1. New Mexico State University
Electric Backpacking Stove Capstone Project
Prepared for: Dr. Young H. Park and Dr. Edward Pines
ME 426/ME 427
Spring 2016
Group Members:
Damon Alfaro, Austin Ayers, Arthur Cox, Marcus Fluitt, Aaron Harrison, Reese Myers,
Benjamin Nelson, and Sandra Zimmerman

2. Table of Contents
Project Management
Facet 1: Recognize & Quantify the Need
Facet 2: Define the Problem
Facet 3: Concept Development
Facet 4: Feasibility Assessment
Facet 5: Preliminary Design
Facet 6: Analysis & Synthesis
Weekly Progress Reports
Purchase Requisition & Ordering Information
Meeting Agenda & Minutes
Contact Log
Final Report
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3. Project Management
As an engineer, you will be called upon to design a wide variety of devices and systems. You
may be asked to design simple mechanical components such as a holding fixture for use in a
manufacturing assembly environment. On the other hand, you may have to design an entire
machine or building, along with all of the related subcomponents. You may be responsible for
the entire project individually, or you may have an entire team of engineers, scientists, and
business staff working on the developed formal design procedures, and you will probably be
asked to use that procedure. Other business may not have a formal design and review
procedures, and the decision of how to manage the entire design project yourself. We will use a
design procedure in this class. This formal approach fosters a strong team­oriented working
relationship with the client, helps students to learn what to expect in working together. The
multi­faceted approach to product development allows us to perform concurrent engineering, by
performing activities on more than one facet at a time, but it also leads us in the direction of
where the primary focus of the team should be at various stages in the process.
Facets 1­7 (requirements)
Facet 1. Recognize and Quantify the Need
● Market Demand
● Assess competing solutions for the need
● Budgetary Parameters
Facet 2. Define the problem
● Design Objective
● Design Constraints – Budget, Time, Legal, Personnel, Material properties and
availability, manufacturability
● Design Specifications
Facet 3. Concept Development
● Brainstorming Techniques (Pros and Cons, what is the essential elements for the concept)
● Any other methods
● Literature Review
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4. Facet 4. Feasibility Assessment
● Technical Feasibility
● Economical Feasibility
● Schedule Feasibility
● Evaluation Criteria
Facet 5. Preliminary Design
● Preliminary Drawing Package
● Assembly and Component Drawings
● Bill of Materials and Supplier Identification
Facet 6. Analysis and Synthesis (Engineering Models – Simulation, Testing, and/or Hardware)
● Software simulation and CAD model
● Rapid prototype and physical representations
● Proof of concept Prototype
Facet 7. Detailed Design (DFx)
● Comprehensive Drawing Packages
● Review of Codes and Standards
● Design factors include: Safety, Manufacturability, Maintenance, Assembly,
Manufacturing, Disassembly, Recycling, Quality
Facets 8­11 (optional)
Facet 8. Production Planning and Tooling Design
● Pre­Production Prototype
● Flexible work cell design, die design, fixtures, tooling, automation
● Process diagrams and process flow sheets
Facet 9. Pilot Production
● Commercial market assessment
● Development plan by manufacturer(s)
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5. ● Demonstration of latest vendor product to user community
Facet 10. Full Scale Production
● Capitalization
● Standardization and interchangeability
● Product marketing demonstration to potential buyers
Facet 11. Product Acquisition and Deployment
● Customer feedback for continuous product improvement
● Product maintenance and logistics support
● User training
● Sales, Service, and Support
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6. Facet 1: Recognize & Quantify the Need
Market Demand
Backpacking and camping are common hobbies amongst people around the world. Whether it be
Yellowstone National Park in Wyoming, The Everest Base Camp Trek in Nepal or Copper
Canyon, Mexico, two necessity remain constant, food and clean drinking water. The need for
food and clean water are the most basic needs to sustain human life, regardless of the location or
season.
Streams or lakes commonly supply water for hikers, but the danger remains the of this water is
undrinkable. Fresh water sources often contain bacteria or protozoa such as ​Giardia Lamblia and
Cryptosporidium. These particles can cause illnesses that are not seriously harmful while
medical treatment is readily available but can cause serious harm or death if isolated while
backpacking in remote locations. Water is treatable through three general solutions: Boiling,
Filtering and Chemical Treatment. All of these solutions are relatively simple and easy to
achieve through lightweight tablets or filtering devices. While finding and purifying water is
simple enough, food provides a more difficult predicament.
In the case of many (but not all) locations, immediately available food presents itself in the form
of fruits, berries and nuts. In the case that a hiker does find food in nature, the novice nature man
probably does not know the difference between a potential food source and a potentially
poisonous fruit; thus many bring food they can prepare using a source of heat. Raw food such as
red meats, poultry, or fish may spoil, attract wildlife and require an additional pot or pan to cook.
Because of this, most backpackers use already prepared dehydrated meals or MREs (Meals
Ready to Eat) that only require boiled water to become ready for consumption. These meals are
used by deployed military troops, providing a lightweight and easy to prepare meal that is perfect
on short or long trips. For the purpose of the electric backpacking stove we aim to create an
apparatus focused on preparing these MRE type meals.
The electric backpacking stove provides a means of bringing water to a boil through the use of
an immersion heating coil powered via a solar­rechargeable battery. This will provide a means to
both treating water and preparing MRE packs. Current camping stoves use non­renewable fuels
such as isobutane, propane, white gas and kerosene carried in canisters to create heat via an open
flame. While open flame methods provide an incredibly efficient source of heat, they encounter
two problems. Open flame methods present a potentially large fire hazard if left unattended or
used inside of a tent. Along with that, these fuel sources are nonrenewable and are not readily
available in nature during an expedition. Through the use of both the immersion coil and solar
charging systems we can eliminate the risks of starting a fire or running out of fuel. The goal of
the system is to provide a cleaner (more environmentally friendly), safer and more
self­sustainable cooking apparatus for backpackers. Although competing solutions may be
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7. cheaper, as will be discussed, we believe that the potentially advantages of this system will spark
the interest of the target demographic.
Assess Competing Solutions for the Need
Two primary classes of camping stoves are currently on the market. The first is a camp stove
that is approximately the size of a briefcase and weighs approximately 10 pounds. These are
meant to be used on camping trips where the participants can drive up to the camp site and must
only move equipment a short distance prior to set up. These stoves have large cook areas and
high heat output along with separate large fuel tanks. These stoves while very useful for certain
types of camping are much too heavy to be considered viable solutions for backpacking.
Backpacking stoves are much lighter much more limited as far as cook surfaces and also
generally more expensive. These are meant to be carried in a back pack long distances, perhaps
over several days, weeks or months. The electric stove we are developing is designed to be
competitive with backpacking stoves where customers have already displayed a willingness pay
more to sacrifice conveniences such as cook area and heat output in exchange for size and weight
considerations
Within the backpacking stove market, a variety of competing solutions have successfully
coexisted for many years largely based on the consumers valuing different attributes based on
application requirements. Different fuel types include wood, white gas, isobutane­propane,
kerosene and solid tablets. Each of these solutions has relative benefits such as boil times, wind
resistance, light weight. Weights range from 10 ounces to 2 pounds, prices range from $80 to
over $200 and boil times range from 3 to 8 minutes. Each of these solutions relies on burning
either wood or a petroleum product in order to provide heat. Our stove would be the first on the
market that provides a heat source to boil water that is a viable backpacking option with no
combustions or the emissions combustion entails.
Budgetary Parameters
This project is not designed to provide the low cost options to the market need. We are seeking
to create a premium product that conscious consumers are willing to pay more for even at the
expense of carrying more weight. The high end of the market is around $220, our goal is to
design this stove at a prototype cost of $200. Efficient purchasing that comes with scale
production along with pricing at the high end of the market would provide the margin for the
product. The highest cost item in our system is the battery pack which we are assembling
ourselves from individual cells. Solar panels are the next biggest contributor to cost and the
remaining items while critical to system integration contribute only minor marginal cost to the
system.
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8. Item Cost
Battery Pack $171
Solar Panels $40
Immersion Coil $10
Electrical Wire $2
System Integration Parts $30
Total $253
The prices listed above are based on testing costs. There are several opportunities for cost
savings that we hope will reduce the prototype cost of the system to approximately $200. These
opportunities include having to make some parts rather than purchase them, and having a better
understanding of the gages and lengths of wire required to build the system.
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9. Facet 2: Define the Problem
Objective
The traditional backpack stove consists of a fuel bottle that must be attached to a stove­like
apparatus to sustain an open flame used to heat a variety of objects. This apparatus is paired with
a pot or a pan used to prepare food and boiling water. The most commonly used systems on the
market today operate using non­renewable liquid/gas fuels, such as butane and propane. The
issues with these systems lie in that the fuel is non­renewable and often times the more
lightweight canisters are not intended to be refilled for reuse. By using this traditional
backpacking stove design one would be using fuel that can never be recovered while
simultaneously creating waste from the non reusable fuel canister. In addition to the waste
produced by the system, one would not be able to boil water once their fuel supplies are
depleted. The fuels that are consumed are not readily available or harvestable in any environment
where the tradition stove would be used. In addition, inclimate weather creates further issues.
Sustaining a constant lit flame could prove to be difficult due to high winds or precipitation.
These systems are intended strictly for outdoor use as use inside of tents provides an extreme fire
hazard.
The thought behind our system is to design an alternative solution to preparing food while
