Dear Haiti Clean Stove Project Members:

Congratulations on finishing finals and thanks for the hard work during the semester! It’s impressive to see what we had accomplished in the past semester as a team.

In January, HCSP welcomed some new members as the semester started. Zong and David shared their findings from their winter break trip, which was critical for planning the Spring Break Research. Also, Jialing and Corey shared some of the results from emission testing using the Kiln box in Dr. Tami Bond’s research lab.

There were three small teams formed, with each aimed to achieve different goal. The design team led by David modified the designs based on the usability and performance testing feedback. Brian as usability team lead not only used the TLUD stove to simulate cooking rice and beans but also improved the usability experimental procedures. Meanwhile, the emission testing team led by Jialing conducted testing on prototype 1.0.

During the month of March, there were many opportunities and challenges. In between tasks, each member of the Haiti Clean Stove Project demonstrated strong leadership and team working skills. Starting off with Engineering Open House (EOH), Shivani and Anthony as the Outreach Committee made informative posters which effectively presented the problems in Haiti as well the outlook of the solution-clean biomass cookstoves. EOH was successful only because of everyone’s enthusiasm. As spring break approached, the travel team was ready for a trip to Haiti. Five of us took advantage of spring break and conducted scientific usability research on how well our TLUD prototypes can be adapted by Haitian cooks. The HCSP were also fortunate to be selected as one of the 250 Dell Social Innovation Challenge semi-finalists from among more than 2500 applicants. Zach took the responsibility to follow up and put together a strong application. In the meantime, we compiled the findings in a report along with a two-year-proposed plan, which was submitted to the US EPA “People, Prosperity, Planet” grant as the Phase I report. 

After analyzing results from field usability testing and performance testing on campus, the design team made further technical advancement and finished making the new prototype (2.0) by adding a layer of insulation as well as one more set of secondary air holes. In April, Zong, David and I attended the National Sustainable Design Expo in Washington, DC. During the two days of the Expo, we were happy to share our project with others and were also excited to learn about other great projects which aim to satisfy people’s needs, provide prosperity and protect the planet. 

Here, I want to take the chance to remind ourselves that we are fortunate to receive help from different people and departments. Special thanks go out to Dr. Tami Bond and her grad students Cheryl and Ryan from the UIUC Environmental Engineering Department; Professor Mark Taylor from the architecture department and two of his students Joseph and Min who provided great advice for the P3 proposal and the poster presentation; our sponsor Chip Energy for their fabricating help and technical advising; the school’s business department and the Institution Review Board (IRB) for ensuring the proper research process; and John and Nadine for translating documents into Haitian Creole. Last but not least, I am deeply grateful to Wilson H’Odiore for hosting the travel team when we were in Haiti.

In the next semester, the executive board and I-- Sarah (President), HouIn (Treasurer), Shivani (Outreach Lead), David (Technical Lead) and Jafir (Information Lead)—will continue to make the Haiti Clean Stove Project a fun learning experience for all the members.

Wishing everyone a wonderful summer break,

Sarah Huang
HCSP President
May 12th, 2013

     Traveling to Haiti during spring break was a very unique experience for the entire team. We reached Port-Au-Prince airport on March 7, 2013 and were picked up by our contact’s driver. Wilson, our Host, put us up in his own house. It was very beautiful and spacious. Our testing site was also an adequate size plot area for our usability test participants to learn and use the different cook stoves. It was a shady area with tents to allow us to have enough shade from the sun and chairs for us to sit down and focus during our usability testing. It was always cleaned up in the evening after our testing was over. Wilson’s personal driver was also responsible for picking us up and dropping us home from the test site everyday.

     Haitian hospitality was not limited to good housing and usability locations. Wilson had his friend, Jeanine, cook us breakfast and dinner everyday. She kept in mind everyone’s dietary restrictions while making the food.  The dinner generally involved a main vegetarian dish, a main non - vegetarian dish, rice , appetizers such as fried plantains from the garden in the house or sweet potatoes, rice and freshly  - made juice. Breakfast generally included bread rolls with Haitian - made/ American – made peanut butter and Haitian – style scrambled eggs. The team enjoyed every meal we had at the house where we lived. At the testing site, we were also provided with coffee everyday to replenish our energy and we all also tried sweet coconut water that the participants made when they used the coconuts in cooking their rice and beans. The participants were also very kind in offering their cooked rice and beans for our lunch. Every meal was scrumptious and was definitely one of the main highlights of this trip.

