Abstract

In this research, physical properties of corn and barley seeds were first determined and then, to obtain the change in pressure drop, power consumption and mechanical seed damage as a function of air velocity during suction conveying of corn and barley, a suction-type pneumatic conveying system was designed and constructed and finally the pneumatic conveying characteristics of corn and barley seeds were determined under seven air velocities. The results indicated that the geometric and arithmetic mean diameters and sphericity of corn seeds were 80, 63 and 20%, respectively, more than the barley seeds. Pressure drop increased nonlinearly and linearly with an increase in air velocity for corn and barley seeds, respectively. However, power consumption was nonlinearly increased with air velocity for both seeds. Mechanical damage of both seeds increased linearly as the air velocity was increased. There was a turning point at which the pressure drop increased rapidly with an increase in air velocity. The lowest pressure drop for corn and barley occurred at the air velocity of 20 and 15 m s^-1, respectively. Therefore, for reducing the specific energy consumption and mechanical damage to corn and barley seeds at the conveying capacity of 15 ton h^-1, the air velocity in pneumatic conveying must be decreased below 20 and 15 m s^-1, respectively.

Key words: Pneumatic conveying, conveying characteristics, pressure drop, power consumption, mechanical damage.