EFFECTS OF MOISTURE AND FINE MATERIAL ON STATIC PRESSURE DROPS IN A BED OF GRAIN SORGHUM AND ROUGH RICE

摘要

Static pressure drops across columns of grain sorghum and rough rice were measured to determine the effects of grain moisture content, fine material, and airflow rate on airflow resistance. For grain sorghum, five levels of moisture content (12.0%, 13.5%, 15.0%, 16.5%, and 18.5% w.b.) and four levels of fine material (0%, 2%, 4%, and 8% by weight) were investigated with airflow rates ranging from 0.03 to 0.17 m 3 /m 2 s. For rough rice, four levels of moisture content (11.8%, 15.2%, 17.4%, and 19.5% w.b.) and four levels of fine material (0%, 1%, 3%, and 5%) were considered with airflow rates ranging from 0.05 to 0.38 m 3 /m 2 s. For both grains, airflow rate was the most significant factor affecting the static pressure drop. The static pressure drop decreased with increasing moisture content for both grains. However, the fine material content had a positive relation to the static pressure drop for grain sorghum but a negative relation for rough rice, possibly because of the large particle size of fine material in the rough rice sample. For both grains, the statistical model SP = a(Q) + b(Q) 2 + c(Q)(mc) + d(Q)(fm) --- where SP is static pressure drop; Q is airflow; mc is moisture content; fm is fine material content; and a , b , c , and d are constants --- adequately described the relationship among static pressure drop, airflow, grain moisture content, and fine material with an R 2 = 0.997