Abstract: The impact of rapid pressure fluctuations (frequency >0.02 min−1) on gas transport in two filter sands with different gas permeability (kg) was investigated. Pressure fluctuation–induced gas transport characterized as a dispersion process governed by a pressure fluctuation–induced dispersion coefficient (Dp) was measured using a column containing the sand, connected to a membrane pump for generating pressure fluctuations. Measurements of Dp in both sands were carried out for different combinations of pressure-fluctuation amplitude (A) and frequency (f). To assess if Dp is affected by the presence of a background steady gas flux in addition to the gas movement induced by the pressure fluctuations, Dp measurements were carried out for different constant pore gas velocities (u). Measurements of Dp corresponding to a total of 102 combinations of u, A, f, and kg were carried out. The results showed that the value of Dp increases with increasing A, f, and kg but is independent of u. Relations between Dp and A, f, and kg were generally strong.
1Environmental Engineering Section, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark. Dr. Tjalfe G. Poulsen is corresponding author. E-mail: email@example.com
2Department of Earth Sciences, Uppsala University, Villavägen 16 SE-752 36, Uppsala, Sweden.
Received June 22, 2011.
Accepted for publication September 12, 2011.
Financial Disclosures/Conflicts of Interest: Funding was provided in part by the Villum Foundation, Søborg, Denmark. The authors have no conflicts of interest to report.