Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 1996
Publication Date: N/A
Interpretive Summary: Moisture affects every aspect of cotton harvesting and processing. Excessive moisture results in grade losses, fiber deterioration, and decreased machine performance while low moisture can cause fiber breakage and results in operating difficulties. Techniques and procedures were developed for determining the effects of temperature on moisture absorption rates for gin run (fuzzy) cotton seed at 20 and 35 deg C and for drying rates at 20, 35, 50, 75, 100, 120, and 130 deg C. Temperature had definite effect on the drying rates of the gin run cotton seed. The data for the drying portion of the study were found to fit equations shown in the literature. The moisture absorption data showed evidences of metabolic activity after a few hours. This information will be used in conjunction with equilibrium moisture data to estimate the moisture content of harvested seed cotton during cotton harvesting and ginning.
Technical Abstract: Moisture control during the harvesting, storage, and processing phases of cotton production is essential for producing a quality product. Basic information relating environmental parameters to equilibrium moisture content and the moisture transfer rates for cotton and its component parts will lead to a better understanding of the processes involved and design and control criteria for cotton conditioning equipment. This report depicts the moisture absorption and desorption rates for cotton seed. Absorption values are shown for temperatures of 20 and 35 C and desorption values for temperatures ranging from 20 to 130 C (68-266 F). The moisture data were plotted against time and found to be exponential in nature. Nonlinear regression analysis was used to fit the value of the coefficients in the theoretical falling rate equation to the experimental data. Results indicate that moisture absorption by cotton seed does not follow the exponential solution to the diffusion equation, but appears to undergo two absorption phases. The first absorption phase appears to be physical in nature and approximates the curves of other biological materials. The second phase, which shows an increased moisture absorption rate after a leveling off period, may indicate increased metabolic activity. The desorption (drying) data fit the theoretical falling rate (exponential decay) function reasonably well, especially at temperatures above 100 C. Temperature significantly affected the coefficient containing the diffusivity parameter in the nonlinear equations. A generalized solution, suitable for modeling, was determined as a function of absolute temperature. Moisture transfer rates increased as temperature increased from 20 to 130 deg C.