Date of Award

8-2025

Document Type

Thesis

Degree Name

Master of Agriculture (MAgr)

Committee Chair/Advisor

Aaron P. Turner

Committee Member

Kendall R. Kirk

Committee Member

A. Bulent Koc

Abstract

Fuzzy cottonseed is a valuable byproduct of the cotton ginning process. When cottonseed exits the cotton gin, it often retains high temperatures and moisture contents. Once in a storage facility, the cottonseed needs to be conditioned for safe storage. The overall objectives of this study were to analyze quality changes in cottonseed according to storage conditions, determine the airflow resistance properties of fuzzy cottonseed, develop a computational fluid dynamics (CFD) model of a representative cottonseed storage facility, and analyze cottonseed aeration fan strategies, runtimes, and costs. Changes in quality dictate the allowable storage time for cottonseed and are impacted by temperature and moisture content. For the cottonseed quality test, samples of cottonseed were stored at 8%, 10%, 12%, 14%, and 16% w.b. moisture content, temperatures of 7.2° C and 22° C, and storage durations of 3 months, 6 months, and 9 months. Results of this study indicate that at higher temperatures and moisture contents greater than 12% w.b., cottonseed incurred a significant increase in free fatty acid (FFA), a significant reduction in oil content, and a significant reduction in grade. Low temperatures (7.2° C) and moisture contents of 8 to 10% w.b. retained good seed quality characteristics. Improved knowledge of airflow through cottonseed may improve conditioning techniques and guide senor placement for monitoring systems. For the CFD study, airflow resistance coefficients of cottonseed stored at a density of 400 kg/m3 was experimentally determined. These laboratory tests utilized an airflow chamber to vary airflow velocity and measure pressure drops between two points in the seed pile. Power law resistance coefficients were determined to be C0 = 34960.27 and C1 = 0.68843. The CFD airflow model was constructed using a solid model of a cottonseed storage facility, which was input to a Finite Volume CFD solver. Operating conditions and airflows were measured at the model warehouse. The final CFD model produced an airflow velocity contour map of the storage facility, indicating several “dead zones,” areas with low airflow velocities. Uniformity and dead zones were analyzed at the 1m, 3m, 5m, and 7m levels from the floor of the seed pile. Uniformity ranged from 64% at 1m to 85% at 7m. Notable dead zones occurred at the 1m, 3m, and 5m levels and ranged from 1.18% to 1.86% of the plane area (7m2 to 12m2). The final objective analyzed energy use in cottonseed storage, for three storage warehouses with different seed pile depths, target airflow rates, and two different climates. Also presented in this study were three common aeration strategies and a basic heat balance calculation, which shows the minimum aeration time to achieve seed pile temperatures less than 15.6° C. This study gave a wide range of expected fan runtimes and cooling costs, which ranged from 0.132 to 2.094 hours of aeration and from $0.21 to $3.61 per Mt conditioned. This range of costs corresponded to 0.08% to 2.00% of crop value at the time of sale.

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