Rotor Eff ciency

The time required for a particle to traverse a rotor is known as the pelleting efficiency or k-factor. The k- or clearing factor, which is calculated at the maximum rated rotor speed, is a function of rotor design and is a constant for a given rotor. k-Factors provide a convenient means of determining the minimum residence time required to pellet a particle in a given rotor and are useful for comparing sedimentation times for different rotors. The fe-factor is derived from the equation:

fe = ln (rmaX — rmin) x 1013/(3600tt>2) = 2.53 x 1011 x ln (w — rmm)/rpm2 [18]

where rmax and rmin are the maximum and minimum distances from the centrifugal axis, respectively.

Eqn [18] shows that the lower the fe-factor, the shorter the time required for pelleting. If the sedimentation coefficient of a particle is known, then the rotor fe-factor can also be calculated from the relation:

kadj = k(rprnmax/rprnact)2

term, 6. In Stokes' equation, the term 6m^r describes the frictional coefficient, f0, for a spherical particle. The correction term, 6, is calculated as the ratio of the frictional resistance, f, encountered by a particle of nonspherical geometry to that encountered by a sphere of the same volume, or:

The equation describing the terminal velocity for nonspherical particles in a centrifugal field may be rewritten as:

where T is the time in hours required for pelleting and S is the sedimentation coefficient in Svedberg units.

When k is known (normally provided by the manufacturer), then eqn [19] may be rearranged to calculate the minimum run time required for particle pelleting.

For runs conducted at less than the maximum rated rotor speed, the k-factor may be adjusted according where rpmmax and rpmact are the maximum rated rotor speed and actual run speed, respectively.

fe-Factors are also useful when switching from a rotor with a known pelleting time, t1, to a second rotor of differing geometry by solving for t2 in the relation:

where t1, t2, fe1 and fe2 are the pelleting times and fe-factors for rotors 1 and 2, respectively.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment