Currently, the community of Ullo, Ghana has a school that houses between 1000 and 1500 students. Every day, cooks are making 2-3 meals a day for these students using stoves by the school in the kitchen area. The kitchen uses about 3500 L of water every day. The current stoves being used are shown in the figure to the right
These stoves create the following concerns:
- Efficiency: the open design of the stoves creates a lack of focused heat to the pot. Therefore, more fuel is needed to heat the pot of water.
- Smoke and User Health: these stoves are not well ventilated and do not direct the smoke away from the user. This means that the user can easily breathe in the smoke easily which is a safety concern.
- Reliability: due to the construction of the stoves, the stoves break down easily when rain or other harsh weather comes. This means the community has to rebuild the stoves often.
To cook on these stoves, the team uses 3 different sizes of pots. These pots are very large and heavy. The sizes are named by 50, 30, and 60. The dimensions of the 50 are 67cm in diameter and 53cm for height. The dimensions of the 30 are 56cm in diameter and 40 cm in height. And the dimensions of the 60 is 77cm in diameter and 59cm in height.
The team was tasked with creating stoves that fit the size of pot needed, improve all current state concerns, and is low cost for the community to rebuild.
In Fall 2018, a team travelled to Ullo to implement a small-town water system. While there, the team noticed the concerns with the stoves. This led to the creation of the engineering team to face the problems of the stoves. From January 2019 to December 2019, the team researched stove designs and created a design that was believed to be ideal. The design used a brick size that was currently made in the community to save cost and limit added complexity to the design. Due to the unusual brick sizes, the team created a design that was less optimal on the efficiency of the design, yet it would still be an improvement from the current state. The design is shown to the right.
In December 2019, a new travel team went to Ullo to implement these stoves. Unfortunately, the brick sizes from the plans did not match the community’s brick size. This caused the stove to not be implemented. In January 2020, the team worked on a new design which is shown in the section below. The following issues from the previous design were addressed and updated:
- Size of Bricks: changed to use EWB set size of bricks.
- Inlet Size: changed to accommodate the size of wood in the community.
- Height of Combustion Chamber: changed to create a more ideal ratio between inlet size and height. The needed height of the camber caused the air chamber to be moved underground, so the air could still flow properly, but the height of the entire stove was optimal.
- The shape of Design: became more efficient in terms of the number of bricks; improved on ergonomics from the previous design.
After our last winter travel trip, the kitchen stoves group decided to redesign the kitchen stoves from the ground up. We ended up this the design we currently have now, which is made from two types of bricks and features design improvements such as, Dakota fire hole, optimized burning conditions, and refined ergonomics.
In Figure 1, you can see the Dakota fire hole which provides air circulation into the fire forcing smoke up and out the back Chimney, which is the opening above the Dakota fire hole.
In Figure 2, you can see the opening to insert fuel into the stove, which has been made larger to better fit the type of wood they use in Ullo. Additionally, you can see the crossbar holders at the top which allows one to lift the pot out of the stove. Finally, in this view, you can see the total height of the stove which is 42.5in.
In Figure 3, you can see the internals of the stove. Its central shaft has a uniform cross-sectional area, which allows for the best airflow. As well you can see the gap between the shaft and outer walls that will be filled with insulative materials. Lastly, from this view, you can see the removable grate we have at the bottom which makes ash removal easier. note: the grate could be made as seen, but a more open metal grate is the best option.
We will continue to polish our current design and attempt to create a downsized prototype model to test. As well we will work on creating easy to read the instruction manual for creating the stove. Finally, we will implement our new design in the winter of 2020 and modify our designs based on the data we collect then.