Date of Award
Master of Science
Agricultural and Biosystems Engineering
With a growing push towards independence from foreign oil, research has turned to alternative feedstocks for biofuels. One of these feedstocks is corn stover, which is mostly a by-product of corn grain production. Studies show that a main issue with the corn stover supply chain for biofuels is the logistical and handling costs. Currently, transporting large square bales of stover by truck is the most common system. A main factor in the handling and transportation cost is the density and size of the package of corn stover. Research has shown that creating a larger package considerably reduces these costs.
A machine was proposed to compact and, if possible, package the material in an anaerobic state to prevent deterioration. The machine produced a module approximately 2.4 m by 2.4 m and could have variable length. Three horizontal plungers slid forward and backward inside the compression chamber to compact the stover. At the rear of the chamber, a two-paired door system provided back and sidewall pressure to densify the module. A pressure distribution model created for the compaction chamber predicted that angling these doors results in nearly zero back pressure at the rear of the chamber.
Structural, hydraulic, electrical, and control systems were included in development and fabrication of a working prototype large module builder. This prototype was tested for achievable density and pressure distribution inside the compaction chamber. Compaction capabilities were comparable to other commonly used methods, with an average density of 151 kg/m3 when the doors were held at an angle, which was 25% greater than the density with the doors fully open. In addition, the predictions for pressure within the compaction chamber nearly followed a one-to-one relationship with calculated pressures from test data. A regression line for the data produced a slope of 1.12 and an R-squared of 0.82.
Klein, Ann, "Mechanism for compaction and densification of large stover modules" (2014). Graduate Theses and Dissertations. 14007.