Airflow Resistance of Rough Rice as Affected by Moisture Content, Fines Concentration and Bulk Density

THE effect of moisture content, fine material con­ centration and bulk density on the airflow resistance of long-grain rough rice was determined. Airflow resistance was measured at air velocities ranging from 0.013 to 0.387 mis, bulk densities from 480 to 604 kg/m3, fines concentrations from 0 to 30% and moisture contents from 12 to 24 %. Airflow resistance was accurately described by an empirical equation comprised of these variables with over 99% of the variance in resistance being accounted for by the variables. Inclusion of each variable significantly improved the prediction of airflow resistance. Using an air velocity of 0.10 m/s and typical design conditions of 18% moisture content, bulk density of 577 kg/m3 and clean rice (0% fines concentration) as a base condition, it was found that increasing fines concentration by 1% increased airflow resistance by 0.87 % , increasing bulk density by 16 kg/m3 (1 Ib/ft3) increased resistance by 3.37% and increasing moisture content by 1% decreased resistance by 3.73%.