environmental protection agency p3 grant for the creation...

Environmental Protection Agency P3 Grant for the Creation of an Ultra-Low Cost Solar Oven

Multidisciplinary Design Project: 05301

Technical Data Package Friday, February 18, 2005

Team Leader: Emma Fulton (BS IE)

Team Members : Josh Bates (BS ME)

Otman El Allam (BS ISE) Natasha Privorotskaya (BS/MS ME)

Jon Steiner (BS ME)

© Bates, El Allam, Fulton, Privorotskaya, Steiner of 57

Introduction ................................................................................................................4

Needs Assessment .....................................................................................................6 Project Mission Statement.....................................................................................6 Scope Limitations .....................................................................................................6 Stakeholders ...............................................................................................................6 Key Business Goals ..................................................................................................7 Financial Analysis.....................................................................................................7 Primary Market........................................................................................................7 Secondary Market....................................................................................................7 Order Qualifiers ........................................................................................................7 Order Winners...........................................................................................................8 Innovative Opportunities.......................................................................................8 Additional Support and Resources ....................................................................8

Project Planning .......................................................................................................9 Work Breakdown Structure .................................................................................9 Design Structure Matrix ......................................................................................13

Research ......................................................................................................................17 Venezuela: Environment......................................................................................17 Venezuela: Economy and Manufacturing .....................................................17 Venezuela: Energy Consumption Rate and Water Pollution.................18 Venezuela: Diet........................................................................................................18

Specifications ............................................................................................................19 Quality Function Deployment (QFD)..............................................................19 Attribute Ranking ..................................................................................................21

Feasibility Assessment ........................................................................................24 Concept Development .........................................................................................26

Basic Definition of Solar Oven...........................................................................26 Three Main Types of Solar Ovens ....................................................................26 Commercial Units ...................................................................................................27 The Solar Oven Generations ..............................................................................28 Materials Selection.................................................................................................29

Main Construction Material...................................................................................30 Wood Selection.........................................................................................................34 Metal for Reflectors .................................................................................................35 Cover Material .........................................................................................................38 Inside Liner Material ..............................................................................................40

Initial Concepts........................................................................................................41 Four Reflector Box ..................................................................................................42


Single Reflector Box ................................................................................................44 Pyramid Reflector Box ............................................................................................46

Develop Testing Methodology ........................................................................48 Laser Test..................................................................................................................48 Indoor Test................................................................................................................51 Outdoor Test.............................................................................................................52

Future Work .............................................................................................................53 Acknowledgements ...............................................................................................53

Works Cited ..............................................................................................................54 Appendix A: Updated Project Schedule ..................................................57


Introduction After food is cultivated and gathered, it still cannot be consumed unless it is properly cooked. Firewood is the major energy source for cooking in developing countries, normally accounting for 50-90%1 or more of all energy consumption. Everyday, 2 billion people cook their meals using firewood1; the rate of firewood consumption exceeds its replacement. The usage of firewood as a primary source of fuel contributes to the deforestation, soil erosion, and worsening welfare of the world’s populous. Although electric cooking is convenient, the production of electricity is very expensive and sometimes not available in rural areas. In many places, women and children walk many miles to collect firewood, and the distance is likely to increase dramatically as the forests continue to be depleted. The use of solar ovens might represent an affordable and, perhaps the only feasible means of cooking for those faced with fuel shortages and little or no income. Solar ovens, using the sun’s free energy, offer tremendous potential for aiding in the solution of the world’s fuel problem. Besides cooking, the solar oven can do a variety of jobs: dry agricultural products as well as heat and pasteurize water. The extensive use of solar ovens will greatly reduce the following: deforestation, air pollution, family health problems, amount of time required to collect fuel, and consumption of conventional fuels. Solar ovens have a tremendous potential to better the lives of millions of people, but must be designed to fit the needs of the end users. Currently, the use of solar ovens is very limited. This is due to their high manufacturing costs and the inappropriateness of current designs for multiple environments. Many designs utilize material that is not locally available, or require highly skilled labor. These are some of the reasons why the promotion of solar cookers worldwide has traditionally been non-commercial. The commercialization of solar ovens is not a worthwhile venture for entrepreneurs, since the manufacturing and sale of solar ovens may not provide the best return on investment. The intention of this project is not to reinvent the basic solar oven design, but rather to design, test, and build an effective solar oven suitable for the rural inhabitants of Latin America. The design must be able to be mass-produced at low cost us ing the capital, labor, and materials that are typically available in Latin American nations. The team is required to design for manufacturing, assembly, logistics, and distribution. Furthermore, the team must estimate the social, environmental, and economic impacts if their design were it to be widely adopted. A prototype oven will be sent to Venezuela in March 2005 for testing and to determine any changes that are necessary to meet the needs of the end users. As such, the team will consider Venezuela as a representative sample of Latin American

1 Nandwani, Shyam S. "Solar Cookers- Cheap Technology with High Ecological Benefits." Ecological Economics. Vol. 17. 2. 1996. 73-81. Science Direct. 2005. Elsevier B.V. 15 Feb. 2005 <http://www.sciencedirect.com/>.


countries, assuming that it includes all attributes that the team must consider during the project. Following this activity, the team will redesign the solar oven and perform the final tests. It is the goal of this project to complete all analysis before the deadline set by the Environmental Protection Agency of April 12, 2005. This paper will first address the Needs Assessment, which the first step in the project. It generated the input needed for the planning process, detailed in the section following.


Needs Assessment

Project Mission Statement Design, test, and build a low-cost solar oven for use in Latin American countries using locally available resources, mass production methods, and labor.

Scope Limitations

The design of the solar oven is subject to the following scope limitations. 1. Design should only incorporate locally available resources, production methods,

and labor 2. Design must be mass-producible at the lowest feasible cost per unit 3. Design must be durable 4. Design must be able to cook sufficient quantities of food for a typical family size 5. User testing must be performed to ensure ease of use 6. Design must be able to pasteurize the water 7. Thermal analysis must be conducted on prototypes 8. Design must be benchmarked against two commercially available units 9. Conduct an economic analysis 10. Project should also include an analysis of social and environmental impacts 11. A lifecycle and durability analysis must be performed to ensure a long- lasting

product, and whether the materials chosen are able to withstand the environment Stakeholders

Customer End Users Faculty Mentor Faculty Sponsor Faculty Coordinator Team Leader Team Members Consultants Additional Resources

EPA P3 Award Latin American citizens Dr. Brian Thorn Dr. Andres Carrano Dr. Jacqueline Mozrall Emma Fulton (BS ISE) Josh Bates (BS ME) Otman El Allam (BS ISE) Natasha Privorotskaya (BSMS ME) Jon Steiner (BS ME) Dr. Sjyam S. Nandwani Ing° Rodolfo Carrillo Carlos Plaz (MS IE) Chris Wood (MS IE)


Key Business Goals With the P3 Award funding from the Environmental Protection Agency, develop a low-cost solar oven design for use in Latin American countries using locally available resources, mass production methods, and labor.

Financial Analysis The P3 Award funding provided by the Environmental Protection Agency will support the work of the Solar Oven Multidisciplinary Student Design Team at the Rochester Institute of Technology. This team is comprised of five students. Funding will be used to purchase testing equipment, fabrication equipment, design materials, three commercially available solar ovens, and to send the team to Washington, D.C. to present final results.

Primary Market The preliminary market for this project is the people in Latin American countries at or below the poverty line, who live in rural areas. The purpose of the project is to enable them a way to cook using solar power. This usage would decrease the deforestation of their country and the negative health impacts associated with fire cooking.

Secondary Market The people around the world who are at or below the poverty line, including but not limited to the follow regions: Sub-Saharan Africa, Europe, Central Asia, Middle East, North Africa, and South Asia.

