DLab II: Energy & Development Designing for the Market

Izzy Bronstein Janice Pang Hannah Park

Solar CookerDesign Notebook

Table of Contents

Deliverable 1 1Initial Design Brief

Deliverable 2 5Brainstorm on project considerations and put in a decision matrix

Deliverable 3 9Specific Design criteria, and metrics.

Deliverable 4 11Brainstorming for design concepts.

Deliverable 5Annotated bibliography/project background using Endnote or similar(One per group member, to be included in the notebook)Janice Pang 13Hannah Park 16Izzy Bronstein 20

Deliverable 6 21Proposed design concepts, Idea evaluation, project timeline, and budget

Deliverable 711 23Design Reviews / Prototype Demo / Prototype evaluation / Design Review

Deliverable 12 25Project summary of background, methods, and results & design notebook

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D eliv erab le 1

Who is the client/ what is the their business?Solar Cookers International and their business is helping the women in the Iridimi Refugee Camp in Chad find sustainable means to cook food for their families.

Solar Cookers International is nongovernmental organization that spreads solar cooking awareness and skills worldwide, particularly in areas with plentiful sunshine and diminishing sources of cooking fuel.

What is the Problem Statement?The women in Chad require a solar cooker because without a solar cooker, they must collect firewood to cook their food and this creates danger for women (having to leave camp to find cooking materials), a strain on nonrenewable material in an arid climate.

What are the project goals? Why?The solar cooker should:

Be durable / sustainable Cook food in 3 hours or less Generate income for women Maintain a nowaste process Improve the lifetime of the solar cooker

Who is the target market/customer?Women in the Iridimi Refugee Camp in Chad.

The Iridimi Refugee Camp houses over 18,000 refugees that have fled the Darfur region of Sudan. The area is devoid of vegetation; there is abundant sun and very little rainfall—between 3” and 5” (7.5 12.5 cm) yearly.

What are the specifications (if any)?The solar cooker should:

Last for 5+ years Hold one (or two) 35 liter pots Allow cooking pot to reach temperatures between 121149* C Use rigid or semirigid materials Use a heattrapping “greenhouse” material allowed by the UN/ JWW

Greenhouse materials =/= plastic bags Last for 12+ years

Use local materials

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Benchmarks?

Find different types of reflective materials

Aluminized Panel

Old CDs

Tin can

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Windshield Shade

IXPE (crosslinked polyester) foam insulation /Reflective metalized polyester film (MPET film/ 3mm IXPE foam / white PET film).

Find different types of rigid or semirigid materials

Two bent pieces of sheet metal

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The Barbaboa Cooker (old umbrella)

Find efficient “greenhouse” material that would replace plastic bag currently used

Kenylon monolayer film, which resists breakage and is able to withstand temperatures up to 375 degreesFahrenheit. The unique kenylon film is produced from FDA approved materials.

What is the approximate budget (prototype/in quantity)?

Prototype: Research how much current solar cookers cost

A prebuilt Cookit from Solar Cookers International : $29.00 USD A cooking pot : $14.00 USD High temperature cooking bag: $ 2.50 USD

Available: http://shop.solarcookers.org/

Research cost of materials Cardboard Aluminum foil Glass

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Paint Wood Hay Cotton Plastic bags Clay

Total: Approx. $150.00 USD

In quantity:We hope that each solar cooker will cost under $3 to produce, as the average price point is approximately $7. There are about 3,000 families in the refugee camp, and although each one has a solar cooker (approximately) they are falling apart and losing their value. We propose a pilot program of teaching 200 women how to create such cookers, and providing them design and materials to create more cookers and possibly sell them.

What is the approximate timeline?See attached timeline.

What are the final deliverables?The final deliverable will be a proposal of more efficient, sustainable materials women in the Iridimi Refugee Camp can use to create a solar cooker. If time allows, another deliverable would be an improved design of the solar cooker using the aforementioned materials.

D e li v e r a b l e 2

Produced locally/national ly

W Low cost

W Zero waste proces s

W Local, simple maintenanc e

W Marketabl e

W Tota l

Design A 5 3 4 3 3

Design B 5 3 4 3 3

Design C 5 3 4 3 3

Design D 5 3 4 3 3

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Solar Cooker Design Consideration(Top 10 are bolded, Top 5 are highlighted)

1. Produced locally/nationally2. Low cost3. Timeefficient4. Durability5. Can hold multiple pots6. Retains heat7. Easily reproducible8. Attractive9. Product lifetime10. Easily maintained11. Ease of use12. Marketable13. Second Life Value I14. Portable15. Weight and Dimensions16. No Waste Process

Who is the client? Who are you designing the technology for?Our client is Solar Cookers International (SCI). SCI works with the United Nations and other international aid organizations to distribute solar cookers to areas in need of sustainable cooking methods; the solar cookers are designed according to the social, environmental, and financial needs of the area and its inhabitants. SCI also aims to integrate solar cookers into the ideal western kitchen. In our case, however, the solar cookers are designed for the target customer, detailed below.

