Falling Film Evaporator¶

DWSIM Plus

Available with a DWSIM Plus (Patreon) subscription.

Falling film evaporator: heats the inlet liquid in a number of increments, each with a share of the pressure drop, and splits the result into a vapor outlet and a concentrated liquid outlet. The heat is set by an outlet temperature, an outlet vapor fraction, or the energy inlet stream. Ports: Material Inlet and Energy Inlet; Vapor Outlet and Concentrated Liquid.

DWSIM.UnitOperations.ExtensionPack.FallingFilmEvaporator
Assembly DWSIM.UnitOperations.ExtensionPack.dll · Object ← BaseClass ← UnitOpBaseClass ← FallingFilmEvaporator

At a glance¶

Falling Film Evaporator in the example flowsheet

Port	Index	Connected in the example
Inlet, material	`0`	Feed
Inlet, energy	`1`	Heating
Outlet, material	`0`	Vapor
Outlet, material	`1`	Concentrate

Example¶

This code runs on every build of this site, and the output below is what it printed.

Python

fs = (Flowsheet.Create("FallingFilmExample")
      .WithCompounds("Water", "Ethylene glycol")
      .WithPropertyPackage(PropertyPackages.NRTL))

feed = (fs.AddMaterialStream("Feed")
        .At(Q.Celsius(60.0), Q.Bar(0.3))
        .SetCompoundMassFlow("Water", 4.0)              # kg/s
        .SetCompoundMassFlow("Ethylene glycol", 1.0))
vapor = fs.AddMaterialStream("Vapor")
concentrate = fs.AddMaterialStream("Concentrate")
steam = fs.AddEnergyStream("Heating")

# Evaporate until 60 % of the inlet moles leave as vapor, in 20 increments.
ffe = (fs.AddFallingFilmEvaporator("FFE-1")
       .WithCalculationMode(FallingFilmEvaporator.CalcMode.OutletVaporFraction)
       .WithOutletVaporFraction(0.6)
       .WithIncrementSteps(20)
       .ConnectFeed(feed)
       .ConnectEnergyFeed(steam, 1)                     # heating duty enters at port 1
       .ConnectProduct(vapor, 0)
       .ConnectProduct(concentrate, 1))

fs.AutoLayout()
fs.Solve()

c = concentrate.Object
glycol = c.GetCompoundMassFlow("Ethylene glycol") / c.GetMassFlow()
print(f"Heat load           = {ffe.Object.HeatLoad:.0f} kW")
print(f"Boiling temperature = {concentrate.TemperatureK - 273.15:.1f} C")
print(f"Vapor flow          = {vapor.Object.GetMassFlow():.3f} kg/s")
print(f"Concentrate flow    = {c.GetMassFlow():.3f} kg/s, {glycol * 100:.1f} wt% glycol")

Output

Heat load           = 6259 kW
Boiling temperature = 73.3 C
Vapor flow          = 2.588 kg/s
Concentrate flow    = 2.412 kg/s, 40.6 wt% glycol

DWSIM 10.2.11.0, generated 2026-10-08.

Properties¶

IDs accepted by GetPropertyValue, SetPropertyValue, the sensitivity analysis, the optimizer, the Adjust block and dynamic events. Units are SI; pass another unit system to GetPropertyValue to get them converted.

ID	Unit (SI)	Input
`Calculation Mode`		yes
`Pressure Drop`	Pa	yes
`Increment`		yes
`Outlet Temperature`	K	yes
`Outlet Vapor Fraction`		yes
`Heat Load`	kW	yes

Learn more¶

User guide
- Falling Film Evaporator
FluentAPI
- Plus.FallingFilmEvaporatorBuilder

API members¶

Public members declared by this class. Inherited members are documented on the base classes.

Constructors¶

FallingFilmEvaporator(): Initializes a new default instance of the FallingFilmEvaporator class.

Initializes a new default instance of the FallingFilmEvaporator class.

C#VB.NET

public FallingFilmEvaporator()

Public Sub New()

FallingFilmEvaporator(string, string): Initializes a new instance of the FallingFilmEvaporator class with a name and description.

Initializes a new instance of the FallingFilmEvaporator class with a name and description.

Parameter	Type	Description
`Name`	`String`	The name of this unit operation.
`Description`	`String`	A brief description of this unit operation.

C#VB.NET

public FallingFilmEvaporator(string Name, string Description)

Public Sub New(Name As String, Description As String)

Properties¶

CalculationMode: Gets or sets how the heat added is determined: OutletTemperature (0) heats up to...

Gets or sets how the heat added is determined: OutletTemperature (0) heats up to OutletTemperature; OutletVaporFraction (1, default) evaporates up to OutletVaporFraction; EnergyStream (2) adds the energy flow of the connected energy inlet stream. In the first two modes the computed heat load is written to the energy inlet stream.

