Class CompressorChartMWInterpolation

java.lang.Object

neqsim.process.equipment.compressor.CompressorChart

neqsim.process.equipment.compressor.CompressorChartMWInterpolation

All Implemented Interfaces:

Serializable, Cloneable, CompressorChartInterface

public class CompressorChartMWInterpolation
extends CompressorChart

Compressor chart with multiple performance maps at different molecular weights.

This class allows storing multiple compressor maps, each measured at a different molecular weight (or gas composition), and interpolates between them based on the actual operating molecular weight.

Use case: When compressor maps are measured at several discrete MW values (e.g., 18, 20, 22 g/mol), this class interpolates the performance parameters (head, efficiency) for an actual MW that falls between the measured values.

Interpolation method: Linear interpolation between the two nearest MW maps. Extrapolation uses the nearest boundary map.

Version:

1.0

Author:

NeqSim Development Team

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	CompressorChartMWInterpolation.InterpolationIndices	Internal class to hold interpolation indices and fraction.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	allowExtrapolation	Flag to allow extrapolation outside the MW range.
private boolean	autoGenerateStoneWallCurves	Flag to auto-generate stone wall curves when maps are added.
private boolean	autoGenerateSurgeCurves	Flag to auto-generate surge curves when maps are added.
private StreamInterface	inletStream	Reference to inlet stream for automatic MW detection.
private boolean	interpolationEnabled	Flag indicating if interpolation is needed.
private static final org.apache.logging.log4j.Logger	logger	Logger object for class.
private List<CompressorChart>	mapCharts	List of compressor charts corresponding to each MW.
private List<Double>	mapMolecularWeights	List of MW values for which maps are defined, sorted in ascending order.
private double	operatingMW	Current operating molecular weight for interpolation.
private static final long	serialVersionUID	Serialization version UID.
private boolean	useActualMW	Flag to automatically use the inlet stream's molecular weight.

Fields inherited from class CompressorChart

chartConditions, chartSpeeds, chartValues, fanLawCorrectionFitter, fanLawCorrectionFunc, flow, flowPolytropicEfficiency, head, isStoneWall, isSurge, maxSpeedCurve, minSpeedCurve, polytropicEfficiency, redflow, redflowPolytropicEfficiency, redhead, redpolytropicEfficiency, reducedFlowFitter, reducedHeadFitter, reducedHeadFitterFunc, reducedPolytropicEfficiencyFitter, reducedPolytropicEfficiencyFunc, referenceSpeed, refMW, refPressure, refTemperature, refZ, speed, stoneWallCurve, surgeCurve

Constructor Summary

Constructors

Constructor	Description
CompressorChartMWInterpolation()	Default constructor for CompressorChartMWInterpolation.