avoiding these conflicts. Our goal is to design a battery powered system charged via renewable
energy sources (wind power, solar power, etc.) that achieves the same goal as traditionally
designed stoves (boiling water) while avoiding the aforementioned problem associated with
existing designs. The following initial objectives have been placed on our system:
➢ Design must be cost effective, priced around $200.
➢ System must comply to a lightweight design, around 2 lbs in weight. The lower the weight,
the easier the system becomes to use. Best competing solution weighs 10 ounces.
➢ System must possess the ability to boil 1 liter of water in 15 minutes.
➢ System must possess the ability to sustain energy for 2 meals a day during a 2 day trip
without recharge.
➢ System must possess the ability to be recharge portions of the initial charge in order to
facilitate extended trips.
➢ System must require the same, if not less effort to operate than traditional designs.
➢ The stove will have safety systems in place to prevent the user from shocks, burns or
accelerated discharge of the battery.
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10. These objectives have been placed on our system in order to make the design competitive with
current designs while providing additional benefits. Encompassing these benefits into the design
will more than likely increase the price. We feel that these benefits, such as being better for the
environment and the ability to recharge, will provide incentive for users that compensates for the
increased price.
Design Constraints
➢ Budget:​ All foreseen expenses have been carefully estimated for materials, and testing
equipment. A budget of ​500.00 dollars​ has been estimated to cover all cost. Personal
funds for experimentation are not included in the budget.
➢ Time:​ The project is to be designed, tested, and reported by the end of spring semester of
2016. The design binder is to be submitted at the critical design review on April 30​th​
of
2016. If promised delivery dates persist, testing will be underway by April 15​th ​
of 2016.
➢ Legality:​ Process and development procedures are determined to fall within the safe
practice procedures to ensure safety of group members as well as future customers.
➢ Material Properties and Availability:​ All material are to be chosen with regards of
expense, performance, weight, and practicality.
➢ Manufacturability:​ Proper construction of the heating coil assembly and solar panel
array will be designed and inspected prior to the testing date. These systems will be
created and tested in a controlled lab environment.
Design Specifications:
The primary physical constraints that dictate this project is power output in relation to the
feasibility of packing the batteries relative weight.
System Design Requirements
1. The system will have appropriate safety systems so that the user is protected from shocks
and burns.
2. The system will be capable of boiling 1 liter of water in under 15 minutes.
3. The system will have the battery/charging capacity such that it can be used twice a day.
4. The battery, circuitry, and all components must be small enough to be carried in a
backpack. This system will be designed with a compact form factor for practical packing
considerations as well as marketable appeal.
5. The battery, circuitry, and all components must be light enough as to not create an
excessive hindrance upon the user during backpacking. This system will be designed so
that the total weight of the system is as light as possible while fulfilling all other
requirements.
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11. FACET 3: Concept Development
Brainstorming
Brainstorming is a group technique for generating ideas in a nonthreatening, uninhibiting
atmosphere. It is a group activity in which the collective creativity of the group is tapped and
enhanced. The objective of brainstorming is to generate the greatest number of alternative ideas
from the uninhibited responses of the group.
Approach
Brainstorming can be done either individually or in a group. In group brainstorming, the
participants are encouraged, and often expected, to share their ideas with one another as soon as
they are generated. Complex problems or brainstorm sessions with a diversity of people may be
prepared by a​ chairman​. The chairman is the leader and​ facilitator​ of the brainstorm session.
The key to brainstorming is to not interrupt the thought process. As ideas come to mind, they are
captured and stimulate the development of better ideas. Thus a group brainstorm session is best
conducted in a moderate­sized room, and participants sit so that they can all look at each­other.
A flip chart, blackboard, or overhead projector is placed in a prominent location. The room is
free of telephones, clocks, or any other distractions.
In order to enhance creativity a brainstorm session has four basic rules:
Focus on quantity
This rule is a means of enhancing​ divergent production​, aiming to facilitate problem solving
through the maxim ​quantity breeds quality​. The greater the number of ideas generated, the
greater the chance of producing a radical and effective solution. An individual may revisit a
brainstorm, done alone, and approach it with a slightly new perspective. This process can be
repeated without limit. The result is collaboration with your past, present and future selves.
No criticism
It is often emphasized that in group brainstorming,​ criticism​ should be put 'on hold'. Instead of
immediately stating what might be wrong with an idea, the participants focus on extending or
adding to it, reserving criticism for a later 'critical stage' of the process. By suspending judgment,
you create a supportive atmosphere where participants feel free to generate unusual ideas.
However, persistent, respectful criticism of ideas by a minority dissenter can reduce​ groupthink​,
leading to more and better ideas.
Unusual ideas are welcome
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12. To get a good and long list of ideas, unusual ideas are welcomed. They may open new ways of
thinking and provide better solutions than regular ideas. They can be generated by looking from
another perspective or setting aside assumptions. If an idea is too "wild" to be feasible, it can be
tamed down to a more appropriate idea more easily than think up an idea.
Combine and improve ideas
Good ideas can be combined to form a very good idea, as suggested by the slogan "1+1=3".
Also, existing ideas should be improved. This approach leads to better and more complete ideas
than just generation of new ideas, and increases the generation of ideas, by a process of
association​.
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13. Facet 3: Concept Development
Brainstorming
In our first meeting, we introduced how we were going to propose new ideas. We brainstormed
renewable energy ideas and then split up into groups to research each topic. Our research
included feasibility, power output, cost, human factor and weight. Our pros and cons for each
idea are as follows:
➢ Solar Panels:
o Pros:
▪ Free energy
▪ Light weight
▪ Relatively Simple
▪ Direct current
▪ Relatively low price
o Cons:
▪ Efficiency from sun is low
▪ Fragile
▪ Weather­dependent
➢ Turbine:
o Pros:
▪ Produces a lot of energy
o Cons:
▪ Heavy
▪ Expensive
▪ Too large (A = 1 ft^2)
▪ Complicated
➢ Piezoelectric:
o Pros:
▪ Able to produce energy anytime the person is walking
▪ Can obtain energy at any time of the day
o Cons:
▪ Too complex
▪ Not enough power
➢ Thermoelectric:
o Pros:
▪ Can recycle heat off the boiling water
▪ Temperature change­dependent
o Cons:
▪ Doesn’t produce enough energy
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14. ➢ Crank:
o Pros:
▪ Easy to use
▪ Cheap
▪ Use it in any weather condition
o Cons:
▪ Little­to­none energy output
▪ Required too much energy from the person
▪ Bulky
Aaron, Arthur and Sandra organized all the ideas above into a decision matrix, presented it to the
group, and then the group made some final decisions. We ended up choosing thermoelectric
generator and solar panels. Solar panel because it was the most reliable source of main energy,
according to our decision matrix (shown below). However, we still needed a second power
source in case the weather became unfavorable, so we also chose the thermoelectric generator.
Figure: Decision Matrix
Approach
Our group met every Wednesday from 2:30­3:30 p.m. in the Aggie Innovation Space conference
room. We discussed ideas, progress and next steps. Whoever came up with an idea, had to do
individual research to provide the pros and cons, and then would be examined by the rest of the
group. Every member had his/her own strengths, and tasks were assigned accordingly.
The group administrators (Reese, Arthur and Sandra) met with our advisor, Dr. Abdelkefi, most
Mondays from 1:30­2:00 p.m. in his office. The administrators kept Dr. Abdelkefi up­to­date on
what was discussed during our Wednesday meeting. Dr. Abdelkefi would provide feedback to
our current struggles, strategies and successes.
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15. FACET 4: Feasibility Assessment
Feasibility Assessment Steps
Step 1 Prepare and distribute the plan for performing a feasibility assessment of the proposed
design concepts.
(1) Prepare a list of questions based on the Needs Statement and Problem Definition that
can be equally applied to each design concept. Be sure to cover technical, economic,
schedule, market, and performance issues with the questions.
(2) Agree on a weighting scale to be used in answering each question. Assume 0 indicates
that the concept totally fails to meet the criteria, while a 3 indicates full compliance. Make
sure that the scale for each question is applicable to all concepts, and will discriminate
between concepts.
(3) Assign individuals to perform background research required to answer each feasibility
question for each concept. Each response should be supported by appropriate
documentation.
Step 2 Each individual should research their assigned feasibility question and concept, and
prepare a written report on their findings.
Step 3 Prepare a formal MS Word report summarizing all available information about the
feasibility assessment. The report should consisted of (i) summary of the Step 1 tasks,
consisting of the questions and scoring criteria, (ii) a tabulation of results of the
assessment, (iii) a radar chart comparing the concept alternatives, (iv) a
recommendation (v) supporting documentation for each response to each question, such
as price quotes, stress analysis, parts count, market data etc. This report should become
Section of your final report at the end of the semester.
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16.
Step 4 Distribute the report to all team members so that everyone has a common basis for
subsequent facets of the design process.
Additional Information
All team members should bring any background information they have available to the team
meeting, including knowledge of bar codes, molding manufacturing, retail needs, automation,
related experiences, questions they would like to have answered, etc.
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17. Facet 4: Feasibility Assessment
The intent of the project was to engineer a system that would be able to compete with liquid gas
fueled outdoor stoves while providing an eco­friendlier and rechargeable approach. To begin to
design our electric backpack stove, we assessed the needs of our system in order to function
properly and be competitive on the market. From analyzing the pros and cons of other systems,
similar and dissimilar, we have decided on the main factors that will provide a successful system.
The predominant driving factors of the system are as follows:
