Study on the pore structure characteristics of maize grain piles and their effects on air flow distribution.

• The effect of broken kernel content on pore structure parameters was studied. • The porosity and permeability in the grain pile decrease with increase in the broken kernel content. • The small pores (diameter < 1 mm) and isolated pores increase with increase in the broken kernel content. • The pore throat size of grain piles decreases and the tortuosity increases with increase in the broken kernel content. • The average coordination number of pores increases with increase in the broken kernel content. The airflow in grain piles is affected by the content of broken grains, which causes changes in the pore structure within the grain pile. To investigate the changes in structural parameters at different broken grain contents, CT scanning and image processing were used to study the pore structure characteristics of broken maize grain contents of 0 %, 4 %, 8 % and 15 % respectively. The airflow distribution in the grain pile under different broken grain contents was studied by numerical simulation. The results showed that as the broken kernel content increased from 0 to 15 %, grain pile porosity gradually decreased, with a change rate of 6.97 %. An increase in the content of broken grains causes a decrease in the diameter and volume of the pores in the grain piles. The average value of the pore coordination number in the grain pile decreased as the broken grain content increased. When the content of broken grains is 0–15 %, the rates of change of pore diameter and tortuosity in the grain piles are 14.94 % and 24.94 %, respectively. As the broken grain content increased, the length and diameter of the pore throat in the grain pile decreased, while the fractal dimension and tortuosity increased. The increased broken grain content in the grain piles impedes the flow of air through the pores, thus affecting ventilation efficiency. [ABSTRACT FROM AUTHOR]