This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada
In filling and packing processes of foods (e.g. milk powder, coffee), inert gases are used to prevent the contact of the food with oxygen which may lead to a reduced shelf life. Therefore, during the filling and packing process huge efforts are made to reduce the ambient oxygen level by injecting inert gases. This requires huge amounts of inert gases, e.g. nitrogen or carbon dioxide, as the typical requirement for residual oxygen in filled packages is less than 1%. The costs of the inert gases as well as the optimization of the systems to reduce the amount of inert gases are the main challenges in the development which itself is currently based on experimental studies.
In this work, a simulation-based approach was developed to model the gas – transport phenomena of multi – species gaseous mixtures during falling processes of bulk material. The experimental and numerical studies were carried out for varying particle diameters, falling height and different gas species. The transport behaviour of the gas species was evaluated by means of the residual oxygen level inside the particle bulk. Two different numerical models were used to simulate the falling processes – a Lagrangian and an Eulerian approach. For the representation of different gas species and the calculation of diffusion processes, additional transport equations for the species have been added.
The simulation and the experimental results show a good agreement for the residual oxygen, the behaviour of the falling particles and the dependencies of falling height and mean particle diameter. The model can be used in different applications where the influence of inert gases in bulk materials are of interest, for e.g. in conveyor systems.
|Date||18th June 2019|
|Organisation||Bergische Universität Wuppertal|