Date of Award
The URI design team 13 was tasked by The Compost Plant to create an aeration device for a static pile of food-waste-based compost in a 24'x24'x8' bay. It was required by the sponsor that the device be: temperature controllable, be able to evenly aerate the compost pile so that its temperature throughout would be maintained between 130 and 160° F, be compatible with on-site farm equipment specifically a 504 John Deer Front Loader, cost less than $15,000 to produce, function with a commercially available blower, be safe, and provide for temperature data logging.
In order to satisfy these requirements specified by the project sponsors, Team 13 underwent a rigorous design process in Fall 2017 which included background research into the fundamentals of composting, a patent search on current aeration devices, a quality function deployment analysis (QFD) to ensure that the customer parameters were met, and the creation of a detailed design specification that set targets for the project. The Team generated 120 design concepts for different aspects of a design solution. These concepts led to the design of a positive aeration device called the vertical aerator, which was the best design solution because of its simplicity, scalability, and ease of use. For the Compost Plants bay size, two of these devices would be used.
Once the design of the vertical aerator had been set, the team began validating and re-designing it so that it complied with the generated design specifications. The main design specifications were that it had to provide the recommended volumetric ow rate of 1,200 cfm to the pile, for both devices to be temperature controllable, aerate a region of wood-chips 2 ft in radius measured from the center of each leg that represented the nominal distance to the edge of the wood-chip layer without drying out the pile, weigh less than 8,000 lbs, cost less than $15,000 to produce, resist clogging from particles with sizes 0.5in 2in and have a Factor of Safety (FOS) of >3 when suspended above the ground.
By testing the device using simulations, mathematical calculations, industry standard approximations, research, and experiments on a full-scale PVC model in Spring 2018 it was determined that the final design met all of the listed design specifications. Specifically, it was shown that the device delivered approximately 600 cfm (two devices deliver 1,200 cfm) to the pile in an even manner, equally aerated in all directions a 2 ft region of wood-chips, was unlikely to dry out the pile, weighed approximately 1,900 lbs, cost $10,464.28, resisted clogging, was compatible with a temperature data logging scheme, and had a minimum FOS of 3 when suspended.
In addition to this, the economic, social, political, and environmental impacts among other effects of the device were investigated. The method for operating and manufacturing the device were also determined and redesign efforts were made by the team to ease the manufacturability and safety of the device.
Marcantonio, Jeffrey; Otto, Alison; Palmer, Michael; and Zebleckas, Joseph, "The Compost Plant -- Design of an Aeration Device for an Aerated Static Pile of Compost" (2018). Mechanical Engineering Capstone Design Projects. Paper 39.