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An Inexpensive Inverted Downdraft Biomass Gasifier for Experimental Energy-Thermal-Fluids Demonstrations

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2013 ASEE Annual Conference & Exposition


Atlanta, Georgia

Publication Date

June 23, 2013

Start Date

June 23, 2013

End Date

June 26, 2013



Conference Session

Topics in Biomass and Gasification Processes

Tagged Division

Energy Conversion and Conservation

Page Count


Page Numbers

23.173.1 - 23.173.16



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Paper Authors


Matthew J. Traum Milwaukee School of Engineering Orcid 16x16

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Dr. Matthew J. Traum is an assistant professor of mechanical engineering at the Milwaukee School of Engineering (MSOE). He received a Ph.D. in mechanical engineering from the Massachusetts Institute of Technology [2007] where he held a research assistantship at MIT’s Institute for Soldier Nanotechnologies (ISN). At MIT he invented a new nano-enabled garment to provide simultaneous ballistic and thermal protection to infantry soldiers. Dr. Traum also holds a master’s degree in mechanical engineering from MIT [2003] with a focus on cryogenics and two bachelor’s degrees from the University of California, Irvine [2001]: one in mechanical engineering and the second in aerospace engineering. In addition, he attended the University of Bristol, UK as a non-matriculating visiting scholar where he completed an M.Eng thesis in the Department of Aerospace Engineering [2000] on low-speed rotorcraft control. Prior to his appointment at MSOE, Dr. Traum was a founding faculty member of the Mechanical and Energy Engineering Department at the University of North Texas where he established an externally-funded researcher incubator that trained undergraduates how to perform experimental research and encouraged their matriculation to graduate school. Dr. Traum also serves as the founding Chief Technology Officer at EASENET, a start-up renewable energy company he co-founded with his former students to commercialize residential scale waste-to-energy biomass processor systems.

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Kyle Pace


Jeremy R Anderson EASENET

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Jeremy is a retired Navy Diver, sustainable energy engineer, and social entrepreneur. Growing up in a rural Texas community Jeremy endured great hardships, forming the unmatched resiliency that drives his continued successes. Out of high school, Jeremy joined the Navy and quickly ascended the ranks to First Class Petty Officer in only six years. Starting out as a Hull Maintenance Technician, Jeremy found an affinity for design and fabrication; this led to his acquiring the rates coveted title “Super Welder” in only three years. Having reached this apex so quickly, and fearing stagnation, Jeremy sought more challenging opportunities to expand his skill sets. The search ended when Jeremy decided to become a Navy Diver and thus a member of one of the militaries most elite communities. His aptitude for leadership shown true as he directed many high-risk/high-stress diving operations resulting in numerous awards and accolades. After eight years of honorable service, he was no longer able to dive and was medically retired from the Navy.

Jeremy’s current path started with an acceptance into the Mechanical and Energy Engineering program at the University of North Texas. In the spring of 2010, Jeremy began performing renewable energy research. Soon after, he was leading a team of researchers and collaborating with a green energy start-up. He was the first and only UNT engineering student to be selected as a McNair Scholar, a competitive scholarship offered to top juniors and seniors at select schools around the country. In the summer of 2011, Jeremy accepted a research assistantship at the Milwaukee School of Engineering. This move allowed Jeremy to focus on his passion for innovation, leading to a grant in aid of research from Sigma Xi. This grant funded his development of a novel pyrolysis biomass processor that extracts energy from biomass waste streams. Now, Jeremy is leveraging all of these experiences to lead EASENET in transforming the world of energy.

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An Inexpensive Inverted Downdraft Biomass Gasifier for Experimental Energy-Thermal-Fluids DemonstrationsAbstractTo facilitate experimental introduction of biomass-to-energy technologies in an upper-divisionundergraduate thermodynamics course, a small, inexpensive wood chip gasifier was designed,constructed, and tested. This device, which was built from a metal vacuum-flask-style thermosbottle, was constructed for less than $50. The design is both simple and economical; inexpensiveenough that it could also be implemented as a student project. In the reported experiments, thegasifier processed cedar wood chips (rabbit cage litter – available from any pet store), but itcould also accommodate a variety of other biomass feedstock.Oriented in an ‘inverted downdraft’ configuration, the gasifier motivates teaching opportunitiesthrough experiments in heat transfer, fluid mechanics, thermodynamics, and combustion. Theapparatus could provide rich outdoor demonstrations in a lecture class or it could serve as astudent laboratory exercise (as reported here) in any energy-thermal-fluids course. Within asingle charge of wood chips, there are two reaction zones. The top wood layer smolders,converting chemical energy to heat. This heat conducts downward through the chips into topyrolysis layer. Here, the wood is converted to syn-gas composed of flammable hydrogen andcarbon monoxide as well as inert carbon dioxide. Natural convection drives the syn-gas throughthe gasifier’s burner (the thermos bottle’s neck). In parallel ambient air is drawn up the spacebetween the thermos inner flask and outer wall. At the burner, combustible fuel combines withoxygen in the air to support a flame.To juxtapose biomass gasification and subsequent syngas combustion against directly burningthe wood chips, students also burn an identical mass of cedar wood chips placed in an open-aircontainer. Students measure the initial and final wood chip masses for both combustiontechniques to quantify energy conversion efficiency through ash generation. They findgasification converts more than 99% of the biomass to syn-gas while direct burning leavessubstantial ash and even unburned wood behind. Students also take temperature measurementsinside the flames for both combustion techniques. Experimental results compare qualitatively toadiabatic flame temperature predicted for hydrogen and carbon monoxide versus cellulose andlignin in that the syn-gas produces a much hotter flame than does direct wood chip combustion.

Traum, M. J., & Pace, K., & Anderson, J. R. (2013, June), An Inexpensive Inverted Downdraft Biomass Gasifier for Experimental Energy-Thermal-Fluids Demonstrations Paper presented at 2013 ASEE Annual Conference & Exposition, Atlanta, Georgia. 10.18260/1-2--19187

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