2. Experiments and
methodologies
2.1. Material
characterization
In the current study, the standard cylindrical hardwood pellets and
spherical LDPE particles, both belonging to the Geldart D type, have
been used as the test material. The characterization has been conducted
following the procedures established in Tucker et
al .26. Briefly, the particle size and shape
statistics of the spherical LDPE have been obtained using a SympaTEC -
QICPIC® particle analyzer which is compliant with the ISO 13322-1/2
Standard. The principle of QICPIC® operation is based on the analysis of
dynamic particle images obtained from backlighting a thin sheet of
passing particle samples. Calculation of the minimum superficial gas
velocity has been performed.
An in-house small-scale fluidization test has been performed to
determine the minimum superficial gas velocity
(U mf ) of the LDPE particles by determining the
pressure drop over the bed as a function of the superficial gas
velocity. The resulting U mf is used to
non-dimensionalize the superficial gas velocity for all test cases in
the study. All wood pellets have been cut into the same length with
aspect ratio, AR = L /D = 2, where L andD correspond to the length and diameter of the cylindrical wood
pellets, respectively. The size of the wood pellet is too large for
standard QICPIC® analysis, thus standard imaging is applied to measure
the particle dimensions, to ensure the monodisperse nature of the
prepared wood pellets. All related material properties have been
summarized in Table 1.
Table 1. Properties of the cylindrical and spherical particles.