Formation mechanisms of particle structures and their rearrangement in cross-flow filters for gas purification

Cross-flow filtration has been used for several decades to separate particles from engine exhaust gases. Due to the stricter regulations of particle emissions, cross-flow filters are used in mobile applications (such as diesel engine commercial vehicles and passenger cars) but also in ships, gasoline engines, biogas and waste incineration plants.

The principle of the cross-flow filtration is based on a parallel overflow through the filter medium. During this process, particles are deposited on the filter surface as well as in the pores of the filter. This results in a better separation efficiency, but also in an increase of pressure drop and energy consumption. The emerging particle layer can break during the filtration process or rather the regeneration of the filter and can lead to rearrangement processes of the particles and agglomerates on the filter media. These rearrangement processes are dependent on a number of process-engineering parameters such as the inflow velocity, temperature and loading. During engine combustion, a heterogeneous particulate system is formed from inert (inorganic) and reactive (organic) components. This mixed system shows a different rearrangement behaviour as a homogeneous particulate system.

The objective of this project is to analyse the formation mechanisms and rearrangements of heterogeneous particulate systems in cross-flow filtration processes. Thereby the formation mechanisms during aerosol generation as well as the global rearrangement processes on the filter wall will be investigated in connection with process-engineering parameters and filter properties.

                         Possible rearrangement processes of inert-reactive particle systems, according to Sappok et al.