Heat Transfer During Cooling of Bulk Distillers Dried Grains with Solubles (DDGS)

Abstract

Abstract. DDGS is often transported in railcars and trucks from the ethanol plants to the feed mills and animal farms. During unloading, flowability of DDGS is often reduced due to caking of DDGS bulk. Based on published research, the environmental relative humidity, DDGS glass transition temperature, syrup content, and duration of cooling of DDGS piles influence the caking behavior of DDGS. The objective of this study was to develop and validate a heat transfer model for predicting the cooling pattern of DDGS piles. A finite volume method approach was used to develop the heat transfer model. Ergun’s equation was used to implement airflow resistance in the porous media of the DDGS bulk. The heat transfer inside the pile was simulated for winter (6°C) and summer (24°C) ambient conditions. The model agreed well with the experimental temperature measurements from the three sets of experiments with two sizes of experimental piles. The overall predicted temperatures were 2.7°C and 0.7°C higher than the observed temperatures for small- and medium-size experimental piles, respectively. This heat transfer model could be used to predict the temperature variations in DDGS bulk during storage and as a measure to predict the caking behavior. Keywords: Caking, DDGS, Finite volume method, Heat transfer.