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vol. 8, nr. 4 (2006)
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Influence of method of deposit formation on airflow resistance in wheat
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Józef Łukaszuk, Marek Molenda, Józef Horabik
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Institute of Agrophysics, Polish Academy of Sciences, ul. Doświadczalna 4, 20-290 Lublin |
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vol. 8 (2006), nr. 4,
pp. 881-891
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abstract:
Relationship between airflow velocity V and pressure drop p was examined in samples of wheat of moisture content of 10% wet basis. The sample was a cube of 0.35 m side and contained approximately 35 kg of grain. Three methods of filling the test chamber were used that generated samples of different density and packing structure. Characteristics of p(V) were determined in three mutually perpendicular directions (Z – vertical, Y and X – horizontal) and for airflow velocities in the range from 0.03 to 0.35 m s-1. Samples prepared using different methods varied in density from 768.61 to 831.60.4 kg m-3. Repeatability of density and airflow resistance were also dependent on the method of sample formation. Standard deviations of density were found in a range from 0.35 to 1 kg m-3. Samples of higher density posed larger resistance to airflow. The airflow resistance was found to be dependent on the flow direction. At the airflow velocity of 0.3 m s-1 in axially filled unconsolidated or consolidated samples (methods A and C) pressure drop in vertical direction was 50 or 38% higher than those in horizontal directions X and Y. In asymmetrically filled sample (method B) airflow resistances in horizontal direction were different as well. In this case, at airflow velocity of 0.3 m s-1, pressure drop in direction Z was 30% higher than in direction X and 93% higher than pressure drop in direction Y. Changes in the airflow resistance of such values may be expected in practice and should be considered in process design and in operation of equipment in technologies using airflow of gases through masses of granular materials, such as drying, aeration, cooling or fumigation.
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keywords:
grain, density, airflow resistance, airflow direction
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original in:
Polish
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