Drying of water from porous structures investigated by time-resolved X-ray tomography

In this contribution, we apply time-resolved X-ray tomography to study drying of water in porous ceramic substrates used in emission control technologies. A time resolution of 2 s is achieved, and allows to observe the spatiotemporal distribution of water in structured porous materials. An image processing framework based on machine learning is introduced to track pore emptying and filling in a large number of 3D scans. Drying curves are extracted from the tomographic data to investigate drying in materials with different structural properties. Water redistribution by capillary pumping and rapid pore emptying by Haines jumps are observed, and their impact on drying dynamics is discussed. The relationship between the evolution of water clusters and different drying regimes is established. The obtained information on the interplay between pore emptying, water redistribution and the size of water clusters provides an important link between the structural properties of dried materials and their drying rate.