Who is the target customer? Who will actually be using the device? Be specific.The target customers are women in the Iridimi Refugee Camp in Chad, who use the solar cookers to cook for families of 57 people. Most of these women were born and raised in the refugee camps; during this time, the women have received little to no formal education. They have, however, had previous experience with solar cookers. The current models used (and how they are used by the women) are detailed below.

What are the specifications given for the technology? Base material: Cardboards Reflector: Alu foil A cooking pot : Dark color, 3Pound, 9.75 inches width, 5.75 inches height, Steel with a

porcelain coating. A heatresistant bag (or similar transparent cover) : autoclavable polypropylene Designs: Panelstyle cooker

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Weight: half a kilogram Size : it folds to the size of a big book Current price: $37 USD. Cooking time: 3 hours Temperature: 121149C

What are the technical, social, environmental, and financial considerations? Income sources of families in the refugee camp Locally available materials to be tested as basematerial for the cookers. Locally manufactured Low cost (less than $10 USD) Durability (last for at least 5 years) Materials must be lightweight, unbreakable, and fold and flat for shipping Easy to store indoors Net zero production process Reflector must be waterproof and UV resistant Big enough to hold one to five liter pots. A low carbon footprint

What are other existing designs?There are seven primary types of solar cookers, including box, panel, parabolic, fresnel,

trough, intheground and evacuated tube cookers. In total there are more than 350 designs for creating solar cookers publicly available, each with their own distinct advantages and disadvantages. Panel cookers, including the popularly distributed CooKit are the most affordable and easiest to assemble. Box cookers are also quite cheap, and while slightly more difficult to assembly, they can cook more food and more types of food and are much more durable than panel cookers. While we plan to consider in the ground and parabolic options, these are not as popularly distributed due to cost, and unfamiliarity in the region.

There are several types of panel cookers to consider, as well as the standard solar box cookers:

CooKit: The mostly popularly distributed solar cooker from Solar Cookers International, the CooKit uses semirigid material (typically cardboard) and foil that reflects heat onto a pot that, covered by a transparent cover keeps the heat within the cooker. It can be made in communities from locally found materials and can be easily shipped across borders.

$ 45.40 USD (including a cooking pot and cooking bag)http://shop.solarcookers.org/

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HotPot: The HotPot is the evolved version of the CooKit. While it is much more durable and cooking types similar to that of a box cooker with higher speeds, it is quite expensive and cannot be created in individual communities, but rather must be shipped from a factory in Mexico.

$124.95 USD http://solaroven.co/solarovens/hotpotsolaroven.html?gclid=CPGOvL3r2roCFaU5QgodM mMAZQ

Copenhagen Solar Cooker Light: This cooker is easily assembled and disassembled, as it is simply pieces of vinyl held together by clips and bootlace. While it is incredibly effective, simple and cheap design, it can only cook a very small amount and does not have a long product lifetime.It does, however work very well, although the vinyl materials are rarely available locally.

$33.00 USDhttp://shop.solarcookers.org/?pn=Copenhagen+Solar+Cooker+Light&cn=Solar+Cookers&p=660&c=27

Double Angle Cookers: The design of these satelliteshaped, 12 sided cookers, is intended to make the transparent material that acts as a greenhouse material unnecessary. There are also recent designs of projects that combine concepts such as the CooKit and double angle cookers that allow for panels to capture the maximum sunlight in a cheap, portable design.

Solar Box Cooker: Box cookers, which can be made of any rigid or semirigid materials can cook many pots, made in any community with efficient materials and can be placed at any angle to properly capture the sunlight. However, the simplest box cookers cannot properly reflect enough to cook a pot effectively.

$299.00 USDhttp://shop.solarcookers.org/?pn=All+American+Sun+Oven&cn=Solar+Cookers&p=657&c=27

What will a successful design do?A successful design will not only be a durable, easily replicated, easily maintained way of efficiently using solar cooking to heat food, but will also be attractive to customers and have high demand in the community. It will also make effective use of local products, without sacrificing durability and lifetime. It will also maintain heat without using materials prohibited by the UN and other international aid organizations, and provide enough room to cook a meal for the average family of 5 to 7 people.

What is the timeline?See Attached.

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What is the project budget?See Deliverable 1.

What is the cost and quantity of products needed?See Deliverable 1.

What is the end deliverable?The final deliverable will be a proposal of more efficient, sustainable materials women in the Iridimi Refugee Camp can use to create a solar cooker. If time allows, another deliverable would be an improved design of the solar cooker using the aforementioned materials.

