modelGasCooledHEX
Extends from HEXtubesDefinition.
Information
This partial model performs the calculation of the heat exchange coefficient, and pressure drop, of the gas part (normally air) of an air cooled, finned tubes, exchanger.The LMTD correction factor is also calculated.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Flow data | |||
| Modelica.Units.SI.Distance | iElevDiff (from HEXtubesDefinition) | 0 | inner pipe differential elevation: out elev. - in elev. |
| Modelica.Units.SI.Distance | oElevDiff (from HEXtubesDefinition) | 0 | outer flow differential elevation: out elev. - in elev. |
| Real | iNumVelocityHeads (from HEXtubesDefinition) | 2*iNumSerial | inner flow number of velocity heads to consider in pressure loss |
| Integer | iNumUturns (from HEXtubesDefinition) | iNumSerial - 1 | number of U turns in each exchanger |
| Inner pipe data | |||
| Boolean | iIsCircular (from HEXtubesDefinition) | true | if false, the inner pipe is not circular |
| Modelica.Units.SI.Distance | iDi (from HEXtubesDefinition) | 0.0 | inner pipe internal diameter, if circular |
| Modelica.Units.SI.Area | iSection (from HEXtubesDefinition) | 0 | inner pipe flow section, if not circular |
| Modelica.Units.SI.Distance | iPerimeter (from HEXtubesDefinition) | 0 | inner pipe perimeter, if not circular |
| Modelica.Units.SI.Distance | iThickness (from HEXtubesDefinition) | 1e-3 | inner pipe thickness |
| Modelica.Units.SI.Distance | iRoughness (from HEXtubesDefinition) | 1.5e-005 | inner pipe roughness. SS:1.5e-5, Steel new:4.6e-5, Steel old:2.0e-4, Concrete:1.5e-3 |
| Modelica.Units.SI.Density | iRhoWall (from HEXtubesDefinition) | 8000 | inner pipe wall density |
| Modelica.Units.SI.ThermalConductivity | iKwall (from HEXtubesDefinition) | 16 | inner pipe wall thermal conductivity. Al=210, Cu=390, Steel=50, SS=17 |
| Modelica.Units.SI.Distance | iLTube (from HEXtubesDefinition) | 0 | stright length of each individual inner pipe |
| Integer | iNumPipes (from HEXtubesDefinition) | 1 | number of inner pipes that form a common pass |
| Integer | iNumParallel (from HEXtubesDefinition) | 1 | number of parallel inner passes. Normally it is the number of exchangers |
| Integer | iNumSerial (from HEXtubesDefinition) | 2 | number of serial inner passes (Each hairpin has two serial passes) |
| Integer | iNumRows | number of pipe rows passed by the gas flow | |
| Boolean | iStaggered | true | if false, inline distribution |
| Modelica.Units.SI.Distance | iTubePitch | 2*iDi | distance between tubes |
| Modelica.Units.SI.Distance | iDop | iDi + 2*iThickness | inner pipe outer diameter, or width, perpenticular to gas flow |
| Heat transfer | |||
| Modelica.Units.SI.ThermalInsulance | iFoulingF (from HEXtubesDefinition) | 0.0002 | inner pipe side fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water |
| Modelica.Units.SI.ThermalInsulance | oFoulingF (from HEXtubesDefinition) | 0.0002 | outer flow fouling factor.Typical: 0.00018 for thermal oil, or treated cooling water |
| Boolean | useHTcorr (from HEXtubesDefinition) | true | if true, the heat transfer correction factor is used |
| Boolean | counterCurrent (from HEXtubesDefinition) | true | true if flow is counter-current, otherwise it will be considered co-current |
| Boolean | useBYnusselt | false | if true, the Briggs and Youg Nusselt calc. will be used, otherwise the Ganguli's one |
| Fins data | |||
| Boolean | useFins (from HEXtubesDefinition) | false | if true, fins are taken into account in calculations |
| Modelica.Units.SI.Density | finRho (from HEXtubesDefinition) | 0 | fin density. Al=2700, Cu=8930, Steel=7830, SS=8000 |
