Class HumidAir

java.lang.Object
neqsim.thermo.util.humidair.HumidAir
public final class HumidAir extends Object
Utility class for common humid air calculations.

The methods are adapted from the ASHRAE Handbook Fundamentals (2017) and the CoolProp implementation HumidAirProp.cpp. Saturation vapour pressures are calculated from the IAPWS formulation of Wagner and Pruss (2002).

Author:
esol

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final double
    EPSILON
    Ratio of molar masses M_w/M_da.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    HumidAir()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    cairSat(double temperature)
    Humid air saturation specific heat at 1 atmosphere.
    static double
    dewPointTemperature(double humidityRatio, double pressure)
    Dew point temperature from humidity ratio and pressure.
    static double
    enthalpy(double temperature, double humidityRatio)
    Specific enthalpy of humid air on a dry-air basis.
    static double
    humidityRatioFromRH(double temperature, double pressure, double relativeHumidity)
    Humidity ratio from temperature, pressure and relative humidity.
    static double
    relativeHumidity(double temperature, double pressure, double humidityRatio)
    Relative humidity from humidity ratio.
    static double
    saturationPressureWater(double temperature)
    Saturation vapour pressure of water.

    Methods inherited from class Object

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

  • Field Details

    • EPSILON

      private static final double EPSILON
      Ratio of molar masses M_w/M_da.
      See Also:

  • Constructor Details

    • HumidAir

      private HumidAir()

  • Method Details

    • saturationPressureWater

      public static double saturationPressureWater(double temperature)
      Saturation vapour pressure of water.

      Implementation of the IAPWS equation for the vapour pressure of water valid above the triple point. For temperatures below the triple point, a simplified sublimation correlation is applied.

      Parameters:
      temperature - Temperature in K
      Returns:
      saturation pressure in Pa

    • humidityRatioFromRH

      public static double humidityRatioFromRH(double temperature, double pressure, double relativeHumidity)
      Humidity ratio from temperature, pressure and relative humidity.

      Formula from ASHRAE Fundamentals (2017) with enhancement factor neglected.

      Parameters:
      temperature - Temperature in K
      pressure - total pressure in Pa
      relativeHumidity - relative humidity [-]
      Returns:
      humidity ratio (kg water/kg dry air)

    • relativeHumidity

      public static double relativeHumidity(double temperature, double pressure, double humidityRatio)
      Relative humidity from humidity ratio.
      Parameters:
      temperature - temperature in K
      pressure - total pressure in Pa
      humidityRatio - humidity ratio (kg/kg dry air)
      Returns:
      relative humidity [-]

    • dewPointTemperature

      public static double dewPointTemperature(double humidityRatio, double pressure)
      Dew point temperature from humidity ratio and pressure.

      Calculated iteratively using the saturation pressure correlation.

      Parameters:
      humidityRatio - humidity ratio (kg/kg dry air)
      pressure - total pressure in Pa
      Returns:
      dew point temperature in K

    • enthalpy

      public static double enthalpy(double temperature, double humidityRatio)
      Specific enthalpy of humid air on a dry-air basis.

      Correlation from ASHRAE Fundamentals (2017) in kJ/kg dry air.

      Parameters:
      temperature - temperature in K
      humidityRatio - humidity ratio (kg/kg dry air)
      Returns:
      specific enthalpy in kJ/kg dry air

    • cairSat

      public static double cairSat(double temperature)
      Humid air saturation specific heat at 1 atmosphere.

      Correlation from CoolProp based on EES, valid from 250 K to 300 K.

      Parameters:
      temperature - temperature in K
      Returns:
      specific heat in kJ/kg·K