C#VB.NET

public FallingFilmEvaporator.CalcMode CalculationMode { get; set; }

Public Property CalculationMode As FallingFilmEvaporator.CalcMode

ComponentDescription: Gets or sets the CAPE-OPEN component description for this unit operation.

Gets or sets the CAPE-OPEN component description for this unit operation.

C#VB.NET

public override string ComponentDescription { get; set; }

Public Overrides Property ComponentDescription As String

ComponentName: Gets or sets the CAPE-OPEN component name for this unit operation.

Gets or sets the CAPE-OPEN component name for this unit operation.

C#VB.NET

public override string ComponentName { get; set; }

Public Overrides Property ComponentName As String

EvaporationProfile: Gets or sets the evaporation profile: one item per calculation increment with the temperature, pressure, heat added...

Gets or sets the evaporation profile: one item per calculation increment with the temperature, pressure, heat added and phase properties at that point. Calculated result.

C#VB.NET

public List<FallingFilmEvaporator.EvaporationProfileItem> EvaporationProfile { get; set; }

Public Property EvaporationProfile As List(Of FallingFilmEvaporator.EvaporationProfileItem)

HeatLoad: Gets or sets the total heat added to the process stream, in kW.

Gets or sets the total heat added to the process stream, in kW. Calculated result.

C#VB.NET

public double HeatLoad { get; set; }

Public Property HeatLoad As Double

IncrementSteps: Gets or sets the number of increments the heating is divided into; each increment adds a row to...

Gets or sets the number of increments the heating is divided into; each increment adds a row to EvaporationProfile. Default 10.

C#VB.NET

public double IncrementSteps { get; set; }

Public Property IncrementSteps As Double

IsPremium: Gets a value indicating whether this unit operation is a premium (DWSIM Patreon) unit operation.

Gets a value indicating whether this unit operation is a premium (DWSIM Patreon) unit operation. Always True; the object palette lists it under the Premium category.

C#VB.NET

public bool IsPremium { get; }

Public ReadOnly Property IsPremium As Boolean

MobileCompatible: Gets a value indicating whether this unit operation is compatible with mobile interfaces.

Gets a value indicating whether this unit operation is compatible with mobile interfaces. Always False.

C#VB.NET

public override bool MobileCompatible { get; }

Public Overrides ReadOnly Property MobileCompatible As Boolean

ObjectClass: Gets or sets the simulation object class category (Exchangers).

Gets or sets the simulation object class category (Exchangers).

C#VB.NET

public override SimulationObjectClass ObjectClass { get; set; }

Public Overrides Property ObjectClass As SimulationObjectClass

OutletTemperature: Gets or sets the specified outlet temperature, in K, used when CalculationMode is OutletTemperature.

Gets or sets the specified outlet temperature, in K, used when CalculationMode is OutletTemperature. Default 300 K.

C#VB.NET

public double OutletTemperature { get; set; }

Public Property OutletTemperature As Double

OutletVaporFraction: Gets or sets the specified outlet vapor mole fraction, used when CalculationMode is...

Gets or sets the specified outlet vapor mole fraction, used when CalculationMode is OutletVaporFraction. Default 0.3.

C#VB.NET

public double OutletVaporFraction { get; set; }

Public Property OutletVaporFraction As Double

PressureDrop: Gets or sets the total pressure drop across the evaporator, in Pa, distributed evenly over the increments.

Gets or sets the total pressure drop across the evaporator, in Pa, distributed evenly over the increments. Default 0.

C#VB.NET

public double PressureDrop { get; set; }

Public Property PressureDrop As Double

Methods¶

Calculate(object): Calculates the object.

Calculates the object.

Parameter	Type	Description
`args`	`Object`

C#VB.NET

public override void Calculate(object args = null)

Public Overrides Sub Calculate(args As Object = Nothing)

CloneXML(): Creates a deep copy of this object by round-tripping through XML serialization.

Creates a deep copy of this object by round-tripping through XML serialization.

C#VB.NET

public override object CloneXML()

Public Overrides Function CloneXML() As Object

CloseEditForm(): Closes the editor of this object, if it is open.

Closes the editor of this object, if it is open.

C#VB.NET

public override void CloseEditForm()

Public Overrides Sub CloseEditForm()

DeCalculate(): Decalculates the object.

Decalculates the object.

C#VB.NET

public override void DeCalculate()

Public Overrides Sub DeCalculate()

DisplayEditForm(): Opens the editor of this object.

Opens the editor of this object. A host that has no editor for it does nothing.

C#VB.NET

public override void DisplayEditForm()

Public Overrides Sub DisplayEditForm()

GetDefaultProperties(): Returns the identifiers of the properties shown by default for this unit operation.

Returns the identifiers of the properties shown by default for this unit operation.

C#VB.NET

public override string[] GetDefaultProperties()

Public Overrides Function GetDefaultProperties() As String()

GetDisplayDescription(): Returns the description string for this unit operation type.

Returns the description string for this unit operation type.

