(173ai) Insight to Crystallisation Fouling from 4D X-Ray: A Three Step Process?

Crystallisation fouling presents a costly challenge, as it lowers the efficiency of heat exchangers, decreases the throughput of desalination membranes and clogs underground pipelines. Optimal maintenance requires accurate knowledge of the kinetics of the formation of crystallisation fouling.

Current methods for comprehensive in situ investigations are limited. The most commonly used ex situ or 2D experiments cannot capture dynamic effects or describe formation kinetics. This work uses X-ray computed tomography (CT) scanning to address this challenge.

We recorded the formation of crystalline fouling in situ by installing a custom-built flow loop inside a CT cabinet. To record the temporal changes in the crystalline fouling, we had to sparsely sample and underexpose the specimen, so we employed a custom reconstruction algorithm ensured accurate reconstructions. The high spatiotemporal resolution of the experiment made it possible to study the processes of crystal formation.

Our findings show how the growth rate can vary 300 % in the initial phases of growth. Even though we performed measurements for 150 hours, the rate at which growth formed was not constant. This non-equilibrium effect reflects the complexity of crystallisation formation in natural systems. Our findings provides a foundation for unveiling the dynamics of fouling mechanisms, which will aid in developing more accurate prediction models.