Order Qualifiers The solar oven has been designed to enable the widespread adoption of solar ovens. The design must adhere to the following criteria so that the design is feasible for the end users:

1. Inexpensive method to cook food 2. Can be mass-produced locally using local labor [within that country’s boundaries] 3. Significantly decrease the need to search for firewood, thereby enabling the

gatherers to enter another sector of the workforce 4. Ceases the exploitation of children as firewood gatherers 5. End the exposure to smoky conditions associated with long-term firewood

cooking, which, unchecked, can lead to respiratory ailments and eye diseases 6. If adopted countrywide, the use of the designed solar oven would significantly

decrease the rate of deforestation and the emission of carbon dioxide into the atmosphere


Order Winners The final solar oven design must meet the following criteria in order to be considered a success. The final design will be chosen via both qualitative and quantitative measures, which will enable these criteria to be utilized effectively.

1. Inexpensive design (The current target price is $20, but will mostly determined by whether the prototypes meet the specifications; the Specifications section details these criteria)

2. Heats up quickly 3. Reaches temperatures necessary to cook food and pasteurize water 4. Easy to use 5. Durable

Innovative Opportunities The following are two opportunities for the team to enhance the solar oven design to meet the needs of the end users:

1. Enable users a means to identify that the necessary time and temperature has been reached for water pasteurization

2. Design for portability possibly by way of shoulder straps to easily relocate oven

Additional Support and Resources Part of the P3 award funding has been allocated to purchase woodworking tools: table saw, band saw, drill press, tabletop router, circular saw, and radial arm saw. The purpose of this lab is to enable the team the necessary means to manufacture prototypes, and then perform subsequent testing on those designs. Additional support is available for the team through the National Center for Remanufacturing and Resource Recovery, the Brinkman Manufacturing Laboratory, and the Kate Gleason College of Engineering at the Rochester Institute of Technology. The next section of the report will address the planning of the project, what activities need to be completed, and in what order.


Project Planning Work Breakdown Structure

A Work Breakdown Structure (WBS) was utilized in the original planning of the activities the solar oven team must complete. Figure 1 is the preliminary work breakdown structure created for the Solar Oven Team for Level 1 activities. There are seven main work packages: Needs Assessment, Research Latin American Countries, Develop Testing Methodology, Concept Development, Choose prototype(s) to send to Venezuela, Redesign prototype, and Determine Effects on Society. Traditionally, a WBS also assigns resources to each of the work packages. As the WBS was created before the team was put together, resource allocation is not included.

Solar Oven Project 05301

Needs Assessment

Develop Testing Methodology

Research Latin American Countries

Concept Development

Choose prototype(s) to send

to Venezuela

Determine effects on society

Redesign prototype

Figure 1: Work Breakdown Structure (Level 0 and 1)

Each work package was further broken down into further levels of activities. Figure 2 shows the breakdown for the needs assessment. The two activities in level 2 are to determine requirements and to benchmark against commercially available units.

Needs Assessment

Benchmark against commercially available units

Determine requirements

Figure 2: Needs Assessment (Level 1 and 2)


The research of Latin American countries, shown in Figure 3, was further broken down into five subtasks (level 2): environment, labor and skills, diet, materials, and production methods. These five subtasks are important to achieve the main objective which is to design, test, and build a solar oven that is suitable for the end users in Latin American countries.

Environment

Diet

ProductionMethods

Materials

Labor/Skills

Research Latin American Countries

Figure 3: Research Latin American Countries (Level 1 and 2)

The fourth work package is concept development, whose further subtasks are identified below in Figure 4. The main subtask is to research current low-cost oven deigns, then to create multiple designs. Finally, the team must narrow down the design choices, by completing a feasibility assessment.

Concept Development

Research existing low-cost ovens

Create multiple designs

Narrow down design choices /

Feasibility Assessment

Figure 4: Concept Development (Level 1, 2, 3, and 4)


One of the major challenges the team faces is the environment of Rochester, NY, which is vastly different than that of Latin American countries. The team must be able to simulate the sun’s intensity. Therefore, developing testing methodology is a crucial step in the team’s design process and is shown below in Figure 5. This work package is broken down into one main activity: to research standard solar oven testing standards. Then, the team will design the testing apparatus and order equipment based off previously gathered information.

Develop Testing Methodology

Research standardized solar

oven testing standards

Order equipment to simulate

environment

Design testing apparatus

Figure 5: Develop Testing Methodology (Level 1, 2, and 3)

User testing is another crucial step in the design process for these solar ovens. Without this work package, the team would never obtain true end user data, merely speculating the needs of the end user and how well the design meets those needs. As such, the fifth work package shown in Figure 6 is very important; this work package includes building prototypes, generating the bill of materials associated with each design, and testing the prototypes.

Choose prototype(s) to send

to Venezuela

Build prototypes

Test prototypes

Develop BOM and Costs

Figure 6: Choose Prototype(s) to send to Venezuela (Level 1, 2, and 3)


The sixth work package is to test the final prototype, and the tasks associated with this work package are shown in Figure 7. Each subtask is dependent upon the previous subtask; this work package is detailed through Level 4, which is collecting the end user data gather in Venezuela.

Build final prototype

Test final prototype

Redesign prototype

Collect end user data

Figure 7: Redesign prototype (Level 1, 2, 3, and 4)

Figure 8 details the final work package, which is to determine the effects on society in terms of the environmental, social, and environmental impacts (the level 2 activities).

Determine effects on society

Economic

Social

Environmental

Instruction manual (English, Spanish),

pictoral)

Determine manufacturing cost

Subsidizing agency (gov’t, world health

org, red cross, religious orgs.)

Potentially utilize software support to determine impacts

Figure 8: Determine Effects on Society (Level 1, 2, and 3)


Design Structure Matrix The Design Structure Matrix2 (DSM) Excel macro, created by professors and students at MIT and the University of Illinois-Urbana Champaign, was utilized to assist in the planning process. It allows a planner to input the proposed order of work packages, see Table 1. On the lower half of the matrix are feed-forward activities, meaning that the work package number listed on the X-axis must occur before the item on the Y-axis. For example, there is a circled “1” in Table 1 which indicates that work package #4 (on the X-axis) must occur before work package #5 (on the Y-axis). The upper half of the matrix represents feedback activities, meaning that one would have to complete a later work package before completing an earlier package: complete work package #6 before #4. Taking these inputs, the program rearranges the work packages into a sequence to streamline the process; all the activities that feed into a later activity are completed prior to that activity. The strength of this program is that it recognizes and helps the planner handle iteration loops, when work package #2 must be completed before package #3 and work package #3 must be completed before package #2. To handle an iteration loop, the program has a built- in “tear” function to assist the user in minimizing the size of the iteration loop. Through this planning method, the team was able to identify a potentially dangerous iteration loop, that of redesign. If this loop had not been identified during the planning stage of this project, the team may have been caught in a cycle of designing, building, and testing multiple ovens in sequential order rather than create multiple prototypes designs at once and having only one redesign step, which the team will do in response to the end user testing. The program output is a partitioned sequence of events, shown in Table 2. The sequence was then taken to the stakeholders for their input. They helped the team determine any additional tasks that needed to be completed, and a “reality check” of timelines and task sequence. The team members were also engaged in the planning process by giving estimates on the time to complete the individual tasks. Figure 9 is a snapshot taken from the original project schedule generated in MS Project, which is the combined result of utilizing the DSM project planning technique, meetings with the stakeholders, and input from the project team. An updated project schedule is available in

2 The Design Structure Matrix- DSM. Ed. Steven D. Eppinger, Daniel E. Whitney, and Ali A. Yassine. June 2004. Massachusetts Institute of Technology and University of Illinois at Urbana-Champlaign. 13 Feb. 2005 <http://www.dsmweb.org>.


Appendix A with estimated resources. This schedule will be revised prior the beginning activities in Senior Design II.