     Usability testing was a major part of our trip. Apart from the spacious and shady testing site mentioned earlier, the participants chosen were very active learners. They were patient during our first day of instruction of how to use the TLUD prototype and Eko Ayiti stoves. A very important aspect of this testing was communicating with the participants, instructing them about how to use the stoves and how to troubleshoot blowouts as well as interviewing them before and after the stove was used. We had two brilliant translators, Karim and Frankie, who were present at all times to help us communicate with our testing participants. 
    Hence combining all the aspects of good accommodation, delicious local food and organized testing setup and planning, the spring break trip ran smoothly and the team enjoyed it very much. We are very pleased with the Haitian hospitality and kind culture and want to visit Leogane soon!

If you are interested in planning a field study and want to enlist the services of Wilson and his company J'HO please contact him through the following means:

Wilson J. H'Odiore
JH'O Business group & CO
BA Electrical Engineering (Uncompleted) (NYU-Brooklyn Polytechnic Institute)
BA Operations Management (ASU)
(509) 4822-6613
(509) 4822-6614
wilson.hodiore@gmail.com
wilson.hilaire@gmail.com

 

In the DCL this Tuesday the 12th of February we started a process of logical brainstorming to change Superstove 1.1 into 1.2. The major design changes we thought of were as follows: midlevel rails; outside hook and handle; and internal hook and external handle.

In order to test the stove’s usability, we found a test subject who was relatively unfamiliar with the design and willing to simulate traditional Haitian cooking on a few of our prototypes. Our plan was to test eight tasks: filling the fuel chamber, lighting the fuel, placing the stove in the frame, placing the pot on the pot supports, stirring the pot, turning the flame down to a simmer, recognizing when the stove is low on fuel, refuelling, and disposing the fuel. Prior to testing our stoves, our subject would fill a brief questionnaire, and we would give them a quick tutorial on how to use the stove. In order to fully simulate the range of Haitian cooking styles, we observe/record our subject frying eggs quickly, then slowly simmering rice and beans. After each round of cooking, the cook would complete a post-test evaluation. This information, combined with our observation of critical incidents, gave a lot of insight on potential improvements to the design.

Our first experiment was on the Stove Pipe Stove made by Chip Energy. The major design problems with this stove were the air control and an operational problem. Even with the air control provided, it was not possible to change the tempurature enough to make a difference. The other problem was the need for an external table or surface to put materials on so tasks would be easier and safer.

Our second experiment was on Superstove 1.0. There were two major task failures, related to loading and unloading the stove onto the rails. The subject had difficulty determining the correct placement of the stove and nearly dropped it in the process. The absence of a convenient handle and an initially lopsided flame were also noted as major concerns.

The Usability team is also applying our newly gained experience towards designing an illustrated Stove User Guide, with instructions written in Haitian Creole. It will contain a basic diagram explaining how our TLUD stoves works, showing the step-by-step process of using the stove, and highlighting some of the counterintuitive aspects of our design in comparison to traditional cookstoves. For example, adding more fuel does not make the fire stronger; only the air control can. Additionally, we’re developing a standardized set of field testing procedures, rewriting the user questionnaires, and making life easier for the field testers we’re sending to Haiti.

After last weeks focused brainstorm and design session, we have been exploring this stove design. We wanted to narrow down a good stove design by choosing between alternative design elements, one by one.

- Pot support: part of the stove burner, or separate? We chose "separate", designing a stand made of rebar that gives the right height, is stable, and accommodates multiple sizes (4"dia to 14"dia pots & pans).
An important aspect of this is that the stove can be refueled without moving the pot, making it more safe and convenient.
- Stove burner supported by the stand, or on its own legs? We chose supported by the stand, to give a consistent "gap" between the burner and the support, to direct the flame up and not out the sides.
- Height of the stove? We combined 2 heights to decide and overall height. These were the "riser height", from the top down to the secondary air holes, and the "fuel height", from the secondary air holes down to the bottom. Using a burn rate of 1.8mm/min using wood pellets (4.25in/hr), we decided that a fuel height of 9" would be sufficient by giving over 2 hours of expected burn time. The riser height is 3", which in our experience has been effective, giving an overall height of 12".
- Primary air control? We decided on a threaded plug and coupling, which we recently saw in another stove video.
- Handle ?? A very hotly debated topic! We considered a single handle (like a pan), 2 pan handles, smaller loop handles, having one in front and one in back, and hundreds of others. The issues were that the stove is very hot, somewhat heavy (around 8 lbs of steel and fuel), and that the stove needs to flip over to dump out the char. We settled on one handle sticking out to give good leverage and to easily spin the stove upside down using one hand.

Rebar cut to lengths for 4 legs, 8 cross bars, a support loop, and 4 pot support bars.

Using a vice and a "cheater bar" made it easy to put the 45° bend in the legs.

It took a lot of effort trying to bend the support piece into an accurate radius. First we bent it with a hydraulic manual Harbor Freight tube bender, but saw this would only give us about 90° and not 180°. Then we tried to bend it around a thick metal round of 8"OD (shown above), as we wanted about an 8" diameter in the rod, but the springback kept us from making the bend tight enough. We ended up making many adjustments, bending by hand and using a vice; not an efficient or consistent method..

For the inner and outer, we used convenient stock sizes of 12"x18" and 12"x24", giving just short of 6"dia and 8"dia parts. The zinc was ground off the edges using a flapper wheel in preparation of welding (the zinc causes spatter and releases toxic gases when welded). Secondary air openings of 0.25"dia were drilled. Openings for the primary air control part were cut; a circle in the inner cylinder for a close fit (this will be welded around to seal), and a rectangle in the outer cylinder (easier to cut, this simply lets in secondary air).

Still to do: cut the stove top plate, cut the support plate w/ concentrator hole, make the support cone, weld together the stand, and weld together the stove.

Hopper Stove

For the hopper stove, we attempted to use wood pellets to fill up the fuel chamber past the hopper. However due to the extremely large fuel chamber, we soon realized that this was impractical. With wood pellets the stove would burn for a very long time. Thus we then elected to use looser biomass ( in the background of the picture below this paragraph). The stove burned with a very high firepower due to the large area of pyrolysis created by the large fuel chamber.

Due to the fidelity of the prototype, there was some seepage of air through the side walls of the prototype. However the refueling system did work to some extent as the burnt fuel shrunk our pre-heated pellet fuel dropped in. The low density biomass was consumed quickly and the addition of more pellets kept the stove going longer. As they were preheated, the stove did not get put out by a large introduction of cold fuel. However the air leakage from the hopper was great and the stove was direct burning most of the time. The stove was more rocket than TLUD in its behaviour.

The char was rather difficult to dispose off after we were done with the test. While the Refueling Team was not focusing on ease of disposal of char in this prototype. Our difficulties reinforce the importance of designing a stove with features that allow for the char to be easily dumped out.

Overall our design recommendations are as follows:

1. Create a smaller inner fuel chamber such that the maximum firepower corresponds with an appropriate high heat setting.
2. The hopper diameter can be made smaller to create a more gradual feed of pellets
3. The cover mechanism must be made developed further to allow for easy opening and closing.

Refueling can be ignored it the stove can last 2 hours on single fuel load. This is entirely feasible with pellets provided the stove has its maximum firepower tuned well to strike a balance between the amount of fuel loaded and the rate at which it is consumed to create an appropriately sized flame. 

However, for lower density biomass, refueling is an important aspect that cannot be ignored.

Modified Quad with Sliding Plate

The modified quad stove was tested with a 1/4 fuel load. Loading up the stove with more pellets would cause the stove to burn for a very long time. We main wanted to investigate how the stove performed while on burning fuel and evaluate its stability, minimization of hot spots and safe dumping of char.


We found that the height of the stove resulted in a very strong updraft that caused the flame to shoot out to a very large height. The stove while relatively stable, was still somewhat shaky given its tall height. Compared to the stove pipe stove, it was not as stable. 


In terms of hot spots, the 4 legs formed a barrier, preventing people from getting too close to the outer cylinder. However, the entire top plate was extremely hot. In fact, it started deforming and separating from the inner cylinder as both components were not joined in anyway.


 Picking it up was very safe as we could just grab the wooden legs. However it required 2 people to lift it due to its weight and size. That being said, the stove was never meant to be moved around too much. This was it was design to allow the dumping of char without any need to pick up the stove.

Although there were no primary air holes drilled into the stove, the flame was strong. There was more than enough air coming through the air gaps at the inner cylinder and slider plate interface. Furthermore as the plate deformed slightly under heat, the air gaps grew bigger, such that we could see the char glowing at the bottom.

Emptying the stove proved to be extremely easy as the slider plate worked to perfection. As the handle was not insulated it was hot to the touch. However this can be easily solved by attaching a piece of wood to the handle.

The following design recommendations have been put forth:

1. The height of the stoves makes the design inherently unstable. It would be worthwhile to reconsider the importance of the preference of Haitians for a standing height stove. If the design sacrificed height, costs could be lowered, portability would be increased and stability would be improved tremendously. Furthermore there was no pot mounted on the stove. Doing so would shift the center of mass higher above the ground resulting in even greater instability. The trade off would be lower fuel capacity and a less powerful draft.
   
2. The slider plate performs the function of dumping char very well. However the lack of precision in the part coupled with thermal deformation would create air gaps that do not afford the control of primary air.

Conclusions
This test run brought up some interesting considerations for the teams as they move forward towards a final design.

1. Shorter burn time per load and refueling vs Longer burn time per load without refueling.  As highlighted earlier, designs need to be tuned for the appropriate maximum firepower and balanced against the fuel capacity of the stoves. With pellets, the stoves have a very high probability of lasting long enough to finish cooking without requiring large fuel chambers. If this was the case, then perhaps refueling might not be needed.
   
2.  Moving parts vs A tight seal.  The use of moving parts results in a less than adequate seal. Primary air control might be sacrifice for easy dumping of char from the bottom or refueling. It will be interesting to see how solutions can be designed to address this issue moving forward
3. Height vs Stability.  As stated earlier, our user studies have indicated that Haitians do prefer to cook standing up. A large stove increase up draft strength and increases fuel capacity at the expense of higher material costs, increased instability and decreased portability. It will be interesting to see how the groups decide to settle this trade off. 

With the first round prototypes done, the teams took the feedback from the rest of the group to make improvements to their design, for some this consisted of minor adjustments, for other a whole new design direction had to be taken

The creative design process focuses on low-fidelity prototyping and many iterations.  Some people propose thinking through every thing before creating prototypes. However, it is almost impossible to quickly consider all the implications of a certain design just through drawings, calculations and discussions.  Thus, HCSP believes in quick, dirty prototypes that can be tested, modified and disposed of easily. 

The Refueling team reconsidered their initial design direction and opted to try a hopper system seen in some designs on the internet. In fact Fritz, a local Haitian businessman we met on our summer trip, also suggested trying something similar. Thus Brian's team focused on building such a low-fidelity prototype to test the concept using tin cans.

Safety had slight changes to make to its Quad-based design. The team was particularly concerned about the safety of emptying the fuel from the stove. This would be a problem if the stoves was large and heavy such as the standing height prototype they had created.

The team experimented with a rotating hinged trap door with a handle that rose up to the top of the stove. The team members were trying to reduce the amount of movement required to empty the stove from the bottom by eliminating the need for a user to stoop down to move a slider at the bottom. However the team realized that for a low-cost stove, the mechanism involved were rather complicated and that the simplicity of a trap door outweighed the inconvenience of stooping down to empty char. Thus the team went back to the slider option.

The flame control team moved towards further developing a testable prototype for their screw-based control mechanism for air control.

This involved putting ascrew into the primary air inlet/hole, and turning it to cause an up/down movement. The screw's large head would eventually close of the inlet. The team hypothesized that this would create a high resolution control system.

To finish of the prototypes, the team headed to the FabLab near the Architecture Annex. This place was a community run workshop for aspiring hobbyist and inventors. They had drills, a CNC machine, rapid prototyping machines and lots of other cool stuff.

The teams did a show and tell again with their newly created prototypes. The Refueling Team even got to test out their prototype outside Engineering Hall. While the stove managed to function, the hopper system did not work out too well due to certain design issues.Back to the drawing board!