Method Summary

Modifier and Type	Method	Description
void	addMapAtMW(double molecularWeight, double[] speed, double[][] flow, double[][] head, double[][] polyEff)	Add a multi-speed compressor map at a specific molecular weight.
void	addMapAtMW(double molecularWeight, double[] speed, double[][] flow, double[][] head, double[][] flowPolyEff, double[][] polyEff)	Add a multi-speed compressor map at a specific molecular weight with separate flow arrays.
void	addMapAtMW(double molecularWeight, double[] chartConditions, double[] speed, double[][] flow, double[][] head, double[][] polyEff)	Add a compressor map at a specific molecular weight.
void	addMapAtMW(double molecularWeight, double[] chartConditions, double[] speed, double[][] flow, double[][] head, double[][] flowPolyEff, double[][] polyEff)	Add a compressor map at a specific molecular weight.
void	addMapAtMW(double molecularWeight, double speed, double[] flow, double[] head, double[] polyEff)	Add a single-speed compressor map at a specific molecular weight.
void	addMapAtMW(double molecularWeight, double speed, double[] flow, double[] head, double[] flowPolyEff, double[] polyEff)	Add a single-speed compressor map at a specific molecular weight with separate flow arrays.
private CompressorChartMWInterpolation.InterpolationIndices	findInterpolationIndices(double mw)	Find the two nearest MW maps and their interpolation weight.
private int	findMapIndex(double molecularWeight)	Find the index of a map by molecular weight.
void	generateAllStoneWallCurves()	Generate stone wall curves for all MW maps.
void	generateAllSurgeCurves()	Generate surge curves for all MW maps.
CompressorChart	getChartAtMW(double molecularWeight)	Get the chart at a specific MW.
double	getDistanceToStoneWall(double head, double flow)	Get the distance to stone wall as a ratio, using interpolated stone wall curve.
double	getDistanceToSurge(double head, double flow)	Get the distance to surge as a ratio, using interpolated surge curve.
StreamInterface	getInletStream()	Get the inlet stream reference.
List<Double>	getMapMolecularWeights()	Get the list of molecular weights for which maps are defined.
int	getNumberOfMaps()	Get the number of MW maps defined.
double	getOperatingMW()	Get the operating molecular weight.
double	getPolytropicEfficiency(double flow, double speed)	Get method for polytropic efficiency from reference curves.
double	getPolytropicHead(double flow, double speed)	Get method for polytropic head from reference curves.
double	getStoneWallFlow(double head)	Get interpolated stone wall flow at a given head.
double	getStoneWallFlowAtSpeed(double speed)	Get the stone wall flow at a specific speed, interpolated between MW maps.
double	getStoneWallHeadAtSpeed(double speed)	Get the stone wall head at a specific speed, interpolated between MW maps.
double	getSurgeFlow(double head)	Get interpolated surge flow at a given head.
double	getSurgeFlowAtSpeed(double speed)	Get the surge flow at a specific speed, interpolated between MW maps.
double	getSurgeHeadAtSpeed(double speed)	Get the surge head at a specific speed, interpolated between MW maps.
boolean	isAllowExtrapolation()	Check if extrapolation outside the MW range is allowed.
boolean	isAutoGenerateStoneWallCurves()	Check if auto-generation of stone wall curves is enabled.
boolean	isAutoGenerateSurgeCurves()	Check if auto-generation of surge curves is enabled.
boolean	isInterpolationEnabled()	Check if MW interpolation is enabled.
boolean	isStoneWall(double head, double flow)	Check if operating point is at stone wall (choke), using interpolated stone wall curve.
boolean	isSurge(double head, double flow)	Check if operating point is in surge, using interpolated surge curve.
boolean	isUseActualMW()	Check if automatic MW detection from inlet stream is enabled.
private double	linearInterpolate(double valueLower, double valueUpper, double fraction)	Linear interpolation between two values.
void	setAllowExtrapolation(boolean allow)	Enable or disable extrapolation outside the MW range.
void	setAutoGenerateStoneWallCurves(boolean autoGenerate)	Enable auto-generation of stone wall curves when maps are added.
void	setAutoGenerateSurgeCurves(boolean autoGenerate)	Enable auto-generation of surge curves when maps are added.
void	setHeadUnit(String headUnit)	Set the head unit for all maps.
void	setInletStream(StreamInterface stream)	Set the inlet stream reference for automatic MW detection.
void	setInterpolationEnabled(boolean enabled)	Enable or disable MW interpolation.
void	setOperatingMW(double mw)	Set the operating molecular weight for interpolation.
void	setStoneWallCurveAtMW(double molecularWeight, double[] chartConditions, double[] stoneWallFlow, double[] stoneWallHead)	Set stone wall curve for a specific MW map.
void	setSurgeCurveAtMW(double molecularWeight, double[] chartConditions, double[] surgeFlow, double[] surgeHead)	Set surge curve for a specific MW map.
void	setUseActualMW(boolean useActual)	Set whether to automatically use the inlet stream's molecular weight.
private void	updateOperatingMWFromStream()	Update the operating MW from the inlet stream's fluid.