05301 Design Structure Matrix

Work Subpackages 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27Needs assessment 1 1 1 1 1

Benchmark against comm. units 2 2 1

Determine requirements 3 3 1 1 1

Develop testing methodology 4 1 4 1 1 1 1 1

Order testing equipment 5

1 5 1

Research testing standards 6 6

Research Latin American countries 7 1 7

Research Latin environment 8 1 8 Research Latin diet 9 1 9

Research Latin production methods 10 1 10

Research Latin materials 11 1 11

Research Latin labor/skills 12 1 12 Concept development 13 1 1 1 1 1 1 1 1 13 1

Research low-cost ovens 14 1 1 14

Create multiple designs 15 1 1 1 1 1 1 1 1 1 1 15

Choose final concept design 16 1 16 1 1 1

Narrow down design choices 17 1 17 Build prototypes 18 1 1 1 1 1 1 1 18 Test prototypes 19 1 1 1 1 1 1 1 1 1 1 1 1 19

Feasibility assessment 20 1 1 1 1 1 1 1 1 1 1 1 20 Develop B.O.M. 21 1 1 1 1 1 21

Develop assembly drawings 22 1 1 1 1 1 1 22

Write instruction manual 23 1 1 1 1 1 1 1 1 1 1 1 23

Determine effects on society 24 1 1 1 1 1 1 1 24 1 1 1

Determine economic impact 25 1 1 1 1 1 25

Determine social impact 26 1 1 1 1 1 1 1 26

Determine environmental impact 27 1 1 1 1 1 1 1 27

Table 1: Design Structure Matrix

X-axis Y-axis

Work package 4 to be completed before work package 5.


DSM Program: Partitioned Sequence 1 Determine requirements 2 Research Latin American countries 3 Research Latin diet 4 Research Latin production methods 5 Research testing standards 6 Benchmark against comm. units 7 Research Latin environment 8 Research Latin materials 9 Research Latin labor/skills

10 Conduct needs assessment 11 Develop testing methodology 12 Order testing equipment 13 Research low-cost ovens 14 Concept development 15 Create multiple designs 16 Narrow down design choices 17 Build prototypes 18 Test prototypes 19 Choose final concept design 20 Feasibility assessment 21 Develop B.O.M. 22 Develop assembly drawings 23 Determine economic impact 24 Determine social impact 25 Determine environmental impact 26 Write instruction manual 27 Determine effects on society

Table 2: DSM Program Partitioned Sequence


ID Task Name Start Finish Predecessors

1 Preliminary Research Fri 12/10/04 Sun 1/9/05

2 Research Latin American countries, environment Fri 12/10/04 Fri 12/17/04

3 Research latin diet (carlos) Fri 12/10/04 Fri 12/17/04

4 Research testing standards Fri 12/10/04 Fri 12/17/04

5 Research low-cost ovens Fri 12/10/04 Sun 1/9/05

6 Research latin materials Fri 12/17/04 Fri 1/7/05

7 Research latin production methods Fri 12/17/04 Fri 1/7/05

8 Get commercial Sun 1/9/05 Sun 1/9/05

9 Conduct needs assessment Fri 12/10/04 Sun 1/9/05

10 Determine incident angles of sun, watt/sq meter Fri 1/7/05 Sun 1/9/05

11 Develop testing methodology Fri 12/10/04 Fri 12/17/04

12 Order testing equipment Mon 1/10/05 Wed 1/12/05

13 Create multiple designs Mon 1/10/05 Fri 1/14/05

14 Narrow down design choices Fri 1/14/05 Fri 1/14/05

15 Prepare for concept design review in class Fri 1/14/05 Fri 1/21/05

16 Purchase materials for prototypes Fri 1/14/05 Fri 1/21/05

17 Build prototypes Fri 1/14/05 Sun 1/23/05

18 Test and analyze prototypes and commercial units Mon 1/24/05 Sat 1/29/05

19 Determine cost of prototypes Mon 1/24/05 Sat 1/29/05

20 Feasibility assessment (use to determine final) Sun 1/30/05 Sun 1/30/05

21 Choose final concept design Sun 1/30/05 Sun 1/30/05

22 Failure analysis (for SD requirements) Mon 1/31/05 Fri 2/4/05

23 Develop B.O.M. Mon 1/31/05 Fri 2/4/05

24 Develop assembly drawings Mon 1/31/05 Sun 2/6/05

25 Send design to venezuela for user testing Fri 3/11/05 Fri 3/11/05

26 Prepare for PDR Tue 2/8/05 Fri 2/18/05

27 Based off user testing, incorporate any necessary design changes Mon 3/7/05 Fri 3/11/05

28 Build new prototype(s) Fri 3/11/05 Sat 3/19/05

29 Determine economic impact Sun 1/9/05 Sun 1/9/05

30 Determine social impact Fri 3/11/05 Sat 3/12/05

31 Determine environmental impact Sun 1/9/05 Sun 1/9/05

32 Write instruction manual Sun 1/9/05 Sun 1/9/05

33 Determine effects on society Sun 1/9/05 Sun 1/9/05

Figure 9: Original Project Schedule (MS Project)

The first step of the project was to research Latin American countries, and the knowledge gathered from that research is summed up in the following section. As the project’s baseline country is Venezuela, the research focuses on that country.


Research Venezuela: Environment

Venezuela is located on the northern coast of South America, north of Brazil, with a total area of 912,050 sq Km, or about twice the size of California3. The country's climate is principally tropical3, defined by Merriam-Webster as "of, being, or characteristic of a region or climate that is frost- free with temperatures high enough to support year-round plant growth given sufficient moisture.4" Temperatures rarely vary more than a few degrees; Caracas, the capital, has a yearly range of temperature from 18-20°C (64-68°F)3. Consequently, Venezuela's climatic zones are defined by rainfall rather than by differences in temperature3. Caracas, in the northern coastal lowlands, is relatively dry, with cumulative, average yearly rainfall readings reaching 150cm (58in)3; the solar oven prototypes will be tested in Rochester, NY, which has a total rainfall each year of 86.31 cm (33.98in) 5. In the coastal lowlands of Venezuela, the dry season extends from December to April, and the wet season covers the remainder of the year3. The Amazon region has no distinct dry season, and annual rainfall exceeds 200cm (78in), distributed evenly throughout the year3; therefore, it is important to note that the effect of rainfall on the solar ovens will vary greatly between different regions of the Latin American countries.

Venezuela: Economy and Manufacturing

Venezuela’s market economy is dominated by its principal natural resource, oil, which accounts for approximately a third of GDP, 82% of export earnings in 2003, and over half of the government's operating revenue 6. Venezuela is one of the world's largest oil producers, and belongs to the Organization of Petroleum Exporting Countries (OPEC)7. Other exports are iron ore, bauxite, aluminum, coffee, cocoa, rice, and cotton, textiles, apparel, beverages6. Venezuela also produces cement, tires, paper, fertilizer, and assembles cars for both the domestic and export markets6. The country’s main imports are manufactured goods especially machinery, vehicles, chemicals, and food6.

The country is not self-sufficient in most areas of agriculture. Venezuela imports roughly about two-thirds of its food need annually6. In 2003, U.S. firms exported

3 “Venezuela.” The World Factbook. 16 Dec. 2004. Central Intelligence Agency. 13 Feb. 2005 <http://www.cia.gov/cia/publications/factbook/geos/ve.html>. 4 “Tropical.” Merriam-Webster Online. 2005. 13 Feb. 2005 <http://www.m-w.com>. 5 “Monthly Climatology Graph.” The Weather Channel. 2005. 13 Feb. 2005 <http://www.weather.com>. Path: Local Forecast; 14623; Averages. 6 United States. Bureau of Western Hemisphere Affairs. Background Note: Venezuela. U.S. Department of State. Feb. 2005. Bureau of Public Affairs. 12 Feb. 2005 <http://www.state.gov/r/pa/ei/bgn/35766.htm>. 7 Feld, Lowell. “Venezuela Country Analysis Brief.” Country Analysis Briefs. 3 June 2004. Energy Information Administration. 12 Feb. 2005 <http://www.eia.doe.gov/emeu/cabs/venez.html>.


$373 million worth of agricultural products, including wheat, corn, soybeans, soybean meal, cotton, animal fats, and vegetable oils6.

