com.synerset.hvacengine.fluids.watervapour.WaterVapourEquations Maven / Gradle / Ivy

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HVAC|Engine is a comprehensive library for calculating moist air properties, including crucial thermodynamic processes such as heating, dry cooling, real cooling with condensate discharge, mixing single or multiple air streams, and more. Immutable, thread-safe, very accurate.
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package com.synerset.hvacengine.fluids.watervapour;

import com.synerset.hvacengine.common.Validators;
import com.synerset.hvacengine.fluids.humidair.HumidAirEquations;
import com.synerset.hvacengine.fluids.liquidwater.LiquidWaterEquations;
import com.synerset.unitility.unitsystem.humidity.RelativeHumidity;
import com.synerset.unitility.unitsystem.thermodynamic.*;

public final class WaterVapourEquations {

    public static final double WATER_VAPOUR_MOLECULAR_MASS = 18.01528;     // [kg/mol]   Water vapour molecular mass
    public static final double WATER_VAPOUR_SPEC_GAS_CONSTANT = 461.52;    // [J/(kg*K)] Water vapour specific gas constant
    public static final double WATER_VAPOUR_SUTHERLAND_CONSTANT = 961.0;   // [K]        water vapour Sutherland Constant

    private WaterVapourEquations() {
    }

    /**
     * Returns water vapour dynamic viscosity
     * REFERENCE SOURCE: [4] [u,kg/(m*s)] (6.14) [4]
     * EQUATION LIMITS: {-40oC,+300oC},{1atm (1.013bar)}

     *
     * @param tvw water vapour temperature, oC
     * @return water vapour dynamic viscosity, kg/(m*s)
     */
    public static double dynamicViscosity(double tvw) {
        double tk = tvw + 273.15;
        double aNum = Math.sqrt(tk / 647.27);
        double bAux = 647.27 / tk;
        double cDnum = 0.0181583 + 0.0177624 * bAux + 0.0105287 * Math.pow(bAux, 2) - 0.0036744 * Math.pow(bAux, 3);
        return (aNum / cDnum) * Math.pow(10, -6);
    }

    public static DynamicViscosity dynamicViscosity(Temperature temperature) {
        Validators.requireNotNull(temperature);
        double dynVisVal = dynamicViscosity(temperature.getInCelsius());
        return DynamicViscosity.ofKiloGramPerMeterSecond(dynVisVal);
    }

    /**
     * Returns water vapour kinematic viscosity, m^2/s

     *
     * @param tw    water vapour temperature, oC
     * @param rhoWv dry air density, kg/m3
     * @return kinematic viscosity, m^2/s
     */
    public static double kinematicViscosity(double tw, double rhoWv) {
        return dynamicViscosity(tw) / rhoWv;
    }

    public static KinematicViscosity kinematicViscosity(Temperature temperature, Density waterVapourDensity) {
        Validators.requireNotNull(temperature);
        Validators.requireNotNull(waterVapourDensity);
        double kinVisVal = kinematicViscosity(temperature.getInCelsius(), waterVapourDensity.getInKilogramsPerCubicMeters());
        return KinematicViscosity.ofSquareMeterPerSecond(kinVisVal);
    }

    /**
     * Returns dry air thermal conductivity, W/(m*K)
     * REFERENCE SOURCE: [4] [k,W/(m*K)] (6.17) [5]

     * EQUATION LIMITS: {0oC,+220oC},{1atm (1.013bar)}

     *
     * @param tw water vapour temperature, oC
     * @return dry air thermal conductivity, W/(m*K)
     */
    public static double thermalConductivity(double tw) {
        return 1.74822 * Math.pow(10, -2) + 7.69127
                * Math.pow(10, -5) * tw - 3.23464
                * Math.pow(10, -7) * Math.pow(tw, 2) + 2.59524
                * Math.pow(10, -9) * Math.pow(tw, 3) - 3.1765
                * Math.pow(10, -12) * Math.pow(tw, 4);
    }

    public static ThermalConductivity thermalConductivity(Temperature temperature) {
        Validators.requireNotNull(temperature);
        double thermCondVal = thermalConductivity(temperature.getInCelsius());
        return ThermalConductivity.ofWattsPerMeterKelvin(thermCondVal);
    }