Budget/Cost
The intent of the project is to design a system that would be marketably competitive in the future.
This means that the cost of the system is to be as low as possible in order to compete with the
alternative solutions of liquid gas fuels. As well we must then take into consideration the price in
order to be more readily available to backpackers with less expendable incomes. Cutting the cost
of the system will generate a higher profit from sales and the flexibility to lower pricing to
appeal to more consumers.
Power/Capacity
Battery capacity dictates the amount of energy that can be stored and therefore used by the
heating coil to boil water. An emphasis has been placed on being self­sustainable, the battery
must hold enough charge to go periods of time without recharge. The energy input into the
system must then also be efficient enough to supply the battery with the energy needed within a
relatively short period of time. Sustainment of this charge is imperative for the system to operate.
Our location, New Mexico (Southwest United States), provides a prime opportunity to use solar
energy captured through cells due to the amount of sunlight the region receives yearly.
Weight/Size
The electric backpack stove system needs to be lightweight and relatively small in order to
compete on the market with alternative solutions. A large, heavy system will burden the user and
prove undesirable for prolonged use in the field. To overcome this, we had to look into lighter
batteries over power/capacity because of the ability to recharge. That being said, our recharge
options were limited to making individual solar cells that can be on light weight material instead
of using pre­made heavier solar panels.
Complexity/Ease of Use
Taking the user into consideration our system is desired to be as easy and simple to use as
possible. We do not want the stove to be either too complex for the user to operate, or too
complex to design, manufacture and assemble. Complexity dictates what/how many input and
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18. output systems are desirable for use. For example, the piezoelectric transducer proved to be very
complex for the input of energy the option was available to provide.
Safety
Safety is a major driving factor for any project/product that is intended for use by the public. The
risk on this project comes in two forms: risk of battery failure in the form of fluid discharge and
electrical discharge, and the risk of starting a fire due to the heating element.
Feasibility Questions
No
.
Type Question
1 Technical Does the team have enough background to implement renewable
resources?
2 Technical Does the team have the skills to build the system?
3 Performance Does the system produce enough energy to bring the water to a boil?
4 Performance Will the input system supply enough energy to produce another boiling
cycle?
5 Economic Can the system(s) be produced within the allotted budget?
7 Marketing Is the system competitive with alternative solutions from a performance,
pricing and technical standpoint?
8 Marketing Is the allure of being eco­friendly enough to compensate for a potentially
higher price?
The following tables will be used to assess the three subsystems of the project:
➢ Energy Input
➢ Battery/Energy Storage
➢ Energy Output/Heating Element
These systems will be allocated points on the basis of how well each option will adhere to the
predominant driving factors we feel will be most successful to our project (0­lowest, 10­highest).
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19. Energy Input Assessment:
Solar
Power
Hand
Crank
Piezo
Electric
Water/Wind
Turbine
Cost 7 6 4 4
Power
Input
6 8 2 9
Weight/Siz
e
6 6 8 8
Complexity 7 10 3 3
Ease of Use 10 3 8 10
Safety 9 9 8 8
Total 45 42 33 42
For our renewable energy choices, we looked into solar panels, thermoelectric generators,
piezoelectric transducers, a wind/hydro turbine, and a hand crank. After doing research in each
of these fields, it became apparent that either solar panels or a turbine would be our best option
for a main rechargeable power source; however, weather conditions could interfere with their
performance, so we decided to include an additional power source to supplement them. We
looked into incorporating either the thermoelectric generator, the piezoelectric transducer, or the
hand crank to be the supplemental power source.
Solar panels became our main option for power over turbines for a couple of reasons. The
turbine would generate more power than the solar panel but the main problem was the size and
complexity of the design that made it unfeasible. The blade diameter had to be at least a foot in
size making it impractical to carry and in turn made the turbine too heavy. Solar panels can be
set in series giving us the desired output of energy. Also, buying solar cells gives us the
flexibility to model and attach the solar panels for travel in a way that is comfortable and
lightweight. The solar panels would weigh in roughly around one pound and are relatively easy
to wire. The main concern for the solar panels is not having sunlight, thus creating the use for
supplemental power sources.
For our supplemental power sources, all three did not have a high power output making them a
bad choice for a main power source. The piezoelectric transducer was ruled out due to the fact
that it was too complex for both the user and for us to manufacture. It ran off of AC current and
our battery was running off of DC current, meaning we needed to convert the current. Also, the
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20. amount of wire that would have to run from the user’s feet made it hard to use and also unsafe. A
hand crank would be the most reliable source of recharge since it will work in any kind of
weather; however, it had a very low power output to the amount of energy required to operate it.
It is just not plausible for someone to have to crank for an hour just to eat dinner. The
thermoelectric generator was the most plausible choice because even though it has a low output
of power, it would be returning some of the power that is outputted by the battery during cooking
to the generator. Also, it is lightweight, small, and easy to use.
Battery Assessment:
Lead
Acid
Lithium
Ion
Nickel
Cadmium
Cost 9 6 8
Power Input 9 8 5
Capacity 9 6 2
Power
Output
9 9 5
Weight/Size 0 8 7
Complexity ­ ­ ­
Ease of Use ­ ­ ­
Safety 5 7 7
Total 41 44 34
Battery selection was relatively simple, we needed the lightest battery possible that was capable
of holding and discharging enough energy to boil the desired volume(s) of water. For our system,
the only viable option was a variant of a Lithium Ion battery, whether that be LiPo or LiFePo.
This is because the Lead Acid batteries, commonly used as car batteries, are much too heavy to
expect a backpacker to carry around for hours/miles of hiking. On the other hand, nickel
cadmium batteries, often used in cameras and smaller devices, were not capable of holding
enough energy to achieve our goals. Lithium Ion batteries, however, provided the best of both
worlds due to it's the ability to hold the necessary energy and still remain relatively low weight.
Because our project is still in the early stages of development, we have not been able to narrow
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21. our search down to a specific battery model to be our final choice. Testing will proceed with a
battery capable of achieving our goals regardless of weight in order to prove that it is achievable.
Energy Output (Heating) Assessment​:
Induction
Heating
Immersion
Coil
Electrical
Burner
Wrapping
Coil
Cost 5 9 5 8
Power
Output
­ ­ ­ ­
Weight/Size 5 7 4 5
Complexity 3 9 7 8
Ease of Use 7 8 7 6
Safety 7 8 6 5
Total 27 41 29 32
From the assessment of our heating options, we have discovered that an immersion coil is far and
away the best option for our system. The immersion coil option provides the simplest to develop,
easiest to operate, least expensive, lightest and safest option to use. Immersion coils are simply
inserted into the water and, through Joule (resistive) Heating, will bring the water to a boil.
Immersion coils are commonly made of NiChrome wire coiled into a tight spiral. This will be
attached to the battery system by copper leads, allowing an electric current to run through the
wire. Once boiling has been achieved the leads shall be disconnected so no current is running,
this will eliminate risk of electric shock as well as discontinue any further heating of the wire.
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22. Facet 5: Preliminary Design
Design
➢ Battery
We want the lightest battery that is capable of storing and discharging enough power to boil the
desired amount of water in a pot. We found our best battery option to be the Tenergy 3.2V 20Ah
LiFePO4. Our design is to verify that the battery chosen will be able to bring the water to a boil,
will be able to recharge from the renewable energy sources attached, and will be at a reasonable
weight so that the customer will be happy.
Figure 1: Tenergy 3.2V 20Ah LiFePO4 Rechargeable Battery
➢ Coil
We want a coil that is easy to work with, inexpensive, light and safe. We found that an
immersion coil is our best option for heating. It is made of NiChrome wire wound in a tight
spiral and it attaches to the battery using copper leads that allow an electric current to run
through the wire. Our design is to insert the coil into the water and, through resistive heating,
bring the water to a boil. Once the water is boiling, we want the copper leads to be disconnected,
so that the current will become zero. This is to ensure safety—eliminate any risks of electric
shock and any further heating of the wire.
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23.
​ Figure 2: Drawing of how to form the coil for testing
Figure 3: How to insert the coil into the pot of water
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24. ➢ Solar Panel
We want a main renewable energy source that can generate enough power to keep the battery
running for three days. We found that solar panels are ideal because we can set them up in series
to generate the amount of power needed. We can also design the solar panels in whichever way
we prefer to ensure they are comfortable and lightweight for the backpacker. Our design will be
to create a cover made out of solar panel cells in series that can be attached to a backpack.
Figure 4: Individual cells Figure 5: End goal – connect in series to form a
backpack cover similar to this
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25. ➢ Thermoelectric Generator
Due to unpredictable weather conditions, we want a second renewable energy source as backup.
We found that the thermoelectric generator was our best option because the heat generated from
the battery power output would return to the generator to be recycled. Also, it is lightweight,
small and easy to use. The idea for our design is use two to four thermoelectric generators and
attach them to the stove itself.
​Figure 6: Thermoelectric Generator
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26. Bill of Materials and Supplier Identification
➢ Solar Panel Test:
Supply Quantity Supplier Total Cost
80’ Solar Cell Tabbing
Wire
1 Amazon.com $14.09
8’ Solar Cell Bus Wire 1 Amazon.com Included in
price
above
Solar Flux Pen 1 Amazon.com Included in
price
above
Solar Panel Diode 2 Amazon.com Included in
price
above
Monocrystalline cell solar
panels
125mmx125mm at
2.8W
10 Amazon.com $25.99
4’x8’x1/4” OSB wood
sheet
2 Home Depot $3.84
2’x4’x10’ plank of wood 1 Home Depot $3.84
30A fuse 1 Home Depot $4.36
Gorilla glue adhesive 1 Home Depot $18.36
Pack of 40 wood screws 1 Home Depot $15.37
Timer 1 Target borrowed
26