C#VB.NET

public override string GetDisplayDescription()

Public Overrides Function GetDisplayDescription() As String

GetDisplayName(): Returns the display name for this unit operation type.

Returns the display name for this unit operation type.

C#VB.NET

public override string GetDisplayName()

Public Overrides Function GetDisplayName() As String

GetIconBitmapBytes(): Returns the raw bytes of the icon image for this unit operation.

Returns the raw bytes of the icon image for this unit operation.

C#VB.NET

public override byte[] GetIconBitmapBytes()

Public Overrides Function GetIconBitmapBytes() As Byte()

GetProperties(PropertyType): Get a list of all properties of the object.

Get a list of all properties of the object.

Parameter	Type	Description
`proptype`	`PropertyType`	Type of the property.

C#VB.NET

public override string[] GetProperties(PropertyType proptype)

Public Overrides Function GetProperties(proptype As PropertyType) As String()

GetPropertyDescription(string): Returns the description of the specified property.

Returns the description of the specified property.

Parameter	Type	Description
`p`	`String`	The property name.

C#VB.NET

public override string GetPropertyDescription(string p)

Public Overrides Function GetPropertyDescription(p As String) As String

GetPropertyUnit(string, IUnitsOfMeasure): Gets the units of a property.

Gets the units of a property.

Parameter	Type	Description
`prop`	`String`	Property identifier.
`su`	`IUnitsOfMeasure`	Units system to use. Null to use the default (SI) system.

C#VB.NET

public override string GetPropertyUnit(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyUnit(prop As String, su As IUnitsOfMeasure = Nothing) As String

GetPropertyValue(string, IUnitsOfMeasure): Returns the value of a named property, converting from SI to the current unit system.

Returns the value of a named property, converting from SI to the current unit system. Falls back to extra properties if the property is not found in the base implementation.

Parameter	Type	Description
`prop`	`String`	The property identifier string.
`su`	`IUnitsOfMeasure`	Optional units-of-measure system used for conversion; uses the shared SI system when `Nothing`.

C#VB.NET

public override object GetPropertyValue(string prop, IUnitsOfMeasure su = null)

Public Overrides Function GetPropertyValue(prop As String, su As IUnitsOfMeasure = Nothing) As Object

GetReport(IUnitsOfMeasure, CultureInfo, string): Generates a plain-text results report for this unit operation.

Generates a plain-text results report for this unit operation.

Parameter	Type	Description
`su`	`IUnitsOfMeasure`	The unit system used for formatting output values.
`ci`	`CultureInfo`	The culture info used for number formatting.
`numberformat`	`String`	A .NET numeric format string (e.g. "G6") applied to output values.

C#VB.NET

public override string GetReport(IUnitsOfMeasure su, CultureInfo ci, string numberformat)

Public Overrides Function GetReport(su As IUnitsOfMeasure, ci As CultureInfo, numberformat As String) As String

GetStructuredReport(): Generates a structured (tabular) results report for display in the UI.

Generates a structured (tabular) results report for display in the UI.

C#VB.NET

public override List<Tuple<ReportItemType, string[]>> GetStructuredReport()

Public Overrides Function GetStructuredReport() As List(Of Tuple(Of ReportItemType, String()))

LoadData(List<XElement>): Restores the unit operation state from a list of XML elements previously produced by SaveData.

Restores the unit operation state from a list of XML elements previously produced by SaveData.

Parameter	Type	Description
`data`	`List<XElement>`	The list of `XElement` objects containing serialized state.

C#VB.NET

public override bool LoadData(List<XElement> data)

Public Overrides Function LoadData(data As List(Of XElement)) As Boolean

SaveData(): Serializes the unit operation state to a list of XML elements for persistence.

Serializes the unit operation state to a list of XML elements for persistence.

C#VB.NET

public override List<XElement> SaveData()

Public Overrides Function SaveData() As List(Of XElement)

SetPropertyValue(string, object, IUnitsOfMeasure): Sets the value of a property.

Sets the value of a property.

Parameter	Type	Description
`prop`	`String`	Property identifier.
`propval`	`Object`	Property value to set at the specified units.
`su`	`IUnitsOfMeasure`	Units system to use. Null to use the default (SI) system.

C#VB.NET

public override bool SetPropertyValue(string prop, object propval, IUnitsOfMeasure su = null)

Public Overrides Function SetPropertyValue(prop As String, propval As Object, su As IUnitsOfMeasure = Nothing) As Boolean

UpdateEditForm(): Redraws the editor of this object with the current values, if it is open.

Redraws the editor of this object with the current values, if it is open.

C#VB.NET

public override void UpdateEditForm()

Public Overrides Sub UpdateEditForm()

Fields¶

f: The classic (WinForms) editor window open for this unit operation, if any.

The classic (WinForms) editor window open for this unit operation, if any. Not saved with the flowsheet.

C#VB.NET

public EditingForm_FallingFilm f

Public f As EditingForm_FallingFilm