The economically active population in Venezuela accounts for about 11.38 million of the entire population, known as "the labor force"3. Venezuela is a country with a high and extremely cost-effective labor force; the labor force is growing faster than the total employment opportunities. Of the total labor force, approximately 23% belongs to the manufacturing sector3.

Venezuelan factories manufactured a wide range of products, specialized rubber goods, new paper products, ships, aluminum, and wood, among others3. According to the team’s contact, Mr. Carrillo, the manufacturing sector of Venezuela is basic, in regards to the machines, transportation, and the skill of the laborers. As such, the team must design a solar oven whose construction does not require advanced tools, machines, and highly skilled labor.

Venezuela: Energy Consumption Rate and Water Pollution Although a major world producer of oil, Venezuela is facing a challenge in protecting its environment while encouraging the continued development and expansion of its fuel industry. Venezuela has a high-energy consumption per capita8, and the use of solar-powered devices would provide a means to reduce this energy consumption rate.

Venezuela is facing another large problem with the pollution of their water due to the oil production and oil spills, which affects the potable water supplies8. Because of this, seeking potable water in rural areas remains a daily challenge for those living in poverty conditions8. As such, the solar ovens must be able to pasteurize water, and provide a means for the users to know that the water has been pasteurized.

Venezuela: Diet

Though Venezuela has a flourishing oil industry, 80% of its population lives in poverty in rural areas, making one U.S. dollar as their daily income6. With the low income, the core foods of the Venezuelan diet include chicken, pork, beef, stews, soup, and pancakes9. One typical dish, Pabellón criollo, contains shredded meat with fried plantains, cheese, black beans, and rice9. The solar ovens, meant to replace cooking using firewood, must be able to cook these types of foods.

8 - - -. “Venezuela: Environmental Issues.” Country Analysis Briefs. July 2004. Energy Information Administration. 13 Feb. 2005 9 “Wine Brats: 6 in 6 South America.” Wine Brats. 2004. 13 Feb. 2005 <http://www.winebrats.org/education/grapejuice/9in9/soamerica.html>.


Specifications The team completed research on Venezuela, the team’s baseline Latin American country. The project sponsor and an ISE graduate student, Carlos Plaz, traveled during Christmas break to get the voice of the end users—the rural inhabitants of Latin America. As a result of this trip, the team was well prepared to specify the needs of the end users, which were the attributes desired in the solar oven design. The team had to then relate the customer requirements (attributes) with engineering requirements. This exercise was completed using the Quality Function Deployment Method, which is detailed in the next section.

Quality Function Deployment (QFD)

The Quality Function Deployment Method (QFD) has seven main steps, according Yousef Haik, author of "Engineering Design Process." The first step is to identify the customer requirements in terms of the product attributes. The team, along with the project sponsor and mentor, generated a list of attributes that the end users are believed to desire. The team sponsor and one of the graduate students, Carlos Plaz, had spoken with some end users in Venezuela. Therefore, the team felt confident that these represent the needs of the end users. The QFD method also requires that the team determine the relative importance of the attributes. This ranking was done via an Attribute Important Matrix using the Pairwise Comparison Technique shown in Table 3. The team then took the weights and assigned a rate to each level of weights; this is shown in Table 4. The final list of important attributes then needed to be ranked in order of importance, shown in Table 5. [Note: the most important attribute is low-cost, which corresponds with the main objective of the project- to develop a low-cost solar oven.] Thirdly, the QFD method requires that the attributes be ranked against competing products. For the solar oven project, the commercially available units are considered the competing products. The commercially available units will be tested at the same time as the team's prototypes; therefore, this full comparison will occur during Senior Design II. The fourth step of the QFD method is to draw a matrix of product attributes against engineering characteristics; this creates a measurable characteristic the design must meet. For example, the solar oven team cannot design to 'easy to use' without further clarifying this attribute as something measurable, such as the total setup time. The fifth step is to identify the strength of each attribute to the corresponding engineering characteristic(s). The strength of the relationship was measured through the following numerical values as recommended by Haik: 9 indicates a strong relationship, 3 indicates a medium relationship, 1 indicates a weak relationship, while no value indicates no relationship. The team must also identify the relationship between each of the engineering characteristics, and, finally, the team must set target figures for each characteristic. This helps identify if the design met that characteristic, and to what degree of success. As the testing has yet to occur as of the Preliminary Design Review, the object target values are not yet available. The information generated through the QFD method was inputted into a House of Quality (HOQ), as shown in Figure 10. The team utilized this information to help guide the concept development process; the team paid attention to the end user’s needs, the attributes.


The HOQ is nearly complete; the team will utilize the testing information gathered about the commercial units to complete the table. This work will be completed during Senior Design II.


Attribute Ranking

Table 3: Attribute Importance Matrix

If Weight Greater

Than Rate

0.160 10 0.130 9 0.120 8 0.100 7 0.070 6 0.050 5 0.035 4 0.020 3 0.010 2 0.000 1

Table 4: How to Rate Attributes


Order of Weights ATTRIBUTE Weight

Importance (10=high,

1=low)

1 Low cost 0.167 10 2 Reaches Temperature Quickly 0.136 9

3

Able to Pasteurize Water and Measure Completion of Pasteurization 0.129 8

4 Easy to use 0.121 8 5 Durable 0.106 7 6 Capable of cooking large meals 0.098 6 7 Retains heat 0.076 6 8 Easy to clean 0.053 5 9 High packing density (stackable) 0.038 4

10 Light weight 0.038 4 11 Easy to Store/ Portable 0.030 3 12 Made of eco-friendly materials 0.008 1

Table 5: Importance Order of Attributes


Figure 10: House of Quality


Feasibility Assessment The biggest concern the team had was to figure out how many units to prototype. The team went through a feasibility assessment exercise to address this question. The questions asked were in regards to the project at large in relation to the number of prototypes to build. Each question was ranked against the number of prototypes and the team’s confidence in being able to build that number of prototypes. The scale was from 0 to 3 with 0 having the lowest confidence level and 3 having the highest confidence level. The ratings the team assigned to each number of units is shown in Table 6. The resulting radar chart is shown in Graph 1.

Technical 1. Can the team test all the design features with this number of prototypes? 2. Is this enough prototypes to compare attributes through the testing process? Economic 1. Does the team have the money to complete the project? Schedule 1. Can the team meet the PDR requirements on time? 2. Can the team meet the EPA requirements? 3. Can the team meet the CDR requirements? 4. Does the team have enough time to make this many prototypes? Resources 1. Does the team have the necessary equipment and enough room to work? 2. Does the team possess an adequate number of team members?

# of Units T1 T2 E1 S1 S2 S3 S4 R1 R2 SUM Build 1 Unit 0 0 3 3 1 3 3 3 3 19 Build 2 Units 1 1 3 3 1 3 3 2 3 20 Build 3 Units 2 2 3 3 2 3 3 1 3 22 Build 4 Units 3 3 2 2 3 3 2 0 2 20

Table 6: Feasibility Numbers


Graph 1: Feasibility Assessment

0

1

2

3T1

T2

E1

S1

S2S3

S4

R1

R2

Build 1 UnitBuild 2 UnitsBuild 3 UnitsBuild 4 Units


Concept Development Basic Definition of Solar Oven

“A solar oven is basically an insulated box with an aperture that has a transparent glass or plastic cover (glazing). Solar ovens use the "greenhouse effect" to cook food. Short wavelength solar radiation passes through the glazing, and strikes the interior sides of the oven and the cooking pot. The interior sides of the oven can be either reflective or black. If reflective, the sunlight reflects onto the pot and heats it. If the sides are black, the sunlight is absorbed and then re-radiated at longer wavelengths, heating the oven interior and cooking the food. The glazing also helps to keep the heat in the box.10”

Three Main Types of Solar Ovens There are three main types of solar ovens: box, parabolic, and panel11. Each of these designs has certain attributes, which make them more feasible for large-scale manufacturing in countries with very basic manufacturing facilities. Each of these types will be discussed in more detail below. The first type is called the box cooker, which is considered to be the most frequent type of solar oven constructed for individual use; it is easy to use and to build11. The box oven is a basic box, generally rectangular, made with an attached interior box covered with transparent glass or plastic, and nearly limitless reflectors attached. These reflectors are typically attached via a hinge. The box type ovens are sometimes double-walled, thereby creating insulation to retain the heat. The box oven takes longer to heat up to cook the food12, but tends to retain the heat longer than the other solar cookers types.

