DesignReport

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

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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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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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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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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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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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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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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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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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 30th of 2016. If promised delivery dates persist, testing will be underway by April 15th 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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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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http://en.wikipedia.org/wiki/Chairman

http://en.wikipedia.org/wiki/Facilitator

http://en.wikipedia.org/w/index.php?title=Divergent_production&action=edit

http://en.wikipedia.org/wiki/Criticism

http://en.wikipedia.org/wiki/Groupthink

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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http://en.wikipedia.org/wiki/Association

http://en.wikipedia.org/wiki/Association

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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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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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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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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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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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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Energy Input Assessment:

Solar Power

Hand Crank

Piezo Electric

Water/Wind Turbine

Cost 7 6 4 4

Power Input

6 8 2 9

Weight/Size

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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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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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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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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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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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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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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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

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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

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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

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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.

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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.

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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

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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

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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





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”

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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

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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.

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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.

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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.

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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

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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.


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.

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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.

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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:

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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

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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 10th 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:

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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

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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.


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.

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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.

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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

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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

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To: Dr. Park





2/17/16 Meeting attendees: Reese Myers, Marcus Fluitt, Austin Ayers, Benjamin Nelson,

Aaron Harrison, Sandra Zimmerman, Damon Alfaro, and Arthur Cox


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:

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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)

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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.


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


To: Dr. Park








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

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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

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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.


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

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To: Dr. Park



Date: March 2, 2016





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.


o Narrowed down batteries o Calculated power requirements

Marcus/Reese:

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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


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


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.

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To: Dr. Park



Date: March 9, 2016





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

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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


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


To: Dr. Park



Date: March 30, 2016





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

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


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

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To: Dr. Park



Date: April 6, 2016





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

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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.


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

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To: Dr. Park



Date: April 13, 2016


4/6/16 Meeting attendees: Reese Myers, Austin Ayers, Benjamin Nelson, Aaron Harrison,

Sandra Zimmerman and Arthur Cox


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)

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Finished facet 3


Arthur is ordering parts and scheduling a time to use the lab for battery testing

Waiting to test our battery


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

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To: Dr. Park





4/13/16 Meeting attendees: Reese Myers, Damon Alfaro, Austin Ayers, Benjamin Nelson and

Sandra Zimmerman


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


Reese is checking up on battery arrival

65

Reese is following up with Arthur on reserving battery testing space two days after arrival


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

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To: Dr. Park





4/20/16 Meeting attendees: Reese Myers, Damon Alfaro, Aaron Harrison, Marcus Fluitt,

Arthur Cox, Austin Ayers, Benjamin Nelson and Sandra Zimmerman


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


Fixing the battery for testing Composing the binder

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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

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To: Dr. Park



Date: May 4, 2016


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


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

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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

Purchase Requisition & Ordering Information

71

72

73

74

75

76

77

78

Meeting Agenda

79

80

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Meeting Minutes 2/3/16 3:30 – 4:45 pm Attendees: Reese Myers, Arthur Cox, Ben Nelson, Sandra Zimmerman, Marcus Fluitt,

Austin Ayers, Damon Alfaro, Aaron Harrison

Established team roles and who would fulfill them.

Team Roles:

o Lead Engineer: Reese Myers Responsibilities: Accountable for final deliverable, delegation of work,

contributing team member o Team Lead: Arthur Cox

Responsibilities: Scheduling (Meetings and Project Center), Communication with Team, Purchasing

o Documentation: Sandra Zimmerman Responsibilities: Keeping Meeting Minutes, Emailing Progress report,

Accountable for binder.

Established system requirements.

Delegated research for system components, agreed to discuss methods of fulfilling system requirements.

