Mpala, Kenya: A Summer of Teaching, Research, and Learning A Summary of My Experience Ishani Sud Project Conducted Under the Guidance of Dr. Soboyejo Abstract The purpose of the project was to introduce engineering solutions to two villages in Kenya. This involved extensive planning and research at Princeton University prior to the trip, followed by six weeks of implementation within the Kenyan community.

1. How To Build A Box Solar Cooker
2. Solar Cooker Project High School
3. Solar Box Cooker Project Manual

Now You're Cooking! Building a Simple Solar Oven. Easy-to-build solar oven that you will be making and testing in this project. The oven is a box within a box. The inner box is covered with a plastic window (made from a heavy plastic cooking bag available at most grocery stores). In this comprehensive solar oven guide we cover all the details, review the best. A solar cooker is also a fun project to do with kids and makes a great school.

One of the main purposes was to introduce the communities to solar solutions, specifically the use of a solar oven instead of wood fueled stoves. The solar oven was developed at Princeton University by Ishani Sud and Lauren Wang under the supervision of Dr. To facilitate the technology transfer, the local schools were chosen as the vehicle of delivery. Two schools were chosen.

At one school, the Mpala school, standard one and standard two students were taught; at the other school standard seven and standard eight students were taught. Julianne Davis was the primary teacher for the younger class and Ishani Sud was the primary teacher for the older class.

Both classes had slightly more than twenty-five students. Teaching took place two days a week at each school, focusing on issues like conservation, solar energy, and renewable vs. Nonrenewable resources. The older student’s were able to explore more complex topics including the relationship between the earth and the sun.

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The older students also spent one additional day each week physically building the solar ovens. Small experiments were conducted throughout the building process to help students understand specifically how the ovens functioned. The final step involved a “parent-day” during which the students shared with the parents what they learned. The older students also showed their parents how the solar ovens work.

Care was taken to explain the oven’s usage in a culturally sensitive manner, explaining how local recipes can be adapted for cooking in the solar oven. Several other projects were also started, including solar charged lanterns for lighting in an ecotourism lodge and solar panels for charging batteries for a mobile clinic. Designs were also developed for a solar/manual pool pump and a solar hot water heater. Purpose The objectives of the project were to introduce engineering solutions to two villages in Kenya and educate local school children about solar energy and conservation.

The main solar solution provided was that of the solar oven. The solar oven project began within the framework of the food group which was part of the Global Science Club at Princeton University. It was designed and developed by Ishani Sud and Lauren Wang under the guidance of Dr. The design objective was to create a solar powered cooking/drying apparatus for rural areas at minimum cost. Therefore, the focus was on using locally available materials. In addition to designing the ovens, a main objective was delivering the technology in a culturally sensitive manner that the locals could accept and incorporate into their own lives. Planning Curriculum Two different classes were selected for instruction.

The classes were at two different schools. One class consisted of standard 1 and standard 2 students. The other consisted of standard 7 and standard 8 students.

The goal was for the students to understand how the solar ovens worked and also understand why they are a better option than burning wood. Curriculum was developed using standard templates for teaching. Nancy Rubenstein, a registered teacher in the United States assisted with curriculum development. Ishani Sud prepared the curriculum for the older students, and Julliane Davis developed the curriculum for the younger students. The conceptual topics to be covered included conservation, food webs, the solar system, and renewable vs. Nonrenewable resources.

For the older students, a series of demonstrations were developed to qualitatively introduce the concept of material selection for the solar ovens to the students. These included: black metal vs. White metal in the sun, metal vs. Wood in the sun, and glass allowing light through. Solar Ovens FIGURE 1.

Solar Cooker Basic Design Figure 1 shows the basic solar cooker design. For this project, the cooker design was built and tested at Princeton, NJ. However, building with the dimensions and materials used in Princeton was not practical in Kenya, so modifications were made. The general idea was to find the best material available for each of the solar cooker components while taking into account cost and availability. The purpose of component A in Figure 1 is to optimize reflection of sunlight into the solar cooker. For component A the most reflective locally available material within cost restraints should be selected. Component B should be a highly transmissive sheet that allows light through, but also has insulative properties.

