In the case of a SPLITT cell operating under a gravitational field, the relation which allows one to set the diameter cutoff of a spherical solid particle can be obtained by combining eqns [4], [6] and [7]. In fact, if V(t) = AV and:

centrifugal a>2rd2Ap





then the diameter at which 50% of the particles exit outlet b is called the cutoff diameter dc, expressed as:


in which only half of V(a') is considered (cf. eqn [4]). Once dc has been chosen for a given channel, the difference between V(a) and 0.5V(a') is set according to eqn [14]. However, the two constituents flow rates V(a) and V(a') are not uniquely defined by this equation, but some criteria useful for setting the flow rates are available in the optimization of SPLITT operations literature. In general, in order to obtain a separation with a good resolution, the practical rule which states the following necessary but not sufficient condition:

can be followed. This condition ensures that regions I and II will be narrow, which automatically increases the transport region, i.e. the cell space in which the separation process occurs. For maximum resolution, typical experimental conditions, are chosen to obtain a V(a')/V(t) ratio within 0.1-0.3. From a theoretical point of view, the high resolution in the operative transport mode is, as already stated, contingent on compression of the feed sub-stream, a', into a thin lamina near wall A, and the sharpness of the separation, as in chromatography, can be judged by the number N of the theoretical plates generated during transport. Generally, for field (gravitational) driven migrations, the effective N is given by the ratio of two energies:

Fwt nd3Apgwt


where d0 and d1 are respectively the diameters of the particles exiting from a and b. The particles falling between these two sizes (d1 and d0), which are not fully resolved, exit from both outlets in different proportions, so the difference should be small. According to eqn [17] the ratio of V(a) to V(a') allows control of the range of unresolved particles which exit both outlets a and b.

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