Developement Process of the E2W Mark 8 Solar Cooker

Main PageList of ResultsAbout Me

Below is my report over my research of solar ovens



The solar oven was first designed in 1776 by a man named Horace de Saussure. His design consisted of three boxes, stacked inside of each other, with each box covered with a pane of glass. His experiment, called a hot box, was used to prove why the air temperature in the mountains was cooler than the air temperature in the lower altitude plains. This began a series of experiments and research into hot boxes by a number of notable scientists.

In the 1830's an astronomer by the name of Sir John Herschel used a hot box to cook food. His design, a glass covered and insulated box, created temperatures of up to 240 degrees Fahrenheit. this significantly surpassed the boiling point of water, about 212 degrees Fahrenheit. Herschel used the box to cook a number of food items including stew and eggs. From then on there have been many designs and modifications to solar ovens, each more efficient than the next.

Solar ovens are versatile and can be customized to fit almost any body's living space and needs. Whats better yet is that extremely efficient solar ovens can be made on low budgets. These low budget ovens can work surprisingly well and be used to cook any food or pasteurize any water.There are several different designs of solar cookers and an infinite number of modifications. Still solar ovens can be organized into three different categories, panel, box, and concentration oven.

A solar panel oven consists of several reflective panels surrounding a usually dark colored pot. The panels are angled to direct sunlight into the walls of the pot, generating heat. This style of cooker varies greatly from Saussure's design. It does not use glass panels to retain heat, nor does it insulate the pot from the open air temperature surrounding the pot. Still this does not mean that the panel cooker is any less efficient than any other solar oven. Panel cookers have been reported to reach temperatures as higher than 100 degrees Celsius. Panel cookers are probably the most easily accessible solar oven for most people, often times consisting of little more than an unglued cardboard box and aluminum or tin foil. Often times a panel cooker will be confused for a concentration oven.

A Concentration oven consists of a parabolic mirror focusing onto a dark pot. By using a magnifying glass effect the concentration oven can focus a large area of sunlight onto a small surface area of the pot. This way ore energy from the sun will be converted into heat energy. Concentration ovens are a bit more difficult to produce. They require a bit of engineering knowledge as well as tedious placement of angles if the shape is in separate pieces. However these concentration ovens are extremely efficient. They can reach temperatures of up to 140 degrees Celsius, higher than the boiling point of water. The concentration oven varied significantly differently from Saussure's design, unlike the box oven.

The box oven is one of the best options for anybody to have. The box oven is almost exactly like Saussure's original model. Almost all box oven consist of a box with a clear lid and a dark, insulated material. Box ovens also often use a reflective surface to mirror more sunlight into the system. The box can be built out of common household materials and built to last. A box can be made to be portable or to reside in the side of a house. Box ovens tend to be stronger and more rigid. This allows for more prolonged use and resistance to abuse that can happen all too often. Box ovens can also reach temperatures of 180 degrees Celsius. This makes them extremely useful and efficient, the best choice for almost everyone. The majority of the project was done using a primarily box style oven that i had built and tested.

Box ovens are simple to make and there are many options to customize it to one's needs. I built a box oven to test its effectiveness and availability. I wanted to prove that the box oven was a viable option for people in third world or rural areas where there was massive deforestation. Also I wanted to prove that some people's carbon footprint could be reduced significantly.

The first obstacle was to gather materials. I had found a basic design that I decided to use and then set to gather the necessary materials. To prove how easy it would be to create a solar box oven I decided to build it with a budget consisting of all the money I had in my pocket at the time. The grand total for the budget was a sum of $14.06. In the store I bought the necessary materials, all of which needed to be found in a house. This included items such as aluminum foil, cling wrap, a picture frame, and a dish to put food into. The total spending on the project materials was $13.76. Next I needed to gather the rest of the materials.

The final materials that were necessary were either found in my living space or donated by extremely helpful people, such as my physics professor Nelson Kilmer. These materials, I felt, were easy to encounter in an everyday suburban household. These final necessities were two cardboard boxes, a particle board box, foam board, a foam cooler, some carpet, a black t-shirt, and a lot of duct tape.With all my materials gathered it was time to build the first prototype.