The second type is called the parabolic cooker. The parabolic cooker is harder to build, requires direct sunlight, and can be dangerous to use due to the potential exposure of the user to the concentrated sunlight10. The parabolic cooker also requires more direct sunlight, which makes it very inconvenient to use; to keep the sunlight concentrated on the pot, these types of cookers must be adjusted every 10 to 15 minutes11. These types of cookers were not considered for this project because of the potential harm to end-users and the high cost of manufacturing. The third type of solar oven is called the panel cooker. The panel cooker is the simplest and cheapest12. The panel cooker is mainly comprised of reflective panels to

10 “Energy Savers: Solar Cooking Devices.” U.S. DOE Energy Efficiency and Renewable Energy Home Page. 17 June 2004. U.S. Department of Energy. 14 Feb. 2005 <http://www.eere.energy.gov/consumerinfo/factsheets/db5.html>. 11 Dwyer, Tamara. “Solar Cooking: Types of Solar Ovens.” Solar Cooking Pages. 24 May 1999. 14 Feb. 2005 <http://www.exoticblades.com/tamara/sol_cook/types.html>. 12 Suharta, Herliyani, K. Abdullah, and A. Sayigh. “The Solar Oven: Development and Field-Testing of User-Made Designs in Indonesia.” Solar Energy. Vol. 64. 4-6. Great Britain: Elsevier B.V., 1998. 121-32. Science Direct. 2005. 13 Feb. 2005 <http://www.sciencedirect.com>.


reflect the sunlight12. The pot is sometimes covered with a glass bowl or plastic to trap the heat19. However, it is inconvenient due to its potential instability during windy weather11.

Commercial Units Part of the project is to benchmark against commercially available units. The purpose of the benchmarking is to compare the prototype temperatures to a proven design. Also, the study of the commercial units is an excellent way for the team to learn about solar ovens, their construction, and the attributes that made the commercial units successful. The first unit is called Global Sun Oven®, a high performance solar box oven. It has a strong plastic box that is both durable and simple to clean. It features a self-sufficient leveling leg to maintain the oven's maximum exposure to the sun. It attains temperatures of 360 to 400°F (182-204°C). The unit weighs 21 pounds. This design also has a carrying handle, making it portable. According to the product’s website, the oven is used in daily in 126 countries, despite the high cost of $210 (USD). [13] The second unit, the SOS Sport®, is a durable and lightweight (11 pounds) solar oven. The oven costs $120 (USD), which makes it a much cheaper alternative to the Global Sun Oven®. It is exceptionally convenient for its ease of use, portability, and waterproof resistance. It is a very large oven that can contain two pots and reaches 275 0 F temperature; this makes it convenient for making large meals. However, the design is certainly not durable, as the oven broke during transport; this is certainly not acceptable for an oven that claims to be “one of the best solar ovens developed in the past 25 years.” [14] The team’s third commercial unit, The Suncook,15 has a plastic body, two lids of tempered glass, and aluminum mirrors to reflect the sun. The walls act as “compound parabolic concentrators” to minimize the time spent by the user readjusting the oven’s orientation. The Suncook is easily stored as all the parts collapse into the plastic body. Unfortunately, the design is far from portable at 26 pounds. The total cost of this commercial unit was $220 (USD). [15]

13 “Global Sun Oven.” Beulah Land. 14 Feb. 2005 <http://www.beulahland.com/sunoven/index.htm>. 14 Solar Oven Society. “The SOS Sport.” The Kerr-Cole Sustainable Living Center. 26 Mar. 2004. 14 Feb. 2005 <http://solarcooking.org/bkerr/sport_brochure.htm>. 15 Sun Co., Portugal, www.sun-co.pt. Brochure.


The Solar Oven Generations

Suharta et al (1998) write in their paper, “The Solar Oven: Development and Field-Testing of User-Made Designs in Indonesia,12” about their work which attempts to design simple ovens for the end user to create themselves. The authors feel that this is the missing link with widespread adoption of solar oven use. As such, the authors went through four “generations” of solar oven designs.

The first generation oven was a very simple design, built only to absorb the solar radiation reflected form the sun and to store the energy inside the oven walls. The opening of the box, located on top, was covered with a transparent material to act as an insulator. The box was also equipped with a reflector attached to the lid, which served to enhance the amount of solar rays reaching the interior; the rays would hit the reflector and bounce back into the box, thereby greatly increasing the amount of solar energy the interior received. Additionally, this cover was solid and could serve to contain the heat after cooking was complete. This design was capable of creating a temperature of 80°C, which meet the water pasteurization temperature 65°C (149° F)16.

Cost effectiveness and performance improvements were the crucial objectives of the second generation. As with the first generation, these ovens were to be built by the end users; therefore, the availability of material and simplicity of construction tools were heavily considered. The other additions in the second generation included the following: a 450 tilt to the oven walls and a door located on the side rather than the top to minimize heat loss. This design was capable of reaching a temperature of 160°C, twice that of the first generation.

The third generation focused on reducing the height of the oven, which meant that additional solar heat might be exploited for heating the food rather than heating the oven body itself. The design in the third generation reduced cost while adding durability, such as using bamboo rod instead of an iron rod to support the reflector.

The fourth generation further reduced its size, while changing the materials used significantly. The fourth generation used three layers of glass to insulate the oven, silicon rubber sealant for the joints, and an aluminum sheet painted black for the absorber plate. Both the third and fourth generations max temperature was 175°C.

The RIT Solar Oven Team considered the four generations of solar cookers, as mentioned above. Essentially, the team is taking lessons- learned from all four generations to come up with designs. However, the team is concerned with a few attributes that Suharta et al appear not to be such as durability and the use of recycled materials. It is not the belief of the team that the use of glass is durable. Suharta et al added a very thin layer of aluminum in the fourth generation, but did not mention the origin. The team plans to utilize recycled material as the aluminum source. The team chose to incorporate a plethora of the ideas generated by Suharta et al. Instead of designing in four generations, the team utilized these ideas in the construction of three prototypes.

16 Solar cooking archive. Solar cookers International. 17 Feb. 2005 <http://http://www.solarcooking.org/>.


Materials Selection The team used the CES Selector software, which has information on materials, including properties and pricing. The numbers generated by the software are only representative, and, therefore, do not necessarily correspond to the specific material used during the construction of the prototypes. The information was, nonetheless, useful to determine which materials have the most potential to meet the needs of the end users. The following sections detail how the team made the materials choices.


Main Construction Material

The information in this section will validate the team’s material choices. Graph 2 shows the relationship of thermal conductivity to price. Thermal conductivity is a measure of how well the oven will retain heat. It relates directly to the efficiency of the oven, and is, therefore, an important property. A material with a low value of thermal conductivity will not conduct heat collected inside the oven to the outside. The only feasible alternatives to wood are concretes and polymer foam. The team did not consider polymer foam, as it is difficult to manufacture and cannot be guaranteed to be available in all Latin American countries. Again, concrete is too heavy. Therefore, wood is the best choice of materials when comparing price to thermal conductivity.

Graph 2: Price vs. Thermal Conductivity


Graph 3 shows density vs. thermal conductivity. As materials with low conductivity and low density are desirable, the colored region of the graph contains the possible candidates. The least dense materials are foam, followed by wood. Foams were eliminated as a choice due to local availability.

Graph 3: Density vs. Thermal Conductivity


The team has been charged with designing a durable solar oven. The team defines durability as being weather resistant; the solar oven must not degrade due to ultraviolet rays and must be water resistant. Graph 4 shows the UV resistance for the three types of wood as being nearly the same and “good” at the same price level. The only better options are concretes, limestone, or cement-bonded particleboard; all three options are too heavy for this application.