27.
➢ Battery Test:
Supply Quantity Supplier Total Cost
3.2V 20Ah LiFePO4 batteries 4 Allbattery.com $143.96
Protection Circuit Module 1 Allbattery.com $35.95
3.2V charger 1 Batteryspace.com $80.64
5 yards of nickel chromium
wire
1 Amazon.com $7.86
Backpacking pot minimum
with a volume of 1L
1 Target $4.99
Insulated Styrofoam
container
1 Target $9.98
Spoon 1 Target $0.98
10 yards of 10­gauge copper
wire
1 Home Depot $11.48
10A fuse 2 Home Depot $4.56
Multi­meters 2 New Mexico State
University
borrowed
Thermocouple 1 New Mexico State
University
borrowed
Timer 1 Target borrowed
27

28. FACET 6: Engineering Modeling and Analysis
Engineering Model
Developing an engineering model is when you can actually put your ideas to the test. An
objective of engineering model development is to learn how to plan a test program for your
engineering model. We will use the following steps for the engineering model:
Step 1: Build the model generated during the preliminary design phase. The model may be a
software computer simulation, such as a finite element model, or it can be a scale
model, or a full scale prototype. In addition to building the model, we need to prepare a
test plan, and sequence of operations, along with a series of questions to be
investigated.
Step 2: Perform the testing indicated in the test plan. Be sure to recall all original data in your
logbooks, and document all experiments and interpretation of the experimental data as
well.
Step 3: Prepare a report of your findings, along with an interpretation of your results.
Step 4: Use the findings from your experiments and your report findings to make
improvements to your design.
Analysis and Synthesis
During an engineering design, you will undoubtedly encounter a number of problems need to be
resolved. Attacking each problem in a methodical fashion will allow you to be more productive
individually, and to communicate the results of your analysis more readily to the other members
of your design team. You will commonly iterate between synthesis and analysis during your
design. The engineering problem solving method presented here is a reasonable template for
28

29. solving problems ranging from a classwork­problem to a large­scale analysis in support of an
industrial design.
Stage 1. Problem Statement
Before solving a problem, you must state clearly and concisely the problem that you have been
tasked to solve. Think of the problem statement as if you were writing your own homework
assignment.
Stage 2. Summarize Known Information
During this stage of the analysis, you gather historical information, and relevant facts pertinent to
your design. Sometimes, the known information comes directly from the problem statement.
More commonly, the known information is taken from reference materials, supplier data sheet,
material property database, and things of that nature.
Stage 3. Summarize Desired Information
Unlike the problem statement, which sets forward a strategic goal, the list of desired information
consists of a series of tactical tasks that must be accomplished in order to achieve the full
solution.
Stage 4. Assumptions
We need to list the basic assumptions and constraints under which our analysis will proceed. For
example, if we make the assumption of one dimensional heat transfer, we would list that
assumption at this point in the design document, and identify whether it is a conservative or a
non­conservative assumption. Further, we need to support the validity of our assumptions, or
note that the validity remains to be determined.
Stage 5. Schematic and Given Data
In this stage, we gather drawings, sketches, and numerical data to support our design. This is
where we deal with instrumentation issue, gathering property information, and things of that
nature. This step becomes rather voluminous. You may gather the data in a spreadsheet format.
29

30. Stage 6. Analysis
This is the stage where we get into the essence of the problem. If you developed a mathematical
model for your problem, you recall the governing equations of physics that apply to the problem.
Then you substitute the known information, apply the simplifying assumptions, and solve for the
unknowns.
Stage 7. Review results
Before we make any judgments about a design, we must convince ourselves that the analysis
performed was reasonable and accurate. After you have completed an analysis, have an
independent member of your design team check your problem statement, known information,
desired data, your sketches, your assumptions and their justification, and your solution. Stand
back together and confirm whether your answers appear reasonable and have the proper units.
Stage 8. Synthesis
Use the findings from your analysis to revise the underlying design of your product, device, or
system. Many times, the solution you develop from the analysis will require you to revise your
drawings. Sometime, you can fundamentally simplify the design concept based on your
findings. On other occasions, your detailed analysis findings may lead you to the conclusion that
you need to rethink your design at a more basic level.
30

31. Facet 6: Analysis & Synthesis
Engineering Model
Two testing plans were developed for our current system. Through these tests, we hoped to test
the individual performance and capabilities to obtain a baseline of operations. The two test plans
were Solar Panel Testing (input system) and Battery/Coil Testing (energy storage/output
system).
Battery Testing
Battery testing follows the following test plan developed by the group. It served the purposes of:
A. Discovering if our system is capable of bringing water up to temperature.
B. Discovering if our battery contained enough energy to bring the water to temperature.
C. Discover how many boiling cycles our battery system is capable of producing on a single
full charge.
D. Eventual further analysis of fatigue of battery and performance after multiple uses and
recharges.
➢ Introduction
This test is in support of a capstone group investigating the feasibility of an electric backpacking
stove. The system will include a resistance heater powered by a battery which will be used to
boil water for use in rehydrated meals or hot drinks. The battery will be recharged through one
or more methods during the day. Possibilities under consideration include solar, piezoelectric
energy harvesters, thermoelectric energy harvesters and a hydroelectric turbine.
At this stage of development it is important for us to show that we are capable of boiling water
using a battery without undue heating of the battery prior to devoting too much time to
recharging options. Our research has led us to choose a lithium polymer battery for its
combination of high energy capacity and lightweight. Additionally, lithium polymer batteries
have C ratings high enough to allow us to theoretically boil water within a reasonable amount of
time. C ratings refer to the rate at which energy may be safely drawn from the battery. For the
purpose of testing we are using a heavier cheaper battery with the same C rating as the batteries
we are considering for use in the final product. The resistor will be made from Nickel
Chromium which provides a very high resistivity relative to copper. This allows the system to
31

32. generate much more resistive heat in the resistance coil than it does in the wires connecting the
coil to the battery.
➢ Test Objective
The objective of this test is to validate the Capstone Group’s design in its ability to boil water
using power supplied by a battery. Additionally, this test will provide us with data to establish
correlations between our calculations and what we can expect in applications. Specifically, this
test will provide us with correlations between power output of the system and boil times, which
will allow us to account for heat loss during the boiling process. We will also be able to
establish a correlation between battery capacity and how much of that energy we are able to
transfer to water. This will give us a total efficiency of our system.
➢ Mathematical Model
:Power
:Current
: Resistance
: Resistivity
: Length of wire
: Cross sectional area of wire
➢ Materials:
○ 1 LiPo Battery
○ 1 Resistance Coil
○ 1 backpacking pot minimum volume of 1L
○ 1 insulated container minimum volume of 4L
○ Something to mix water in insulated container
32

