Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In the work presented in this paper, the dissolution rate of a single Taylor bubble of carbon dioxide into water was compared within a square and circular channel of 6 mm hydraulic diameter. The bubbles were held stationary in the down-flowing liquid and observed with high resolution X-ray radiography and tomography. The acquired X-ray images of the bubbles were analyzed with respect to volume, surface area and length of the bubble and were utilized to obtain the liquid side mass transfer coefficient by measuring the changes in the size of the bubble at constant pressure. The X-ray method was chosen since it is not dependent on the refractive index; therefore it is the most accurate method in comparison with other conventional optical techniques. The results for the long term dissolution of single CO2 bubbles show that the dissolution curves for bubbles with different initial size follow the same trend and have relatively constant slope. In addition, the comparison of the results for the square and circular channels showed that, there are some distinguishable differences between the trend of the liquid side mass transfer coefficient, kL in two curves. For square channel, kL increases with decrease of bubble sizes, while no obvious trend could be detected for the circular channel.