Graph 4: Price vs. UV Resistance


As shown in Graph 5, the water resistance for woods is merely average, but the only other choices are concrete, iron, or marble. All of these are either too heavy or expensive. As such, wood is the best choice for the solar ovens. Fortunately, there are methods to make wood more weather resistant, such as lacquers and sealants, but these may be costly and pose certain health risks; the team will need to explore these options during Senior Design II.

Graph 5: Price vs. Fresh Water Resistance


Wood Selection

The team had three main options for wood: particleboard, medium density fiberboard (MDF), or plywood. To determine which variation of wood was the best, the team analyzed density, price, specific heat, thermal conductivity, thermal expansion, environmental resistance, flammability, wear, protection against freshwater and seawater, and UV resistance. Table 7 includes only the properties whose values differed for each material. Thermal Properties The team analyzed three types of thermal properties: specific heat, thermal conductivity, and thermal expansion. The specific heat, how much heat is needed to raise the temperature of the material by 1°C, is the same for all three materials, 0.3965-0.4084 Btu/lb*F. Thermal conductivity was the same for all three materials, 0.1733-0.2022 Btu*ft/h*ft^2*F, and is an indication of how much heat will be lost or gained through the material. However, the three materials differed in the thermal expansion property. Plywood has lower coefficient of thermal expansion (3.333-4.444 microstrain/°F) than MDF and particleboard (5.556-8.333 microstrain/°F). This means that plywood will hold its initial shape when exposed to high temperatures better than the other two materials. The solar ovens will not be subject to extreme temperatures; this is not a property with which to be concerned. If the oven wall were 20 inches long and subjected to 400°F, the wall will expand by approximately 0.067 inches. The design has fairly large tolerances, and, as such, a thermal expansion of 0.067 inches will not affect the integrity of the structure. Other Properties Particleboard has the lowest density, followed by MDF and then plywood. Therefore, an oven made from plywood will be the heaviest. In terms of cost, the wood is priced in increasing order: particleboard, MDF, plywood. According to the software, all three materials have the same environmental resistance, poor flammability, wear, and only average protection against fresh and seawater. The UV resistance is set at "good." Therefore, particleboard is the best choice for the prototypes as it is the least expensive and has the lowest density. The team will be investigating methods to make the wood more weather resistant, and if these additives are toxic to the environment and to the solar oven users.

Density (lb/in^3) Price (US$/lb) Thermal Expansion

(microstrain/°F) Types of Wood

Low High Low High Low High Particleboard 0.0163 0.0271 0.1663 0.416 MDF 0.0217 0.0325 0.3327 0.416

5.556 8.333

Plywood 0.0253 0.0289 0.4158 0.832 3.333 4.444

Table 7: Material Properties of Wood


Metal for Reflectors

The reflector material chosen for the solar ovens is a critical choice. The material must be both economical and lightweight. John Harrison wrote in his paper, “Investigation of Reflective Materials for the Solar Cooker,17” about numerous materials analyzed for use in solar cookers. There were four economically feasible options, but the most promising material was printing plates. Publishing companies use aluminum sheets, 0.3mm thick, in the printing process; these printing plates have a reflectivity rating of 86%17. The team contacted Mr. William Pope of the RIT Printing Applications Laboratory18 to learn more. According to the team’s contact, publishing companies usually use only one side of the sheet during the printing process, where images are implanted onto the metal. As such, the reverse side of the printing plates would be ideal to use as reflectors on solar ovens. The team ensured that there are printing presses in Venezuela by checking with the team’s contacts. Furthermore, the team hypothesizes that every country has a printing press of some type, whether it is for government or private industry publications. Further investigation on the widespread availability of offset printing presses in all Latin American countries will occur during Senior Design II.

17 Harrison, John. "Investigation of Reflective Materials for the Solar Cooker." Solar Energy Web Site. 24 Dec. 2001. Florida Solar Energy Center. 15 Feb. 2005 <http://http://www.fsec.ucf.edu/ Solar/PROJECTS/SolarCooker/reflectivematerialsreport.pdf>. 18 Pope, William; Manager, Technology Transfer; Printing Applications Laboratory; RIT; [email protected].


Graph 6 shows the price vs. density for metals. The metals under 50 USD/lb are aluminum foams, aluminum alloys, and cast iron. As stated previously, it is questionable at best if the foams are available locally in Latin American countries, and if they are low cost. Cast iron may be available, but it is much more dense than aluminum and not suitable for use as a reflector.

Graph 6: Price vs. Density (Metals)


Graph 7 shows the price (USD/lb) vs. UV resistance. Aluminum has very good UV resistance, just like most metals, and is suitable for the application as a reflector.

Graph 7: Price vs. UV Resistance


Cover Material

Another material that the team needed to choose was that of a transparent cover. Nearly all commercial units and homemade units utilize a transparent material on the top of the solar oven. Its purpose is to trap heat inside the oven while allowing the sun to continue to heat the inside. Graph 8 shows the price of materials on a scale from optical quality to opaque. The solar oven needs to use a material that is either transparent or of optical quality. As such, the other materials in Graph 8 are disregarded because they are translucent or opaque: PVC, particleboard, and concrete. One of the most commonly available materials, acrylic (labeled “PMMA-unfilled” in the graph) rates at transparent and has a fairly low cost: 0.9897-1.375 USD/lb. The density of acrylic is between 0.04191-0.04408 lb/in^3. The thermal properties examined were thermal conductivity and thermal expansion. Thermal conductivity is important so the heat generated within the oven cavity stays in that cavity and does escape to the outside environment; a lower value is better. Graph 9 shows the price vs. thermal conductivity where acrylic is the second least conductive material, with foam being the least. Foam has been eliminated in the materials selection process due to lack of local availability: acrylic is the obvious choice. Acrylic has a much smaller value for thermal expansion than particleboard: 40-90 microstrain/°F versus 5.556-8.333 microstrain/°F, respectively. This may be something the team would need to look into since the cover may retain more of its shape than the particleboard under the same conditions; the cover may be too small if the oven expands to the maximum amount. The other properties of acrylic that were examined include the water resistance and flammability. Acrylic is durable, meaning that it has very good water and UV resistance. It has poor flammability. The team will also have to determine what effects the scratching of the material will have on performance, as well as other potential issues. These include the weather resistance of acrylic, including water absorption. The team will need to address how the end users would clean the acrylic and how the end users would replace the acrylic if it were to break. The investigation into these issues will occur during Senior Design II.


Graph 8: Price vs. Transparency


Graph 9: Price vs. Thermal Conductivity ('Clear' Covers)

Inside Liner Material

The team also had to choose a material to line the insides of the oven. Many of the sources suggested using matte black paint19. The team is currently investigating black paint, Formica, and other materials. The concern from the team’s sponsor is that black paint would merely ‘trap’ any bacteria. It is for this reason that the team is investigating the use of Formica in the prototypes.


Initial Concepts The goal of the project is to adapt current designs to suit the needs of the end users. This means that the designs must utilize locally available materials, production methods, and labor. The concept generation was fairly simple as a result. The team members each reviewed numerous papers and websites19. The team members were then charged to come up with their own designs, or choose which of the ones reviewed they felt had the most potential to meet the needs of the end users. During this design phase, the team generated six box cooker designs, three add-on features suitable for any design, one stand to hold a cooker, and one pyramid design. The project sponsor expected three designs to be prototyped; with only seven full designs, it was not necessary use a complicated method to choose the most promising designs. The team utilized a voting technique; each team member was given two votes. The results of the vote and the meeting with the project sponsor resulted in the decision to build two box types and the pyramid cooker. The designs chosen are highlighted in the table below in yellow.

Designs Explanation # of Votes Box 1 0 Box 2 0 Box 3

Basically the same box type

1 Box 4 Tilted top with 4 reflectors 3 Box 5 Flat top, 4 reflectors 1 Box 6 Flat top, 1 reflector 6 Pyramid Large % metal 3

Table 8: Voting Results

The three designs the team prototyped is in the next session, along with the Bill of Materials (BOM) for each design. The team included the cost of the reflective materials in the BOM. As the team has not yet researched how much it would cost to purchase the used printing plates, the project sponsor is requiring the team to consider the cost per plate at $1 (USD).

