Meltable Discrete Element Method (Meltable-DEM)
The first simulation tool to study melting, solidification and bonding of particles.
Recent years have seen the wide adoption of Discrete Element Method (DEM) by the pharmaceutical and materials processing industries to improve their production process. . DEM’s unique capabilities in simulating the motion and mechanical interactions of individual particles enable the simulation of the full-scale processes with high degree of fidelity which can lead to the reduction of downtime and a lower cost in new product design.
However, current DEM models lack the ability to deal with situations where particles melt and solidify in response to temperature changes. As a consequence, important processes in pharmaceutical and materials processing industries, such as hot fluidized melt granulation and sintering, are still beyond the reach of existing DEM technologies.
This invention is a method to enable existing Discrete Element Method models to address for the first time granular systems with particles undergoing melting and solidification. Besides the intrinsic capabilities of DEM in simulating the motion and mechanical interactions of particles, the invention enables these motion and interactions to be affected by melt and solidification. Particles can partially or totally melt, with the time evolution of the molten zones calculated by thermo-mechanical laws describing the melt-solidification transitions. Particle interactions can now be completed to include melt viscosity and solid bonding upon solidification that agglomerates particles into clusters.
Above: Fluidized hot melt granulation simulated using the Meltable-DEM: [left] Hot molten particles are continuously dropped into a drum of rotating colder particles; [right] After few drum rotations and the cooling of some of the molten particles solid bonds are established through solidification, to form larger clusters (differentiated by colour). This simulation replicates the fluidized hot melt granulation process used by the pharmaceutics industry to tailor grain size distributions. The method can optimise the efficiency and accuracy of the controlled clusters’ size distribution and strength, by carrying out systematic simulations investigating the effects of the drum rotation rate, its roughness, drop sizes and their rate of injection, and the thermo-mechanical parameters defining the drops and the rotating granular media.
- This invention can be incorporated into existing commercial Discrete Element Method softwares to enhance their applicability to meltable media.
- This invention can also be employed specifically by pharmaceutics companies interested in optimising fluidized hot melt granulation, and by process engineering dealing with sintering.
Dr. Yixiang Gan, A/Prof. Itai Einav, Dr. Pierre Rognon