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Drying Kinetics of Distillers Wet Grains (DWG) Under Varying Condensed Distillers Solubles (CDS) and Temperature Levels

¹Graduate research assistant, professor, and graduate research assistant, respectively. Department of Agricultural and Biosystems Engineering, South Dakota State University, Brookings, SD. ²Assistant professor, Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA. ³Corresponding author. Phone: 515-294-4019. Fax: 515-294-6633. E-mail: karosent@iastate.edu

Distillers dried grains with solubles (DDGS) is a widely used animal feed. But transportation of DDGS is often troublesome because of its stickiness. DDGS is formed by combining condensed distillers solubles (CDS) with distillers wet grains (DWG) and then drying. As a first step toward understanding drying behavior, this study's objective was to investigate batch-drying kinetic behavior of DWG with three CDS addition levels (10, 15, and 20% wb) and three drying-temperature levels (100, 200, and 300°C). Multiple nonlinear mathematical models were used to fit experimental drying data for moisture content versus drying rate. A new comprehensive model was developed (R² = 0.89, SEM = 18.60) from a modified Chen and Douglas model to incorporate CDS and drying-temperature terms. Drying temperature affected drying rate more significantly than did changes in CDS level; thus, drying temperature was the main effect and CDS was a subeffect. Increasing the drying temperature increased the drying rate significantly for all levels of CDS addition. This model can be used for predicting DWG drying behavior under broad operating conditions; it can be used to help the industry produce better DDGS, which may thus result in better DDGS handling and transport characteristics.