SimpleH20 does not consider enthalpy of vaporization

I suggest to add h_\mathrm{vap} here:

    static const Scalar gasEnthalpy(Scalar temperature,
                                    Scalar pressure)
    {
        static const Scalar tRef = getParam<Scalar>("SimpleH2O.ReferenceTemperature", 293.15);
        return gasHeatCapacity(temperature, pressure)*(temperature - tRef) + 2453.5e3;
    }

We could even make h_\mathrm{vap} depending on T_\mathrm{ref} as there as simple equations for that.

http://www.personal.psu.edu/users/m/r/mrh318/physical-consts/Popiel-Wojtkawiak-HTE-1998.pdf

https://www.scirp.org/pdf/AS20120200008_25514260.pdf (Bananas!)

It would still be a constant.