Modeling Distillers Dried Grains with Solubles (DDGS) Mass Flow Rate as Affected by Drying and Storage Conditions

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Bhadra, Rumela
Muthukumarappan, K.
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Rosentrater, Kurt
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Center for Crops Utilization Research
In the 1980s a crisis existed in American farming—a crisis of overproduction, underutilization, and decreasing international market share for raw commodities. Also, the United States’ growing dependence on imported oil and long-term forecasts for increasing oil prices put America at risk. To address this crisis, Center for Crops Utilization Research (CCUR) was established in 1984 through a special appropriation from the Iowa legislature. The center was tasked to respond to the urgent need to improve America’s agricultural competitiveness. Four decades later, there are new opportunities to increase demand for Iowa’s crops. Consumer demand is increasing for new healthful food ingredients, biobased alternatives to petroleum-based products, and sustainable and environmentally friendly industrial processes. The rapid advancement of new food processing technologies and industrial biotechnology enable those demands to be met in an economically viable way. While CCUR’s core mission of increasing demand for Iowa crops remains relevant, the center is also taking these opportunities to grow our connection with companies and entrepreneurs to help them to test, troubleshoot, and optimize their ideas in an industrial-friendly setting.
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Agricultural and Biosystems Engineering

Since 1905, the Department of Agricultural Engineering, now the Department of Agricultural and Biosystems Engineering (ABE), has been a leader in providing engineering solutions to agricultural problems in the United States and the world. The department’s original mission was to mechanize agriculture. That mission has evolved to encompass a global view of the entire food production system–the wise management of natural resources in the production, processing, storage, handling, and use of food fiber and other biological products.

In 1905 Agricultural Engineering was recognized as a subdivision of the Department of Agronomy, and in 1907 it was recognized as a unique department. It was renamed the Department of Agricultural and Biosystems Engineering in 1990. The department merged with the Department of Industrial Education and Technology in 2004.

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  • Department of Agricultural Engineering (1907–1990)

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Ethanol production in 2015 was over 15 million gallons in the United States, and it is projected to increase in the next few years to meet market demands. With the continued growth in the ethanol industry, there has been enormous expansion in distillers grains production. Because the local market for distillers dried grains with solubles (DDGS) is often saturated, it is essential to transport DDGS long distances, across the United States and to international markets. Caking and agglomeration of DDGS particles in hoppers and other storage structures are typical during transportation. The current study deals with DDGS prepared by combining condensed distillers solubles (CDS) with distillers wet grains and then drying at varying temperatures. DDGS was stored in conical hoppers under varying ambient temperature, consolidation pressure, and time conditions. We investigated the effects of CDS (10, 15, and 20% wb), drying temperature (100, 200, and 300°C), drying time (20, 40, and 60 min), cooling temperature (0, 25, and 50°C), consolidation pressure (0, 1.72, and 3.43 kPa), and consolidation time (0, 3, and 6 days) levels on various flow parameters. To examine these factors, Taguchi’s experimental design with an L18 orthogonal array was implemented. Response surface modeling yielded mass flow rate = f(Hausner ratio, angle of repose) with R2 = 0.99, and it predicted moisture content for good, fair, and poor flow. Results showed that drying temperature, drying time, and cooling type were the main factors in predicting mass flow rate. The Johansson model for predicted mass flow rate was calibrated with experimental data, and a new parameter, compressibility factor, with a value of 0.96 g2/(min cm3), was determined to quantify the divergence of compressible and cohesive materials (such as DDGS) for free-flowing bulk solids. Thus, the predicted models may be beneficial for quantitative understanding of DDGS flow.


This article is published as Bhadra, Rumela, Kurt A. Rosentrater, and K. Muthukumarappan. "Modeling Distillers Dried Grains with Solubles (DDGS) Mass Flow Rate as Affected by Drying and Storage Conditions." Cereal Chemistry 94, no. 2 (2017): 298-309. doi: 10.1094/CCHEM-04-16-0114-R. Posted with permission.