Thermo-Physical Properties of Distillers’ Spent Grain Pellets at Different Moisture Contents and Condensed Distillers’ Soluble Concentrations

Abstract

The thermo-physical properties of distillers’ spent grain (DSG) pellets are the key input parameters for the heat and mass transfer modeling of the drying process and for the design of the suitable drying and storage systems. The main thermo-physical properties like particle density, thermal conductivity, and specific heat capacity of DSG pellets were determined using standard laboratory methods. The effects of moisture content, percentage of condensed distillers’ solubles (also called solubles), and temperature on these selected properties were determined. The average particle density of the DSG pellets with 0, 10, 30, and 50 % solubles was found to be in the range of 898.8–1136.7 kg/m3. It was observed that the particle density of DSG pellets increased with an increase in condensed distillers’ soluble concentration and decreased with an increase in moisture content. Thermal conductivity (0.17–0.42 W/(mK)) and specific heat (1.76–3.47 kJ/(kgK)) of the DSG pellets increase linearly with an increase in moisture content, soluble concentration of the sample, and temperature of the drying medium. Three multiple linear regression equations were developed for predicting these properties as a function of moisture content, soluble concentration, and temperature with R2 value ≥0.86.