| Separation Actions Sieving plus Air
The sieving separation action is normally based on the aerodynamic properties, dimensions, specific weight, the conditions of the surface, differences in shape, etc.
Figure 1 shows the pneumatic separation in a vertical air stream. If the gravity force (Q) is greater than the vertical force
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Based of the air flow rate, four different conditions are described as follows (Tabatabaifar and Persson, 1995):
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When the vertical force is much smaller than the gravity force (R<<Q), crop material resting on the sieve;
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When the vertical force increase, crop materials are expanded by the air stream;
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When the vertical force is equal to the gravity force (R=Q), the entire crop layer will be lifted intact;
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When the vertical force is greater than the gravity force (R>Q), the crop materials dissolved into each other and move along the air stream.
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Reference:
Karpenko, A.N. and Zelenev, A.A. (1965) Grain-Cleaning Machines, 266-290, Agricultural Machines . Israel Program for Scientific Translations, Jerusalem 1968.
Tabatabaifar, A., Persson, S.P.E. (1995) Layer Breakup and Particle Movement on A Chaffer Sieve. American Society of Agricultural Engineers . 37(5):1035-1313
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