Professor Department of Chemical Engineering City College of New York       Dipl. Eng, 1969, Polytechnic Institute, Bucharest, Romania M.Sc. (M.E), 1975, D.Sc., 1978, Technion , Israel	Gabriel I. Tardos

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Research Interests:

Powder Science and Technology; Granulation (size increase) of fine powders; Theory and practice of powder flows; Fluid-particle systems; Electrostatic effects; Air pollution control.

Study of agglomeration of small powder particles in rotating drums, fluidized beds and high shear mixers, owing to such effects as high temperatures and the addition of liquid species (binders), is aimed toward basic understanding of the phenomenon of agglomeration. Theoretical modeling seeks to determine lower limits on fluidization velocity and defluidization conditions as a function of bed temperature, bed material viscosity and strength and other parameters. By using dilatometry we are developing experimental methods to measure surface softening, viscosity, and minimum sintering temperatures for a variety of particles.

Related to the above, is our work on the dynamic strength of liquid bridges between pairs of liquid-coated particles. The surprising result that the strength of a dynamic bridge is sometimes orders of magnitude greater than that of the static bridge, accounts for the high gas velocity needed to keep sticky particles fluidized. Based on the study of liquid bridges between small particles, a new theory of agglomeration of fine powders in a mixer-granulator was proposed. This new theory is being applied to drum, fluid bed and high shear granulation - processes widely utilized in such industries as pharmaceuticals, agricultural products and detergents. The model is being tested with experiments at small and large scales as well as by a numerical model based on the concepts of molecular dynamic simulations (MDS).

Study of the effect of electrostatic forces on the filtration efficiency of fibrous filters has motivated a new theoretical model. It considers the effects of neighboring fibers on the flow field as well as on the electric field to predict the total bed collection efficiency of an electrostatically enhanced fibrous filter. The model takes into account inertia, interception and electrostatic forces on dust particles in the filter and gas humidity on the filtration process. Careful experiments complement and verify the theoretical results.

RECENT PUBLICATIONS

1. Chapters in Books
   1. Tardos, G.I., "Granular Bed Filters," chapter in the "Handbook of Powder Science and Technology," M.E. Fayed and L. Otten, (Eds.), Van Nostrand Reinhold Co., Toronto, London, New York, Second Edition,(1997).
   2. Tardos, G.I., "Separation of Airborne Dust in Deep Bed Filtration," chapter in "Advances in Aerosol Filtration," K.R. Spurny, (Editor), CRC Press LLC, Lewis Publishers, Boca Raton, New York, USA, (1998).
   3. Turton R., G.I. Tardos and B.J. Ennis, "Fluidized bed Coating and Granulation," chapter in "Selected Topics on Fluidization, Solids Handling and Processing," W.C. Yang, (Ed.), Noyes Publications, Chapter 6, pp. 331-429, (1999).
   4. Tardos G.I. and P.J. Mort, "Granulation and Coating in Fluidized beds," Chapter in "Handbook of Fluidization Technology," W.C. Yang, (Ed.), Elsevier, Amsterdam, New York, (in press, 2000).
2. Technical Publications
   1. Tardos, G.I. and R. Gupta, "Forces generated in solidifying Liquid Bridges between two small Particles," Powder Technology, Vol. 87(2), pp. 175-180, (1996).
   2. Tardos, G.I., I.V. Nicolaescu and B. Ahtchi-Ali, "Ingress of atmospheric moisture into bulk packed powders," Powder Handling and Processing, Vol. 8, (1), pp. 7-16; Part II: "Application to powder caking", Vol. 8(3), pp. 215-220, (1996).
   3. Tardos, G.I. and Q.Y. Lu, "Precision dosing of powders by vibratory and screw feeders," Advanced Powder Technol., Vol. 7(1), pp. 51-58, (1996).
   4. Tardos, G.I., "A Fluid Mechanics approach to slow, frictional Powder Flows," Powder Technology, Vol. 92, pp. 61-74, (1997).
   5. Tardos, G.I., I.M. Khan and P.R. Mort, "Critical parameters and Limiting conditions in Binder Granulation of fine powders," Powder Technology, Vol. 94, pp. 245-258, (1997).
   6. Khan, M.I. and G.I. Tardos, "Stability of wet Agglomerates in Granular shear flows," Vol. 347, pp. 347-368, J. of Fluid Mechanics, (1997).
   7. Apicella, E., M. D'Amore, G.I. Tardos and R. Mauri, "Onset of instability in sheared gas fluidized beds," AIChE Journal, Vol. 43, pp. 1362-1365, May (1997).
   8. Tardos, G.I., M.I. Khan and D.J. Schaeffer, "Forces on a slowly rotating, rough cylinder in a Couette device containing a dry, frictional powder," Physics of Fluids, Vol. 10(2), pp. 335-341, February, (1998).
   9. Elbicki, J.M., and G.I. Tardos, "The influence of fines on the flowability of alumina powders in test hoppers," Powder Handling and Processing, May-June, pp. 147-151, (1998).
   10. Mort, P.R. and G.I. Tardos, "Scale-up of agglomeration processes using transformations," KONA, Vol. 17, pp. 64-75, (1999).
   11. Talu, I., G.I. Tardos and M.I. Khan, "Computer simulation of wet granulation," Powder Technology, Vol. 110, pp. 59-75, (2000).
3. Other Recent Publications
1. A FLUID MECHANISTIC APPROACH TO SLOW (COULOMB) AND INTERMEDIATE POWDER FLOWS
2. AGGLOMERATE GROWTH AND BREAK-UP IN WET GRANULATION OF FINE POWDERS
3. Particle size control by torque measurements in fluidized beds during drying and granulation from solutions
4. Use of stress fluctuations to monitor wet granulation of powders