PhD Defence by Isaac Appelquist Løge

Principal supervisor:
Associate Professor Philip L. Fosbøl

Examiners:
Associate Professor Alexander Shapiro, DTU Chemical Engineering
Senior Researcher Niels H. Schovsbo, GEUS, Denmark
Dr. Salina Baraka-Lokmane, TotalEnergies, France

Chairperson at defence:
Associate Professor Martin Andersson

A copy of the PhD thesis is available for reading at the department

Popular science summary
Transport of both energy and material is crucial for modern society. Energy transport occurs in heat exchangers, and material can be transported in pipelines. The formation of crystals is
a challenge in both these systems; for heat exchangers, the heat transfer efficiency is lowered significantly by the presence of crystals, and pipelines quickly become clogged when crystals
form. Also, in a household are, the consequences of crystal growth observed; in areas with hard water, kettles will chalk up, and shower heads will clog. The unwanted growth of
crystals is called scaling and is present in many industries. 

Developing an understanding of scaling is crucial to developing efficient mitigation strategies. Traditionally, scale research has been focused on what occurs in the liquid phase. However, scaling is ultimately a surface problem. This work has developed a new method for investigating scaling on the surface. Scaled-down steel cylinders were used as a mimic for pipelines, and X-ray CT scanning was used to visualize the growth occurring inside the cylinders when exposed to a solution which was prone to cause scale.

Simulations of fluid dynamics complemented the experimental method in the fluid phase and advanced image analysis, which allowed numerous insights to be gained on BaSO4 formation;
• how fluid flow affects attachment and detachment processes,
• why do specific substrates promote or inhibit crystal growth,
• how chemical potential accelerates nucleation processes which can lead to unstable
deposited structures,
• how crystals develop over timespans much longer than previously investigated
• how chemical inhibitors can accelerate deposition and the mechanism behind it.

The knowledge gained in the project can be used to design solutions, which can reduce the economic consequences of scaling.