Simple and rapid method for measuring gas dispersion in porous media: Methodology and applications

In this article, a simple and rapid method for measuring gas dispersion coefficients in porous media is proposed. The method is easy to apply and requires only relatively inexpensive equipment. It is based on the use of atmospheric air and nitrogen as tracer gases combined with a fast oxygen electrode for oxygen concentration detection. The method was tested using 103-cm-long, 14-cm-diameter columns containing a homogeneous filter sand. The sand columns were packed to different dry bulk densities ranging from 1.06 to 1.55 g/cm and gravimetric water contents ranging from 0.005 to 0.1 g H2O/g solids. Oxygen and nitrogen breakthrough curves were measured on these columns for pore gas velocities ranging from 6 to 35 cm/min. The data were fitted to the advection-dispersion equation yielding values for gas dispersion coefficients that were then used to calculate gas dispersivity values as a function of pore gas velocity, dry bulk density, and gravimetric water content.