Class TubeInsertModel

java.lang.Object
neqsim.process.mechanicaldesign.heatexchanger.TubeInsertModel
All Implemented Interfaces:
Serializable
public class TubeInsertModel extends Object implements Serializable
Enhanced tube insert models for heat exchanger performance improvement.

Models the effect of tube-side inserts on heat transfer and pressure drop. These devices are commonly used for debottlenecking existing heat exchangers — increasing heat transfer at the expense of higher pressure drop.

Supported insert types:

  • Twisted tape: A flat strip of metal twisted into a helical shape and inserted into the tube. Creates swirl flow that disrupts the boundary layer. Characterized by the twist ratio y = H/(2*D), where H is the 180-degree twist pitch and D is the tube ID. The Manglik-Bergles (1993) correlation is used.
  • Wire matrix (HiTRAN): A wire coil or matrix insert that promotes turbulence throughout the tube cross-section. Modeled using the manufacturer's published j and f factor correlations.
  • Coiled wire: A helical wire inserted along the tube wall. Creates local turbulence at lower pressure drop penalty than twisted tape. Uses the Ravigururajan-Bergles (1996) correlation.

References:

  • Manglik, R.M. and Bergles, A.E. (1993). "Heat transfer and pressure drop correlations for twisted-tape inserts in isothermal tubes: Part I—Laminar flows." J. Heat Transfer, 115(4), 881-889.
  • Manglik, R.M. and Bergles, A.E. (1993). "Heat transfer and pressure drop correlations for twisted-tape inserts in isothermal tubes: Part II—Transition and turbulent flows." J. Heat Transfer, 115(4), 890-896.
  • Ravigururajan, T.S. and Bergles, A.E. (1996). "Development and verification of general correlations for pressure drop and heat transfer in single-phase turbulent flow in enhanced tubes." Exp. Thermal and Fluid Science, 13, 55-70.
Version:
1.0
Author:
NeqSim Development Team
See Also:

  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      Serialization version UID.
      See Also:

    • insertType

      private TubeInsertModel.InsertType insertType

    • twistRatio

      private double twistRatio
      Twist ratio y = H/(2*D), where H = 180-degree pitch, D = tube ID. Typical: 2.5 to 10.

    • tapeThickness

      private double tapeThickness
      Tape thickness (m). Typical: 0.5 to 1.5 mm.

    • tapeWidthFraction

      private double tapeWidthFraction
      Tape width fraction (tape width / tube ID). Typically near 1.0 for full-width tapes.

    • wireDiameter

      private double wireDiameter
      Wire diameter (m). Typical: 0.5 to 2 mm.

    • wireCoilPitch

      private double wireCoilPitch
      Wire coil pitch (m). Typical: 5 to 20 mm.

    • matrixDensity

      private double matrixDensity
      Matrix density factor (0 to 1). Higher = denser matrix. Typical: 0.3 to 0.7.

    • roughnessRatio

      private double roughnessRatio
      Wire roughness height e/D. Typical: 0.01 to 0.05.

    • helixAngle

      private double helixAngle
      Helix angle of the coiled wire (degrees). Typical: 30 to 70.

  • Constructor Details

    • TubeInsertModel

      public TubeInsertModel()
      Constructs a TubeInsertModel with no insert (plain tube).

    • TubeInsertModel

      public TubeInsertModel(TubeInsertModel.InsertType type)
      Constructs a TubeInsertModel with a specified insert type.
      Parameters:
      type - the insert type

  • Method Details

    • getHeatTransferEnhancementRatio

      public double getHeatTransferEnhancementRatio(double Re, double Pr)
      Calculates the heat transfer enhancement ratio h_enhanced / h_plain.
      Parameters:
      Re - Reynolds number for plain tube flow
      Pr - Prandtl number
      Returns:
      enhancement ratio (always >= 1.0)

    • getPressureDropPenaltyRatio

      public double getPressureDropPenaltyRatio(double Re)
      Calculates the pressure drop penalty ratio f_enhanced / f_plain.
      Parameters:
      Re - Reynolds number for plain tube flow
      Returns:
      friction factor ratio (always >= 1.0)

    • getPerformanceEvaluationCriteria

      public double getPerformanceEvaluationCriteria(double Re, double Pr)
      Calculates the performance evaluation ratio (PEC) at constant pumping power.

      PEC = (h_enh/h_plain) / (f_enh/f_plain)^(1/3)

      PEC > 1.0 means the insert gives net benefit at constant pumping power.

      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      PEC value

    • applyEnhancement

      public double[] applyEnhancement(double plainHTC, double plainPressureDrop, double Re, double Pr)
      Applies the insert enhancement to a plain-tube HTC and pressure drop.
      Parameters:
      plainHTC - plain-tube heat transfer coefficient (W/(m2*K))
      plainPressureDrop - plain-tube pressure drop (Pa)
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      array of [enhanced HTC (W/(m2*K)), enhanced pressure drop (Pa)]

    • calcTwistedTapeHeatEnhancement

      private double calcTwistedTapeHeatEnhancement(double Re, double Pr)
      Calculates heat transfer enhancement for twisted tape insert.