33. ○ 2 leads of copper wire (gauge to be determined)
➢ Test Procedure
1. Instrument boiling pot with Thermocouples (orientation to be determined when we know
how many thermocouples we will have)
2. Fill pot with 1L of water
3. Immerse resistance coil in water, avoid contact with sides or bottom of container
4. Place 1 thermocouple at center of resistance coil
5. Place 1 thermocouple between resistance coil and wall of container
6. Start recording Thermocouple data
7. Start timer and connect leads to battery
8. Monitor battery temperature, disconnect leads if battery temperature reaches 60C
9. When water reaches rolling boil, stop time and disconnect battery lead.
10. Save Thermocouple data to a flash drive as “Test_1_Boil_Data.xls”
11. Wait until resistance coil has cooled to below 30C
12. Fill an insulated container with 4 L of water
13. Immerse resistance coil in water, avoid contact with sides or bottom of container
14. Place 1 thermocouple at center of resistance coil
15. Place 1 thermocouple between resistance coil and wall of container
16. Start recording Thermocouple data
17. Start timer and connect leads of battery
18. Monitor voltage at battery leads, when voltage drops below 10.8V disconnect leads and
stop timer
19. Save Thermocouple data to flash drive as “Test_1_SpecificHeat_Data_xls”
33

34. ➢ Analysis:
1. For boil data, calculate:
a. Time to boil
b. Efficiency
2. For specific heat, calculate:
a. Actual Capacity/Advertised Capacity
Test Setup
Materials Used:
➢ MSR Stainless Steel Pot
○ 7 inch Diameter
○ 3 inch Deep
○ 115.5 in^3 Volume
➢ Battery Pack
○ 4 3.38V LIFePO4 Battery Cells
○ 1 Circuit Discharge Controller
○ 10 Gage Copper Wire
○ Custom Foam Board Battery Case
➢ NiChrome Wire
○ 1ft Coil
■ Measured Resistance: 4.5 Ohms
■ Calculated Resistance: 2.25 Ohms
○ 2ft Hex Coil
■ Measured Resistance: 9 Ohms
■ Calculated Resistance: 4.5 Ohms
➢ 1 Liter Tap Water
Upon arrival at the designated lab space, a class was underway where the test was to take place.
Arthur spoke with Dr. Ben Ayed and the test was moved to the lab next door. This required the
computer with the thermocouple software to be moved to the new testing room. Despite
repeated attempts, the supervising TA, Arthur and Reese were unable to log on to the computer.
As an alternative, we used the the multimeter with a single thermocouple.
A NiChrome coil was prepared prior to testing based on the resistivity and dimensional qualities
of the wire. When the resistance was measured using two separate multi­meters, the resistance
34

35. came in at 9 Ohms, nearly twice the designed resistance. As a result, an alternative resistor was
made using one foot of excess NiChrome Wire.
Test Procedure and Observations
Iteration 1
1. The MSR Pot was filled with 1 Liter of water and the 1 foot resistor was attached to the
battery pack with the switch in the “OFF” position. The resistor was positioned in the pot
such that no part was touching the bottom or sides of the pot and all but approximately 1”
of the coil was submerged in the water.
2. The Thermocouple was placed near the center of the coil, care was taken to prevent any
part of the thermocouple from touching any part of the resistance coil.
3. The multi meter was attached to the battery pack and set to read the voltage.
4. The switch was set to the “ON” position and timer was started.
5. Temperature and Voltage readings were recorded manually every 30 seconds.
6. Localized vaporization was visible on one pole of the coil in addition to the portion of the
NiChrome wire which was not submerged turning red immediately upon start up.
7. After several seconds the wire started turning back to silver and bubbles stopped,
seeming to indicate current had stopped flowing.
8. Some time later (exact time not known) the wire showed color and vaporization evidence
of heating up again, eventually breaking at the portion not submerged.
9. The switch was turned to the off position
10. No increase in water temp was recorded over the one minute duration of the test
Iteration 2
1. The resistance wire was replaced with the original 2 foot hexagonal version.
2. Resistance wire and thermocouple were repositioned in order to have no contact with the
pot or each other.
3. Alligator clips and a portion of the copper wire were submerged in order to eliminate any
of the NiChrome wire being out of the water.
35

36. 4. The switch was turned back to the “ON” position, temperature and voltage readings were
recorded every 30 seconds.
5. Again localized vaporization was immediately evident and temperature began to rise a
measurable amount.
6. Water became yellowish in color, with some foam after several minutes, exact time not
noted.
7. Initial thermocouple began reading temperatures above 218F and was replaced, readings
away from coil with new thermocouple showed 180F
8. After 40 minutes water was still not boiling, fairly uniform temperature of 188 was
recorded. Test was stopped.
9. Upon closer inspection, alligator clip no longer has chrome like finish but appears to be
made up of copper. Uncertain as to whether copper has plated the clip or the finish has
corroded leaving copper exposed.
10. Resistor is coated with some kind of yellowish dull substance, unsure what origin of
substance is.
11. Battery pack remains cool to the touch throughout both iterations
12. Insulated container testing was not conducted due to failure of first test.
36

37.
➢ Analysis
Figure 1: Temperature and Voltage vs. Time
It is to be concluded that heat transfer to water is insufficient with the current heating element
design. Localized heating in addition to steam demonstrate heat addition to the system is
occurring; however, heat losses to environment may have been underestimated. Temperature of
the system continues to gradually increase, but net energy into the system is much to low in order
to achieve a sufficient boil time. Increasing current closer to batteries capability may be
required. This will also require either creating a new discharge control or conduct a test without
one. Additionally, it may be necessary to examine alternate coil implementations in order to heat
the water more effectively.
Material Concerns:
Discoloration of water is a serious concern for the viability of the immersion coil. Further
research must be done to identify the source of the discoloration and methods to shield the water
from this source. Any shielding used for the NiChrome must also be capable of keeping the wire
cool enough to prevent melting.
37

38.
➢ Results
Our original setup had multiple thermocouples that would be hooked up to the lab computer
program to record multiple temperatures throughout the water in the pot. However, due to
complications with the computer, we were only able to use one thermocouple using a voltmeter.
Because we were using a voltmeter to read the temperature, we are not entirely sure that the
readings were accurate.
After 15 minutes, the voltmeter failed causing us to have a lapse in temperature readings. We
were able to acquire a new j­type that could give us more accurate readings. At this point, we had
been running this experiment for almost 30 minutes and the water was not boiling yet. We
decided to try to just get the water to boil, since we were over the optimal time range in which
we wanted the water to boil. At 41 minutes, we stopped the experiment, even though the water
was not boiling.
Another problem that arose from this experiment was that the water started to turn yellow and
smelled of burnt plastic. After taking the coil out of the water and examining the battery leads
and coil, we suspect we actually copper­plated the alligator clip through ionization of the copper
in the wires from the battery. Only the positive end was plated; the negative end was able to be
wiped clean and the coil was also dirtied. Because the water most likely had copper mixed in,
this could affect the boiling temperature of the water.
Figure 2: Alligator Clip Figure 3: Coil
38

39.
Figure 4: Experiment After Testing Was Complete
We did have some good results that we can take from this experiment. The battery itself did not
heat up, which we were worried would be a problem. The voltage from the battery was also very
consistent staying at 12.6 for most of the test and dropping to 12.4 towards the end over a 41
minute time span. Another valuable lesson we learned was that the leads from the batteries had
to be connected to the nichrome as close to the water as possible; otherwise, the current will melt
the wire.
➢ Analysis and Synthesis
We observed that we need to create better insulation for the wires on the battery lead to prevent
ionization of copper. We also need to be able to boil water in a reasonable time.
The positive lead had exposed wire that was in the water. There was also localized boiling near
the coil in the water.
We found that we need to obtain shrink tubing or another material to crimp over exposed wire
securely. To get the water to boil and boil in a reasonable time, we will need to test different
lengths of wire to change the resistance. This is the easiest fix. If this does not work, we will
have to rework the battery either by getting more cells, adding weight or wiring it differently to
gain more power.
We are assuming that the copper is the only material ionizing and not the the metal from the
alligator clips of the nichrome wire. This is a conservative assumption. The validity of this
assumption is well backed because of the color of the water and the color of the alligator clip.
39

40. The other alligator clip and the nichrome wire are easily cleanable, showing no signs of actual
damage; however, the validity could still be determined if this problem continues.
The boiling of the water could be prevented from the copper that is ionized in the water. We are
assuming that it is changing the boiling temperature of the water and that is why we are only
getting localized boiling.
40