19 Solar Cooking Archive. Solar Cookers International. 17 Feb 2005 <http://www.solarcooking.org>


Four Reflector Box

This design was heavily influenced by the book, “Heaven’s Flame: A Guide to Solar Cookers,20” which discussed the ideal materials and the use of a door. The book mentioned that wood, sheet metal, or cardboard should be used for the oven box, while plastics should be avoided. Radabaugh also suggests designing the oven with an access door in the back for three reasons. First, the user can avoid sun glare. Secondly, the user is not required to reach through the reflectors or to have to remove them to access the cooking pot. Thirdly, the acrylic or glass on top of the box is better protected from accidental damage. The main advantages of this design are the rear access door, good insulation, and a large reflectance area. Additionally, it is a proven design. The Bill of Materials is presented below and shows a total material cost for this unit of $33.67.

Figure 11: Four Reflector Box

20 Radabaugh, Joseph. Heaven's Flame: A Guide to Solar Cookers. 1991. 2nd ed. Ashland, OR: Home Power, 1998.


Four Reflector Box

Item # Qty Length, in Width, in Material Unit Cost ($) Total Cost ($) 1 4 18.00 18.00 Reflector 0.47 1.86 2 4 10.00 1.50 Reflector strips 0.02 0.09 3 1 15.25 13.00 Inside Bottom 0.69 0.69 4 1 14.00 7.75 Inside Front 0.38 0.38 5 1 14.00 2.75 Inside Back 0.13 0.13 6 2 13.00 11.25 Inside Side 0.51 1.01 7 1 19.50 17.00 Outside Bottom 1.15 1.15 8 1 18.25 9.50 Outside Front 0.60 0.60 9 1 18.25 14.00 Outside Back 0.88 0.88 10 2 17.00 14.00 Outside Side 0.82 1.65 11 1 12.75 2.00 Door Bottom 0.09 0.09 12 1 12.75 2.00 Door Top 0.09 0.09 13 1 14.00 8.50 Door Front 0.41 0.41 14 1 12.75 7.25 Door Back 0.32 0.32 15 2 8.50 2.00 Door Side 0.06 0.12 16 1 2.00 0.50 Barrel bolt 2.19 2.19 17 2 1.50 1.50 Door Hinge (with screws) 0.60 1.19 18 4 1.50 1.50 Reflector hinge (with screws) 0.60 2.38 19 1 19.50 17.50 Acrylic safety glazing 4.92 4.92 20 4 1.50 0.50 Spacers 0.00 0.01 21 1 N/a N/a Glue 0.96 0.96 22 16 0.19 0.50 Stove bolt 0.11 1.81 23 1 14.00 2.75 Inside Back Formica 0.68 0.68 24 2 11.50 11.25 Inside Sides Formica 2.30 4.60 25 1 14.00 7.75 Inside Front Formica 1.93 1.93 26 1 15.25 13.00 Inside Bottom Formica 3.52 3.52

Total cost ($) 33.67

Table 9: Bill of Materials Four Reflector Box


Single Reflector Box

This was one of the most common designs the team found when researching solar ovens, only the designs found were constructed of cardboard. The team’s design was built with particleboard. To facilitate easy adjustment to capture the sun’s rays, a slider was added to the side. This design is easy to build, fairly inexpensive, portable, and can retain heat when the lid is closed. The total cost for this unit is $15.38, which is shown in Table 10.

Figure 12: Single Reflector Box


Single Reflector Box

Item # Qty Length, in Width, in Material Unit Cost ($) Total Cost ($) 1 4 15.00 15.00 Reflector 0.32 1.29 2 1 14.75 14.75 Outside Bottom 0.75 0.75 3 1 14.75 14.75 Outside top 0.75 0.75 4 1 14.00 8.00 Outside Back 0.39 0.39 5 1 14.00 8.00 Outside front 0.39 0.78 6 2 14.00 8.00 Outside side 0.39 0.78 7 4 13.25 1.00 Plastic support 0.05 0.18 8 1 13.50 2.38 Cover support 0.11 0.11 9 2 1.50 1.50 Door Hinge (with screws) 0.60 1.19 10 2 1.50 1.50 Hinge (with screws) 0.60 1.19 11 2 13.25 13.25 Plastic sheets 0.16 0.32 12 1 N/a N/a Glue 0.96 0.96 13 1 1.30 0.25 Screw 0.04 0.04 14 1 8.00 2.00 Screw 0.05 0.05 15 2 13.25 8.00 Inside sides Formica 1.88 3.77 16 1 13.31 13.31 Inside bottom Formica 3.15 3.15


Table 10: Bill of Materials, Single Reflector Box


Pyramid Reflector Box The pyramid reflector box is a combination panel and box cooker. It is a panel cooker because the reflective material extends to the base of the design. However, panel cookers do not typically have any box around them, which is why most panel cookers are unsteady during windy conditions. As such, the team decided to combine the two types of cookers together into this design. Also, the team had already chosen a reused material, the aluminum printing plates, for a metal. This design was thought to be less expensive than the other two. The total cost is $19.65, as shown in Table 11.

Figure 13: Pyramid Reflector Box


Pyramid Reflector Item # Qty Length, in Width, in Material Unit Cost ($) Total Cost ($)

1 3 24 18 Reflector 0.62 1.86 2 1 18 12 Reflector 0.31 0.31 3 1 18 18 Outside Bottom 1.12 1.12 4 1 18 18 Outside top 1.12 1.12 5 1 17.38 7.5 Outside Back 0.45 0.45 6 1 17.38 7.5 Outside front 0.45 0.45 7 2 17.38 7.5 Outside side 0.45 0.45 8 3 10 1 Continuous hinge nickel 1.96 5.88 9 1 N/a N/a Glue 0.96 0.96 10 18 0.1875 0.5 Stove bolt 0.11 1.98 11 1 16.875 16.875 Inside Bottom Formica 5.06 5.06


Table 11: Bill of Materials Pyramid Reflector


Develop Testing Methodology One of the major challenges for this project is the environment of Rochester, NY: its difference in climate from Venezuela, difference in latitude and longitude, and lack of sunshine. As such, the team must essentially recreate the energy of the sun to test the effectiveness of the solar oven designs. The team referenced Dr. Funk’s paper, “Evaluating the International Standard Procedure for Testing Solar Cookers and Reporting Performance,21” when designing these tests. He details the conditions under which the solar ovens should be tested. For example, wind speeds should be under 1 m/s (2.2 mph) at all times. The wind speed in Rochester, NY is 9.6 miles per hour22, far greater than the ideal testing environment. Other issues arose including the ambient temperature. Due to the difference in environments, the team is using the standards as a guideline to develop the testing methodology. The team will conduct three tests in total: a laser test, an indoor test, and an outdoor test.

Laser Test The team will shine lasers onto the reflectors to determine the angle of the reflectors. The incident angle of the sun in Venezuela is vastly different that the angle in Rochester, NY. The team first had to determine the angles in Venezuela, which was done with the Square 1 software the team had purchased. Figure 14 is a visual representation of how the software determines angles. The object in the center is a sample solar oven, and the big yellow dot is the sun. The sun rotates on the axis labeled from 07 to 18, which are the hours of the day. This axis represents the azimuth angle of the sun, defined as the angle measured clockwise (eastward) in a horizontal plane, usually from north (true north, Y-north, grid north or magnetic north)23. The sun is at its furthest points apart on December 22nd and July 21st. The data generated from the Square 1 software is shown in following tables: Table 12 for the winter data and Table 13 for the summer data.

