Process

Milestones

Throughout the spring semester, the Stove team will meet three milestones that are listed as follows.

· The survey and Focus Group results will be analyzed and applied to our designs by February 17, 2012

o This entails questioning about wants and needs in backpacking stoves from

people who participate in backpacking. This will better define the needs

and wants of backpackers such as: improved fuel efficiency, faster boil time, or

light weight in a backpacking stove. These results will be

applied to our current designs with the help of Mr. Miller to begin prototyping.

· A prototype of a manufactured backpacking stove that will be able to analyze heat loss over the canister.

This will be completed by March 30^th, 2012

o The prototype will be manufactured using the machine shop and be used to

analyze heat loss and efficiency of the backpacking stove. While testing,

changes will be made to the prototype to improve upon the stove in areas

needed. By March 30 we expect to have a final design for prototyping.

· Results from testing the final prototype of a backpacking stove will be complete by April 20^th, 2012

o The data will show heat losses and efficiency of the final prototype created. This will be

our final product and we will know what the final results of the stove are as well

as analyze where we could have improved.

Testing Tools

Some tools we used in the testing process were thermometers provided by Northern Arizona University

in the Thermal Fluids Laboratory in the Engineering building. We used these thermometers to take the

temperature of the water before and during testing. Another tool our team used during testing was a

Data Acquisition system that would read temperature values from the voltage differences in thermocouples

and read them into LabView where we could analyze instantaneous temperatures at multiple locations on

our backpacking stove. Those tools were also provided by Northern Arizona University to students

in the Engineering building Thermal Fluids Laboratory. As you can see in the in the picture below, our

team is using thermocouples to measure the temperatures of the water to know when it reaches 190^oF, the

exhaust temperature at the bottom of the shroud, as well as exhaust temperature at the exit of the vents.

Modified JetBoil prototype during testing

Development

Radiant Heat -Surface Color:

When trying to improve the efficiency of the top of the line JetBoil camping stove, our team recalled from

our heat transfer class that a shinny surface does not absorb very much radiant heat and dark surfaces do.

We painted the bottom of the prototype black with a barbeque ceramic based spray paint. Blackening

of the bottom of the prototype improved the efficiency by 4%!

JetBoil prototype reflective bottom

JetBoil prototype blackened bottom

Radiant Heat -Reflective Disk:

We also learned from our heat transfer class is that if we put a reflective plate below the burner we can minimize

the amount of heat lost below the burner. We found that on some of our prototypes it helped the efficiency yet

on some it did not. We would need to find optimal geometry of the reflective disk to improve on the efficiency.

Reflector below burner

Convective Heat- Shroud:

We also decided to add a shroud around the side of the food canister that would act as a windscreen

and also create a path for the exhaust gases to move up along the food canister utilizing the heat from

the exhaust to exchange into the food canister. Before adding the shroud, exhaust heat would just be lost

into the ambient air. When the exhausted moved up the walls of the food canister we improved the

efficiency by 25%! We also found out that if the ventilation holes at the top were not big enough to let all the

exhaust escape then it would back up the exhaust causing it to choke the flame on the burner putting out the

flame. Also, if the ventilation holes were too big it would not have as great of improved efficiency.

Shroud prototype testing

We tested each variable separately and found out how they improved the efficiency. Once we had tested each variable

we added theses designs to our final prototype and final marketable model. Our final model is show on the Final

Design page. You can access that page by clicking here.

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