Agreed on meeting Wednesday 2/10/2016 at 2:30, Arthur to investigate meeting locations

82

Meeting Minutes 2/10/16 2:30 – 3:15 pm Attendees: Reese Myers, Arthur Cox, Ben Nelson, Sandra Zimmerman, Marcus Fluitt,

Austin Ayers, Damon Alfaro, Aaron Harrison

Individual Research Results: Cranknot enough output Energy Harvesting5W Solarpower capacity exists, packaging less than ideal Batteries

Things to do: Heat Transfer Method Budget IP

Want: 60007000 mAH

Need: charge controller over 56 W

For 3day capacity: Harvesting and solar Battery capacity

New task assignments: Heat Transfer: Reese and Marcus Batteries: Damon and Ben Solar Energy: Aaron and Austin Energy Harvesting: Sandra and Arthur

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Meeting Minutes 2/17/16 3:30 4:30 pm Attendees: Reese Myers, Arthur Cox, Ben Nelson, Sandra Zimmerman, Marcus Fluitt,

Austin Ayers, Damon Alfaro, Aaron Harrison Discussed:

o Feedback from our new advisor: Dr. Abdelkefi o Individual research:

Aaron: 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 Damon:

Batteries: o 15 oz LiIon Battery 10Ah can charge 40A o Poly LiIon 10Ah, energy density: 170 wh/kg, weighs: 2.15

kg Ben:

Batteries: o Lithium Iron Phosphate 16V 20Ah has 100% voltage until

it dies Austin:

Solar panel: o Calculated possible coil/solar options

Marcus/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: Energy harvesting:

o Thermoelectric (converting heat energy into electricity) Requires low temp side and a high temp side

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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 Arthur:

Energy harvesting: 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)

Things to do: o Aaron and Austin: Figure out the number of solar cells we need and wattage per

pound of each cell o 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) o Sandra and Arthur: Determine numbers for watt output, cost and weight o Reese and Marcus: Look at resistors and what materials to use

85

Meeting Minutes 2/24/16 2:30 3:30 pm Attendees: Reese Myers, Arthur Cox, Ben Nelson, Sandra Zimmerman, Marcus Fluitt,

Austin Ayers, Damon Alfaro, Aaron Harrison Discussed:

o Feedback from Dr. Abdelkefi 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

o Individual research: 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 Solar panel 4:

.02375 lb per cell 105 W per lb need 13 panels area is 336 in^2

o Solar panel 5 .11 lb per cell 25 W per lb need 12 panels area is 300 in^2

DC Immersion coil: 12 V 60 W o 11 min till boil


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:

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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: more to come next meeting


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 o $19.00 for 2

o Electromagnetic transducer: No new info: more to come next meeting

o Possibly use pressure cooker??? Things to do:

o Prepare one PowerPoint slide for each subgroup’s conclusions o Aaron and Austin: Double check energy requirements o Damon and Ben: Look at resistance stuff internal resistance, wattage output o Sandra and Arthur: figure out power output for thermoelectric, figure out whether

piezo or electromagnetic is better o Reese and Marcus: Also look at resistance stuff internal resistance, wattage

output

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Meeting Minutes 3/2 2:303:30 pm Attendees: Benjamin Nelson, Aaron Harrison, Arthur Cox, Sandra Zimmerman, Austin

Ayers, Damon Alfaro, Reese Myers, and Marcus Fluitt Discussed:

o How do we get DC current from a generated AC current? o If we use multiple systems, how do we make the circuit? o How do we prevent one system from cancelling out another within the circuit? o How do we avoid burning out the battery when using multiple systems? o Need to focus on:

Maximize current Make a test plan Write a proposal Order parts

o Subgroup research: Marcus/Reese: resistance

Heating methods o Maximizing Current has a larger impact on power output

than maximizing Resistance o C values for chosen battery will limit our current o Resistance will be dictated by battery pack voltage and

maximizing current o Coil length and form can be optimized for the vessel,

hollow wire OD and ID can be fixed to establish final R o Wire diameter determines the amperage heating wire can

safely handle (given by AWG Standards) o Higher Amperage (current) will produce more heat

o Shaping Coil: Spiral or Coil Shaped Ben: batteries

Narrowed down batteries that fit the power requirements Aaron/Austin: solar panel

Checked calculations Deciding on how much sunlight a solar panel can generate if the

backpack is not always focused directly at the sun, as well as how much sunlight is in a day (taking into account clouds, under treetops, etc.)

o 45 hours of max power? Need 1014 solar panels

Arthur/Sandra: energy harvesting

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Need to find a piezoelectric transducer that uses less than 100 Hz because human motion is low frequency (varies depending on how fast walking, running, etc), so we need the transducer to match that frequency.

