Today at ISU
Cyclone News
Admissions

MAKING ROUND CHIMNEYS FIT INTO SQUARE HOLES
 

When ME graduate student Nathan G. Johnson traveled to Honduras over Thanksgiving break, he took tin snips, a spot welder, and metal-bending equipment with him. More important than the tools though, he brought a new design and ideas to improve the manufacturing process of wood stoves, the standard cooking device used in developing countries.

Johnson’s journey began during his freshman year in ME with a desire for using his technical skills to better the quality of life everywhere. This led him to develop engineering skills for humanitarian applications, which culminated with his senior honors project concerning proper design of hand-made wood stoves.

With wood stoves being used in two to three billion households throughout the world, problems associated with them affect nearly half the world every day. Johnson learned about the concerns related to stove design through Mark Bryden, an ME associate professor and associate chair and co-founder and current president of ETHOS (Engineers in Technical and Humanitarian Opportunities of Service).

Thanks to engineers like Bryden and their collaborations with nongovernmental organizations (NGOs), wood stoves are being redesigned to increase fuel efficiency and reduce particulate emissions to remove deadly indoor air pollutants. With his honors project, however, Johnson researched another area of concern that hadn’t received much attention up to now—safety. He examined hazards associated with wood stoves and discovered burns, scalds, cuts, and loss of property often occurred during cooking.

Johnson has continued his investigation as a graduate student. As part of his MS thesis, he developed a set of standardized safety principals and metrics to quantify and minimize the hazards. The standards address considerations such as: Can the surface temperature cause burns? If the stove tips over, is it likely that burning fuel will fall out? Do flames surround the cook pot that may lead to clothing or hair catching on fire? Is there enough heat emitted to cause surrounding walls to start on fire?

While Johnson did some safety testing on new stoves during his trip to Honduras, his primary goal involved improvement of manufacturing processes. A key part of advancing products used in developing countries is ensuring that they can be manufactured efficiently by microenterprises within the country. At the request of Trees, Water and People, an NGO that works to help nations sustain their natural resources, Johnson and Bryden had traveled to Honduras in August to get to know the people and learn about their manufacturing process.

Students in Bryden’s Sustainable Engineering and International Development class then developed designs to address methods of improving the product and decreasing manufacturing time. Seniors Jeremy Hunter, ME, from Mondamin, Iowa, and Jed Cline, ABE, from Lohrville, Iowa, proposed the idea of an exit manifold, opening from stove to chimney, that came back at a 45-degree angle. Johnson, who advised the students, says the design takes less materials and time to make. Perhaps most importantly, it eliminates a point where hot flue gases were getting trapped. “When the combustion gases stagnate, tar and ash build up much quicker and result in faster part burn-out,” Johnson says. “One of the things we want to eliminate is the burden of getting replacement parts.”

The primary challenge of the design was to effectively fit a round chimney into a rectangular manifold and figure out how to fasten the manifold to the stove to maintain stability. Johnson solved these problems on his trip to Honduras in November. He also used his tools and knowledge to cooperatively implement the new design with the manufacturers. “It’s a hand-manufacturing process done by three or four people,” Johnson says. “One of the major issues is understanding the people and culture and working with them rather than just imposing our ideas on them.”

Johnson, who began his PhD work in January, is majoring in mechanical engineering, economics, and sociology. “I want to promote more focus on international development within the context of sustainable engineering and appropriate technology,” he says. “My focus is to develop technology that’s not only useful and easy to manufacture, but economically and culturally acceptable.”

In addition, Johnson is working with Bryden on an experimental course, Applied Methods in Sustainable Engineering and International Development, aimed at giving students hands-on experience with both designing new technology and working with the microenterprises in Honduras to implement their ideas. The course will also help students gain cultural understanding and appreciation for the people they are working to help.