Date of Award
Master of Agriculture (MAgr)
Aaron P. Turner
Biomass and feed pellets can be handled and stored using similar equipment used for other bulk materials; however, their unique physical characteristics can lead to handling challenges. Understanding the flow characteristics of these materials is essential for handling and storage system design, but these characteristics are not well defined in less-than-ideal conditions. The overall objective of this study was to evaluate how moisture content and level of fines influence the angle of repose (AoR) of hardwood, pine bedding, and feed pellets along with determining the impacts of displacement on the shear stress of fuel pellets utilizing a modified linear wall friction test. For the AoR experiments, three moisture contents (equilibrium, two and four percentage points above equilibrium) and four-particle fine levels (0%, 5%, 10%, and 15% fines) were evaluated. Multiple methods for measuring AoR were assessed, and an image analysis tool using a polyline fit to the pellet boundary was developed and used to measure the respective angles. The stacking (dynamic) AoR was least impacted by moisture and fine levels, showing no differences among fine levels, and only the low moisture content differed. Draining (static) AoR was linearly correlated with the tilting table method, but the tilting table AoR was on average 15.5º higher. Utilizing the combined test fixture, the overall stacking (dynamic) AoR for hardwood, pine bedding, and feed pellets across all moisture contents and percent fine levels were 33.8º, 35.0º, and 35.4º, respectively, while draining (static) AoR was 39.9º, 44.2º, and 42.7º. A modified linear wall friction test was developed and conducted on corn and fuel pellets across ultra-high molecular weight polyethylene (UHMW-PE) and galvanized steel surfaces over a 20 cm displacement. Two loading methods (standard and sequential) were used under three normal stresses (5 kPa, 10 kPa, and 15 kPa). The coefficient of friction of fuel pellets was impacted by the wall surface, normal force, and displacement. Overall, across all three normal loads and both loading methods, the coefficient of friction (COF) of fuel pellets using the standard loading method on UHMW and steel were 0.25 and 0.21, while corn was 0.20 and 0.16.
Dean, Ryan, "The Physical Properties and Handling Characteristics of Pelletized Biomass Materials" (2022). All Theses. 3884.