  A multiphysics modeling approach for heat conduction in metal hydride powders
is presented, including particle shape distribution, size distribution,
granular packing structure, and effective thermal conductivity. A statistical
geometric model is presented that replicates features of particle size and
shape distributions observed experimentally that result from cyclic hydride
decreptitation. The quasi-static dense packing of a sample set of these
particles is simulated via energy-based structural optimization methods. These
particles jam (i.e., solidify) at a density (solid volume fraction) of
0.665+/-0.015 - higher than prior experimental estimates. Effective thermal
conductivity of the jammed system is simulated and found to follow the behavior
predicted by granular effective medium theory. Finally, a theory is presented
that links the properties of bi-porous cohesive powders to the present systems
based on recent experimental observations of jammed packings of fine powder.
This theory produces quantitative experimental agreement with metal hydride
powders of various compositions.