      Manglik-Bergles (1993) correlation:

      • Laminar (Re < 2300): Nu_tt/Nu_plain = (pi/(pi - 4*delta/D)) * (pi + 2 - 2*delta/D)/(pi - 4*delta/D) * (1 + 0.769/y)^(1/3)
      • Turbulent: Nu_tt = 0.023 * Re_sw^0.8 * Pr^0.4 * (pi/(pi - 4*delta/D))^0.8 * (pi + 2 - 2*delta/D)^0.2 * (pi/(pi - 4*delta/D))^0.2 * phi^n

      Simplified enhancement ratio used here: 

      h_ratio = (1 + 2.0/y) * (pi/(pi - 4*delta/D))^(0.8) for turbulent
h_ratio = (1 + 0.769/y)^(1/3) * geometric_correction for laminar
      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      heat transfer enhancement ratio

    • calcTwistedTapeFrictionPenalty

      private double calcTwistedTapeFrictionPenalty(double Re)
      Calculates friction factor penalty for twisted tape insert. 
      f_ratio = (1 + 2.75/y) * (pi/(pi - 4*delta/D))^1.29 for turbulent
      Parameters:
      Re - Reynolds number
      Returns:
      friction factor ratio

    • calcWireMatrixHeatEnhancement

      private double calcWireMatrixHeatEnhancement(double Re, double Pr)
      Calculates heat transfer enhancement for wire matrix insert.

      Based on published HiTRAN data fits: typical enhancement 2-5x for turbulent flow, 3-8x for laminar flow (due to early transition to turbulence).

      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      heat transfer enhancement ratio

    • calcWireMatrixFrictionPenalty

      private double calcWireMatrixFrictionPenalty(double Re)
      Calculates friction factor penalty for wire matrix insert.
      Parameters:
      Re - Reynolds number
      Returns:
      friction factor ratio

    • calcCoiledWireHeatEnhancement

      private double calcCoiledWireHeatEnhancement(double Re, double Pr)
      Calculates heat transfer enhancement for coiled wire insert.

      Ravigururajan-Bergles (1996) general correlation for rough/enhanced surfaces: 

      Nu_enh/Nu_plain = [1 + (2.64*Re^0.036 * (e/D)^0.212 * (p/D)^(-0.21) * (alpha/90)^0.29
                       * Pr^(-0.024))^7]^(1/7)

      Simplified for coiled wire:

      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      heat transfer enhancement ratio

    • calcCoiledWireFrictionPenalty

      private double calcCoiledWireFrictionPenalty(double Re)
      Calculates friction factor penalty for coiled wire insert.
      Parameters:
      Re - Reynolds number
      Returns:
      friction factor ratio

    • toMap

      public Map<String,Object> toMap(double Re, double Pr)
      Returns all insert model results.
      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      map of results

    • toJson

      public String toJson(double Re, double Pr)
      Converts results to JSON string.
      Parameters:
      Re - Reynolds number
      Pr - Prandtl number
      Returns:
      JSON string

    • createTwistedTape

      public static TubeInsertModel createTwistedTape(double twistRatio)
      Creates a twisted tape insert model with specified twist ratio.
      Parameters:
      twistRatio - twist ratio y = H/(2D), typical 2.5-10
      Returns:
      configured TubeInsertModel

    • createWireMatrix

      public static TubeInsertModel createWireMatrix(double density)
      Creates a wire matrix (HiTRAN-type) insert model.
      Parameters:
      density - matrix density factor (0.3-0.7)
      Returns:
      configured TubeInsertModel

    • createCoiledWire

      public static TubeInsertModel createCoiledWire(double roughnessRatio, double helixAngle)
      Creates a coiled wire insert model.
      Parameters:
      roughnessRatio - wire roughness e/D (0.01-0.05)
      helixAngle - helix angle in degrees (30-70)
      Returns:
      configured TubeInsertModel

    • getInsertType

      public TubeInsertModel.InsertType getInsertType()
      Gets the insert type.
      Returns:
      insert type

    • setInsertType

      public void setInsertType(TubeInsertModel.InsertType insertType)
      Sets the insert type.
      Parameters:
      insertType - insert type

    • getTwistRatio

      public double getTwistRatio()
      Gets the twist ratio for twisted tape.
      Returns:
      twist ratio y = H/(2D)

    • setTwistRatio

      public void setTwistRatio(double twistRatio)
      Sets the twist ratio for twisted tape.
      Parameters:
      twistRatio - twist ratio y = H/(2D)

    • setTapeThickness

      public void setTapeThickness(double thickness)
      Sets the tape thickness for twisted tape.
      Parameters:
      thickness - tape thickness (m)

    • getMatrixDensity

      public double getMatrixDensity()
      Gets the wire matrix density factor.
      Returns:
      matrix density (0 to 1)

    • setMatrixDensity

      public void setMatrixDensity(double density)
      Sets the wire matrix density factor.
      Parameters:
      density - matrix density (0 to 1)

    • setWireDiameter

      public void setWireDiameter(double diameter)
      Sets the wire diameter for wire matrix / coiled wire inserts.
      Parameters:
      diameter - wire diameter (m)

    • setRoughnessRatio

      public void setRoughnessRatio(double eOverD)
      Sets the roughness ratio for coiled wire insert.
      Parameters:
      eOverD - roughness ratio e/D

    • setHelixAngle

      public void setHelixAngle(double angle)
      Sets the helix angle for coiled wire insert.
      Parameters:
      angle - helix angle (degrees)