In the same way as mentioned in my third repot (part 3), evaluations of the particle cut size,
dc, from the author's formula and the equilibrium particle size
dR=E, from the collection efficiency are also done with cyclones for the separation of various dusts. Considering the effects of the re-entrainment of dust near the discharge port on the collection efficiency, the values of the ratios of
dR=E to
dc are expressed by correlation with the particle Froude number based upon inlet velocity
uo and the height of imaginary cone defined as
Fr=
uo/√
gH, in stead of correlating the diameter ratio with particle Reynolds' number
Re which was obtained in my previous paper (part 3).
When there is no re-entrainment in cyclones on the whole, the values of the grain diameter ratio (
dR=E/
dc) become on average equal to 0.6 (constant) so far as the investigations are concerned, which embodies the availability of the au hor's equation for particle cut size.
When dust re-entrainment into the gas stream at the base of the vortex core is followed, the following expression holds on the whole:
dR=E/
dc=
K uo/√
gH in which the proportional constant
K depends on the particle properties and the inlet leading as shown in Fig. 5.
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