (from TwoFluidPorts) | ||
| FreeFluids.Interfaces.FluidPortB | PortB (from TwoFluidPorts) | ||
| FreeFluids.Interfaces.HeatPortB | PortH |
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 | average wall temperature (tube inside) | |
| Medium.Temperature | Tsurf | average superficial temperature (tube outside) | |
| Modelica.Units.SI.TemperatureDifference | LMTD | Logarithmic mean temperature difference, referenced to Tsurf | |
| Modelica.Units.SI.Area | SactiveHT | internal surface potentially active for heat transfer, due to partial perimeter usage | |
| Modelica.Units.SI.Area | SusedHT | internal surface used for heat transfer, due to partial perimeter or partial length usage. Probably to be deprecated | |
| Modelica.Units.SI.CoefficientOfHeatTransfer | H | average heat transfer coefficient of unique or main mechanism |