Dear all,
I would be very grateful if somebody could give me
some answer to the questions given below.
I’m operating a submerged packed bed (7 cm diameter +
40 cm height) with a porous material (porosity =
0,50). I’ve done a tracer assay for different flow
rates and I’ve evaluated the dispersion trough the
Peclet number (computed trough the first and second
moments of the distribution). My questions are:
1) What does mean the dispersion value I’ve got? Does
it give a general dispersion in the media or a
particular dispersion in a given direction (axial or
longitudinal)?
2) Does the dispersion only occur trough the void
space in the media? Does it also occurs into the
grains? I mean, is it possible to have any internal
dispersion?
3) The dispersion seems to be stronger with the
increase of the velocity (I understand). But the
tracer recovery decreases with the increment of the
velocity, witch would mean that more tracer is
retained for the high velocities I’m using (I’m just
applying velocities from 0,29 to 0,65 m/h). The tracer
does not adsorb and has a high molecular weight (low
diffusion). Why the tracer keeps retained for more
long periods at high velocities (i.e. 0,65 m/h)?
I tank you in advance for any help.
Sincerely
Claudia
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