8 hours of downtime when we are not generating energy from energy harvesting and/or solar panels

Turbines using the creek’s water movement? o Can generate energy during downtime

Need to do next: o Form new groups:

Recharge research: (Sandra, Arthur, and Aaron) Combine solar with energy harvesting Isolate 2 or 3 systems How much energy we are going to generate Calculations for average person

Testing schematic/Test scaling: (Ben, Marcus and Damon) Circuitry diagrams Draw a sketch for the boiling water component of our project Budget Feasibility Consider what the customer wants Figure out if we can use fewer batteries or heavier batteries

Test plan: (Austin and Reese) Apparatus Procedures Etc.

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o Need to talk with Dr. Ayed for lab testing because she already has thermocouples set up

Thermocouples will help us determine if the thermoelectric generator will work

o Subgroup research: Austin/Reese: Test Plan

Test Objective: o The objective of this test is to validate the Capstone Groups

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.

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.

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11. Wait until resistance coil has cooled to below 30C 12. Fill an insulated container with _? 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”

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 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: 12ft/min Need to do next:

o Subgroup tasks: Recharge research: (Sandra, Arthur, Ben and Aaron)

Hydro/Wind Turbine: Find torque required to spin it and the energy we can capture from wind and water

Next steps on solar energy: o Flux o How to put the panels together?

Testing schematic/Test scaling: (Marcus and Damon) Compose some drawings of the battery and the circuits Determine connection from the battery to the wire

Test plan: (Austin and Reese) Create proposal and send out today Finish test plan

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o Waiting on approval for battery test plan o Arthur discussed with Dr. Ayed and Dr. Garcia to ask about using lab equipment

for testing the battery. We need to write out an excerpt about our test plan and what our project is

before we can use the lab. o Subgroup research:

Marcus/Damon/Reese/Austin: testing stuff Submitted test plan for battery

Arthur/Sandra/Aaron/Ben: Recharge research Ruled out piezoelectric and wind/water turbine

o Turbine would be too big, heavy and expensive o Piezo would be too complicated with wiring and converting

A/C power to D/C power Our final product will consist of a solar panel and a thermoelectric

generator to recharge our battery. o For our solar panel, we need to solder the cells together

Need to do next: o Subgroup work:

Documentation for PDR: (Sandra, Reese, and Ben) Take the work we’ve already done and organize it into presentation

Test plan/Testing schematic/Test scaling: (Austin, Damon, Marcus, Arthur and Aaron)

Proceed with solar panel test plan: o Need to know how to get the max amount of sun (think

about orientation)

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o Need to work on ordering solar panel parts for testing o Subgroup research:

PDR Documentation (Sandra, Reese, and Ben): Dr. Pines feedback:

o Start working on binder o Increased our budget to $500 o Don’t worry about money, so we should test with a better

battery Test Plan/Testing Schematic/Test Scaling: (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

Need to do next: o Arthur: Order parts o Subgroup work:

Test plan/Testing schematic/Test scaling: (Arthur and Ben) Discuss battery prices Submit solar panel test plan

Compose facet 1: (Reese and Marcus) Compose facet 2: (Austin and Damon) Compose facet 3: (Sandra and Aaron)

All facet groups will gather corresponding work from previous weeks and prepare it for the final binder

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Ayers, and Reese Myers Discussed:

o Gantt Chart: Reese composed a Gantt chart to organize our next steps These steps include:

Reserve testing location for battery and solar panel Build battery pack and solar test setup Perform battery test and solar panel test

o Subgroup research: Group 1: (Facet 1—Reese and Marcus) Group 2: (Facet 2—Austin and Damon) Group 3: (Facet 3—Sandra and Aaron)

Need to do next: o Arthur: Order parts and schedule a time to use the lab for battery testing o Schedule the groups for testing:

Subgroup work: Battery testing: Ben, Reese, and Damon

o Includes building the battery pack and testing in the lab Solar Panel testing: Austin, Aaron, and Marcus

o Includes setup and testing in the lab Facet editing/composing: Sandra and Arthur Scheduling/ordering and purchasing parts/handling money: Arthur

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Meeting Minutes 4/13 2:303:30 pm Attendees: Benjamin Nelson, Sandra Zimmerman, Austin Ayers, Damon Alfaro and