Methods inherited from class CompressorChart

addCurve, addCurve, addSurgeCurve, checkStoneWall, checkSurge1, checkSurge2, equals, fitReducedCurve, generateStoneWallCurve, generateSurgeCurve, getChartConditions, getDischargeTemperatures, getFlow, getFlows, getGamma, getHeads, getHeadUnit, getInletPressure, getInletTemperature, getMaxSpeedCurve, getMinSpeedCurve, getPolytropicEfficiencies, getPolytropicExponent, getPowers, getPressureRatios, getReferenceDensity, getSpeed, getSpeeds, getSpeedValue, getStoneWallCurve, getSurgeCurve, hashCode, isUseCompressorChart, plot, polytropicEfficiency, setCurves, setCurves, setGamma, setInletPressure, setInletTemperature, setMaxSpeedCurve, setMinSpeedCurve, setPolytropicExponent, setReferenceConditions, setReferenceDensity, setStoneWallCurve, setSurgeCurve, setUseCompressorChart, setUseRealKappa, useRealKappa

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface CompressorChartInterface

getRatioToMaxSpeed, getRatioToMinSpeed, isHigherThanMaxSpeed, isLowerThanMinSpeed, isSpeedWithinRange

Field Details

serialVersionUID

private static final long serialVersionUID

Serialization version UID.

See Also:

• Constant Field Values

logger

private static final org.apache.logging.log4j.Logger logger

Logger object for class.

mapMolecularWeights

private List<Double> mapMolecularWeights

List of MW values for which maps are defined, sorted in ascending order.

mapCharts

private List<CompressorChart> mapCharts

List of compressor charts corresponding to each MW.

operatingMW

private double operatingMW

Current operating molecular weight for interpolation.

interpolationEnabled

private boolean interpolationEnabled

Flag indicating if interpolation is needed.

autoGenerateSurgeCurves

private boolean autoGenerateSurgeCurves

Flag to auto-generate surge curves when maps are added.

autoGenerateStoneWallCurves

private boolean autoGenerateStoneWallCurves

Flag to auto-generate stone wall curves when maps are added.

allowExtrapolation

private boolean allowExtrapolation

Flag to allow extrapolation outside the MW range.

useActualMW

private boolean useActualMW

Flag to automatically use the inlet stream's molecular weight.

inletStream

private transient StreamInterface inletStream

Reference to inlet stream for automatic MW detection.

Constructor Details

CompressorChartMWInterpolation

public CompressorChartMWInterpolation()

Default constructor for CompressorChartMWInterpolation.

Method Details

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double[] chartConditions,
 double[] speed,
 double[][] flow,
 double[][] head,
 double[][] polyEff)

Add a compressor map at a specific molecular weight.

Multiple maps can be added at different MW values. The maps are stored sorted by MW.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

chartConditions - reference conditions [temp °C, pres bara, density kg/m³, MW g/mol]

speed - array of speed values (RPM)

flow - 2D array of flow values for each speed curve (m³/hr)

head - 2D array of head values for each speed curve (kJ/kg or meter)

polyEff - 2D array of polytropic efficiency values for each speed curve (%)

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double[] speed,
 double[][] flow,
 double[][] head,
 double[][] polyEff)

Add a multi-speed compressor map at a specific molecular weight.

Convenience method without chartConditions - uses default conditions based on MW.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

speed - array of speed values (RPM)

flow - 2D array of flow values for each speed curve (m³/hr)

head - 2D array of head values for each speed curve (kJ/kg or meter)

polyEff - 2D array of polytropic efficiency values for each speed curve (%)

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double[] speed,
 double[][] flow,
 double[][] head,
 double[][] flowPolyEff,
 double[][] polyEff)

Add a multi-speed compressor map at a specific molecular weight with separate flow arrays.

