Effects of Dissolution Fingering on Mass Transfer Rate in Three-Dimensional Porous Media

Dissolution mass transfer from the trapped phase to the flowing phase in porous media occurs in various hydrogeology processes. One of the important phenomena is dissolution fingering and its effect on dissolution mass transfer. In this work, dissolution mass transfer in porous media with various particle sizes and distribution was investigated in pore scale and meso-scale by using X-ray microcomputed tomography. The specific interfacial area and mass transfer coefficient were measured by following the representative elementary volume concept, and the effect of dissolution fingering was evaluated. Linear instability theory was used for the prediction of dissolution finger width (lambda) at the onset of dissolution fingering. Although dissolution fingering tends to develop when the porous media container diameter (Ly) is smaller than half of lambda, its effect on mass transfer coefficient starts to occur when Ly is larger than the whole lambda. Starting this point, dissolution fingering decreases the mass transfer coefficient by three times. For validation, an additional experiment with a larger porous media container size was performed, and three dissolution fingers were successfully observed. Their size was found to be comparable with the theoretical prediction based on linear instability theory.

Automated summary

The study investigated dissolution mass transfer in porous media with different particle sizes and distributions using X-ray microcomputed tomography. It found that dissolution fingering has an effect on mass transfer coefficient, with a significant decrease observed when the porous media container diameter (Ly) is larger than the whole lambda. Validation experiments showed successful observation of dissolution fingers, with sizes comparable to theoretical predictions based on linear instability theory.