This could be a number of materials (glass, plexiglass, polymer sheet, etc.) Component C should be a highly absorbent layer or material. This material converts solar radiation into heat. Care should be taken to select materials that can withstand high temperatures without burning or releasing toxic gases. While boiling water within the cooker, the water vapor within the cooking chamber will increase, making black cloth a better choice to common household paint. D denotes the convective heat transfer from the component C to the air within the cooking chamber. The equation governing this property is Newton’s law of convection: Q=h(T W-T 0) T W is the surface temperature of Component C (K), T 0 is the air temperature (K), and h is the heat transfer coefficient (W/m 2K).

Component E is an insulative material. There are two criteria for the component E. First, the heat diffusion through the material has to be small enough to allow the cooking chamber to reach a sufficient temperature. Second, the diffusion rate should be low enough to allow sufficient cooking time before the exterior of the cooker reaches unsafe temperatures.

The equation governing this property is: Q=(T-T 0)(2t) 1/2(λC pρ) 1/2 Where t is time, λ is the thermal conductivity, C p is the specific heat, and ρ is the density. Heat diffusion is minimized by minimizing (λC pρ) 1/2 (Ashby, 1993). Given a certain choice of materials for insulation, based on cost and availability, the material with the lowest (λC pρ) 1/2 is therefore the best choice. Several prototypes were developed at Princeton based on the design in Figure 1. Based, on the success of these models, it was determined that optimizing the model for Kenya would require selecting the appropriate metal, black material, wood, and glass based on their respective purposes. The equations and process included here provide an ideal method of selection.

In Kenya, much of the selection was governed by availability. The Experience Unique Approach to Teaching Lessons were kept as simple and active as possible. An effort was made to include a variety of material and teaching techniques.

Also, crafts and active demonstrations were included to help students understand concepts despite a language barrier. For example, on the first day of class, the older students learned about the solar system. They painted and put together solar system models.

The active demonstration was physically modeling how planets farther from the sun require the longest to make a full revolution. One student was selected as the sun. Nine students then formed a line and were assigned a planet corresponding to their position in line.

The students then “orbited” the sun, counting the number of steps required for them to complete the revolution. The students then reported the number of steps they took, and the students could see that Pluto has a longer orbit than Mercury. It quickly became apparent that the typical method of teaching was dictation and memorization. Emphasis was not placed on understanding. When students were asked if they understood, they always replied “yes,” whether or not they had absorbed the material. Therefore, an attempt was made to ask questions to determine whether or not students had understood material.

For example, a student might be asked if Jupiter’s orbit takes more than or less than 365 days. Solar Ovens The last day each week, for the older students, was devoted to physically building the solar ovens. Students were divided into four groups of six students.

Each group had one adult supervisor. The students took pride in their work and were able to understand directions. The solar cooker can be optimized by optimizing each of the component pieces. Therefore, testing can either be done on each piece individually, or in a controlled environment a single component can be varied at a time and the difference in overall temperature noted. When working in undeveloped areas, the second method of testing might be the easiest. One test that can be done is measuring the temperature within the cooking chamber as a function of the angle of component A relative to the box.

This should be done under controlled conditions, where only the angle is being altered, with the luminosity and exterior temperature being held constant. Temperature for Varying Angles of Component A Graph 1 summarizes results obtained from Kenya over the summer of 2005. The materials used were Cyprus wood, black cloth, aluminum metal, and glass. Certain items should be noted. First, due to logistical problems, only one thermometer was available.

It is impossible to know its degree of accuracy. Second, the exterior temperature was not constant, and the position of the light source (the sun) was not constant. Therefore at one point 50 degrees might result in direct sun reflection into the cooking chamber, while at a later time point this may no longer be true. In practice the position of component A can be adjusted by the user based on the sun’s position. Also, the box used for these experiments was carefully assembled using all necessary tools. Results may vary in villages where quality may vary due to lack of needed tools. However, the above graph demonstrated the potential range of the solar ovens.

Parent Days A parent day was held at each of the two schools. The parent days were held on Saturdays. The entire village communities were invited. In addition to sharing material with the parents, students at the schools that could not be a part of the classes due to size constraints, had a chance to participate. The parent days included a variety of activities including crafts, games, and demonstrations. The demonstrations included the students creating a sundial using a metal rod and rocks to mark the hours, placing black and white metal in the sun, and inflating a balloon using baking soda and vinegar. The children were particularly intrigued with the crafts stations where they had popsicle sticks, Styrofoam, paints, paper, pipe cleaners, and a variety of other standard craft materials.

