Fluidization and Multiphase Flow
Professor Daniel Lepek is a recognized expert in the field of fluidization, particularly in the area of nanoparticle fluidization. Dr. Lepek has given talks on this subject at both national and international conferences; most recently at the World Congress of Particle Technology in Nuremberg, Germany. His work in this area has led to major publications in highly-ranked chemical engineering journals. In particular, his work was selected by the editors and featured as the cover image for the January 2010 AIChE Journal.
Fine and ultraﬁne powders are receiving an increased interest in academia and industry due to their unique chemical, physical, and mechanical properties. Fluidization is one of the best techniques currently available to disperse particles, especially for coating, pharmaceutical, and petrochemical applications. Nanopowders have been classiﬁed based on their gas-ﬂuidization characteristics into two groups: APF (agglomerate particulate ﬂuidization) and ABF (agglomerate bubbling ﬂuidization). APF ﬂuidized nanopowders show minimal bubbling, and large expansion similar to liquid-ﬂuidized beds. ABF ﬂuidized nanopowders exhibit large bubbles and have little expansion. Large bed expansion and homogeneous dispersion is critical to achieving optimal gas-solid contacting for increased reactivity in most processes. Although much work has been done to enhance the ﬂuidization properties of APF nanopowders (e.g. Degussa Aerosil R974 silica), ABF nanopowders (e.g. Degussa Aeroxide TiO2 P25) still need to be the subject of more studies.
(SEM image of a silica nanoparticle agglomerate)
At The Cooper Union, Dr. Lepek has worked closely with both undergraduate and graduate students to further explore the hydrodynamic behavior and mixing properties of nanoparticles. The results of this research work have been published and presented at national and international meetings. Students and collaborators who are interested in working on projects relating to fluidization and multiphase flow, should contact Dr. Lepek directly.