| Modelica.Units.SI.ThermalConductivity | finK (from HEXtubesDefinition) | 0 | fin thermal conductivity. Al=210, Cu=390, Steel=50, SS=17 |
| Modelica.Units.SI.Distance | finThickness (from HEXtubesDefinition) | 0.0 | fin thickness |
| Modelica.Units.SI.Distance | finDistance | distance between fins | |
| Boolean | finIsCircular | true | if false rectangular fin is used |
| Modelica.Units.SI.Distance | finDiameter | fin external diameter, if circular | |
| Modelica.Units.SI.Distance | finWidth | side length perpenticular to flow, if rectangular | |
| Modelica.Units.SI.Distance | finHeight | side length along flow, if rectangular | |
Connectors
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | ItotalNumPipes (from HEXtubesDefinition) | total number of individual inner pipes | |
| Modelica.Units.SI.Distance | IiPerimeter (from HEXtubesDefinition) | inner pipe internal wetted perimeter | |
| Modelica.Units.SI.Area | IiSection (from HEXtubesDefinition) | inner pipe internal flow section | |
| Modelica.Units.SI.Distance | IDh (from HEXtubesDefinition) | internal pipe hydraulic diameter | |
| Modelica.Units.SI.Area | IiArea (from HEXtubesDefinition) | total inner pipes internal heat transfer area | |
| Modelica.Units.SI.Distance | IoPerimeter (from HEXtubesDefinition) | inner pipe external perimeter | |
| Modelica.Units.SI.Area | IoSection (from HEXtubesDefinition) | inner pipe external section | |
| Modelica.Units.SI.Area | IoArea (from HEXtubesDefinition) | total inner pipes external heat transfer area | |
| MediumI.ThermodynamicState | IStateIn (from HEXtubesDefinition) | inner flow inlet state | |
| MediumI.ThermodynamicState | IStateOut (from HEXtubesDefinition) | inner flow outlet state | |
| Modelica.Units.SI.Temperature | ITin (from HEXtubesDefinition) | inner flow inlet temperature | |
| Modelica.Units.SI.Temperature | ITout (from HEXtubesDefinition) | iiner flow outlet temperature | |
| Modelica.Units.SI.Temperature | IT (from HEXtubesDefinition) | inner pipe average temperature | |
| MediumI.ThermodynamicState | IStateWall (from HEXtubesDefinition) | inner pipe wall state for correction factors calculation | |
| Modelica.Units.SI.Temperature | ITwall (from HEXtubesDefinition) | inner pipe wall temperature | |
| Modelica.Units.SI.DynamicViscosity | IMuWall (from HEXtubesDefinition) | inner pipe wall dynamic viscosity | |
| Real | IPlossCorr (from HEXtubesDefinition) | internal pipe pressure loss correction factor | |
| Modelica.Units.SI.AbsolutePressure | IPloss (from HEXtubesDefinition) | internal pipe pressure loss by friction, without taking into account the nozzles | |
| Real | IHTcorr (from HEXtubesDefinition) | internal pipe heat transfer correction factor | |
| Modelica.Units.SI.NusseltNumber | INu (from HEXtubesDefinition) | inner pipe Nusselt number | |
| Modelica.Units.SI.CoefficientOfHeatTransfer | IH (from HEXtubesDefinition) | inner pipe average heat transfer coefficient | |
| MediumO.ThermodynamicState | OStateIn (from HEXtubesDefinition) | outer flow inlet state | |
| MediumO.ThermodynamicState | OStateOut (from HEXtubesDefinition) | outer flow outlet state | |
| Modelica.Units.SI.Temperature | OTin (from HEXtubesDefinition) | outer flow inlet temperature | |
| Modelica.Units.SI.Temperature | OTout (from HEXtubesDefinition) | outer flow outlet temperature | |
| Modelica.Units.SI.Temperature | OT (from HEXtubesDefinition) | outer flow average temperature | |
| Modelica.Units.SI.Length | IEquivLength (from HEXtubesDefinition) | internal pipe equivalent length for pressure drop | |
