The present study has provided performance correlations
relating performance indicators viz., pressure coefficient,
non-dimensional 90% cut size and total collection
efficiency to dimensionless numbers viz., Reynolds num-ber and Stokes number. These correlations permit a
designer to evaluate the effect of various design parameters
on the performance of miniature cyclones. The following
conclusions can be drawn from the present study:
(1) As a cyclone separator is scaled down, the nondimensional
pressure drop across the cyclone increases.
However, scaling down is also accompanied by an increase
in the collection efficiency of the cyclone.
(2) While the collection efficiency of a cyclone is not
affected significantly by changes in the conical length, the
pressure drop across the cyclone shows a monotonous
increase with decreasing values of Lc/D, at least for the
range of the values considered in this study.
(3) The performance of a cyclone is very weakly dependent
on the length of the vortex finder.
(4) As the vortex-finder diameter of a cyclone is
increased, both the pressure drop and the collection efficiency
decrease.
(5) The pressure drop across the cyclone is extremely
sensitive to the underflow diameter and even a relatively
small change in the underflow diameter may bring about
a very large increase in the pressure drop across the
cyclone. As the underflow diameter is increased, the pressure
drop across the cyclone decreases and the collection
efficiency increases. However, this also results in a diluted
underflow and most of the air may exit the cyclone through
the underflow.
(6) The overflow diameter and the underflow diameter
are the two most critical dimensions of a cyclone. The
relative size of these two dimensions determines the flow
field inside the cyclone. The pressure drop across the
cyclone, as well as the collection efficiency, are strong
functions of these two parameters. Therefore, the overflow
and the underflow diameters should be selected carefully to
achieve the optimum design.