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United States Department of Agriculture

Agricultural Research Service

Title: Temperature, Drying Rate, and Heat Balance for Gin Dryers

Authors
item Laird, Joseph
item Barker, Gary

Submitted to: Cotton Ginners' Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 23, 1995
Publication Date: N/A

Interpretive Summary: Current cotton gin drying processes were developed by empirical testing of various design ideas. Information showing how moisture content of materials in seed cotton delivered to cotton gins is affected by temperature, relative humidity and vapor pressure conditions that can be imposed in a process has been badly needed so that design of drying processes can be done on a rational basis. The paper provides information on the drying tim expected from exposing the cotton and foreign matter to different conditions in a drying process in graphical form. Examples of how to use the information now becoming available are given. The relationships shown indicate how sensitive the drying process is to temperature and initial moisture content. Also pointed out are areas for additional research to complete the information necessary for design and optimization of seed cotton drying processes. When the work is completed drying process design on an anlytical basis will be possible based on the actual physical response of the materials in the cotton to conditions that can be imposed.

Technical Abstract: Cotton drying systems use heated air to transfer heat into the cotton and to force relative humidity very low. The accompanying increase in vapor pressure gradient moves moisture out of the cotton. Drying time for the different components of harvested cotton as a function of initial moisture content and temperature (150, 200 and 250 degrees F) are shown using experimental data. The test data was developed for small samples under laboratory conditions that maintained maximum exposure of the materials to constant air conditions. Typical calculations are done to show the amount of heat and moisture transfer along with the losses in typical cotton gin drying systems. The results show that the different components of harvested cotton dry at different rates and this has important implications for design and operation of seed cotton drying systems. Possible ways for modifying drying processes to compensate for different drying rates, and areas for additional research are discussed.

Last Modified: 7/28/2014
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