Convenience method without chartConditions - uses default conditions based on MW.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

speed - array of speed values (RPM)

flow - 2D array of flow values for head curves (m³/hr)

head - 2D array of head values for each speed curve (kJ/kg or meter)

flowPolyEff - 2D array of flow values for efficiency curves (m³/hr)

polyEff - 2D array of polytropic efficiency values for each speed curve (%)

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double speed,
 double[] flow,
 double[] head,
 double[] polyEff)

Add a single-speed compressor map at a specific molecular weight.

This is a convenience method for single-speed compressors where flow, head, and efficiency are 1D arrays for a single speed curve.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

speed - the compressor speed (RPM)

flow - array of flow values (m³/hr)

head - array of head values (kJ/kg or meter)

polyEff - array of polytropic efficiency values (%)

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double speed,
 double[] flow,
 double[] head,
 double[] flowPolyEff,
 double[] polyEff)

Add a single-speed compressor map at a specific molecular weight with separate flow arrays.

This is a convenience method for single-speed compressors where efficiency is measured at different flow points than head.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

speed - the compressor speed (RPM)

flow - array of flow values for head curve (m³/hr)

head - array of head values (kJ/kg or meter)

flowPolyEff - array of flow values for efficiency curve (m³/hr)

polyEff - array of polytropic efficiency values (%)

addMapAtMW

public void addMapAtMW(double molecularWeight,
 double[] chartConditions,
 double[] speed,
 double[][] flow,
 double[][] head,
 double[][] flowPolyEff,
 double[][] polyEff)

Add a compressor map at a specific molecular weight.

Multiple maps can be added at different MW values. The maps are stored sorted by MW.

Parameters:

molecularWeight - the molecular weight (g/mol) at which this map was measured

chartConditions - reference conditions [temp °C, pres bara, density kg/m³, MW g/mol]

speed - array of speed values (RPM)

flow - 2D array of flow values for each speed curve (m³/hr)

head - 2D array of head values for each speed curve (kJ/kg or meter)

flowPolyEff - 2D array of flow values for efficiency curves (m³/hr)

polyEff - 2D array of polytropic efficiency values for each speed curve (%)

setOperatingMW

public void setOperatingMW(double mw)

Set the operating molecular weight for interpolation.

The polytropic head and efficiency will be interpolated between maps based on this MW.

Parameters:

mw - the operating molecular weight in g/mol

getOperatingMW

public double getOperatingMW()

Get the operating molecular weight.

Returns:

the operating molecular weight in g/mol

setInterpolationEnabled

public void setInterpolationEnabled(boolean enabled)

Enable or disable MW interpolation.

When disabled, the chart behaves like a standard CompressorChart using the first added map.

Parameters:

enabled - true to enable interpolation, false to disable

isInterpolationEnabled

public boolean isInterpolationEnabled()

Check if MW interpolation is enabled.

Returns:

true if interpolation is enabled

setAutoGenerateSurgeCurves

public void setAutoGenerateSurgeCurves(boolean autoGenerate)

Enable auto-generation of surge curves when maps are added.

Parameters:

autoGenerate - true to auto-generate surge curves

isAutoGenerateSurgeCurves

public boolean isAutoGenerateSurgeCurves()

Check if auto-generation of surge curves is enabled.

Returns:

true if auto-generation is enabled

setAutoGenerateStoneWallCurves

public void setAutoGenerateStoneWallCurves(boolean autoGenerate)

Enable auto-generation of stone wall curves when maps are added.

Parameters:

autoGenerate - true to auto-generate stone wall curves

isAutoGenerateStoneWallCurves

public boolean isAutoGenerateStoneWallCurves()

Check if auto-generation of stone wall curves is enabled.

Returns:

true if auto-generation is enabled

getNumberOfMaps

public int getNumberOfMaps()

Get the number of MW maps defined.

Returns:

number of MW maps

getMapMolecularWeights

public List<Double> getMapMolecularWeights()

Get the list of molecular weights for which maps are defined.

Returns:

unmodifiable list of MW values in ascending order

setAllowExtrapolation

public void setAllowExtrapolation(boolean allow)

Enable or disable extrapolation outside the MW range.