What skills and information will you need to design a successful product?To design a successful project, we must understand:

What materials are locally and nationally available? How do women go about obtaining the materials? What is the process for creating the current model of solar cookers? How are the solar cookers used (vs. what would be the most efficient way to use

them)? We must also possess the following skills: Prototyping

Woodworking Ceramics

Usertesting Efficient communication (between us and the client) Basic mathematics / geometry Basic principles of energy

D eliv erab le 3

Has your problem statement changed since learning more information? Update if needed. Yes, after in class discussion with Kurt, we have changed our problem statement to the following: It has been difficult to source the materials to make sturdy, durable, safe using solar cookers, calling for a need for a design that incorporates local and national materials that will work at the same capability as the previously designed cookers.

What are the important design considerations and corresponding criteria? Make a list. Produced locally / nationally Low cost Zero waste process Local, simple maintenance Waterproof Washable

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UV resistance Inflammable Second life value

What are the metrics (the unit of measurement) on how you will evaluate the design? What are the target values for each metric?

Design Consideration Metric Target Values

Produced locally/nationally Miles materials must travel to get to specific sites (ie refugee camps etc.)

refugee camps

Low Cost $ to produce, including labor cost/time

Less than $10 USD

Zero Waste Process % materials remaining post production

0%

Simple Maintenance Using a usability test, how simply (scale of 110) can women could fix cookers with commonly found problems

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Waterproof Qualitative classification of waterproof, waterresistant and no water resistance

Waterproof

Washable Number of washes with maintained efficiency and use before degradation

1000 washes

UV resistance Can withstand X milliwatts per square centimeter prior to degradation

555 Wh/m2, common exposure in yearlong period

Inflammable Material with highest burning point (in degrees Celsius)

Above 47.6°C (Highest recorded temperature in region)

Second Life Value % materials with second life value

100%

D e li v e r a b l e 4

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Using the Brainstorming process, generate design ideas (at least 20) that will solve the problem as understood:

1. Circular half cut aluminum can2. Pounded out aluminum can3. Aluminum can with cardboard backing4. Vinyl coating on cardboard5. Mirrored surface on cardboard6. UN reflective bag, mounted on cardboard7. Vinyl coated polyester8. CDs mounted on cardboard9. Woven basket with mounted cans10.Beer bottle aluminum cover11.Beer can or aluminum can mounted on wood or cardboard

Sketches

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D e li v e r a b l e 5

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Janice PangApril 29, 2014

Annotated Bibliography

Rijks, Derk. Solar Cookers for Darfur Refugees: Iridimi Camp in Eastern Chad [PDF document]. Retrieved from Solar Cookers Website: http://www.solarcookers.org/programs/chad_powerpoint.pdf

In this Powerpoint presentation, Dr. Derk Rijks, a partner of Solar Cookers International (SCI), details the development of solar cookers in Eastern Chad’s refugee camps in 2005. Specifically, Rijks and his team oversaw the distribution, training, and manufacturing of SCI’s CooKit.

Rijks notes that what little firewood is available is often the reason for conflicts between the local population and the refugees, as firewood is a resource for cooking food. Using only solar power to cook food, however, the CooKit eliminates the need for firewood, thus reducing conflict between the local population and the refugees.

From Rijks presentation, it is clear that SCI and the refugees place a large emphasis on zero-waste process and the use of local resources. The only imported materials are the thermo-resistant bags, cardboard, and aluminum foil; it would be interesting to explore from where the materials are imported. Additionally, since these are the main materials needed to create a CooKit, what are the additional materials that are resourced locally? Perhaps the adhesive, which can be sourced from gum arabic or kassava flour.

Regarding the CooKit production, SCI ensures that local staff supervises training of how to use the CooKit, how to produce the CooKit, the environmental effects of the CooKit’s production and use, and the CooKit’s repair.

It is important to note the empowering effects of the CooKit. Women work in teams to produce the CooKit, simultaneously providing a service and earning a wage. Having a hand in the production, the women are able to claim ownership of their product. Overall, members of the Iridimi Camp have had positive responses to the CooKit, noting the increase in safety and free time (whichallows them to find other wageearning opportunities), as well as its positive effect on the environment.

Harr, Jonathan. January 5, 2009. “Lives of the Saints”. The New Yorker.

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In this feature article, New Yorker reporter at large Jonathan Harr provides a firsthand account ofhis time in Sudanese refugee camps from 2005 to 2007. Coupled with statistics of the refugee’s life expectancy and poor living conditions, Harr’s stories from various sources including aidworkers, Chadian rebels, and the refugees themselves provide an extremelyintimate view of the refugee camps. Harr also provides a brief history of the Sudanese conflict which lead to the displacement of 250,000 Sudanese to the creation of the refugee camps in Chad.

One of most striking story was of the efforts of Japanese aid workers gone wrong. The Japanese aid workers planted trees to create a more uplifting environment in the camps. The refugees, however, saw the planting of the trees as a symbol of the authorities’ intentions to permanently keep them in the camps; enraged, the refugees and aid workers engaged in conflict, resulting in the Japanese leaving the camp.