| Real | OPlossCorr (from HEXtubesDefinition) | outer flow pressure loss correction factor | |
| Modelica.Units.SI.AbsolutePressure | OPloss (from HEXtubesDefinition) | outer flow pressure loss by friction | |
| Modelica.Units.SI.Area | OiArea (from HEXtubesDefinition) | total outer flow internal area for heat transfer | |
| Fraction | OiEfficiency (from HEXtubesDefinition) | outer flow internal area efficiency | |
| Modelica.Units.SI.NusseltNumber | ONu (from HEXtubesDefinition) | outer flow nusselt number for internal heat transfer | |
| Modelica.Units.SI.CoefficientOfHeatTransfer | OHi (from HEXtubesDefinition) | outer flow average heat transfer coefficient to inner pipe | |
| Modelica.Units.SI.ThermalResistance | TRii (from HEXtubesDefinition) | total resitance for the transfer between inner fluid and inner wall | |
| Modelica.Units.SI.ThermalResistance | TRio (from HEXtubesDefinition) | total resitance for the transfer between outer fluid and inner wall | |
| Modelica.Units.SI.ThermalResistance | TRi (from HEXtubesDefinition) | total resitance for the transfer between inner and outer fluids | |
| Modelica.Units.SI.CoefficientOfHeatTransfer | Ui (from HEXtubesDefinition) | global heat transfer coefficient referenced to total inner flow area | |
| Modelica.Units.SI.TemperatureDifference | ILMTD (from HEXtubesDefinition) | LMTD between inner and outer fluids | |
| Fraction | ILMTDcorr (from HEXtubesDefinition) | internal LMTD correction factor | |
| Real | Rntu (from HEXtubesDefinition) | ||
| Real | NTU (from HEXtubesDefinition) | ||
| Modelica.Units.SI.Power | IW (from HEXtubesDefinition) | heat exchanged between inner and outer fluids. Positive if heat enters the inner fluid | |
| Modelica.Units.SI.Area | IiArea1 (from HEXtubesDefinition) | total inner pipes internal heat transfer area used in first stage transfer | |
| Modelica.Units.SI.ThermalResistance | TRi1 (from HEXtubesDefinition) | total resitance for the transfer between inner and outer fluids in the first stage | |
| Modelica.Units.SI.Area | IoAreaRaw | total external surface of tubes without the fins | |
| Modelica.Units.SI.Area | FinsArea | total external surface of fins | |
| Modelica.Units.SI.Area | Sface | total area perpenticular to gas flow | |
| Modelica.Units.SI.Area | Sflow | total free area available for gas flow | |
| Real | OFinRatio | ||
| Real | OPhi | ||
| MediumO.ThermodynamicState | OStateAvg | outer flow average state for physical properties calculation | |
| Modelica.Units.SI.Density | ORho | outer flow average density | |
| Modelica.Units.SI.DynamicViscosity | OMu | outer flow average dynamic viscosity | |
| Modelica.Units.SI.SpecificHeatCapacity | OCp | outer flow average heat capacity | |
| Modelica.Units.SI.ThermalConductivity | OK | outer flow average thermal conductivity | |
| Modelica.Units.SI.PrandtlNumber | OPr | outer flow Prandt number | |
| Modelica.Units.SI.VolumeFlowRate | OQ | total outer volume flow rate at average conditions | |
| Modelica.Units.SI.Velocity | Vmax | gas velocity at the free surface | |
| Modelica.Units.SI.Velocity | Vface | gas velocity as per Sface. Typical: 2.5-3.5 m/s | |
| Modelica.Units.SI.ReynoldsNumber | ORe | outer flow average Reynolds number | |
| Real | Oa | ||
| Modelica.Units.SI.ReynoldsNumber | OReff | outer flow effective Reynolds number | |
| Real | OF | outer flow Fanning's friction factor at average conditions | |
| Modelica.Units.SI.NusseltNumber | ONuGan | gas side Nusselt number as per Ganguli | |
| Modelica.Units.SI.NusseltNumber | ONuBY | gas side Nusselt as for Briggs and Young | |
| Real | OX |