When enabled, linear extrapolation is used for MW values outside the range of defined maps. When disabled (default), the nearest boundary map is used.

Parameters:

allow - true to enable extrapolation, false to use boundary maps

isAllowExtrapolation

public boolean isAllowExtrapolation()

Check if extrapolation outside the MW range is allowed.

Returns:

true if extrapolation is allowed

setUseActualMW

public void setUseActualMW(boolean useActual)

Set whether to automatically use the inlet stream's molecular weight.

When enabled (default), the operating MW is automatically updated from the inlet stream's fluid molecular weight before each calculation. This ensures the compressor chart uses the actual gas composition.

Parameters:

useActual - true to use inlet stream's MW automatically

isUseActualMW

public boolean isUseActualMW()

Check if automatic MW detection from inlet stream is enabled.

Returns:

true if using inlet stream's MW automatically

setInletStream

public void setInletStream(StreamInterface stream)

Set the inlet stream reference for automatic MW detection.

Parameters:

stream - the inlet stream

getInletStream

public StreamInterface getInletStream()

Get the inlet stream reference.

Returns:

the inlet stream, or null if not set

updateOperatingMWFromStream

private void updateOperatingMWFromStream()

Update the operating MW from the inlet stream's fluid.

Called automatically before calculations if useActualMW is enabled.

findInterpolationIndices

private CompressorChartMWInterpolation.InterpolationIndices findInterpolationIndices(double mw)

Find the two nearest MW maps and their interpolation weight.

Parameters:

mw - the target molecular weight

Returns:

InterpolationIndices containing lower index, upper index, and interpolation fraction

getPolytropicHead

public double getPolytropicHead(double flow,
 double speed)

Get method for polytropic head from reference curves.

Returns the polytropic head interpolated between MW maps based on the operating MW.

Specified by:

getPolytropicHead in interface CompressorChartInterface

Overrides:

getPolytropicHead in class CompressorChart

Parameters:

flow - [m3/h], speed in [rpm].

speed - a double

Returns:

polytropic head in unit [getHeadUnit]

getPolytropicEfficiency

public double getPolytropicEfficiency(double flow,
 double speed)

Get method for polytropic efficiency from reference curves.

Returns the polytropic efficiency interpolated between MW maps based on the operating MW.

Specified by:

getPolytropicEfficiency in interface CompressorChartInterface

Overrides:

getPolytropicEfficiency in class CompressorChart

Parameters:

flow - [m3/h], speed in [rpm].

speed - a double

Returns:

polytropic efficiency [%].

getSurgeFlowAtSpeed

public double getSurgeFlowAtSpeed(double speed)

Get the surge flow at a specific speed, interpolated between MW maps.

Specified by:

getSurgeFlowAtSpeed in interface CompressorChartInterface

Overrides:

getSurgeFlowAtSpeed in class CompressorChart

Parameters:

speed - the compressor speed in RPM

Returns:

the surge flow interpolated for the operating MW

getStoneWallFlowAtSpeed

public double getStoneWallFlowAtSpeed(double speed)

Get the stone wall flow at a specific speed, interpolated between MW maps.

Specified by:

getStoneWallFlowAtSpeed in interface CompressorChartInterface

Overrides:

getStoneWallFlowAtSpeed in class CompressorChart

Parameters:

speed - the compressor speed in RPM

Returns:

the stone wall flow interpolated for the operating MW

getSurgeHeadAtSpeed

public double getSurgeHeadAtSpeed(double speed)

Get the surge head at a specific speed, interpolated between MW maps.

Specified by:

getSurgeHeadAtSpeed in interface CompressorChartInterface

Overrides:

getSurgeHeadAtSpeed in class CompressorChart

Parameters:

speed - the compressor speed in RPM

Returns:

the surge head interpolated for the operating MW

getStoneWallHeadAtSpeed

public double getStoneWallHeadAtSpeed(double speed)

Get the stone wall head at a specific speed, interpolated between MW maps.