It is important to remember that the refugees have concerns other than the method to cook their food. These larger issues safety, vulnerability, poverty must be kept in mind and should influence our group’s overall decisions. The most successful design will allow the refugees to cook their food in an environmentallyfriendly and safe manner, while also considering and addressing such larger issues.

Revkin, Andrew. September 23, 2010. “A Path to Cleaner Cooking in Africa”. The NewYork Times.

In this opinion piece, New York Times columnist Andrew Revkin shares an extended quote by Senegalresident Matt McLaughlin on what makes a solar cooker (un)successful. Most notably, McLaughlin points out that not one solar cooker is appropriate for all locations. Solar cookers should be designed and distributed according to the needs of the area’s residents. For example, the solar cooker should be able to properly cook the foods eaten in that area (eg. the solar cooker must cook at the right temperature and speed; compare: rocket cooker vs. CooKit).

Additionally, McLaughlin points out, designers of solar cookers must be aware of the learning curve associated with new solar cookers. It is important that there is appropriate infrastructure to train people how to use, maintain, and even produce the cookers.

McLaughlin’s final point is that those in the developed world have a moral obligation to fund such designs that win in the marketplace, thus boosting the local economy. Similar to the sentinments of the Donaldson piece read at the beginning of the quarter, as designers, one thing to be cautious of is the “white savior complex” of believing that we as westerners have and that we know what is best for our target audience.

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Luhmann, Erin. July 22, 2013. “Innovation in a Chadian Refugee Camp”. The New YorkTimes.

In this opinion piece, New York Times student journalist Erin Luhmann shares an anecdote of refugee Muhammad Moussa’s ground millet operation. Moussa’s work has gained him a respectful reputation within his Abgadam camp, where he has started a business which enables him to earn money and to barter.

Having had their homes, family members, and lives taken from them, it is important that operations especially ones that allow people to make something of their own that can support them financially empower the refugees. It should also be noted that each camp has a designated marketplace where food, tools, and cloth are bought, sold, and bartered. Refugees often earn money by selling vegetables or firewood in the marketplaces; the latter option is a dangerous one, however, as it requires refugees usually women or children to venture far away from their camps, making them vulnerable to the very real threat of rape. Thus, an opportunity, such as the solar cookers, for refugees to make money while also ensuring their safety would be an ideal operation.

Arkin, Jonathan. April 14, 2011. “Featured Organization: The Jewish World Watch Solar Cooker Project”. Blog post. Retrieved from h tt p : // a c t i o nn o w n e t w o r k . c o m / h o m e / c o n t e n t s / ? p = 5810

In this blog post, Action Now Network journalist Jonathan Arkin covers the progress of the Jewish World Watch Solar Cooker Project (SCP). Arkin begins by describing the multiple losses experienced by the refugees: the loss of family, friends, communities by genocide; the loss of home in the move to the refugee camp; and the loss of safety in the refugee camp.

Arkin also provides a donor’s perspective, exploring why people donate to SCP. Most notably, donors feel like they are personally saving a woman or young person from harm; and essentially, by reducing the need for refugees to travel far for firewood, the donors are. Arkin also points out that the SCP’s unreliance on firewood has increased the refugees’ health and neighbor relations.

While these solar cookers are a simple fix to one problem in a series of overarching problems of poverty, displacement, and genocide, it is important to consider how such an operation could possibly address larger issues (as previously mentioned).

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Review & Annotated BibliographyHannah Park

1. Review

Existing Design (Cookit)The current solar cooker design, CooKit, is a cardboard panel cooker covered with aluminium foil. Sunrays are reflected towards a black pot which is placed in a thermoresistant plastic bag. Temperatures from 70 °C to 90 °C (160 F and 200 F) can be reached. The cardboard is foldable and weights only 500 g (1 lb.), it is therefore easily stored. If the CooKit is kept dry and away from termites, the CooKit may last for several years. Considering its durability, the CooKit seems to be a good investment: the purchase costs are lower than the money people spend on firewood. The manufacturing of the CooKit is not difficult. Solar Cookers International published a construction manual (SCI, 2007c). A CooKit can be made in one or two hours and materials needed are cardboard, aluminium foil and nontoxic,waterbased glue (SCI, 2007c). The CooKit has been successfully implemented in refugee camps, for example in Kenya, Namibia, Malawi, Chad, and Sudan. In the Iridimi refugee camp (East Chad), the CooKit is used in 4500 households and women are producing their own CooKits (Toonen, H., 2009).

Problems

Bad cooking time managementBad time management can be frustrating for women: if they cannot serve their husband and families a decent meal in time, they fail one of their important tasks. In consequence, many women prefer using the CooKit for preparing just for themselves and their children, because they does not want to risk being late when their husband wants to eat (Toonen, H., 2009). This problem is related to their cultural context.