The first prototype was relatively simple, and was erected in just under two hours. The particle board box was the outer shell. The inside was carefully covered in cling wrap as a moisture barrier. Over the cling wrap went a layer of aluminum foil, used as insulation a as a reflector of light. The lid of the box was replaced with a foam cooler lid covered in aluminum foil. A carpet and a black t-shirt were stacked, bottom to top, inside the box to provide both insulation and a light absorbing element. Lastly a glass picture frame was attached to prevent heat loss through the top of the box. A picture of this prototype and other prototypes are below. Prototypes from here on will be noted as Marks (Mark 1, Mark 2, etc.). It was time for the Mark 1 to be tested.

The Mark 1 was tested on a sunny Sunday afternoon during a baseball game. As I did not have proper testing equipment yet, my means of testing were limited to placing water into a dish and then drinking the water after a measure of time. I placed the box at an angle facing the sun. After securing the lid and pane of glass I placed a dish of water into the bottom of the box and placed an identical container with the same amount of water in the bare sun outside the box as a control. I left it in the sun to watch a baseball game. After approximately 15 minutes I returned and took a sip of the control. The water was still relatively cold as expected. After opening the box and reaching into the box I could feel heat accumulated in the base of the box. It was starkly contrasted to that of the air surrounding the box and I knew that the Mark 1 had performed. A sip of the hot water out of the dish confirmed that the Mark 1 was a success to some extent. Confident, I placed a bowl of ramen noodles into the box. An hour and a half later they were taken out. The noodles were not as fully cooked as they should be so I knew i needed to improve into a Mark 2 device.

I was open to a large number of ideas provided by peers and professors. After talking to my Physics professor, provided me with some ideas that may make the box even more efficient. His guidance included removing the clear moisture barrier, building angled mirrors into the base and around the top edge of the box, and removing the black shirt. He also provided me with two thermometers and a gauge that read the suns power over an area. After returning to my room and putting an hour into design and assembly the Mark 2 was created. It consisted of an open air container with angles in the base to reflect light into the side of the dish instead of all the energy being in from the top of the box. Three "mirror" panels consisting of cardboard and aluminum foil will built and fixed around the outside to funnel ore light into the box. The glass pane was removed because some glass could absorb almost 20 percent of the light energy it passes. This energy would never get to the food, and the Mark 2 needed all the help it could get. As well the t-shirt was entirely removed from the box. The Mark 2 would not see its own private test date.

Throughout both the Mark 1 and Mark 2 there was one obvious flaw that some new peer was always willing to reveal to me. The box was too tall. Conventional solar ovens were wide and short. The box was certainly wide, but it was so deep that there would be huge shadows cast inside the box. These shadows would cross over the dish and prevent direct sunlight from getting to the food. to compensate one would have to severely angle the box to the point where the food might shift or the lid may slam shut. All the energy was from weaker reflected light. To fix this a designed an elevated platform to be placed inside the box and the dish would sit atop this platform.This process gave me an idea.

I was building trying to find the best designs. This consisted of radical changes which were often multi variable changes. I decided that instead of building radical changes, I would instead do more subtle single variable changes. This proved to be a simple enough process and soon I was building individual parts and leaving them out of the box until I could test each variable individually. The test date could not have come sooner.

On one day I decided to spend the majority of my time testing each part of my box to conclude what the best possible combination would be. The date was October 12, 2010. The day was perfect. There were very few clouds in the sky and the sun was very powerful. I could feel its warmth at 9:00 that morning. My procedure was simple. Each trial would last 15 minutes. Before each trial the box would be realigned with the sun. Two identical dishes would contain the same amount of water. One dish would be placed outside in the grass and sunlight. The other would be placed in the box. After the allotted time the dishes' temperatures would be measured and the change in temperatures calculated. Each test would only consist of one or two variable changes to determine the best possible combination of variables. A detailed list of the data collected is provided in a table below as well as the variables involved. It is easy to see that the box works and works well. After only one hour of cooking ramen with the Mark [] I had a bowl that was hot enough to compare to the microwave. After all of the data collection was done I had my prize, my best possible oven given my budget and handiwork. As I placed a dish of ramen into the box to cook for an hour, I began to wonder what I was reducing my carbon foot print by.

An average Microwave uses about 800 watts, or 0.8 Kilowatts, of power. The average ramen bowl takes about 5 minutes to cook properly in a microwave oven. This means that to cook a bowl of ramen a microwave must use 0.0667 Kilowatt hours for one package of ramen. On average a student can go through 12 packages of ramen in a month. This means that this one student uses about 0.8004 Kilowatt hours per month just in cooking ramen packages. "One megawatt hour of power creates about 852 pounds of CO2 emissions" (). This means that in just one year a single student can produce More than eight pounds of pollution in one year. This is a serious problem that the solar cooker can solve.

