Phd in ENERGY AND ENVIRONMENT

Thesis title: CFD study of the sanitization of surfaces by means of hydrogen peroxide vapor

Indoor confined environments such as rooms, offices, classrooms, meeting areas and commercial spaces represent complex microclimates where people spend a large portion of their time. In these spaces, microorganisms can persist on surfaces and, under certain conditions, remain suspended in the air. For this reason, effective room-scale sanitization strategies have become increasingly important not only in healthcare facilities but also in common indoor environments. Traditional surface disinfection methods are mainly manual and rely on liquid chemical agents applied locally. While effective at small scale, these approaches may lead to incomplete coverage, variability in contact time, and difficulty in reaching hidden or obstructed surfaces. Automated room decontamination systems based on vapor-phase disinfectants aim to overcome these limitations by distributing the active agent throughout the entire volume of the room. Among available technologies, vaporized hydrogen peroxide (VHP) is widely used because of its strong oxidizing properties and its ability to decompose into water and oxygen after treatment. This characteristic makes it suitable for confined spaces, where residue accumulation must be avoided. Hydrogen peroxide acts by generating reactive oxygen species capable of damaging cellular membranes, proteins and nucleic acids, leading to microbial inactivation. However, the real effectiveness of VHP at room scale is not determined only by its chemical properties. The disinfectant is transported by air, and therefore its distribution depends on airflow organization, ventilation rate, room geometry and the presence of obstacles. Poorly organized airflow may generate stagnation zones, recirculation areas or regions with insufficient contact time. As a consequence, a sanitization process must be understood as a coupled chemical and fluid-dynamic phenomenon. Computational Fluid Dynamics (CFD) provides a powerful tool to analyze airflow and disinfectant transport in confined environments. Through numerical modeling, it is possible to predict velocity fields, concentration distributions, and surface exposure patterns. This allows the optimization of ventilation configurations and disinfectant injection strategies before practical implementation. The objective of this doctoral work is to develop and analyze a CFD framework capable of describing hydrogen peroxide vapor transport in confined indoor environments. The study focuses on generic enclosed spaces such as rooms and offices, evaluating how ventilation design, air change rate and surface characteristics influence disinfectant distribution and overall sanitization effectiveness.