Dependence on weather conditions (strong wind, rain, cloud cover and general lack of sunshine)If sun rays are blocked by clouds or dust in the air, the cooking will be slowed down (Toonen, H., 2009). The survey results on family cooker use rate over time and sunny weather perception indicates strong usedependence on weather (Biermann, E., et. al., 1999).Therefore, the CooKit cannot replace firewood entirely, and a complementary element has to be found. Toonen (2009) suggests the use of Jatropha oil; Jatropha fruits contain oil which can be easily processed. There is still little documentation and field experience on the use of Jatropha oil on thehousehold level, thus further research is needed.

The small capacity of CooKit

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The current size is not large enough for larger families (510 people) and small families, wanting to prepare multiple dishes separately. This is solved by promoting the use of two CooKits. The price of the CooKit might be a problem, although people are able to save money by using the CooKit. Schwarzer, K. (2003) presents the the flat plate collector cookers which have a very good chance for largescaleuse in various applications, such as in large families, schools, hospital, food stations, etc.

Lack of black cooking potsFrom the Market Research Africa study (2003), 11% of nonusers stated the lack of black pots as the reason for not using their solar cooker. The Kenyan study (UNHCR, 2004) concluded that it is vital to have a properly painted black pot. A comparative water boiling test was carried out with an aluminium pot painted black vs. an unpainted pot of the same type and it was found that it took an average of30% longer to boil water using the latter.

2. Annotated Bibliography

Cuce, Erdem, and Pinar Mert Cuce. "A Comprehensive Review on Solar Cookers." AppliedEnergy 102 (2013): 1399421. Print.

In this paper, a thorough review of the available literature on solar cookers is presented. The review covers a historic overview of solar cooking technology, detailed description of various types of solar cookers, geometry parameters affecting performance of solar cookers such as booster mirrors, glazing, absorber plate, cooking pots, heat storage materials and insulation. Moreover, thermodynamic assessment of solar cooking systems and qualitative evaluation of thermal output offered by solar cookers are analyzed in detail. Complex designs of solar cookers/ovens with and without heat storage material are illustrated and furthermore possible methods to be able to enhance the power outputs of solar cooking systems are presented.

Toonen, Hilde M. "Adapting to an Innovation: Solar Cooking in the Urban Households ofOuagadougou (Burkina Faso)."Physics and Chemistry of the Earth, Parts A/B/C 34.12 (2009):6571. Print.

There are many different techniques of solar cooker have been tested. Most variants are expensive, and therefore not available for most families in SubSaharan Africa. A cheap solar cooking device is the CooKit, a cardboard panel cooker covered with aluminium foil.

In the adaptation to the CooKit, as to all innovations, it is important that the users are convinced of the advantages. An important step in the adaptation process is learning how to use the cooking device; the best way to do this is by home practice. Monitoring and evaluating the real use is needed, for it is interesting to know if the CooKit is actually used, and also to find out how women have implemented the new technique in their kitchens. In 2005, the SUPO foundation started a

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project in Burkina Faso: Programme Energie Solaire GrandOuaga (PESGO). The aim of PESGO is to indicate criteria determining success and failure in the adaptation of solar energy in urban households. In this paper, a midterm review on this smallscale cooking project is presented. The possibilities and challenges of solar cooking are outlined, taking the urban context of Ouagadougou in account. In PESGO, dependence on weather conditions is found to be one of the challenges: if sun rays are blocked by clouds or dust in the air, the cooking will be slowed down. The CooKit cannot replace firewood entirely, and a complementary element has to be found. SUPO is exploring the use of Jatropha oil as a complement to the CooKit. The Jatropha plant is drought tolerant and its fruits contain oil which can be used as fuel substitute. Further research on its use is interesting, because the combination of the CooKit and Jatropha oil seems to have high potential in thekitchens of West Africa.

Mohamad, M.a., H.h. ElGhetany, and Adel M. Abdel Dayem. "Design, Construction and FieldTest of Hot box Solar Cookers for African Sahel Region." Renewable Energy14.14 (1998):4954. Print.The study presents the result of the experiments of a simple wooden, hot box, with one reflector solar cooker. The experiments with actual loads were performed at the Solar Energy Dept., National Research Centre, Dokki, Cairo (30 °N), EGYPT. The main findings are as follows:

The pot shape and size are the factors affecting the cooking speed. The small ratio pot between height and pot diameter (H/D) is recommended. The cooking process in solar cooker needs a special method, for example : The meat. fish and chicken must be cooked without any water. The rice needs hot water at the start. The best time of cooking is around solar noon at high solar radiation and this cooker can cook two or three meals a day. Most foods can be full cooked at the temperature range between 60 90 °C. Meat has the longest cooking time due to its high heat capacity. A pot with high thermalconductivity should be used.Finally it is expected to save a considerable amount of energy consumption in the Sahel African region, with using solar cookers . It is the turn of education, training and demonstration in the region to achieve the final goal of the work, which aims to spread the solar energy technology for energy saving to solve the problem of deforestation in the region.