Many of the parents, the mothers in particular, were quite young and enjoyed games like jump roping. Unique Issues There were a number of unique issues that future students should be aware of. The first is probably the most obvious, there is a language barrier. Even with a translator, all issues cannot be resolves. First, it takes considerably longer to teach through a translator. Second, complicated explanations are completely lost in translation.

Lessons and explanations need to be communicated in small pieces with plenty of visual aids. Also, there is not a Better Business Bureau, or any means of formal complaint if you are unhappy with customer service. For example, a local wood company claimed to be providing Cyprus, but actually sold pine. They placed a layer of Cyprus on the top.

How To Build A Box Solar Cooker

It is important to make sure you carefully inspect any material that is purchased. Logistics can also create some problems. Road conditions and transportation can be difficult. Things do not always happen on time and shipments can take a very long time to arrive. One should be careful and allow plenty of margin time in schedules. Also, goals should be reasonable and not incredibly ambitious.

My Experience In some sense, it seems like I learned more from the Mpala community than I was able to teach them. The experience was truly wonderful. The locals have a very rich culture, and it was amazing to see how the children entertained themselves without any toys. It was also the first time I had a chance to see a number of species of animals outside of the zoo. The locals knew to be afraid of elephants, I did not.

They were amazed when I told them that we can pet elephants at the circus, or that I had ridden elephants in India. Also, being at a biological research centre, I had a chance to learn from other researchers about their projects. This experience was truly unique. For the first time I could see the potential for engineering solutions in the third world. Simple ideas and designs are greatly appreciated by the locals and have incredible potential. Acknowledgements Dr. Soboyejo Laurel Harvey Mrs.

Rubenstein and Dr. Rubenstein Dr. Miguel Centeno and PIIRS Jody Whitehead Dr. Bruno Bosacchi Mpala Research Centre Administration and Staff Global Science Club All students and friends who helped Julie and I prepare and plan for the trip References Ashby, M. Materials Selection in Mechanical Design. New York: Pergamon Press.

Introduction Many devices have been developed that use solar energy—light and heat emitted from the sun — including solar panels, artificial photosynthesis, and solar ovens. Solar ovens can cook food, pasteurize water, or even sterilize instruments using only the power of the sun. How does a solar oven work? The simple answer is that it is designed to absorb more heat than it releases.

Figure 1, below, shows a picture of the type of efficient, easy-to-build solar oven that you will be making and testing in this project. The oven is a box within a box.

Solar Cooker Project High School

The inner box is covered with a plastic window (made from a heavy plastic cooking bag available at most grocery stores). The plastic window works like a greenhouse roof, allowing direct and reflected sunlight to pass into the inner box, while retaining radiated heat. This box-type solar oven is both easy-to-build and very inexpensive! (Image credits: Solar Cookers International Network, 2006) At the bottom of the inner box, there is a foil-covered shelf, painted black.

The shelf serves two purposes. First, it holds the cooking pot. Second (and more importantly) it acts as a ' heat sink.' The shelf absorbs direct and reflected sunlight, which warms it.

The shelf then radiates the heat, and this radiant energy stays mostly trapped in the inner box and warms it. The plastic window holds the heat in, as does the insulation of the air space (and newspaper) that is between the inner box and the outer box. The section of this project idea gives you step-by-step instructions on building a simple box-type solar oven. To make this into a complete science fair project, you will need to choose some aspect of the solar oven design to improve and test. Your choice should be based on your background research, and on the experience gained from building the first oven.

Build a second oven that includes your design improvement, and make measurements to see if you have improved the oven's performance. You can test your oven by: measuring the internal temperature with an oven thermometer, or by timing how long it takes to boil a given amount of water in a cooking pot. Do not worry about the oven catching fire. Paper burns at 233°C (451°F), and your solar oven will not get that hot.

When you are finished, it would be fun to try using your solar cooker to make a meal. The 'Solar Cooking Hints' webpage listed in the Bibliography, below, has some suggestions. Generally it takes about twice as long to cook food with a solar oven than in a conventional oven, so you will need to plan ahead. Rice is a good first dish to try. Terms and Concepts.

