TY - THES

T1 - Numerical investigation of the interaction between dust explosions and inert particulate additives using an Euler-Lagrangian approach in OpenFOAM

AU - Tomasch, Stefanie

N1 - embargoed until null

PY - 2016

Y1 - 2016

N2 - The occurrence of dust explosions in industry is still a serious threat to plants across all types of applications and should not be underestimated. Besides its own destructive effects the propagation of dust explosions through the plant can indirectly cause other dangerous failures. Extinguishing barriers proved to be a very successful countermeasure to prevent this. The fundamental mechanisms that are responsible for the effective intervention of the material into the combustion process is still subject of research. A reason for the very little knowledge about this topic is that most related processes take place within a few milliseconds and are difficult to record in laboratory experiments. The aim of this thesis was to elucidate the influence of particulate additives on the ignition and flame propagation behaviour in lycopodium/air mixtures using Computational Fluid Dynamics. For this purpose an Euler-Lagrangian approach was used. For a better comparability the geometries were derived from the associated test apparatus with which related experimental tests are carried out at the Chair of Thermal Processing Technology. Concerning the choice of additives it was aimed to represent a broad range of different extinguishing materials with varying response to heat input. Thereby the focus was placed solely on thermal effects. The three extinguishing agents that were used for this purpose are simple inert particles that can only absorb heat according to their thermal capacity, water-laden particles with the ability to evaporate and solid particles that show a simplified melting process. Besides getting a more comprehensive insight into the interaction between flammable dust/air mixtures and particulate inert additives, the determination of the necessary ignition energy and the flame propagation velocity for each set-up was also part of this work.

AB - The occurrence of dust explosions in industry is still a serious threat to plants across all types of applications and should not be underestimated. Besides its own destructive effects the propagation of dust explosions through the plant can indirectly cause other dangerous failures. Extinguishing barriers proved to be a very successful countermeasure to prevent this. The fundamental mechanisms that are responsible for the effective intervention of the material into the combustion process is still subject of research. A reason for the very little knowledge about this topic is that most related processes take place within a few milliseconds and are difficult to record in laboratory experiments. The aim of this thesis was to elucidate the influence of particulate additives on the ignition and flame propagation behaviour in lycopodium/air mixtures using Computational Fluid Dynamics. For this purpose an Euler-Lagrangian approach was used. For a better comparability the geometries were derived from the associated test apparatus with which related experimental tests are carried out at the Chair of Thermal Processing Technology. Concerning the choice of additives it was aimed to represent a broad range of different extinguishing materials with varying response to heat input. Thereby the focus was placed solely on thermal effects. The three extinguishing agents that were used for this purpose are simple inert particles that can only absorb heat according to their thermal capacity, water-laden particles with the ability to evaporate and solid particles that show a simplified melting process. Besides getting a more comprehensive insight into the interaction between flammable dust/air mixtures and particulate inert additives, the determination of the necessary ignition energy and the flame propagation velocity for each set-up was also part of this work.

KW - dust explosion

KW - CFD

KW - extinguishing powder

KW - Staubexplosion

KW - CFD

KW - Löschpulver

M3 - Master's Thesis

ER -