Wentzel, Marlett, and Anastassios Pouris. "The Development Impact of Solar Cookers: A Review of Solar Cooking Impact Research in South Africa." Energy Policy35.3 (2007):1909919. Print.

The article summarises the findings of the various studies and present an overview of use rates and impact data. A variety of factors influence solar cooker use rates, which in turn determine impacts. Some factors are related to the user, some to the environment in which the cooker is used and some to the cooker itself. Ultimately, the data shows that on average, only 17% of solar cooker owners do not use their stoves after purchase and that active solar cooker users utilise their stoves on average for 31% of their cooking incidences. Since the majority of solar stove buyers actually use their stoves and obtain real benefits, this suggests that that solar cookers are indeed not a solutionlooking for a problem but a solution worth promoting.

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Schwazer, K., Silva, M., 2003, Solar cooking system with or without heat storage for families and institution, Solar Energy 75, 3541.

The paper presents the plate collector cooker system, with or without temporary heat storage. The two basic system components are the solar collectors with reflectors and a cooking unit. When thermal storage is needed, a tank filled with pebbles is added to the system. The working fluid, usually a vegetable oil, circulates in natural, thermosiphon flow through a copper piping that connects the components. The system presents interesting features such as the possibility of indoor and night cooking, heat flow control in the pots, modularity, and the possibility of further adjustment to incorporate a baking oven. This indirect solar cooking system meets the required thermal and technical characteristics, such as, efficiency, easy handling, modular design, very low maintenance costs, and long lifetime. Modularity allows manufacturing of smaller units for single-family applications, as well as larger units for institutions. The system is adaptable to a wide variety of local eating and cooking habits. The first prototype of this collector–cooker system was built and installed in the city of Juelich, Germany. Further development and adjustment were performed for the next versions, which were brought to India and Mali. Other systems were installed in Africa (Burkina Faso and South Africa) and in South and Central America. About 250 systems have been built in different sizes to be used by single families or by government institutions.

Biermann, E., M. Grupp, and R. Palmer. "Solar Cooker Acceptance In South

Africa: Results Of A Comparative FieldTest." Solar Energy 66.6 (1999): 40107.

Print.

Since most userrelated evaluations have been carried out by the manufacturers / designers themselves rather than by independent observers, there has been an ongoing debate on the user acceptance of solar cookers and on the type of solar cooker that is best accepted. The study examines the acceptance of solar cookers: ‘acceptance’ here means that ‘solar cookers are used as much as or more than other cooking options in the household or institution’. A oneyear comparative fieldtest of 7 different types of solar cookers, involving 66 families in 3 study areas in South Africa, has been conducted by the South African Department of Minerals and Energy (DME) and the Deutsche Gesellschaft fu r Technische Zusammenarbeit (GTZ).

Overall, families use solar cookers on 38% of all days and for 35% of all cooked meals; they express clear preferences for certain cooker types. Solar cookers, together with wood (stoves and open fires, used on 42% of all days), are the cooking appliances most used. Fuel consumption measurements show overall fuel savings of 38%, resulting in estimated payback periods (through monetary fuel savings) from 8 month onwards, depending on the type and region. Economic analysis, acquisition of test cookers by users after the placement period as well as an independent market study, have led to a second programme phase of commercial pilot dissemination of locally produced cookers, adapted according to fieldtest experiences.

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Izzy Bronstein

Numan Yuksel, B. A., Atakan Avci (2012). "The thermal analysis of paraffin wax in a boxtype solar cooker." Journal of Renewable and Sustainable Energy 4(6).

This study looked into the improvements made to design of several types of solar cookers using a wax as an insulator in the already created designs of box cookers. While the wax heated up hotter than the cooker itself, the efficiency. The contribution of the reflected radiation from the metal shaving within the wax increased the overall efficiency of the cooker, decreased local times. This study is important to our design process because it examines and tests improvements to solar cookers for food consumption. By testing the mean ambient temperature, as well as the subsurface temperature, side surface temperature, and solar radiation, the efficiency and improvements can be tested. We can use similar testing procedures to test our improvements and modifications to the panel solar cooker.

S. Mahavar, et Al. (2012). "Design development and performance studies of a novel SingleFamily Solar Cooker." Renewable Energy 47.

The Single Family Solar Cooker (SFSC) was a recently created design in the realm of box solar cookers. It determines different types of performance considerations, including the adjusted cooking power, weather ability and heat transfer rate. This procedure explained ways of a using a pyranometer to measure solar radiation, which can help understand durability and lifetime measurements. It also provided formulas for cooking power tests in mass times the heat of thewater time the temperature difference of water over the time interval it took for the water to change temperature.

de Souza, Luiz Guilherme Meira, et al (2005). "Optimization project of the construction and effecience analysis of a solar cook for food cooking." 18th International Congress of Mechanical Engineering.