Reese Myers Discussed:

o How to go about building the battery o Subgroup research:

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

Need to do next: o Reese: Check on battery arrival and follow up with Arthur on reserving battery

testing space two days after arrival. o Subgroup work:

Battery testing: Ben, Reese, and Damon Still waiting on ordered components/lab space availability Need to solder outside of the lab Want bigger gage because less resistance

Solar Panel testing: Austin, Aaron, and Marcus Build frame for solar panel testing today Test is outside—do not need to reserve lab space

Facet editing: Sandra and Arthur Still in progress

Taking care of ordered system components: Arthur Still in progress

Composing facet 4: Aaron and Marcus Writing intro and method for final report: Sandra and Reese

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Meeting Minutes 4/20 2:303:30 pm Attendees: Benjamin Nelson, Aaron Harrison, Marcus Fluitt, Arthur Cox, Sandra

Zimmerman, Austin Ayers, Damon Alfaro and Reese Myers Discussed:

o Subgroup research: Battery testing: Ben, Reese and Damon

Lab testing scheduled for Wednesday, April 27 in room 137 from 2:30 to 4:00 pm

Aaron and Marcus: Wrote facet 4

Sandra: Wrote rough draft of the methods section of final report

Reese Wrote rough draft for the intro section of final report

Need to do next: o Subgroup research:

Facet editing/composing: Sandra and Arthur Need to complete 1, 2 and 4

Battery testing: (Ben, Reese and Damon) Testing team needs to sign liability form Ben:

o figure out how to coil o email Damon with the voltage and resistance that we want

Damon: o determine length of wire from Ben’s info o Test resistance with multimeter o make sure wire doesn’t short

Figure out how to make the wire Build battery by Monday, April 25

Solar Panel testing: (Austin, Aaron, and Marcus) Austin

o Schedule solar panel testing o Schedule tasks

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Meeting Minutes 4/27 2:304:00 pm Attendees: Benjamin Nelson, Damon Alfaro, Austin Ayers, Marcus Fluitt, Aaron

Harrison, Sandra Zimmerman, Arthur Cox and Reese Myers Accomplished:

o Performed the battery testing during the meeting o Had a meeting over email addressing the tasks that needed to be done to complete

the final binder o Solar panel setup complete

Need to do next: o Solar Panel testing: (Austin)

Scheduled for Saturday, April 30 o Design Binder:

Arthur: part of facet 5 specifically, bill of materials and supplier

identification Ben and Damon:

results, discussion and improvements for battery testing Austin:

results, discussion and improvements for solar testing Reese:

use Ben, Damon and Austin's info and compose final report Marcus and AJ:

part of facet 6 write up problem statement, known information, desired information (all of this is already basically written in the intro and methods section of the report) and analysis/assumptions (all calculations should be on the drive)

Sandra: finish facet 5 and facet 6, take pictures from our PDR review

PowerPoint slides and put them in the facets and final report, and put together binder for viewing on Monday, May 2nd

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Meeting Minutes 5/4 2:303:30 pm Attendees: Benjamin Nelson, Damon Alfaro, Austin Ayers, Marcus Fluitt, Aaron

Harrison, Sandra Zimmerman, Arthur Cox and Reese Myers Accomplished:

Completed solar panel testing Completed most of the binder components

Need to do next: Work on Design Binder Work on CDR presentation Facet 6 Gantt chart Work on final report Arthur: retrieve receipts from Kristen Torres

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Contact Log

Date Time Name Phone #/EMAIL Content of Conversation

2/22/2016 1:30 PM Dr. Abdelkefi [email protected] Meeting with advisor




3/21/2016 2:00 PM Dr. Park [email protected] Capstone funding


3/28/2016 4:45 PM Dr. Pines [email protected] PDR review

4/13/2016 2:30 PM Dr. Ben Ayed [email protected] Test room planning

4/17/2016 8:31 PM Dr. Ben Ayed [email protected] Test room planning

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Final Report Format

A formal technical report is written at the end of a project. Generally, it is a complete, standalone document aimed at persons having widely diverse backgrounds. Therefore, a detailed description of the project is required. The outline of a typical formal report is:

Title page

Summary (abstract): An abstract or summary should contain a brief overview of the report, including its conclusions and recommendations if there are any. A good length for an abstract is 300 words; some scientific journals actually specify this number of words explicitly. The abstract of a scientific paper or report is considered to be capable of `standing alone' and being published separately. For this reason the heading `abstract' in a report is usually not numbered. Numbering usually starts with the introduction.