41. Solar Cell Testing:
Engineering Model
➢ Introduction & Background
There were a few elementary principles of engineering that were applied to the setup and testing.
First, during the construction of the solar panels, it was critical to determine whether to increase
the systems amperage outputs or its voltage. Since we had only ordered ten panels, and had
determined to place the panels at three different angles, nine of the ten panels would be used
during testing. The other panel would be kept as a spare so that if any panel were broken it could
be repaired.
Since we had only a few panels to work with, we determined that placing the panels in series
would be the most beneficial system. Using Ohm's Law applied to a circuit in series, we knew
that if we were to wire our cells in series, this would increase our voltage output. Although, since
we only had nine cells and each would output a maximum of 0.5 volts, we would only have a
total of 4.5 volts total in our system. The battery that was selected was rated for an output of
twelve volts. Thus, our testing would have to be to scale. So the amount of panels that were
required to even charge the battery to full capacity would need to be three times that of what we
had wired in series.
Figure 5: Capacitor in Series
Since Ohm’s Law states that the cells that are wired in series would represent a linear increase in
voltage, it can be assumed that to increase the voltage of the system, one would simply need to
multiply the number of cells by the required factor to increase the voltage to a useable level.
The solar panel testing was designed to generate initial data and findings of power output from a
limited number of solar cells. This testing was much less complex than that of the battery/coil
tests. We have simply oriented the cells at different angles/orientations to the sun. The testing
apparatus will remain stationary during testing. The voltage and current of each cells will be
recorded throughout the course of an allotted time period. We hope the test gives resourceful
data simulating the cell’s reaction to the movement of the sun throughout the day (trip). This
testing can be related to how many solar cells are going to be necessary to provide the power to
our battery. Testing apparatus and procedure are as follows:
41

42. ➢ Materials/Apparatus:
1. Solar Panel Electrical Setup Kit
2. Solar Panel 10x
3. 4’x8’x1/4” OSB Sheet
4. Screws
5. 7A Fuse
6. 2x4x10
7. Spray adhesive
These materials were assembled in such a way to mimic certain orientations that the backpacker
might use during operation.
Figure 6: Solar Panel Testing Apparatus
➢ Test Procedure:
1. Cut three OSB panels 15”x6”
2. Frame panels with 2x4
42

43. 3. Orient boards 115 degrees end to end to construct a trapezoid
4. Spray adhere 3 solar panels to each of the osb panels
5. Solder panels together in series
6. Solder connection wires to be used in power measurements to complete each circuit for
the entirety of the array as well as each individual panel
7. Orient solar panel array from east to west.
8. Testing the entire array:
a. Connect two multimeters to the test leads
b. Testing time is from 9 a.m. to 3 p.m.
c. Take measurements of both amperage and voltage every thirty minutes
9. Testing individual panels:
10. Repeat steps 8 a­c
Testing will follow this plan strictly. We hope to obtain data relating to the amount of power
output from the system. Obviously, the energy output is proportional to the sun’s position. This
means that the individual cells that are closer to perpendicular to the sun’s angle will have a
greater power output. (Measurement will be performed using a multimeter.)
➢ Results
After assembling and testing the solar cell array, we feel that the testing provided satisfactory
results. There was an incident of a broken solar panel that happened towards the end of testing.
While attempting to remove the alligator clip from the buss wire while detaching the
multi­meter, one of the cells was shattered. Because this happened at the end of testing, we
believe the data to still be relevant and valuable. The continuity of the system was not
compromised, so the broken cell was positioned to be one of the three sides in the shade. This
breakage of the panel did not appear to affect the results seeing how consistent the results
remained even with the broken cell still attached. The reason the 10​th​
cell was not used to repair
this while testing is during the initial assembly an additional cell was destroyed due to their
fragility. We expect that more cells will be needed to be a usable method of recharge for our
system. The obtained results are as follows:
43

44.
Figure 7: Testing Results
Figure 7 illustrates the different output parameters of the system throughout the day. We feel that
the output of the tested system is below what would be necessary for practical use. However, as
stated earlier, this was to be expected to due the limited number of cells and the sizing of these
cells. The main concern is the current of the system, as this will produce a very slow charge
going into the battery. We believe that this performance can be improved by adding additional
cells, improving orientation and improving wiring schematic between the cells. This testing will
provide us with a means to determine the actual amount of cells required to charge our battery.
Of course, this is based off of our experimental data that replicates a non­ideal charging scenario.
This was done to replicate a real life situation while backpacking because one would not be able
to adequately traverse mountainous terrain while keeping their power supply pointed directly at
the sun. We hope to utilize a movable arrangement on the system so that the user may orient the
solar cells in the best position available in order to maximize energy input. Furthermore, a
protective covering or case for the cells could be implemented the next time to avoid
44

45. unnecessary damage to the cells. It would not be viable to carry such a fragile setup in as harsh a
condition as the modern backpacker would.
Additional questions were created during the testing of our device that had not been accounted
for prior to this experiment, such as how to keep the cells from being destroyed in a harsh
environment due to exposure to water, or even impacts. These forces would most likely reduce
the performance of the array, or even destroy its ability to charge the battery all together. An
additional thought would be to use a more efficient panel and exchange cost for performance.
This would reduce the amount of surface area that would have to be covered by the panels. The
less weight, lower surface area, and the gains in efficiency could create a better and more reliable
product. The next step would be to develop a system to be used by the hiker during trips. The
wooden apparatus is much too heavy to expect a person to carry it around for an extended
amount of time.
Analysis and Synthesis
We seek to find a viable source of energy in order to recharge our battery while in the wilderness
(away from common energy sources). This source must be easily attainable for any user to obtain
or make use of.
Smaller solar panels produce around 5­7 Watts per cell (according to producer information). This
provides a viable option of recharge granted that you do not need to replenish the entire battery’s
charge in one trek. We simply seek to replenish the energy used from the previous boil cycle.
From analyzing different methods of energy production, we have determined that solar power
would be the most feasible option. This was due to the fact that the system requires the user to do
little more than carry the solar panels while hiking. This would have to be done by any system in
question without the advantage of the input system working without further human interaction.
Cells would be arranged on a sort of sun­shade that would rest either on the user’s backpack or
above the user’s head which would provide shade to the user as well. In order to accomplish this,
a lightweight suspension system will be needed in order to support the solar cells. This will act
much like a comfortable top of an automobile which has the ability to collapse.
For the design of the solar cell system we desire the following goals/needs to be met:
­ Lightweight: An overall weight of 3 pounds
­ Adequate energy production: Ability to replenish at least one cycle’s use of energy
­ Safety: System is completely safe for users purposes over the entire lifespan of the
product.
45

46. For the beginning baseline of our project, the ability to remain lightweight and produce adequate
power are really the only desirable traits/information at this point in time.
This early in the design process we have yet to explore designs for the entire input system. We
seek the validation that the solar energy will work in practice before designing a complete
system to be relied upon. ​The average efficiency of the solar panels was 30.51%, which is quite
inefficient since the numbers that we were comparing to was an average of the power output of
the cells as advertised, and not a maximum value. Overall, this was still an excellent experiment
and can and will be used in determining the total number of panels that will be used in the future.
We may need to look into trading cost for performance to achieve better results. Further on
during the design process, we can explore reducing system cost after a successful system is
produced. ​Since this was a first semester project, the group put intensive focus on validating
system choices. Next semester, we plan on intensifying efforts into integrating system
components and further exploring viable options for physical prototypical designs. As seen from
the presented data we need to increase power output from the cells. This requires a larger surface
of cells.These limitations are based on the product that we have chosen to go with, we believe
that with enough cells, we will be able to achieve the goal of a viable recharge. We will not be
able to physically determine if the battery and power input subsystems will interact properly until
testing next semester. Further research and tuning is required before energy input system is fully
approved for use; however, we feel that we are on the correct path to success given the current
tests.
46

47. Weekly Progress Report #1
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #1
Date: February 10, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 02/03/16 and 02/10/16
▪ Meeting Attendees: ​Reese Myers, Arthur Cox, Sandra Zimmerman, Austin Ayers,
Damon Alfaro, Marcus Fluitt, Aaron Harrison, Benjamin Nelson
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group​:
▪ Established roles: Reese­ lead engineer, Arthur­ team leader, Sandra­
documentation leader
▪ Established system requirements
▪ Delegated research for system components, agreed to discuss methods of
fulfilling system requirements.
▪ Problems encountered: how to recharge our battery portably
▪ Compared individual research results
▪ Individually
▪ Solar panel research: Aaron and Marcus
● Will be a problem if the backpacker does not have access to sunlight.
▪ Crank research: Austin
● Does not provide a sufficient amount of energy for power our stove
▪ Energy harvesting research: Sandra
● It is a decent source for power but needs to be paired with another
method to get enough power for our stove
▪ Calculations: Reese
47