This study of the most efficient possible parobolic solar cooker provides benchmarks in almost every regard, of shipping, cooking time, durability. By understanding that the painting of the structure, even if it is cardboard significantly protects the cooker, the exact cuts of mirrors thatadapt them to create the perfect direct angle to fit within the glass fiber and polymeric resin to act as the greenhouse material and the use of wax provides our design with benchmarks that, though impossible to reach in a locally created panel design, allow us to understand what can be done with solar cookers and the materials that would be the best possible, so we can find similar materials locally and nationally.

Voigt, John E., and Edward M. Bovier. "Water resistant starch adhesive." U.S. Patent No.3,802,897. 9 Apr. 1974.

This patent was for a waterproof and water resistant can be used both for adhesives

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which is thicker and creates a more durable cooker. While this is a chemically created adhesive, it is

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modelled after a traditional starch based adhesive, which is one of our design possibilities in order to waterproof the solar cookers. It shows the disadvantages and advantages in terms of pot life, maximum temperature and lifespan when using such adhesives. This patent is more than 40 years old, but provides a solid benchmark by which to compare our starchbased adhesives and get ideas for which additional fillers and materials could be useful in increasing the durability and waterproofing the cookers at low cost.

D eliv erab le 6

Produced locally/nationall y

W CookingEfficiency

W Zero Net Waste

W Ease of constructi on and maitence

W Waterpr oof/ durabilit y

W T ot al

OriginalDesign

2 5 4 3 5 4 4 3 2 5 69

Original + Hay base

3 5 3 3 5 4 2 3 3 5 81

Original + Cans

4 5 3 3 3 4 3 3 4 5 83

Original + wheat paste glue

2 5 4 3 5 4 4 3 4 5

Design A: Hay basket to supplement the base materialAccording to our client, the current base material is cardboard which is imported to the refugee camp. The cardboard tends to wear down after 912 months. Thus, to improve the durability of the solar cooker, the refugees could weave a hay basket in the shape of the cooker’s base to supplement the base material in this case, cardboard. Hay baskets are already used as insulatedcontainers in which food can continue to be cooked without fuel. The material for the hay basket is locally available at a low cost; additionally, the training programs already in place are training refugees to produce both solar cookers and to weave hay baskets, so the learning curve would not be very high for this procedure. What’s more, this would be a zerowaste process as the material would itself, hay, become the product.

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One drawback is that the weaving of the hay basket is likely more time consuming than the production of the solar cooker itself.

Another variation of this design would be to have the hay basket itself as the base material; one possible drawback of this design would be its increased chance of flammability as hay is a very dry material.

Design B: Cans to supplement the reflective materialAccording to our client, the current reflective material they use for CooKit is aluminum foil that is thrown by the industry that makes stonewool fire insulation plates which is covered with aluminum foils. In the refugee camps, some boys have tried to use the foil from cigarette packs. The aluminum kitchen foil is also available but not in the poor areas of Africa. However, thealuminum foils are not rigid enough, so it is easily torn. Thus, we came up with idea that using beer cans discarded by industry or individuals could serve as reflective materials for CooKit. Since the major industries of Chad include beer brewing, we assume that aluminum beer cans are easily available in Chad. To build a solar cooker made of cans, the cans should be pounded in flat pieces and mounted on the base material such as cardboard or wood. It might not even need a base material because cans are rigid enough without it. The idea has a lot of advantages over the current design: first, it can be produced locally; second, the production cost is low since the discarded materials are used. As a result, it can be economically available for poor families and widely used even in poorer areas; Moreover, it can be used almost permanently, so the cost will be lower as it is used over time; third, it is waterproof and washable; ;lastly, because the material has high thermal conductivity, the rate of heat transfer from the reflective material to the cooking pot would be more effective. Therefore, the cooking time, which is one of the problems of the current solar cookers, might be faster.

However, the major drawback of this idea is the production process which is not easy to be done solely by women in the refugee camp. They might need help for cutting and pounding cans. Additional studies should be needed on the effective method to attach many pieces of cans together. It is not folded, so it also requires relatively large space for storage.

Budget:Wheat Paste Glue:

Cloth (3 yards $8) Wheatpaste (Flour $6) Sponge Brush ($2) Wax ($8)Cardboard Cooker ($8 each)

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D e li v e r a b l e s 7 1 1 These deliverables were all prototypes, most of which we presented at the final design review. Below are photos of our process (and more are included in Deliverable 12, in which we test and review our prototypes):

A minisolar cooker made of aluminum foil and cardboard

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Chrome paint on cardboard; performed 50* poorer than the original CooKit

Cardboard models made of recycled cardboard from the Student Farm Shop

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D eliv erab le 1 2

Paper macheIngredient:Paper clay (powdered 100% preconsumer recycled paper) + water

Direction:1. Mix water with paper clay.