Table of contents

Introduction: This section contains background to the work to acquaint reader with the problem and the purpose for carrying on the work)

Method: In the `method' section you should describe the way the work was carried out, what equipment you used, and any particular problems that had to be overcome.

Results: Results are usually given as plainly as possible, and without any comment. You should include enough data to enable to reader to be confident that you have done what you said you would do, and that your conclusions will be trustworthy.

Discussion: In this section the author provides an interpretation of the results, compares them with other published findings if there are any and points out any potential shortcomings in the work. In particular, if your findings are unusual, or very much at odds with other people's conclusions, you should explain why you think this might be. Otherwise the reader will probably assume you have just made a mistake.

Conclusion: The conclusion gives the overall findings of the study. It is important to realize that `conclusion' does not just mean `the last bit of the report'. Your conclusions should really be statements that can be concluded from the rest of the work.

Recommendations: In this section the author normally includes any advice he or she wishes to offer the reader. Some people use the recommendations sections for suggestions of further work.

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References and bibliography: The purpose of citing references is to allow the reader to follow up your work, and perhaps check that the conclusions you draw really follow from the sources you cite.

Appendices: The appendices are where the author will usually place any material that is not directly relevant to the report, and will only be read by small number of people. Appendices may be used for mathematical proofs, electrical circuit diagrams and sections of computer programs.

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Final Report

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

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Summary

The Electric Backpacking Stove Team has accomplished many of the goals set out for this semester. Design requirements for the system have been established. Research has been conducted to identify the best solutions to the design requirements, and initial rounds of testing have been completed in order to validate subsystems of the design. Initial testing identified multiple previously unknown issues, such as water contamination and underestimated heat loss to the atmosphere. An initial concern of battery heating was dismissed after observations made during testing. Additionally, expected results of underperforming solar cells were confirmed. Testing results will inform the next iteration of subsystem design, eventually leading to a prototype anticipated to be ready by the end of next semester. Additional research needs to be done to improve the net heat transfer to the system, to protect the water from contamination by the heating element, and to optimize solar panel efficiency. Additionally, system packing and design need to be developed as part of continuing efforts next semester.

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Table of contents

Introduction

Method

Results & Discussion

Conclusion

Recommendations

Appendices

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Introduction

Backpacking is a popular hobby in the US and around the world. In the United States alone, an estimated 38 million people had been backpacking in the last year according to a survey conducted during spring 2015. While some backpackers choose to carry and prepare raw foods, the vast majority utilize dehydrated meals which can be rehydrated for consumption with boiling water. These meals save weight, and enable backpackers to carry otherwise perishable foods such as meats and dairy products.

In order to provide the heat necessary to boil water, a variety of methods are currently utilized including gas stoves, chemical tablets, and wood fires. Many parks prohibit wood fires due to high traffic and/or fire concerns, and gas stoves and chemical tablets are both limited by fuel and require combustion which contributes greenhouse gases to the atmosphere. Our goal is to develop an electric stove which allows the user to boil water for rehydrating meals, is rechargeable to be viable for long trips and is light enough to be used as a substitute for stoves currently available on the market. In addition, being a viable substitute for current market options, our stove would be the only zero emission stove available.

During this semester, the team developed a set of requirements by which to design the stove, researched a wide variety of methods to fulfill these requirements and ultimately executed two separate tests in order to validate the ability of the design choices to fulfill the established design criteria. Although the tests did not result in the desired outcomes, they were valuable learning opportunities and the results did provide important feedback on which we can build next semester. The following report is a summary of the testing conducted and the information gathered as a result.

Method

Our group met weekly to discuss ideas, progress and next steps. If an idea was announced, that individual did his/her own research to offer the pros and cons, and then was examined by the rest of the group. The first several meetings were dedicated to identifying the requirements of the system we intended to design. After the requirements were established the team proceeded to research design solutions in order to meet the requirements established. Tools from class such as decision matrices and brainstorming methods were utilized when applicable. From this, we deduced that we would proceed with testing the battery, the coil, the thermoelectric generator and the solar panel, all of which showed to be the best components for our backpack stove.