Specified by:

getStoneWallHeadAtSpeed in interface CompressorChartInterface

Overrides:

getStoneWallHeadAtSpeed in class CompressorChart

Parameters:

speed - the compressor speed in RPM

Returns:

the stone wall head interpolated for the operating MW

isSurge

public boolean isSurge(double head,
 double flow)

Check if operating point is in surge, using interpolated surge curve.

Parameters:

head - the polytropic head

flow - the volumetric flow

Returns:

true if the operating point is below the surge curve (in surge)

isStoneWall

public boolean isStoneWall(double head,
 double flow)

Check if operating point is at stone wall (choke), using interpolated stone wall curve.

Parameters:

head - the polytropic head

flow - the volumetric flow

Returns:

true if the operating point is beyond the stone wall curve (choked)

getSurgeFlow

public double getSurgeFlow(double head)

Get interpolated surge flow at a given head.

Parameters:

head - the polytropic head

Returns:

the surge flow interpolated for the operating MW

getStoneWallFlow

public double getStoneWallFlow(double head)

Get interpolated stone wall flow at a given head.

Parameters:

head - the polytropic head

Returns:

the stone wall flow interpolated for the operating MW

getDistanceToSurge

public double getDistanceToSurge(double head,
 double flow)

Get the distance to surge as a ratio, using interpolated surge curve.

Parameters:

head - the polytropic head

flow - the current volumetric flow

Returns:

ratio (current flow / surge flow) - 1; positive means above surge

getDistanceToStoneWall

public double getDistanceToStoneWall(double head,
 double flow)

Get the distance to stone wall as a ratio, using interpolated stone wall curve.

Parameters:

head - the polytropic head

flow - the current volumetric flow

Returns:

ratio (stone wall flow / current flow) - 1; positive means below stone wall

linearInterpolate

private double linearInterpolate(double valueLower,
 double valueUpper,
 double fraction)

Linear interpolation between two values.

Parameters:

valueLower - the value at the lower bound

valueUpper - the value at the upper bound

fraction - the interpolation fraction (0.0 = lower, 1.0 = upper)

Returns:

the interpolated value

setSurgeCurveAtMW

public void setSurgeCurveAtMW(double molecularWeight,
 double[] chartConditions,
 double[] surgeFlow,
 double[] surgeHead)

Set surge curve for a specific MW map.

Parameters:

molecularWeight - the MW of the map to update

chartConditions - reference conditions

surgeFlow - array of surge flow values

surgeHead - array of surge head values

setStoneWallCurveAtMW

public void setStoneWallCurveAtMW(double molecularWeight,
 double[] chartConditions,
 double[] stoneWallFlow,
 double[] stoneWallHead)

Set stone wall curve for a specific MW map.

Parameters:

molecularWeight - the MW of the map to update

chartConditions - reference conditions

stoneWallFlow - array of stone wall flow values

stoneWallHead - array of stone wall head values

generateAllSurgeCurves

public void generateAllSurgeCurves()

Generate surge curves for all MW maps.

generateAllStoneWallCurves

public void generateAllStoneWallCurves()

Generate stone wall curves for all MW maps.

findMapIndex

private int findMapIndex(double molecularWeight)

Find the index of a map by molecular weight.

Parameters:

molecularWeight - the MW to find

Returns:

the index, or -1 if not found

getChartAtMW

public CompressorChart getChartAtMW(double molecularWeight)

Get the chart at a specific MW.

Parameters:

molecularWeight - the MW to find

Returns:

the CompressorChart at that MW, or null if not found

setHeadUnit

public void setHeadUnit(String headUnit)

Set the head unit for all maps.

Specified by:

setHeadUnit in interface CompressorChartInterface

Overrides:

setHeadUnit in class CompressorChart

Parameters:

headUnit - the unit of head (e.g., "kJ/kg" or "meter")