Solar energy. Greenhouses. Reflected light. Heat sink. Radiant energy. Insulation Questions.

What is radiant energy? How is it used in a box-type solar oven to heat it up?. How hot does a typical box-type solar oven get?. How hot does an oven need to be to cook food?. Can a solar cooker work on a cloudy day?. Why use a black cooking pot?

Bibliography You can find a bunch of alternative solar oven plans on this webpage:. Solar Cookers International Network.

Build a Solar Cooker. Retrieved July 10, 2014, from You can find other information on how solar ovens work and how to use them on these webpages:.

Solar Cookers International Network. Solar Cooking Hint.

Retrieved July 10, 2014, from. Aalfs, M. Principles of Solar Box Cooker Design.

Solar Cookers International Network. Retrieved July 10, 2014, from. Sponheim, T. Developing an Intuitive Feel for the Dynamics of Solar Cooking. Retrieved July 10, 2014, from. Materials and Equipment.

Cardboard boxes (4). You will be building two solar ovens, and each oven requires two cardboard boxes. Here are some notes on picking out two cardboard boxes for making a single solar oven:. The inner box should have an opening of at least 38 cm × 38 cm, and be large enough to hold the cooking pot that you intend to use.

It should only be about 2.5 cm taller than the cooking pot. The outer box should be larger all around, with at least 1.5 cm of airspace between the two boxes on each side.

It should also ideally be about 2.5 cm–5.0 cm taller than the inner box. The distance between the two boxes does not have to be equal all the way around. Tip: Keep in mind that it is very easy to adjust the size of a cardboard box by cutting and gluing it.

Metric ruler or measuring tape. Straightedge, such as a hard ruler. Utility knife. Large sheets of cardboard (2) for making the lid for each of the two solar ovens.

Each sheet must be approximately 8-16 cm larger than the opening of the inner box, when measuring both dimensions. Metal coat hanger. This is to make a prop for the lids. Pair of pliers. This is for cutting and bending coat hanger.

Sheets of cardboard (2) for making the shelf/heat sink for each of the two solar ovens. Each sheet must be the same size as the bottom of the inner box. Sheets of newspaper (several). A small roll of aluminum foil. Black tempera paint (at least 4 oz.). Make sure it is not 'washable' tempera paint. This can be purchased locally at crafts stores or through online suppliers such as.

Small paint brush. Elmer's white school glue (at least 8 oz.). Reynolds oven cooking bag, 'turkey-size', or 47.5 cm × 58.5 cm, or 19' × 23-1/2' (2; you will need one bag for each of the two solar ovens). Notes on the cooking bag:.

These are available in almost all supermarkets in the U.S. They are rated for 204°C (400°F) so they are perfect for solar cooking.

They are not UV-resistant, thus they will become brittle and opaque over time and may need to be replaced periodically. A sheet of glass can also be used, but this is more expensive and fragile, and does not offer that much better cooking except on windy days. For testing your ovens under the same solar conditions, you will need oven thermometers (2 identical ones) or shallow black cooking pots with covers (2 identical ones). Alternatively, instead of oven thermometers you could use an infrared thermometer (only 1) with a laser pointer so you can aim it accurately inside of the solar ovens, such as this one from.

Note: This engineering project is best described by the engineering design process, as opposed to the scientific method. You might want to ask your teacher whether it's acceptable to follow the engineering design process for your project before you begin.

You can learn more about the engineering design process in the Science Buddies. Building the Solar Oven Base. Fold the top flaps closed on the outer box and set the inner box on top.

Trace a line around the base of the inner box onto the top of the outer box, as shown in Figure 2, below. Carefully cut along the line you made in step 1 to make the outer box have an opening that the inner box can fit inside of. Decide how tall you want your oven (the inner box) to be. We recommend about 2.5 centimeters (cm) taller than your largest pot, and about 2.5 cm – 5.0 cm shorter than the outer box.

(Note that you can change the height of the outer box in step 6, below.) This way there will be a space between the bottoms of the boxes once the cooker is assembled. Carefully use the utility knife to slit the corners of the inner box down to the height you decided on, as shown in Figure 4, below. Cut the corners of the inner box down to the height you want the box to be (based on step 3). Cut the new, extended flaps completely off so that you are left with a box (without flaps) that is the height you want your oven to be. To do this, it is easiest to carefully use a straightedge (e.g., a hard ruler) and the utility knife or a pair of scissors.

