Strona 2_redak - Instytut Agrofizyki im. Bohdana Dobrzańskiego ...

101
ƒ Current solutions of in-line particle size detection allow mainly for quantification
in relation to droplet size empirically calibrated. For a rapid changing
product portfolio and variable ingredients, these abilities may prove
insufficient.
ƒ Some options for absolute in-line particle size quantifications are present, but
current solution are able only to determine qualitative relation to droplet size
calibrated empirically. For a rapid changing product portfolio and variable
ingredients, these abilities may prove insufficient. In-line imaging and image
analysis may deliver quantitative information necessary for process control in
flexible factory conditions. Close monitoring of this information may allow
for process control and quality assessment at the same time.
ƒ The area of characterization of particles arrangement inside a product
matrix remains still in too early a stage of exploration for having significant
implications on the process measurement instrumentation.
13.4. Tendencies in development of applications
Last two decades of 20th century observed an increase in interest in particulate
materials. Industry has been using more and more raw products, and produced
increasing amounts of products in granular form. Global competition enforced
increase in the scale of production that required automatic process control. Market
demands stable quality of products delivered under the same trade mark. Material
in granular form is much easier for storage, processing, mixing dosing, packing and
distribution. Requirements of practice stimulated development of knowledge about
granular materials, particularly in three areas:
ƒ theoretical investigations seeking constitutive model of material,
ƒ methods of determination of material characteristics for use in design of
processes and equipment, and
ƒ elaboration of methods of quality assessment and indices to measure quality.
Beginning in the 80-ties of the previous century, an unprecedented increase
in calculation power of computers commonly accessible took place that enabled
new possibilities of theoretical investigations. New theoretical approaches appeared,
two of them gained matured form: numerical modelling including interactions in
contact areas between individual particles, and the application of earlier known
theories that required extensive calculations.
Regarding modelling behaviour of the bedding of material based on intera-ctions
in contact points between particles, the DEM method that originates from work
of Cundall and Strack [39] remains promising. Good examples of a new approach to
known methods are the applications of the theory of non-symmetric elasticity of
Cosserats by Mühlhaus and co-authors [119] or by Chang and co-authors [33].