48. ▪ Types of batteries research: Arthur, Damon, Ben
WHAT WE ARE DOING NOW
▪ As group & individually
▪ Planning this week’s individual duties.
● Research methods for heat transfer: Reese and Marcus
● Battery research: Damon and Ben
● Solar research: Aaron and Austin
● More energy harvesting methods: Sandra and Arthur
WHAT WE NEED TO DO NEXT
▪ Schedule meetings for every Wednesday at 2:30 pm
▪ Find an advisor: maybe Dr. Abdelkefi??
▪ Research methods of heat transfer, batteries, solar energy and energy harvesting
▪ Budget
▪ Do more calculations
48

49. Weekly Progress Report #2
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #2
Date: February 17, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 2/17/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group​:
▪ met with our new advisor, Dr. Abdelkefi
● attendees: Reese Myers, Sandra Zimmerman, Arthur Cox, and Benjamin
Nelson
▪ discussed the possibility of using a hybrid energy harvester such as combining
piezoelectric, thermoelectric and solar
▪ meeting minutes (attached below)
▪ discussed individual work
▪ Individually​:
▪ Aaron and Austin:
● Solar panel options:
o 2.5 W per cell (40 cells weigh 15.2 oz)
o 2.8 W per cell (10 cells weigh 2.2 lb)
o Considering about 5 hours of direct sunlight a day, we can
produce 26.8 W
● Calculated possible coil/solar options
▪ Damon and Ben:
49

50. ● Batteries:
o 15 oz Li­Ion Battery 10Ah can charge 40A
o Poly Li­Ion 10Ah, energy density: 170 wh/kg, weighs: 2.15
kg
o Lithium Iron Phosphate 16V 20Ah­ has 100% voltage until
it dies
▪ Marcus and Reese:
● Heat transfer method:
o Ruling out induction
o Possible options:
▪ immersion coil­ conducts straight to water, any pot
material will work, remove a layer of resistance,
compact size
▪ wrapping coil­ no lid problems, would enable a lot
of surface area for heat conduction
▪ electric burner­ no lid problems, would enable
cooking eggs again
▪ Sandra and Arthur:
● Energy harvesting:
o Thermoelectric (converting heat energy into electricity)
▪ Requires low temp side and a high temp side
▪ Can cool the low temp side with water or air (we
would use air)
▪ Products already using thermoelectric generators:
woods stoves
▪ Benefit: can recycle the energy lost as heat
o Electromagnetic transducer:
▪ Can produce 300*10^­6 W to 2.5mW per step
(varies depending on weight)
▪ Where to place it (i.e. backpack, sleeve)
50

51. WHAT WE ARE DOING NOW
▪ As group & individually: ​Working on resolving problems due to the high input of
power the stove requires. We’ve determined that energy harvesting and solar panels
cannot power the device alone, so we are working on doing some kind of hybrid of
energy harvesting and solar panels. Before we can determine what the hybrid should
consist of, we need to isolate each harvester/solar panel to figure out it’s individual pros
and cons.
WHAT WE NEED TO DO NEXT
▪ Set a consistent meeting time with Dr. Abdelkefi
▪ Work on our individual research:
▪ Aaron and Austin: Figure out the number of solar cells we need and
wattage per pound of each cell
▪ Damon and Ben: Look at specific battery packs that will hit 700 W to boil
water in 10 min (pay attention to volts and amps)
▪ Sandra and Arthur: Determine numbers for watt output, cost and weight
▪ Reese and Marcus: Look at resistors and what materials to use
▪ Figure out prices and weight for battery and energy harvester/solar panel
51

52. Weekly Progress Report #3
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #3
Date: February 24, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 2/24/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed Dr. Abdelkefi’s suggestions:
● Start with boiling water off of a battery
● Figure out resistance coil
● How many ounces of water the battery can boil
● All of the above will give us a better idea of efficiencies
● Deploy more people towards figuring out coil
▪ Discussed individual work
▪ Individually
▪ Aaron/Austin:
● Solar panel:
o Need 33.6 W per day for solar
o 5 hours of sunlight gives us 484000 J (energy stored)
o Went over possible solar panel options
● DC Immersion coil: 12 V 60 W
52

53. o 11 min till boil
▪ Damon/Ben:
● Batteries:
o 420 WH for three days
o To recharge battery with one day’s sunlight using solar:
33.6W
o Lightest option:
▪ Weight for 7 batteries: 3.57 lb
▪ cost: $244.65
▪ Marcus/Reese:
● Maximizing Power Transform Theorem:
o to get maximum power from a given volt source the
resistance of what you are powering should match the
resistance of the volt source
o Internal resistance heats up the battery
o Can play with our range of resistance
● Immersion coils:
o Do­able
▪ Sandra/Arthur:
● Energy harvesting:
o Thermoelectric:
▪ Possible options:
● Thermoelectric Power Generation Generator
50x50 mm Tile Max Load
o Weight: 1.6 oz
o Price: $29.99
● 40 * 40mm Thermoelectric Power Generator
High Temperature
o Weight:
o Price: $7.99
o Piezoelectric:
▪ Possible options:
● Piezo Ceramic Generator 40x11x1.7 mm
53

54. o $19.00 for 2
● Possibly use a pressure cooker??? More to come.
WHAT WE ARE DOING NOW
▪ As group & individually: ​We are working on narrowing down our possibilities for the
battery and the hybrid energy harvester. So far, we’ve laid out the pros and cons to each
energy harvester:
▪ The piezo is cheap and doesn’t add any weight to our device.
▪ The electromagnetic would add weight, but it isn’t too expensive.
▪ The thermoelectric generator is great because we can recycle the heat that the
stove produces to power the stove.
▪ The solar panels produce the most energy, but can be pricey.
WHAT WE NEED TO DO NEXT
▪ Prepare one PowerPoint slide for each subgroup’s conclusions because our
advisor wants us to be organized.
▪ Work on our sub­group research:
▪ Aaron and Austin: Double check energy requirements
▪ Damon and Ben: Look at resistance stuff­ internal resistance, wattage
output
▪ Sandra and Arthur: figure out power output for thermoelectric, figure out
whether piezo or electromagnetic is better
▪ Reese and Marcus: Also look at resistance stuff­ internal resistance,
wattage output
54

55. Weekly Progress Report #4
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #4
Date: March 2, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 3/2/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed Dr. Abdelkefi meeting:
● Doing a hybrid system will complicate the circuitry
● Where will we place each system?
▪ Discussed individual work
▪ Individually
▪ Aaron/Austin:
● Solar panel:
o Checked calculations
o Max power of sun we can get without requiring the
customer to worry about aiming his backpack toward the
direction of sunlight.
▪ Damon/Ben:
● Batteries:
o Narrowed down batteries
o Calculated power requirements
▪ Marcus/Reese:
55

56. ● Resistance:
o Maximize current
o Resistance is dictated by battery pack voltage
o Coil length and form can be optimized
o High amperage produces more heat
▪ Sandra/Arthur:
● Energy harvesting:
o Find piezo less than 100 Hz
o 8 hours where the customer isn’t generating energy from
sunlight or walking
▪ Use a turbine during that downtime
● power it using the creek’s water motion
WHAT WE ARE DOING NOW
▪ As group & individually: ​We are working on how to be more efficient with our
research. We have set goals to be met by the start of spring break:
▪ Create a decision matrix:
● Do we have knowledge or resources, cost, feasibility, human factor
and weight?
▪ Talk with Dr. Tom Jenkins for solar panel stuff
WHAT WE NEED TO DO NEXT
▪ Maximize current, make a test plan, write a proposal, order parts
▪ Form new groups:
▪ Recharge research:
● Sandra, Arthur, and Aaron
o Combine solar with energy harvesting, isolate 2 or 3
systems to use for our hybrid
o Calculate how much energy we are going to generate for
the average person
▪ Testing schematic/Test scaling:
● Ben, Marcus and Damon
o Work on circuitry diagrams, draw a sketch for the boiling
water component of our project, handle budget and
feasibility, and consider what the customer wants
▪ Test plan:
● Austin and Reese
o Work on apparatus​, ​procedures, etc.
56

57. Weekly Progress Report #5
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #5
Date: March 9, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 3/9/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed Dr. Abdelkefi meeting:
● Need to talk with Dr. Ayed for lab testing.
● We need to test thermocouples to determine if the thermoelectric
generator will work
▪ Discussed subgroup work
▪ Individually
▪ Austin/Reese: Test Plan
● Wrote out the objective (shown in meeting minutes)
● Wrote out the test procedure (shown in meeting minutes)
● Set up the analysis (still in progress)
▪ Ben/Marcus/Damon: Testing Schematic/Test Scaling
● Determined requirements for current using different gages of wire
● Looked up different sets of batteries based of the calculations
● More current, more output
▪ Arthur/Sandra/Aaron: Recharge Research
57

