Hopper-bottom semi-trailer modified for in-shell peanut drying: design, fabrication, and performance testing

Authors: McIntyre, Joseph; TURNER, AARON - Clemson University; TEDDY, BRENNAN - Clemson University; FOGLE, BENJAMIN - Clemson University; Butts, Christopher - Chris; KIRK, KENDALL - Clemson University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2022
Publication Date: 6/13/2022
Citation: Mcintyre, J.S., Turner, A.P., Teddy, B.E., Fogle, B., Butts, C.L., Kirk, K.R. 2022. Hopper-bottom semi-trailer modified for in-shell peanut drying: design, fabrication, and performance testing. Applied Engineering in Agriculture. 38(3):477-488. https://doi.org/10.13031/aea.14869.
DOI: https://doi.org/10.13031/aea.14869

Interpretive Summary: Hopper-bottom trailers modified for peanut drying could provide several advantages to producers and peanut buying point operations. Producers who utilize hopper-bottom trailers for transporting grain would have an additional use for the trailer and would be less prone to harvest delays during peak times when trailer availability from the buying point is limited. Additionally, smaller buying points would benefit from reduced handling steps and dependency on trailer lifts. Computer simulations of airflow through the peanut load was used to develop retrofit designs for a typical hopper-bottom trailer that will produce uniform drying. A hopper-bottom trailer was modified using the designs. Three test loads of peanuts were dried in the hopper-bottom trailer during the 2020 season. During drying samples were collected from multiple locations throughout the peanut load at intervals to assess drying uniformity. Additionally, instrumentation was installed at several locations in the peanut mass, at the air inlet, and outlets to monitor temperature and relative humidity throughout the drying process. The official grade sample moisture for the loads after drying and coasting was 9.1% w.b. and was consistent with the measured moisture of the samples taken during drying.

Technical Abstract: Hopper-bottom semi-trailers retrofitted for peanut drying could provide several advantages to producers and peanut buying point operations. Producers who utilize hopper-bottom semi-trailers for transporting grain would have an additional use for the semi-trailer and would be less prone to harvest delays during peak times when semi-trailer availability from the buying point is limited. Additionally, smaller buying points would benefit from reduced handling steps and dependency on trailer lifts. Computational Fluid Dynamics (CFD) modeling was used to develop retrofit designs for a typical hopper-bottom semi-trailer that would produce uniform drying. Parameters are described for CFD modeling as peanut mass permeability and boundary conditions. Airflow patterns in the semi-trailer air plenum and throughout the peanut mass were the primary simulation variables of concern when evaluating the various designs. Initial design concepts were simulated, and the effect of incremental design changes were noted in the simulated airflow distribution. As fabrication was completed and on-site modifications were made, the model was updated to determine the effect on airflow distribution. Three test loads of peanuts were dried in the modified hopper-bottom semi-trailer during the 2020 peanut harvest season. Samples were collected from multiple locations throughout the peanut load at intervals throughout the drying process to assess drying uniformity. Additionally, instrumentation was installed at several locations in the peanut load, at the air inlet, and air outlets to monitor temperature and relative humidity throughout the drying process. Results of a sample load indicated a moisture content decrease from 12.9% wet basis (w.b.) to 12.0% w.b. after 8.5 hours of drying time. Average moisture content was reduced further to 11.1% w.b. following an additional 8.6 hours after the dryer was shut off. The official grade sample moisture was 9.1% w.b. and was consistent with the observed moisture gradient existing from the top to bottom of the trailer.