The battery testing was carried out by Ben, Reese, Arthur, Aaron and Damon. The test procedure was as follows:

1. Instrument boiling pot with Thermocouples (orientation to be determined when we know how many thermocouples we will have)

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Figure 1: Thermocouples

2. Fill pot with 1L of water


Figure 2: Immersion coil setup Figure 3: Immersion coil placed in pot of water

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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.


11. Wait until resistance coil has cooled to below 30C

12. Fill an insulated container with 4 L of water





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”

The solar panel testing was carried out by Austin. The test procedure was as follows:

1. Cut three OSB panels 15”x6”

2. Frame panels with 2x4

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

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Figure 4: Solder solar panel cells 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

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Figure 5: Solar panel testing

20. Testing individual panels:

a. Repeat steps 8: ac

Arthur dealt with buying materials and equipment, arranging meetings, and booking lab testing rooms. Sandra dealt with organizing the binder and assigning people who were the least busy each week to complete a section of the binder.

Equipment/Materials used:

For research, brainstorming and designing the binder:

Computer

Internet

Microsoft Word

Google Drive

For battery testing:

1 LiPo Battery

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1 Resistance Coil

1 backpacking pot minimum volume of 1L

1 insulated container minimum volume of 4L

Something to mix water in insulated container

2 leads of copper wire (gauge to be determined)

For solar panel testing:

Solar Panel Electrical Setup Kit $14

Solar Panel 10x $26

4’x8’x1/4” OSB Sheet $12

Screws $3

7A Fuse $5

2x4x10 $4

Spray adhesive $7

Problems

The battery testing didn’t go as planned. The water heated, but the battery didn’t have enough power to boil it. Also, the water, when heated, turned yellow. Because we weren’t able to start testing until the end of the semester, we haven’t tried anything to overcome this problem, yet. However, we still received adequate results that will help us prepare for testing next semester.

The results from the solar panel testing showed that the energy stored by the solar panels was much less than calculated. This can be reasonable when there is a slight variation from the expectations because theoretical results are usually higher than experimental due to made assumptions and weather conditions that may have not been accounted for. However, our variation showed to be 1020% of the expected powera problem that needs to be examined next semester.

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Results & Discussion

Battery

The battery test was not a success. We ran into many problems during the test and we didn’t achieve our first goal of boiling water. Even though we made significant progress towards our goal we still have work to do. All the things that we have to revisit include, inaccurate thermocouple data, yellowing of the water, coil heat transfer, and electroplating of our alligator clip.

The data we recorded from the thermocouple is inaccurate but is still relevant. We can scale our accurate temperature readings based on the graph from inaccurate readings. From appendix A, you can see the results from the battery test. The three red dots are accurate temperature readings of the water. The blue line in the graph are our inaccurate temperature readings. The voltage readings we took of the nichrome wires were about double what we were calculating and we have to determine if that was an inaccurate reading or if it was an inaccurate calculation. The Nichrome coil didn’t transfer enough heat to the water to get it to boil. The whole 41 minutes we were doing the test, the highest temperature we got to was 190 degrees fahrenheit. That temperature reading was taken in the middle of our pot where there was the most action from the coil. The pot had a relative 3 degree temperature change from the middle point to the outer part of the coil. Next semester we will have to work on different coil designs and calculate the amount of heat transfer for each one.

We think the electroplating is what caused the discoloration, fishy smell, foaming, and floating particles in the water. It was clear the discoloration was coming from the alligator clip when we started seeing a darker brown color directly adjacent in the bubble and around the alligator clip. It is good to note the position of the alligator clamps in the water. The positive alligator clip was submerged in the water to the point that the copper wire was also in the water. This was not the case for the negative wire and the negative alligator clamp came out looking brand new. As seen in Appendix C. It’s possible that we lost heat transfer from our cable because some of the energy was being used to electroplate our positive alligator clip.

In typical electroplating setups they don’t connect the anode and cathode. Often putting one metal on the anode and the other metal on the cathode. They submerge the two metals in water and when they run a current, the ions are carried through the water to the other metal. It’s possible that our submerged alligator clips did something to this extent. One way to check if this was a reaction of electroplating is to attempt a recreation via this method. Another method would be to make sure the copper cable is not in the water.