Set the inner box aside for now — you will not do anything more to it until step 9. If you need to make the outer box shorter, do it now. Remember, you want the outer box to be about 2.5 cm – 5 cm taller than the inner box. If you need to change the height of the outer box, at each corner measure down to the new height you want the box to be and then make a mark there, along the box's edge.

Then carefully use a straightedge and the utility knife or a pair of scissors to cut the box between the marked spots on the edges. You should end up cutting the box into two pieces as shown in Figure 5, below.

Stack the pieces on top of each other (with one going inside of the other) and tape or glue them back together to make an intact outer box that is the correct height. When the inner box is placed inside of the outer box, there should be enough newspaper wads to support the inner box so that its edges are even with the perimeter of the outer box. Glue aluminum foil to the inside of the inner box. With the inner box placed inside of the outer box, glue the top edge of the inner box to the perimeter of the outer box where they touch, as shown in Figure 9, below. Tip: You may need to use some tape to help hold the boxes together while the glue hardens.

Place the aluminum foil-coated inner box inside the outer box and glue the two boxes together. Finally, make a shelf/heat sink inside the inner box. Cut a piece of cardboard the same size as the bottom of the inner box. Glue aluminum foil to one side, as shown in Figure 10, below. Paint the foil black using black tempera paint and allow it to dry, as shown in Figure 11, below. Tip: To coat the aluminum foil well, apply multiple (2 or 3) thin coats of paint, letting each coat dry before adding the next one. The completed solar oven base should look similar to this one.

Building the Solar Oven's Removable Lid. Take one of the large sheets of cardboard (that you will use for a lid) and set the solar oven base on top of it (centered). Trace the outline of the base onto the lid, as shown in Figure 13, below. Note: Be sure to orient the corrugations of the lid so that they go from left to right as you face the oven so that later the prop may be inserted into the corrugations (see Figure 22, below). Trace around the bottom of the solar oven base onto one of the large sheets of cardboard. (The traced lines are faint in this picture.). Carefully use the utility knife and straightedge (i.e., hard ruler) to cut through one (of the two) sides of the cardboard along the lines you drew.

Solar Box Cooker Project Manual

Then fold the cardboard down along the cut edges to make short flaps for the lid. Also cut the corner flaps so that the lid's flaps can all fold down neatly. Glue the lid's corners to the lid's side flaps to make the lid, as shown in Figure 14, below. You may want to use binder clips to hold the corners together while they glue, as shown in Figure 15, below.

Note: Do not glue the lid to the box! You will need to remove it to move pots in and out of the oven. The lid should fit snugly on the solar oven base. To make the reflector flap, draw a line on the lid, forming a rectangle the same size as the oven opening (inner box size). Cut around three sides and fold the resulting flap up to form the reflector, as shown in Figure 17, below.

As you did in step 2, carefully use the utility knife to cut through one (of the two) cardboard layers where you want the flap to fold. Be sure to cut on the inside of the lid so that the cut makes the lid fold back the correct way (instead of folding inwards). Glue the aluminum foil to the lid's flap.

Next, turn the lid upside-down and glue the oven cooking bag in place, covering the flap's opening, as shown in Figure 19, below. Use the turkey-size oven bag (47.5 cm × 58.5 cm, or 19' × 23-1/2') applied as is, i.e., without opening it up. This makes a double layer of plastic. The two layers tend to separate from each other to form an airspace as the oven cooks. Be sure to glue the bag closed on its open end to stop water vapor from entering the bag and condensing. Alternatively, you could cut any size oven bag open to form a flat sheet large enough to cover the oven opening.

Completed solar oven. Testing the Solar Oven's Performance You will now be testing the solar oven's performance. You can do this by testing how long it takes to boil water or by measuring the temperature inside the oven after letting it heat up. When you test the solar oven, be sure you test it on a sunny day when it is fairly warm outside (10°C, or 50°F) with the solar oven facing the direction of the sun.