21 Funk, Paul A. “Evaluating the International Standard Procedure for Testing Solar Cookers and Reporting Performance.” Solar Energy. Vol. 68. 1. 2000. 1-7. ScienceDirect. 2005. Elsevier B.V. 13 Feb. 2005 <http://www.sciencedirect.com>. 22 "Wind- Average Wind Speed- (MPH)." NOAA Satellites and Information. 23 June 2004. National Climatic Data Center. 17 Feb. 2005 <http://lwf.ncdc.noaa.gov/oa/climate/online/ccd/avgwind.html>. 23 Photonics directory. 2005. 17 Feb. 2005 <http://www.photonics.com/dictionary/lookup/XQ/ASP/url.lookup/entrynum.350/letter.a/pu./QX/lookup.htm>.


Figure 14: Output of Square 1 Software

Table 12: Winter Data from Square 1 Software


Table 13: Summer Data from Square 1 Software


Indoor Test The team contacted Dr. Raffaelle, a professor in the RIT Physics Department who is doing research on silicon solar cells. His setup mimics the sun’s energy to test one solar cell at a time with 4 projector lamps arranged in a square array. His design is meant to help measure the efficiency of silicon solar cells. The team created a testing stand with an array of 9 projector lamps, each connected to a variable voltage controller; this setup is shown in Figures 15 and 16. The team will use a silicon solar cell borrowed from Dr. Raffaelle to measure the wattage per meter squared in the team’s test setup. The team will experiment with the number of lamps on, and at what distance from the solar ovens. The team is currently working with Dr. Raffaelle to determine how to measure the output from the solar cells (voltage and current) and relate that output to the watts per meters squared. Dr. Funk states in his paper, referenced above, that the sun’s energy ranges from 400 W/m2 to 1100 W/m2 depending the exact time, date, location, and weather conditions. The team will arrange the setup in order to reach a uniform distribution of the power within that range.

Figure 15: Testing Stand for Lamps


Figure 16: Lamp Setup on Testing Stand

Outdoor Test

As the weather conditions in Rochester do not closely compare with the conditions in Venezuela, the outdoor test is merely to compare the commercial and prototype units.


Future Work The team has completed three major hurdles for the project: concept generation, prototype building, and establishing a testing methodology. The main goals for next quarter are to test the prototypes and commercial units, analyze the data, and redesign based off the data. The project sponsor and Carlos Plaz, an ISE graduate student, will be traveling to Venezuela in March to do some user testing with the prototyped units. They will also be confirming the availability of certain materials. This trip will provide the team with the necessary “voice of the customer” so the team can design to meet their needs effectively. It is the hope of the team and the project sponsor that through diligent work and with the use of engineering methodology that a suitable design will ensue from this project. The team is well along that path towards a successful design.

Acknowledgements

The team wishes to acknowledge the contributions of the following individuals for guidance during Senior Design I: Dr. Carrano, Dr. Thorn, Dr. Raffaelle, Carlos Plaz, Mr. Wellin, Dr. Mozrall, and Chris Wood.


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Appendix A: Updated Project Schedule ID Task Name Start Finish Resource Names

1 Preliminary Research Fri 12/10/04 Sun 1/9/05

2 Research Latin American environment Fri 12/10/04 Fri 12/17/04 Jon Stiener

3 Research latin diet (carlos) Fri 12/10/04 Fri 12/17/04 Jon Stiener

4 Research testing standards Fri 12/10/04 Fri 12/17/04 Otman El Allam

5 Research low-cost ovens Fri 12/10/04 Sun 1/9/05 Group

6 Research latin materials Fri 12/17/04 Fri 1/7/05 Emma Fulton,Josh Bates

7 Research latin production methods Fri 12/17/04 Fri 1/7/05 Josh Bates,Emma Fulton

8 Get commercial units Sun 1/9/05 Sun 1/9/05

9 Conduct needs assessment Fri 12/10/04 Sun 1/9/05

10 Determine incident angles of sun, watt/sq meter Fri 1/7/05 Sun 1/9/05 Natasha Privorskaya,Joe Massa

11 Develop testing methodology Fri 12/10/04 Sun 1/30/05 Group

12 Create multiple designs Fri 1/14/05 Fri 1/14/05 Group

13 Narrow down design choices Fri 1/14/05 Fri 1/14/05 Group

14 Order testing equipment Mon 1/31/05 Sat 2/5/05 Jon Stiener,Josh Bates,Natasha Privorskaya

15 Purchase materials for prototypes Fri 1/21/05 Mon 1/24/05 Otman El Allam,Emma Fulton

16 Determine cost of prototypes Tue 1/25/05 Fri 2/18/05 Otman El Allam,Emma Fulton

17 Build prototypes Mon 1/24/05 Sun 2/13/05 Josh Bates,Jon Stiener

18 Make thermocouples Mon 1/24/05 Sun 1/30/05 Otman El Allam,Emma Fulton,Natasha Privortskaya

19 Create testing stands Mon 1/31/05 Fri 2/11/05 Otman El Allam,Emma Fulton,Jon Stiener

20 Prepare for concept design review in class Mon 1/31/05 Thu 2/17/05 Otman El Allam,Emma Fulton

21 Test prototypes & commercial units Mon 2/14/05 Thu 3/24/05 Group

22 Thermal analysis using Excel Mon 2/14/05 Sun 3/6/05 Natasha Privortskaya

23 Statistical analysis of thermal differences Mon 2/14/05 Sun 3/6/05 Otman El Allam,Emma Fulton

24 Square 1 software-incident angles Mon 2/14/05 Fri 2/18/05 Jon Stiener

25 Laser Testing (determine angle of reflector) Mon 2/14/05 Thu 3/24/05 Group

26 Choose final concept design Fri 2/11/05 Fri 2/11/05 Group,Brian Thorn,Andres Carrano,Carlos Plaz

27 Prepare for PDR Thu 2/17/05 Fri 2/25/05

28 Create Powerpoint Thu 2/17/05 Tue 2/22/05 Otman El Allam,Emma Fulton

29 Practice Presentation Thu 2/17/05 Fri 2/25/05 Group

30 Compile binder Thu 2/17/05 Fri 2/25/05 Emma Fulton

31 Write report Thu 2/17/05 Fri 2/25/05 Emma Fulton

32 Testing Methodology Thu 2/17/05 Fri 2/25/05 Otman El Allam,Natasha Privortskaya

33 Summation of research Thu 2/17/05 Fri 2/25/05 Group

34 Meet on Sunday to compile/write Thu 2/17/05 Thu 2/17/05 Group

35 EPA Report Info Fri 2/18/05 Sun 3/20/05 Group

36 Determine social impact Fri 2/18/05 Sun 3/20/05

37 Determine effects on society Fri 2/18/05 Sun 3/20/05

38 Determine economic impact Fri 2/18/05 Sun 3/20/05

39 Determine environmental impact Fri 2/18/05 Sun 3/20/05 Chris Wood

40 Begin writing user instructions Fri 2/18/05 Sun 3/20/05

41 Develop user testing methods Fri 2/18/05 Sun 3/20/05

42 Send design to Venezuela for user testing Thu 3/10/05 Fri 3/11/05

43 Redesign ~user testing and benchmarking Mon 3/14/05 Fri 3/18/05 Group

44 Build new prototype(s) Sat 3/19/05 Wed 3/23/05

45 Test redesign Wed 3/23/05 Wed 3/30/05 Emma Fulton,Otman El Allam,Natasha Privorskaya

46 Computer modeling using Square 1 software Wed 3/23/05 Wed 3/30/05 Jon Stiener

47 Thermal analysis using Excel Wed 3/23/05 Wed 3/30/05 Natasha Privortskaya

48 Finite Element Analysis (stress, strain) Wed 3/23/05 Wed 3/30/05 Josh Bates

49 Feasibility assessment Wed 3/23/05 Wed 3/30/05 Group

50 Develop B.O.M. Wed 3/30/05 Fri 4/1/05

51 Develop assembly drawings Wed 3/30/05 Sun 4/3/05 Josh Bates,Jon,Natasha

52 Write instruction manual Sun 4/3/05 Tue 4/12/05

53 Write final paper for EPA Mon 2/21/05 Sun 4/10/05 Group,Andres Carrano

environmental protection agency p3 grant for the creation...

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