BioBlaze - An Automated Hot Composter
Awarded Most Innovative
The composting world is in need of a resurgence of efficiency and ease. From the average homeowner to the experienced composter, time is a valuable resource. Most electric composters on the market are expensive, inefficient, and don’t actually go through the composting process. Being college students looking to save time and explore the composting world, TerraThermic Inc set out to discover a market to create a device that could help solve this composting time requirement.
The target customers were identified to be both homeowners and shops that produce organic waste. Then research was conducted to answer the main customer requirements for such a product. A series of benchmark products were also identified to see market competition and quantified the features through a house of quality. Through concept generation and down selection techniques, TerraThermic Inc boiled ideas down to create our concept of an automated hot composter.
After conducting weeks of market research, prospective consumers detailed the most important design requirements as:
Automated from start to finish
Regulate temperature and humidity
Storing 5 gallons and protect against odors
I focused most of my contribution on all of the electronics and software components, along with conducting all of the analysis for thermal accuracy and humidity.
Design Evolution
Sub Assemblies
Storing and Accessing Compost
To give users adequate access to the compost bin and increase ease of use, the compost bin is laid flat on its side and is never hard bolted into the system housing. Instead, the bin lays on a series of castor wheels so it can be rotated and mixed, while also allowing a user to lift or remove the bin from the housing. After removing the bin from the housing, users can unscrew the lid from the bin for easy access and cleaning. The format of the bin also assures that compost is distributed evenly within the bin volume and does not bunch up or pool in one end. The image below shows a CAD model of the composter prototype and demonstrates the general orientation of the unit.
The compost bin and its housing are disconnected for easy removal, requiring a slip-ring for power transmission. This slip-ring provides a stable 12v power supply without transmitting data. Instead, a Bluetooth module and Arduino handle data communication between the two units. To avoid mechanical complexity and wear, special rollerball electrical contacts from MillMax are used instead of brushes. These contacts feature a rolling ball at their ends, reducing friction between the ring and the electric contact. Springs behind each pin ensure reliable contact without demanding precise alignment between the bin and housing.
Mixing
In terms of mixing, we will employ 3D printing to fabricate a huge gear, which will be subsequently affixed externally to the receptacle. This gear will interface with a micro DC motor operating at a 12-volt potential to induce rotational motion in the container. To facilitate this rotation, a pair of caster wheel assemblies will be deployed to provide structural support to the container and guarantee seamless rotational movement.
Temperature Regulation
To heat the internal volume of the composter bin, a 12v PTC heater has been sourced. This heater will be mounted to the previously discussed mixing bar inside of the compost bin and secured via two strap-clamps. A temperature sensor on the interior of the bucket lid will monitor the temperature inside the bin. At the moment, a single heater is being used pending testing to confirm that it can reach a target of 120 degrees fahrenheit.
Detailed Final CAD Design
The detailed final CAD diagram can be found on the side. The key thing to note here is the two different circuits, one on the frame and one on the lid in order to allow for easy bucket removal.
Accuracy Analysis
The first set of physical tests that were run was the frame stability test. This was accomplished by adding the weighted bucket with lemons into the frame system and rotating the motor nonstop for over 2 hours. Even with the dropping of the heavy lemons from the lip to the bottom of the bucket, the frame held the bucket very well in place by resting the body on the caster wheels and with the suspension of the slip ring system. This meant that our system was able to withstand heavy loads and still work as intended.
The next set of physical testing that was run was a combination of both temperature and slip ring testing. This was conducted in a similar fashion where the bucket with the lemons was run for a continuous period, longer than 3 hours to test if the dropping motion made the slip ring lose contact or if we could maintain and reach the steady state as intended. Our method of verification for the slip ring was through the bluetooth connection from the lid to the frame. If the lid ever lost power, we would notice that the screen would not update its numbers every 3 seconds and would rather display 0 instead. What we noticed here was that the entire cycle, we never lost power and were always able to monitor the internal temperature within.
To ensure no interrupted power delivery and no microcontroller reset during validation testing
To test its ability to accurately maintain temperature, repetitive testing was done to measure how accurate the control system within the system is to maintain 45C. This was done by adding 10 large lemons into the bucket and powering the cycle on to monitor the temperature maintenance. Compared to market products, BioBlaze is 3 times faster at reaching the temperature and maintains the temperature to reduce the composting cycle from 4 months to 2 weeks.
Conclusion
In conclusion, our results show that our maintained temperature accuracy and unique slip ring feature makes us competitive with other products on the market due to their lack of grinding and complete automation. Along with that, BioBlaze is also cheaper than almost all competitors by $130, making us a competitive product in the market. Our next steps are to improve weight distribution, weatherproofing, and simplifying UI.
Functional Video
Electronic Architecture
Top: Electronics within slip ring circuit (bluetooth module on back)
Bottom: Screen UI interface for user mounted onto side panel for safety