AI Insight
This study compares three analytical methods for measuring mass transfer between phases in porous materials using X-ray micro-computed tomography during hydrogen dissolution experiments at different injection rates. The researchers found that all three approaches—Slice-Averaged Concentration, Non-Classified per-Cluster, and Classified per-Cluster—produce similar results for large-scale mass transfer properties, but diverge when estimating detailed pore-scale phenomena like local solute concentrations. The choice of method depends on the required level of detail and available computational resources.
Why it matters
These findings provide practical guidance for scientists studying processes in porous materials, including groundwater cleanup and underground energy storage. By clarifying which analytical approach to use based on research goals and computing capacity, this work can improve the accuracy and efficiency of mass transfer measurements in geological and environmental applications.
Understand the Science
arXiv:2604.07743v2 Announce Type: replace
Abstract: Understanding interphase mass transfer is essential for a variety of applications in porous media, ranging from groundwater remediation to geologic energy storage. While X-ray micro-Computed Tomography ($mu$CT) provides critical textit{in situ} observations, its application in quantifying mass transfer phenomena requires models and workflows compatible with spatial and temporal constraints. Current literature presents three analytical frameworks for evaluating interphase mass transfer using time-lapsed sequences of $mu$CT scans: the Slice-Averaged Concentration (SAC) approach, the Non-Classified per-Cluster (NPC) approach, and the Classified per-Cluster (CPC) approach. Comparing results with previous studies, we identify that further research is needed to understand how these approaches will vary with experimental conditions and how the physical implications of their calculation frameworks should affect the interpretation of the results, as there are often no ground-truth measurements to compare the estimates to. The current study systematically evaluates the frameworks and results of the three approaches as applied to several sequences of time-lapsed $mu$CT scans, each observing hydrogen dissolution experiments at varying injection rates. For each observed advective injection rate, results indicate that system-scale properties, like mass transfer, appear robust to the selected approach. However, approach estimates diverged when approximating more complex, pore-scale phenomena, such as aqueous solute concentration. Ultimately, the utility of one approach over another is determined by the desired level of system detail, at the cost of the computational resources required to achieve it. Our results provide a framework for researchers to select analytical approaches based on available computational resources and the desired level of physical detail.