Fluid density

We consider some fluid at the pressure Patm and the temperature T0. All the air is separated from the liquid part {liquid+vapor}.

We consider a unit volume of fluid at Patm and T0 (unit volume assumption), then from the definition of the parameter “air/gas content” x (see section Air, gas content parameter), we can write:

This gives for the volume of air and liquid part at atmospheric pressure and 273 K:

With the mass conservation, we obtain the mass for the liquid part and for the air:

Equation 10: Mass of liquid and air

And for the volumes:

We define the air volumetric fraction Φ to be:

Equation 11: Air volumetric fraction

In all cases, the fluid density can be computed as:

Equation 12: Fluid density at P and T