    /**
     * Returns water vapour specific enthalpy, kJ/kg

     *
     * @param tw dry water vapour temperature, oC
     * @return water vapour specific enthalpy, kJ/kg
     */
    public static double specificEnthalpy(double tw) {
        double cpWv = specificHeat(tw);
        return cpWv * tw + LiquidWaterEquations.HEAT_OF_WATER_VAPORIZATION;
    }

    public static SpecificEnthalpy specificEnthalpy(Temperature temperature) {
        Validators.requireNotNull(temperature);
        double specEnthalpyVal = specificEnthalpy(temperature.getInCelsius());
        return SpecificEnthalpy.ofKiloJoulePerKiloGram(specEnthalpyVal);
    }

    /**
     * Returns water vapour specific heat at constant pressure, kJ/(kg*K)

     * REFERENCE SOURCE: [6] [cp,kJ/(kg*K)] (-) [-]

     * EQUATION LIMITS: {-40.0oC,+300oC},{1atm (0.1bar, 5.0bar)}
     *
     * @param tw water vapour temperature, oC
     * @return dry air specific heat, kJ/(kg*K)
     */
    public static double specificHeat(double tw) {
        double tk = tw + 273.15;
        double c0, c1, c2, c3, c4, c5, c6;
        if (tw <= -48.15) {
            c0 = 1.8429999999889115e+000;
            c1 = 4.0000000111904223e-005;
            c2 = -2.7939677238430251e-016;
            return c0 + c1 * tk + c2 * tk * tk;
        }
        c0 = 1.9295247225621268E+000;
        c1 = -9.1586611999057584E-004;
        c2 = 3.1728684251752865E-006;
        c3 = -3.3653682733422277E-009;
        c4 = 2.0703915723982299E-012;
        c5 = -7.0213425618115390E-016;
        c6 = 9.8631583006961855E-020;
        return c0 + c1 * tk + c2 * tk * tk
                + c3 * tk * tk * tk
                + c4 * tk * tk * tk * tk
                + c5 * tk * tk * tk * tk * tk
                + c6 * tk * tk * tk * tk * tk * tk;
    }

    public static SpecificHeat specificHeat(Temperature temperature) {
        Validators.requireNotNull(temperature);
        double specHeatVal = specificHeat(temperature.getInCelsius());
        return SpecificHeat.ofKiloJoulePerKiloGramKelvin(specHeatVal);
    }

    /**
     * Returns water vapour density, based on partial vapour pressure derived from relative humidity, kg/m3
     *
     * @param tw   water vapour temperature, oC
     * @param rh   relative humidity, %
     * @param pAbs absolute pressure, Pa
     * @return water vapour density, kg/m3
     */
    public static double density(double tw, double rh, double pAbs) {
        double tk = tw + 273.15;
        double pDa = (rh / 100) * HumidAirEquations.saturationPressure(tw);
        double pWv = pAbs - pDa;
        return pWv / (WATER_VAPOUR_SPEC_GAS_CONSTANT * tk);
    }

    public static Density density(Temperature temperature, RelativeHumidity relativeHumidity, Pressure pressure) {
        Validators.requireNotNull(temperature);
        Validators.requireNotNull(relativeHumidity);
        Validators.requireNotNull(pressure);
        double densityVal = density(temperature.getInCelsius(),
                relativeHumidity.getInPercent(),
                pressure.getInPascals());
        return Density.ofKilogramPerCubicMeter(densityVal);
    }

    /**
     * Returns water vapour density, kg/m3
     *
     * @param tw   water vapour temperature, oC
     * @param pAbs absolute pressure, Pa
     * @return water vapour density, kg/m3
     */
    public static double density(double tw, double pAbs) {
        double tk = tw + 273.15;
        return pAbs / (WATER_VAPOUR_SPEC_GAS_CONSTANT * tk);
    }

    public static Density density(Temperature temperature, Pressure pressure) {
        Validators.requireNotNull(temperature);
        Validators.requireNotNull(pressure);
        double densityVal = density(temperature.getInCelsius(),
                pressure.getInPascals());
        return Density.ofKilogramPerCubicMeter(densityVal);
    }

}