We are not 100% positive that electroplating is the actual reason for the discoloration, foaming, fishy smell, and floaties. We think other possibilities include a coating burn off of the nichrome wire, or a chemical reaction.

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Solar Panel

Overall the solar panel testing was a complete success. Our group was able to assemble and test a working solar cell array. With only one incident of a broken solar panel that happened ¾ of the way through testing. While attempting to remove the alligator clip from the buss wire while detaching the multimeter, one of the cells was shattered. The continuity of the system was not compromised as 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 that results remained even with the broken cell still attached. The reason the 10th cell was not used to repair this while testing is during the initial assembly an additional cell was destroyed due to their fragility.

While the test was a success the results that were observed were a little less that ideal. The observed results of the panels showed that the power generated was not ideal and worse that what was anticipated. The average efficiency of the solar panels was 30.51% as seen in Appendix B. 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 even 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.

Conclusion

Testing provided some important feedback for the stove design as it currently exists. The discharge controller limited the ability of the battery pack to discharge as quickly as it was able. This in conjunction with larger than expected heat losses to the environment hindered the ability of the stove to bring water to a boil. One early concern that the battery pack may create a prohibitive amount of heat was dismissed, as throughout a much longer than expected test the battery pack was always cool to the touch. Additional problems were also discovered in the contamination of the water being boiled. Finally the lack of a functioning DAQ meant that we were unable to gather data pertaining to the usefulness of thermoelectric generators in addition to the solar cells the team currently plans on utilizing.

Solar data provided somewhat expected results in that the power output is less than the max advertised ratings. Also as expected peak power input was in the early afternoon with diminished power output in the morning evening hours. This test also provided information for future design, as the team now has a correlation between advertised power output and actual power output. We also discovered that more durable or flexible solar cells will need to be utilized, as the current design resulted in multiple broken panels just with one day of testing. This would not be sufficient for outdoor travel, and a more rugged solution needs to be found.

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Recommendations

Moving forward it is important to focus on the core functionality of the system, which is the battery pack, resistance heater and solar cells. Auxiliary power sources including thermoelectric generators may be examined again in the future, but in order to develop a complete design, the critical subsystems must be perfected first.

Additional research needs to be conducted in an effort to find a discharge controller that will maximize the power output of the battery. If one cannot be found one or more members of next semester's team will need to do the necessary research to build our own discharge controller.

Some method of preventing contamination of the water needs to be developed and implemented. This may require some method of cooling the NiChrome wire if it is enveloped to prevent melting of the wire. Potential solutions include stainless steel sheathing or other substances that can be heated while remaining inert.

It may be worthwhile to break the solar setup into three separate circuits by the plane on which they rest. This would allow a repeated test to be conducted which would provide us with power output as a function of angle of the sun in addition to time of day. This information would help us optimize the solar cell layout to maximize power with a minimum number of cells.

Finally, an integrated design and packaging needs to be developed for the system. The package needs to contain and protect the battery pack and discharge controller. Contain and protect all uninsulated wire. Provide a method to turn the system on and off, and safeguard against accidental heating when the system is packed away. The packaging must also connect all elements of the system and facility the packing of unused items in a pack during the day.

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Appendices

References: 1. Buse, Karsten. "Lightinduced charge transport processes in photorefractive crystals I:

Models and experimental methods." Applied Physics B: Lasers and Optics 64.3 (1997): 273291.

2. Pingel, S., et al. "Potential induced degradation of solar cells and panels."Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE. IEEE, 2010.

3. Krueger, Wallace F., Anthony R. Shaw, and Jerry L. Smith. "System for mounting solar collector panels." U.S. Patent No. 4,269,173. 26 May 1981.

4. Erling, Peter Stuart. "Framing system for solar panels." U.S. Patent No. 7,012,188. 14 Mar. 2006.

5. 2015, “Number of hikers/backpackers: Number of people who went hiking/backpacking within the last 12 months in the United States (USA) from spring 2008 to spring 2015 (in millions).” http://www.statista.com/statistics/227421/numberofhikersandbackpackersusa/

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Data Tables:

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Documents

DesignReport