(Half water and half paper clay worked best to shape and handle)2. Spread the mixture on top of the table.3. Flattening the clay in 5mm thickness4. Leave it outside until it is dry

Result:Making a prototype with paper mache panel was unsuccessful. The panel itself is rigid and strong but it doesn’t have flexibility. Thus, it is easily broken when we attempt to bend and shape it. Moreover, the surface becomes bumpy when it has dried. We assumed that using mold would help to shape it. However, the paper mache cooker would require relatively large space for storage because it would not be folded.

Mixed reflective materials on CardboardWe made a prototype with various assorted food packages includes Seaweed, Shin Ramen, Trader Joe’s potato chips. The seaweed and Shin ramen packages had high reflectivity whereas the Trader Joe’s potato chip bags had relatively low reflectivity. These materials were pasted on top of a cardboard cutout of the CooKit.

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Test result:The average highest temperature of the prototype differs only by 14 degrees from the Cookit. However, under the best outside temperature condition which was 75 °F, the Cookit achieved an average of 215°F while the prototype achieved an average of only 180°F. By considering the condition that solar cooker should achieve over 200 degree to cook foods, it was a disappointing result. There were many variables in the test; First, the base material was not identical to the original Cookit. Thus, the shape of the base material could affect on the prototype’s efficiency. Second, the various reflectivity of different food packaging could affect on the result. In order to get rid of these variables, we used same base material as the Cookit, and same potatochip bags have same reflectivity in the next test.

Drawbacks of the materials: The reflectivity is varies depending on the types of food packaging. Hard to achieve the consistent performance with different prototypes. Hard to wash off oily surface of the packaging.

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Potato Chip Bags on CardboardSeeing that the potato chip bags were the most reflective material, we created a prototype using only potato chip bags. Like the previous prototype, we pasted the reflective material atop a cardboard cutout of the CooKit.

Test result:The potato chip bag model performed poorly, achieving an average cooking temperature of 175°F (compared to the assorted reflective materials model, which reached an average of 185°F, and the CooKit itself, which reached an average of 190°F.

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Potato Chip Bags on CooKitThe previous tests revealed that the potato chip bags on cardboard were not as effective as the assorted reflective materials on cardboard, which surprised us since, visually, the potato chip bag model was clearly more reflective than the assorted food bags.

We noted that the shape of the potato chip bag model was deformed with a large crease at the base. Believing this to affect the model’s effectiveness, we then created a prototype with potato chip bags atop an actual CooKit, which has a welldefined, premade structure.

Test result:The average highest temperature of the prototype differs only by an average of 10°F from the Cookit. Under the best outside temperature condition which was 79 °F, the Cookit achieved 215°F while the prototype achieved only 205°F. This proved our hypothesis that pasting potato chip bags

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atop the CooKit would yield higher cooking temperatures than pasting assorted reflective materials atop cardboard.

Plexiglass CoveringWe tested two alternative models that would trap heat around the pot, in effect acting as a greenhouse material to replace the plastic bags currently in use in refugee camps around the world. However, the UN does not approve of this material, as it is relatively disposable material, that we found would get several holes if overheated.

We tested a 3 mm plexiglass cover created with five 12” x 12” sheets created using hot glue to weld the sheets together and fill in an gaps in material next to a plastic bag and found that while the fit worked with one of the CookIts, it did not work on the ones we were using for this test, thus there were large gaps between the CookIt and the plexiglass covering. It also was quite heavy and

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ended up pushing the back cover down for part of the testing process as demonstrated in the photo below in the center test. Thus as demonstrated in the graph below, the results of the plexiglass compared to the bag were much poorer.

If reshaped to meet the size of the Cookit and made with a lighter plexiglass, perhaps a1mm, this covering might work better. However it still would be up to testing to see if it would push the top off a solar cooker or let gaps of air in when it doesn't bend in the same way a plastic bag would.

.£l

220

Comparison of CooKit Coverings

( r•CooKit+

Plastic Bag

•CooKit+

& 200 Plexlglass

•CooKit+

.s: Acyrlic

180 Plastic

.e:3: Ill Cl.E:

g.<t

160

140 12:00 12:05 12:10 12:15 12:20 12:25 12:30PM PM PM PM PM PM PM

HorizonraJ axis title

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Plastic Acetone coveringFor our second greenhouse material test we decided to test a plastic sheeting called acrylic

plastic or acetone, which is a very thin, flexible plastic. We attached it together using electrical tape. We created three slits on the left, forward, and right vertical sheets. We also attached onethird sheets on each side of the top panel to create flaps. The box bent to fill the space perfectly and was light-weight enough to keep the box in the Cookit.

In our testing, no holes developed in this material, and after 11 minutes both the Cookit and plastic bag were at the same temperature and cooking rice at approximately the speed.While thebag reach a temperature of 200 degrees after 20 minutes and then flattened out, the acetone box reached the same heat, it just took it an extra 10 minutes as demonstrated by graph above.