Chemical Engineering Science, Vol.57, No.15, 3119-3131, 2002
Stress effects on the conductivity of particulate beds
Conduction in particulate materials affects a variety of applications ranging from packed bed and multi-phase reactors to calcining/drying kilns, from the storage of bulk reactive or temperature-sensitive materials to material processing. A multi-scale, multi-physics modeling technique-thermal particle dynamics (TPD)-is used to examine heat conduction through static, two-dimensional beds of granular materials. Results of both experiments and a microstructurally based continuum model compare well with those obtained from TPD simulation. The TPD technique, therefore, may provide a unique test-bed for validating or extending theories of effective properties in granular media by yielding detailed mechanical and thermal information not easily measured in experiments. Moreover, in testing this technique it is found that, at low compressive loads or in high aspect ratio beds, the conductivity of particulate materials becomes highly anisotropic. This suggests that it is possible to dynamically tune the granular microstructure and hence the bed's properties.