| Summary: | 碩士 === 逢甲大學 === 環境工程與科學所 === 99 === This study investigates density-driven and gravity-induced transport of dense gas mixtures in unsaturated soils. The experiment was conducted with Sulfur hexafluoride (SF6) mixed with nitrogen gas to represent the dense gas mixture. Gas phase density and pressure variations along an unsaturated soil column packed with dry sea sand were observed. In the experiment, the soil column was placed horizontally, vertically upward and downward to assess gravitational effect on the migration of the gas mixture along the column from inlet chamber(IC) to outlet chamber(OC). This study additionally performed GC-ECD calibration curve for detecting SF6 concentration and sorption experiment for assessing the effect of SF6 sorbed onto sea sand. The latter result shows that the sorptive effect is minor.
Results from the transport experiment show that density and
pressure variations are substantial, especially at the column entrance of the dense gas from the IC, and persist during the 6-hr observation of the experiment. Besides, the trend of the pressure variations along the soil column for vertically upward transport of the SF6 gas mixture is opposite to that for the gas transport in other direction. Density variations along the soil column were also affected by the transport direction. However,the pressure difference between observation points in the column and the OC presented from this study is opposite to the results shown in Altevogt et al. (2003). The observed density variation in the column is more substantial than those presented in Altevogt et al. (2003) and Hamamoto et al. (2008).
|
|---|
