The goal of our project, solar thermal cooker, was to create a cheap device that could convert the light from the sun to as much heat as possible. Specifically we wanted to get our solar thermal cooker so hot that we could boil water, and cook sausages. To achieve this goal we need to get at least 212 degrees Fahrenheit. With that in mind we were able to get our solar thermal cooker to about 170 degrees Fahrenheit in an 75 degree windy weather. The group of people that would most like our project would be destitute people living in very poor areas around the world that cannot afford high tech solar thermal cookers. To be able to build our solar thermal cooker you would need the following:
1. One saucer or trash can lid.
2. One roll of reflective tape or aluminum foil (reflective tape would work best)
3. One pair of scissors
4. One roll of duck tape
5. 2 pieces of wood so that it can act for a frame for the saucer, or cut off the bottom part of the satellite dish.
6. one hammer
7. one pack of nails
9. A black pan
10. water with some kind of bowl
Even though it may seem like a lot of materials we spent around 10 American dollars on all of this equipment, especially because you could use aluminum foil. Also, if you are worried that this will take you a long time to assemble, we assembled our project in 3-4 hours. If this seems like a long period of time, we assure you that you shall not be disappointed by the end results. The final dimensions of the project end up being height = 20 inches, width = 31 inches, length = 30 inches. The only materials that would be hard to find would be the reflective tape, but we reiterate that there is no shame in using aluminum foil. Substitute materials are of course the aluminum foil, and if you don't have a hammer you could always use a shoe. In order to not bore you with a ton of pictures we included to of the most essential materials
Step 1: The physics behind the solar thermal cooker
It will be fairly easy to construct the solar thermal cooker, but it is also fun and important to understand the physics behind the solar thermal cooker. Light enters the solar thermal cooker when it hits the parabolic shape of the saucer, which of course is covered in reflective tape.Because of the angle of the saucer the light energy bounces off and hits on a specific point in the floor or in this case a black pan. Remember the key to making sure that the light hits a specific point is the parabolic shape of the saucer. Once the light hits a specific point in the black pan it will begin to absorb the light, and convert the light into heat energy. The pan must be black because the color black absorbs all wavelengths of light which is essential. Alebdo, or the fraction of solar energy reflective from Earth back to Space, goes with the concept of capturing the light and having the solar thermal cooker heat up our food. If we were to build a box cooker it would relate to the greenhouse effect because it would use the sun's warmth in the box and thus making all inner contents hot, which is what is basically happening to our world as we speak.
Step 2: Assembly step one
Our project is fairly simple to construct. First you must find the saucer or the trash can lid. In this case we had the trash can lid to our disposal. Now that you have you trash can lid you must cover the inside of the trash can lid with either reflective tape or aluminum foil. If you use the reflective tape it has a little adhesive that comes off, so be patient. If you use the aluminum foil than you must glue it on. A little tip before you start cutting those materials is to measure out what you are going to cut before you do so, no need for a ruler unless you really need it. Below is a before and after picture of what the saucer should look like. This is by far the hardest and most time consuming step, and it will take you about 2-3 hours to finish. Also make sure that you don't not just cut one huge piece because then you will have a lot of air bubbles.We recommend that you cut out smaller pieces, so that way you will have less air bubbles to deal with.
Step 3: Assembly step 2
Now that you have your saucer all finished up, it is time to move on to the base. The base is also really essential to the project mostly because if the saucer does not have a base then it will just topple over, and its job will never be fulfilled. So we were lucky enough to stumble upon a base of a satellite dish. So we really did not have to do anything but just put the saucer on the satellite dish. If you do not have a satellite dish, no need to worry because we will also instruct you on how to build one. You get four pieces of wood about 3 feet in length and about 5 inches in width. You will use one piece for the bottom. The second piece will go perpendicular to the 1st piece creating an "L" shape. Of course you will have to use a hammer and nails for this. Next, you grab the third piece and place it in a diagonal manner to the 2nd piece. This should form like a hypotenuse of a right triangle with the floor completing the triangle. Next,you do the same with the forth piece on the left side. When you are finished you should have completed your base. Below is a picture of how the satellite should look like (again if you don't have a satellite the steps to build a base are above).
Step 4: Assembly step three
Now that you have both of your base and your saucer completed. Now it is time to put them together. Some people would like to use screws and nails to attach both pieces, but remember we have limited supplies. So we chose to go with duck tape. Once you have your duck tape you will get your saucer and your base and go outside. Once outside, make sure to place the saucer on the base at an angle that gives you the beneficial angle. In other words make sure you position the saucer at the correct angle. Once you are sure that you have the correct angle, you can proceed and duck tape the saucer to the base at the back.
Step 5: Assembly step four
This step is one of the easiest. This is a helpful tip if you are not reaching the maximum amount of heat that you want. You will grab a piece of wood or block and put it underneath the 1st wooden base. That way the light can focus better on the base, and thus cook your food better.
Step 6: Assembly part five
Finally, after all of your hard work. All you have to do is put whatever you want to cook on the base, in our demo we put a tortilla, and wait until it heats up. First, make sure you put a pan on the base so that the food can be placed there. When all is said and done, make sure to enjoy your food. Please excuse us on the picture below. Just get the message that we are cooking a tortilla, when you do the real thing you will of course have a base to put the pan on.
Step 7: Assembly upgrades.We are just theorizing here when we include this optional step. We have seen other groups build some sort of shade for the solar thermal cookers. What this means is that the light only focuses on only the solar therm cooker, and when the light is reflected back minimal light is lost. Although we were not so sure if this could work, we encourage you to try this step if you have the time, money, and patience.
Step 8: End Results
Our design worked well. Our project got up to 178.6 degrees Fahrenheit. As our goal we stated that we wanted to cook sausages, and we are confident by conducting several demos that it will cook our food. We are aware that water boils at 212 Fahrenheit, and since we conducted our project at 75 degree weather in 90 degree weather our solar thermal cooker should reach that temperature. For now we mostly pasteurize our food because this happens at 175 degrees. What this means is that we can kill bacteria very effectively at our current temperature. This is important because by doing this, people will catch less bacterial diseases in their food. The Solar thermal cooker is very light and is more portable than we ever expected it to be. We are pretty content with our end results, and we would change the amount of aluminum foil that we had to use. The reflective tape worked a lot better. We would also mess around with the parabolic shape so that we could get an even better angle. Below is a picture of the solar thermal cooker, and how efficient it cooks
Step 9: Hints and TipsAlthough are project is straight forward, and we have given hints along this whole instructable. Our biggest tip is to have fun building this project. Even if your food source depends on this project it does you no good to stress about it. Also, make sure to save us much materials as you can, because you never know if you will need a replacement in the future.
Step 10: Credits
We (Rico, Jose, and Jeremiah) finally want to thank you for taking the time to read our instructable. We also would like to thank our teacher Mr. Bording for teaching is the content to make this project possible. Please enjoy what we think are ultra cool pictures.