Class ShahCondensation

java.lang.Object
neqsim.process.mechanicaldesign.heatexchanger.ShahCondensation
public final class ShahCondensation extends Object
Shah condensation heat transfer correlation for in-tube and shell-side condensation.

Implements the Shah (1979, 2009) correlation for film condensation inside horizontal tubes. This is one of the most widely used correlations for condensation of pure fluids and mixtures in horizontal tubes, validated against a large experimental database spanning refrigerants, hydrocarbons, water, and organic fluids.

The Shah correlation computes the local condensation coefficient as a function of vapor quality, reduced pressure, and liquid-only Reynolds number: 

h_cond = h_lo * [(1 - x)^0.8 + 3.8 * x^0.76 * (1 - x)^0.04 / P_r^0.38]

where h_lo is the liquid-only heat transfer coefficient (all mass flowing as liquid) computed from Dittus-Boelter or Gnielinski.

Also includes the Shah (2017) enhancement for vertical tubes.

Reference: Shah, M.M. (1979). "A general correlation for heat transfer during film condensation inside pipes." Int. J. Heat Mass Transfer, 22, 547-556. Shah, M.M. (2009). "An Improved and Extended General Correlation for Heat Transfer During Condensation in Plain Tubes." HVAC&R Research, 15(5), 889-913.

Version:
1.0
Author:
NeqSim Development Team
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final double
    MAX_REDUCED_PRESSURE
    Maximum valid reduced pressure for this correlation.
    private static final double
    MIN_REDUCED_PRESSURE
    Minimum valid reduced pressure for this correlation.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    ShahCondensation()
    Private constructor to prevent instantiation.

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    calcAverageHTC(double hLiquidOnly, double reducedPressure, double qualityIn, double qualityOut, int intervals)
    Calculates the average condensation HTC over a quality range by numerical integration.
    static double
    calcLiquidOnlyHTC(double massFluxTotal, double tubeID, double liquidDensity, double liquidViscosity, double liquidCp, double liquidConductivity)
    Calculates the liquid-only heat transfer coefficient using Dittus-Boelter correlation.
    static double
    calcLocalHTC(double hLiquidOnly, double vaporQuality, double reducedPressure)
    Calculates the local condensation heat transfer coefficient using the Shah (1979) correlation.
    static double
    calcVerticalTubeHTC(double hLiquidOnly, double vaporQuality, double reducedPressure, double massFlux, double tubeID, double vaporDensity, double liquidDensity)
    Calculates the condensation HTC with gravity correction for vertical tubes (Shah 2017).
    static boolean
    isInValidRange(double reducedPressure, double reLiquidOnly, double massFlux)
    Checks if operating conditions are within the validated range of the Shah correlation.

    Methods inherited from class Object

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

  • Field Details

    • MIN_REDUCED_PRESSURE

      private static final double MIN_REDUCED_PRESSURE
      Minimum valid reduced pressure for this correlation.
      See Also:

    • MAX_REDUCED_PRESSURE

      private static final double MAX_REDUCED_PRESSURE
      Maximum valid reduced pressure for this correlation.
      See Also:

  • Constructor Details

    • ShahCondensation

      private ShahCondensation()
      Private constructor to prevent instantiation.

  • Method Details

    • calcLocalHTC

      public static double calcLocalHTC(double hLiquidOnly, double vaporQuality, double reducedPressure)
      Calculates the local condensation heat transfer coefficient using the Shah (1979) correlation.

      Valid for: horizontal tubes, Re_lo > 350, 0.002 < P_r < 0.44, vapor quality 0 to 1.

      Parameters:
      hLiquidOnly - liquid-only heat transfer coefficient (W/(m2*K)), i.e., the coefficient if the total mass flow were all liquid, calculated using Dittus-Boelter or Gnielinski
      vaporQuality - local vapor quality (mass fraction of vapor), range 0 to 1
      reducedPressure - reduced pressure P/P_crit, dimensionless
      Returns:
      local condensation heat transfer coefficient (W/(m2*K))

    • calcLiquidOnlyHTC

      public static double calcLiquidOnlyHTC(double massFluxTotal, double tubeID, double liquidDensity, double liquidViscosity, double liquidCp, double liquidConductivity)
      Calculates the liquid-only heat transfer coefficient using Dittus-Boelter correlation.

      This is the baseline HTC assuming all mass flows as liquid: 

      h_lo = 0.023 * (k_l / D) * Re_lo ^ 0.8 * Pr_l ^ 0.4
      Parameters:
      massFluxTotal - total mass flux G = m_dot / A_cross (kg/(m2*s))
      tubeID - tube inner diameter (m)
      liquidDensity - liquid density (kg/m3)
      liquidViscosity - liquid dynamic viscosity (Pa*s)
      liquidCp - liquid heat capacity (J/(kg*K))
      liquidConductivity - liquid thermal conductivity (W/(m*K))
      Returns:
      liquid-only heat transfer coefficient (W/(m2*K))

    • calcAverageHTC

      public static double calcAverageHTC(double hLiquidOnly, double reducedPressure, double qualityIn, double qualityOut, int intervals)
      Calculates the average condensation HTC over a quality range by numerical integration.

      Integrates the local Shah correlation over the quality range using Simpson's rule with the specified number of intervals.

      Parameters:
      hLiquidOnly - liquid-only heat transfer coefficient (W/(m2*K))
      reducedPressure - reduced pressure P/P_crit
      qualityIn - vapor quality at inlet of zone (0 to 1)
      qualityOut - vapor quality at outlet of zone (0 to 1)
      intervals - number of integration intervals (must be even, minimum 4)
      Returns:
      average condensation HTC over the quality range (W/(m2*K))

    • calcVerticalTubeHTC

      public static double calcVerticalTubeHTC(double hLiquidOnly, double vaporQuality, double reducedPressure, double massFlux, double tubeID, double vaporDensity, double liquidDensity)
      Calculates the condensation HTC with gravity correction for vertical tubes (Shah 2017).

      For vertical downflow condensation, applies a correction based on dimensionless velocity: 

      J_g = x * G / [g * D * rho_v * (rho_l - rho_v)]^0.5

      When J_g < 0.98, gravity-dominated regime applies with Nusselt theory enhancement.

      Parameters:
      hLiquidOnly - liquid-only HTC (W/(m2*K))
      vaporQuality - local vapor quality (0 to 1)
      reducedPressure - reduced pressure P/P_crit
      massFlux - total mass flux (kg/(m2*s))
      tubeID - tube inner diameter (m)
      vaporDensity - vapor density (kg/m3)
      liquidDensity - liquid density (kg/m3)
      Returns:
      condensation HTC for vertical tube (W/(m2*K))

    • isInValidRange

      public static boolean isInValidRange(double reducedPressure, double reLiquidOnly, double massFlux)
      Checks if operating conditions are within the validated range of the Shah correlation.
      Parameters:
      reducedPressure - reduced pressure P/P_crit
      reLiquidOnly - liquid-only Reynolds number
      massFlux - mass flux (kg/(m2*s))
      Returns:
      true if within validated range, false otherwise