Shea Nut Roaster
A roaster that produces less smoke and uses less fuel.
At Burn Design Lab, I led the redesign and build effort for a drum-style Shea nut roaster. Shea nuts are roasted domestically in countries where Shea trees grow, such as Ghana, as a step in their refinement towards locally-produced shea butter, which is a healthful cosmetic product. Many roasters used in Ghana for this task are inefficient, and produce a lot of hazardous smoke that is inhaled by the user. This redesigned roaster sought to remedy these issues.
I began by fully redesigning the main combustion chamber to feature a novel, swooping sheet metal design with a riveted double-walled construction. This new design improved insulation, reduced heat losses, and dramatically reduced part count. To validate the complex geometry of this design before committing to a full prototype, I sketched it on paper, modeled it with a surfaces-to-sheet metal workflow in Fusion 360, and then built a 1/3 scale model. Ceramic bricks were then carefully implemented within the combustion chamber. Early CFD analysis was also performed on this geometry by a volunteer engineer, to explore the flow of hot gases through the roaster, identify critical design flaws, and roughly understand heat losses from external sheet metal faces.
I then designed and fabricated a new roasting drum, with a built-in thermometer, sliding metal door, and ergonomic wooden handle.
Finally, I fully redesigned the welded "shroud" and "frame" of the shea roaster, to achieve a 49% part count reduction from the previous shroud and frame design. All of my design efforts were implemented into one master Fusion 360 file.
Fabrication processes for this project included preparing files for waterjet cutting, sheet metal rolling, MIG welding, riveting, sheet metal box braking, sheet metal press braking, and powder coating.
This design was meant to be tested on a field trip to Ghana in spring 2020. Due to COVID-19, the trip and opportunity for testing was cancelled. Instead, Burn Design Lab and I shifted to work with a University of Washington team on N95 Decontamination Chambers. Having left BDL in fall 2020, I am uncertain about the future of this project.