2. Design
There are a wide variety of cyclone separators with different shapes and configurations. The most commonly used one
is the reversed flow cyclone which has a cone under a cylindrical body with a tangential inlet. Separation performance
strongly depends on the structure and length of the double vortex formed in this kind of cyclone. According to the
mathematical model explained in the works by Avci and Karagoz, friction factor which is a function of surface roughness
and the Reynolds number, plays an important role on the cyclone efficiency and pressure drop (Avci & Karagoz, 2003;
Karagoz & Avci, 2005). It was also demonstrated that surface roughness affects axial and tangential velocity distributions,
and consequently the vortex length, in a cyclone (Kaya et al., 2011). These results have motivated the idea that the vortex
length and separation performance can be increased by decreasing friction losses in a cyclone. The design of this new
cyclone is based on the idea that the vortex length and separation performance can be increased by decreasing friction
losses in a cyclone. The new design differs from a classical cyclone with the separation space. It has inner and outer cylinders without a conical part, and a vortex limiter (Fig. 1). The flow enters tangentially into the inner cylinder which has
the main frictional surface and serves as vortex creator. The flow spirals down below the inner cylinder almost without
wall friction through the outer cylinder and then turns back from the limiter plate towards the exit pipe. The vortex limiter
can be moved up and down unable to adjust the vortex length. For example, if the flow rate or inlet velocity increases the
vortex limiter can be slide down to increase the vortex length and to attain high efficiency. The particles move towards the
wall of the outer cylinder and are separated from the vortical flow under the action of centrifugal forces and collected on
the bottom of the outer cylinder. That is the main separation process occurs in the outer cylinder. The new design has
also the advantages of easy manufacture and low maintenance. A prototype was constructed to test its performance.
The geometric dimensions of the prototype are given in Table 1.