Testing how long it takes to boil water: Pour a specific amount of water (such as 2 cups), into a shallow, black cooking pot (you will need two identical ones later for testing two solar ovens at once). Time how long it takes the solar oven to boil the water. In your lab notebook, be sure to record how much water you used and how quickly the water boiled. You may want to create a data table to record this information. Measuring the temperature inside the solar oven: Either use an oven thermometer (you will need two identical ones later for testing two solar ovens at once) or an infrared thermometer to measure the temperature of the solar oven after you have let it warm for a certain amount of time, such as 45 minutes. To use the oven thermometer, keep the thermometer in the oven and then quickly open the oven and read the temperature (if you are unable to read the temperature through the oven bag). To read the infrared thermometer, quickly open the oven and use the thermometer to find the temperature of the black shelf/heat sink.

In your lab notebook, be sure to record the temperature of the solar oven and what method you used to take the temperature. How well did your solar oven perform? Are you surprised by your results?

Do you think you could make it work even better? Improving Efficiency The solar oven you have built should cook fine during most of the solar season. To improve the efficiency to be able to cook on more marginal days, or make the solar oven be more efficient overall, modify your solar oven's design. Think about how you want to modify it and then build a second solar oven using the modified design. Test the original solar oven and your modified solar oven next to each other and see if your modified solar oven is more efficient than the original. Here are some ideas for modifying the solar oven's design to make it more efficient:. Make pieces of foiled cardboard the same size as the oven sides and place these in the wall spaces.

Make a new reflector the size of the entire lid. Make the shelf/heat sink using sheet metal, such as aluminum flashing. Paint this black and elevate this off the bottom of the oven slightly with small cardboard strips. Note that you will want to make the inner box a bit taller to accommodate the elevated shelf. For additional help on thinking about how to improve the basic solar oven design, you may want to check out the Science Buddies' resource on.

After you have built your second solar oven using the modified design, test both solar ovens together by repeating the 'Testing the Solar Oven's Performance' section of the Procedure with both ovens at the same time. Note that you will need two identical, shallow, black cooking pots if you are testing how long it takes water to boil in the ovens. Likewise, you will need two identical oven thermometers or one infrared thermometer if you are testing the temperature inside the ovens. If you are using two identical oven thermometers, check first to make sure that both thermometers give the same reading using your kitchen oven.

If the readings are different, make sure that the difference is consistent, and then use the difference to correct one of the readings so that the measurements can be compared. Place the solar ovens side-by-side when testing them so that the conditions are the same for both ovens. Be sure that both solar ovens are receiving the same amount of light (i.e., one should not be partly shaded). Repeat step 2 at least two more times so that you have compared the two solar ovens in at least three trials. Compare your results for each solar oven. Did the new design perform better than the original design? Are your results what you expected them to be?

Do you think you could improve the solar oven design to make it even more efficient? If you like this project, you might enjoy exploring these related careers.

Solar Energy Systems Engineer Does the idea of harvesting the enormous power of the sun interest you? If you find this exciting, then you should think about installing solar photovoltaic panels on your house to collect free electricity from the sun. But how energy efficient is your home already? Can it get better? How many panels would your house need? What would the system look like?

You can get the answers to these questions and more from your local solar energy systems engineer. These engineers help their residential and commercial clients save on their electric bills and reduce their carbon footprint by performing energy audits and picking and designing the right solar energy system for them. Commercial & Industrial Designer Have you always loved art? Do you have a good eye for beauty, balance, and form?

How would you like to see your designs show up in toy stores? Or in a sporting goods store? Or at a car dealer? Commercial and industrial designers create the shape and form of every type of manufactured good that you can think of—from toys, sporting goods, and medical equipment to high technology products, furniture, toothbrushes, and toasters. They design the form of new products that are as beautiful and pleasing to look at as they are functional.

Variations Here are some of the many possible experiments you can try with your solar ovens. You can probably think of others yourself.

Test with and without a reflector. Try different types of heat-absorbing materials for the oven shelf/heat sink. Try different types of insulation between the inner and outer boxes.

Why is it necessary to paint the shelf black and to use black cooking pots? See for yourself! Try black vs. Shiny shelf and cooking pots.

See the Science Buddies project. Try re-orienting the oven towards the sun once or twice an hour, vs. Leaving the oven stationary. For a more advanced project, study the plans at the webpage. Choose two or three different types of solar ovens to build, and see which design is most efficient at heating a standard volume water (e.g., 1 L).