|Butts, Christopher - Chris|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2003
Publication Date: 6/1/2004
Interpretive Summary: Recent changes in the peanut industry has prompted, equipment manufacturers to examine the design of peanut drying trailers currently in use. Drying trailers have an air chamber, into which heated air is forced, then through a perforated metal floor, and up through the peanuts. Perforated metal, in which the holes make up 23% of the total floor space, is currently used. Some have installed perforated metal with 40% open area. A system using readily available instrumentation and supplies was developed and used to measure how uniform the air is distributed as it flows up through the peanuts. Tests were conducted to measure the airflow distribution in trailers with the two perforation patterns. In these studies, the amount of perforation had no measurable effect on the resistance to airflow, the total airflow, or the distribution of air. Airflow patterns were very similar for all trailers tested.
Technical Abstract: A method to measure airflow distribution within a filled peanut drying trailer was developed. Six 6.4-m peanut drying wagons were loaded with dry farmer stock peanuts at a local peanut processing facility. Three wagons had floors with 23% O.A. and three had floors with 40% O.A. Peanuts were leveled on each trailer and peanut depth ranged from 114 to 130 cm. A 76-cm diam., 1750 rpm, 4-blade vane axial fan, dryer with a 91-cm long straightening inlet transition was connected to each peanut drying trailer. The rated airflow capacity of the dryer was approximately 300 m3/min at 12 mm H2O. Total airflow was measured using a pitot tube traverse across the inlet transition. Static pressure was measured in the wagon plenum using a U-tube manometer. The top of the trailer was divided into 40 sections using a 5 x 8 cell grid. The airflow through each grid cell was measured using a vane anemometer mounted on a conical transition placed in the center of each grid cell. No significant differences in static pressure, total airflow, [or] airflow distribution due to the percent O.A. of the perforated drying floor were detected. The average static pressure observed for wagons with the 23 and 40% O.A. was identical at 12.4 mm H2O. Total airflow measured at the fan inlet averaged 283 m3/min for the 40% O.A. trailers compared to 277 m3/min for trailers with 23% O.A. Specific airflow averaged 9.42 m3/min/m3 for the peanut wagons with 23% O.A. with a standard deviation 1.13 m3/min/m3. Similarly, the drying wagon with a 40% O.A. floor had an average specific airflow of 9.50 ± 1.12 m3/min/m3.