Agriculture Reference
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Fig. 2.2 Cross-sectional surface of switchgrass ground particles under scanning electron microscope
(The MathWorks Inc., Natick, MA) using an image processing and statistical
toolbox. The particle length and particle width were defined as an ellipsoidal major
axis and ellipsoidal minor axis measured by the MATLAB imaging toolbox. These
two major parameters were used in the toolbox to calculate individual particle's
equivalent spherical diameter and aspect ratio. The number of particles, particle
length, particle width, and aspect ratio was reported. For each studied particle, three
imaging replicates were measured and averages reported.
2.2.3
Flowability
Static angle of repose is a flowability indicator of the material, which is a function
of particle shape, friction, and cohesiveness. It is defined as the angle at which a
material will rest on a stationary heap. It also helps to design the loading height and
the pile dimensions of the biomass particles [ 27 - 31 ].
Flowability of biomass grinds can be determined by the angle of repose test
using a Mark 4 version tester developed by Geldart (Powder Research Ltd., UK).
The sample flowability is generally classified as free flowing, fair flowing, and
cohesive [ 32 ]. A flowability study of ground particles of wheat straw, switchgrass,
and corn stover was studied using the Mark 4 version tester [ 19 ]. Twenty-five grams
of biomass grinds collected on each mesh after sieving is slowly poured onto the
uppermost stage with the vibrating chute [ 19 ]. The vibratory chute was shaken
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