58. ● Decision Matrix: Solar panel ended up with the highest total
● Hydro/Wind Turbine: Still looking at it as a possibility
o Rio Grande stream velocity: 12 ft/min
WHAT WE ARE DOING NOW
▪ As group & individually: ​We have set goals to be met by the Wednesday after spring
break:
▪ Finish most of the theoretical research
▪ Start testing the battery, the time it takes the water to boil, and the
thermoelectric generator
WHAT WE NEED TO DO NEXT
▪ Maximize current, make a test plan, write a proposal, order parts
▪ Subgroups:
▪ Recharge research: (Sandra, Arthur, Ben and Aaron)
● Hydro/Wind Turbine: Find torque required and energy that can be
captured from the wind and the water
● Solar energy:
o Flux
o Setup for panels
▪ Testing schematic/Test scaling: (Marcus and Damon)
● Compose drawings of the battery and the circuits
● Determine connection between the battery and the wire
▪ Test plan: (Austin and Reese)
● Create proposal and send out today
● Finish test plan
58

59. Weekly Progress Report #6
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #6
Date: March 30, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 3/23/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed subgroup work
▪ Discussed the opportunity to use Dr. Ayed’s lab to test the battery, the solar
panel and the thermoelectric generator.
● Details:
o Can only use it when one of her lab assistants is present.
o Need to write up a proposal on what we are doing and how we
are going to do it, and submit it to Dr. Garcia for approval.
▪ Individually
▪ Marcus/Damon/Reese/Austin: Testing components
● Submitted test plan for battery
▪ Arthur/Sandra/Aaron/Ben: Recharge research
● Decided that the wind/turbine is too expensive, large and heavy.
● Decided that the piezoelectric generator is too complex because we
would need to figure out how to change its AC voltage to DC.
59

60. WHAT WE ARE DOING NOW
▪ As group & individually: ​We have narrowed down our recharge components from
piezoelectric, wind/water turbine, thermoelectric generator, and solar panel to
thermoelectric generator and solar panel.
▪ The solar panel will be our main source of energy recharge
WHAT WE NEED TO DO NEXT
▪ Documentation for PDR: (Sandra, Reese, and Ben)
▪ Take the work we’ve already done and organize it for presentation
▪ Test plan/Testing schematic/Test scaling: (Austin, Damon, Marcus, Arthur and
Aaron)
▪ Proceed with solar panel test plan
60

61. Weekly Progress Report #7
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #7
Date: April 6, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 3/30/16
▪ Meeting attendees: ​Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,
Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed PDR session
● Dr. Pines feedback:
o Start working on binder
o Increase our budget to $500—don’t worry too much about
money
▪ Discussed solar panel test plan
▪ Individually
▪ Austin, Damon, Marcus, Arthur and Aaron
● Solar panel testing:
o Place the solar panel cells in trapezoid to insure we get the
angle of sun at all times of the day
61

62. WHAT WE ARE DOING NOW
▪ As group & individually:
▪ We are submitting our solar panel test plan
▪ We are planning to move forward with the battery testing, but first Arthur
has to order parts.
WHAT WE NEED TO DO NEXT
▪ Work on facets 1­3
▪ Group 1: (Reese and Marcus)
● Write up facet 1
▪ Group 2: (Austin and Damon)
● Write up facet 2
▪ Group 3: (Sandra and Aaron)
● Write up facet 3
▪ Test plan/Testing schematic/Test scaling: (Arthur and Ben)
● Discuss battery prices
● Figure out what to order
62

63. Weekly Progress Report #8
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #8
Date: April 13, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 4/6/16
▪ Meeting attendees: ​Reese Myers, Austin Ayers, Benjamin Nelson, Aaron Harrison,
Sandra Zimmerman and Arthur Cox
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Discussed:
● Gantt Chart: (composed by Reese)
o To organize our next steps
o Steps include:
▪ Reserve testing location for battery and solar panel
▪ Build battery pack and solar test setup
▪ Perform battery test and solar panel test
▪ Individually
▪ Group 1: (Reese and Marcus)
● Finished facet 1
▪ Group 2: (Austin and Damon)
● Almost finished facet 2
▪ Group 3: (Sandra and Aaron)
63

64. ● Finished facet 3
WHAT WE ARE DOING NOW
▪ As group & individually:
▪ Arthur is ordering parts and scheduling a time to use the lab for battery
testing
▪ Waiting to test our battery
WHAT WE NEED TO DO NEXT
o Schedule the groups for testing:
▪ Subgroup work:
● Battery testing: Ben, Reese, and Damon
o Build the battery pack and perform the lab testing in a few
weeks
● Solar Panel testing: Austin, Aaron, and Marcus
o Set­up the frame and perform the solar panel test in a few
weeks
● Facet editing/composing: Sandra and Arthur
● Scheduling/ordering and purchasing parts: Arthur
64

65. Weekly Progress Report #9
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #9
Date: April 20, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 4/13/16
▪ Meeting attendees: ​Reese Myers, Damon Alfaro, Austin Ayers, Benjamin Nelson and
Sandra Zimmerman
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ How to go about building the battery
▪ Subgroup research
▪ Individually
▪ Battery testing: Ben, Reese, and Damon
● Waiting on ordered parts to come in
▪ Solar Panel testing: Austin, Aaron, and Marcus
● Waiting on ordered parts to come in
▪ Facet editing/composing: Sandra and Arthur
● Edited facet 3
WHAT WE ARE DOING NOW
▪ As group & individually:
▪ Reese is checking up on battery arrival
65

66. ▪ Reese is following up with Arthur on reserving battery testing space two
days after arrival
WHAT WE NEED TO DO NEXT
o Subgroup work:
▪ Battery testing: Ben, Reese, and Damon
● Still waiting on ordered components/lab space availability
● Need to solder outside of the lab
▪ Solar Panel testing: Austin
● Build frame for solar panel testing today
● Test is outside—do not need to reserve lab space
▪ Facet editing: Sandra and Arthur
● Need to edit Facets 1 and 2
▪ Taking care of ordered system components: Arthur
● Still in progress
▪ Composing facet 4: Aaron and Marcus
▪ Writing the intro and method section for final report: Sandra and Reese
66

67. Weekly Progress Report #10
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #10
Date: April 27, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
▪ 4/20/16
▪ Meeting attendees: ​Reese Myers, Damon Alfaro, Aaron Harrison, Marcus Fluitt,
Arthur Cox, Austin Ayers, Benjamin Nelson and Sandra Zimmerman
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
▪ As group
▪ Subgroup research
▪ Individually
▪ Arthur: scheduled lab testing for battery for Wednesday, April 27 in room 137
from 2:30 to 4:00 p.m.
▪ Aaron and Marcus
● Wrote facet 4
▪ Sandra:
● Wrote rough draft for methods section of final report
▪ Reese:
● Wrote rough draft for intro section of final report
WHAT WE ARE DOING NOW
▪ As group & individually:
▪ Fixing the battery for testing
▪ Composing the binder
67

68.
WHAT WE NEED TO DO NEXT
o Subgroup work:
▪ Battery testing: Ben, Reese, and Damon
● Sign liability form
● Find out how to coil
● Determine length of wire
● Test resistance with a multimeter
▪ Solar Panel testing: Austin
● Schedule tasks and testing
▪ Facet editing: Sandra and Arthur
● Complete facets 1, 2 and 4 edits
68

69. Weekly Progress Report #11
To: Dr. Park
From: Electric Backpacking Stove
Subject: Weekly progress report #11
Date: May 4, 2016
WHEN DID THE TEAM MEET AND WHO ATTENDED
● 4/27/16 and 5/4/16
● Meeting attendees: ​Reese Myers, Damon Alfaro, Aaron Harrison, Marcus Fluitt, Arthur Cox,
Austin Ayers, Benjamin Nelson and Sandra Zimmerman
WHAT OUR TEAM ACCOMPLISHED THIS WEEK
● Individually
○ Binder work:
■ Arthur and Sandra: facet 5
■ Marcus and Aaron: started facet 6
■ Austin: Solar panel testing report
■ Damon and Ben: Battery testing report
■ Reese: started final report
■ Sandra: put binder together
WHAT WE ARE DOING NOW
● As group & individually:
○ Finalizing binder
69

70. WHAT WE NEED TO DO NEXT
● Subgroup work:
○ Marcus and Aaron: finish facet 6
○ Reese and Ben: finish final report
○ Austin, Arthur and Damon: prepare PowerPoint for CDR
○ Sandra: finish editing binder
○ Arthur: get receipts from Kristen Torres
70