When using a solar oven a person does not create any pollution. The solar oven relies entirely on sunlight and greenhouse effect. When used light does not emit anything other than heat or light. Granted there is some pollution made in the production of commercial solar cookers. These systems may be worth it though. The above experiment proves that a solar oven can be built using materials that one already has. Thus very little pollution will go into a home recycled solar oven. With this taken into account a person can severely reduce their carbon footprint. The solar oven can also be used for survival.

The solar oven is the best option for people in rural and third world areas. There is an area in the Hindu Kush region that has very little forest left. The majority of the trees in the area had been cut down so that the native people would have firewood to pasteurize their water and cook their food. A woman by the name of Patricia McArdle examined these rural people and wanted to help them. She decided to create a solar oven, a panel style, and showed it to the native people. "the crowd had swelled from 10 to about 40 men. They were scratching their beards, pointing at the CooKit and trying to figure out how this piece of cardboard covered with shiny paper was able to boil water." (McArdle). The men adopted the solar cooker to make their tea and Patricia continues to this day trying to get government support for the placement of solar ovens in rural areas. " I plan to continue working to convince my colleagues in the government to support the spread of solar cooker technology around the world." (McArdle).

Another reason why the solar oven is the best option for people in rural areas is the ease with which some can be repaired. The cooker in the experiment above consisted of parts that would be easily replaceable. The majority of the parts in the box were made with a board and aluminum foil. If some part were to fail it would only take somebody a few minutes to fabricate a replacement piece and replace the broken one. However if the oven in question is a commercial product instead of a home custom home made one, then replacement will become more difficult for rural families. Still though with great care the solar oven will bring warm meals and clean water to many families throughout the rest of history.

There are a few pros and cons that go into using the solar cooker as a primary source of food preparation. Some of the pros are really beneficial. Solar ovens do not produce pollution. This reduces our carbon footprint and will help to withhold global warming. Solar ovens will never run out of energy. Solar ovens rely entirely on the sun. As people have known for their entire lives, the sun will rise tomorrow. As long as the sun is in the sky the solar oven will have energy to cook with. Also the solar oven, if built at home, will be easy to fix. It will take very little time and resources to produce another solar stove or to fabricate and replace a part, making solar ovens much less fickle and less dangerous than a conventional oven. The solar oven is not without its cons however.

A beautiful device such as the solar oven is not without its flaws. The solar oven, again, is totally dependant on the presence of sunlight. If there is no sun then the solar oven will lose its effectiveness dramatically. If it is night time or if the sun is behind thick clouds it will take significantly longer for any food to be cooked. Another flaw is the speed with which it cooks food. A conventional microwave can cook a bowl of ramen in about 5 minutes. A solar oven can take as long as an hour and a half or more if the sunlight is not very strong. This consequence may prevent people in our society form buying the solar ovens due to the fact that everything is in a "right now" mentality. Still the solar oven's pros significantly out weight its cons.

The solar oven is the best viable option for people in rural areas whom need firewood to cook their food. The solar cooker is extremely efficient and will almost always be ready to use. It is easy to use and easily repaired or replaced. it leaves no harmful emissions. It is my hope that the solar oven becomes a much larger part of our society and planet.

Work Cited

Solar Cookers International. "A Simple Solar Water Pasteurizer." solarcooking.org. Solar Cookers International, 15 Feb 2010. Web. 11 Oct 2010.
.
Funk, Paul. "Through the wall ovens." solarcooking.org. Solar Cookers International,
15 Feb 2010. Web. 11 Oct 2010.
McArdle, Patricia. "My Solar Cooker Epiphany." solarcooking.org. Solar Cookers International,
15 Feb 2010. Web. 11 Oct 2010.
.
Mitchell, Deborah. "Cook With a Solar Oven." www.charityguide.org. Charity Guide, 01 Jan
2007.
Web. 11 Oct 2010. .
Butti, Ken. "Horace de Saussure and his Hot Boxes of the 1700's." solarcooking.org. Solar
Cookers International, 15 Feb 2010. Web. 12 Oct 2010.
.
Bernard, Roger. "Open Box Reflective Solar Cooker." www.terra.org. terra.org, 1999. Web. 11
Oct 2010. .
Pardeshi, Shobha. " Parvati solar cooker (double angle funnel)." www.terra.org. terra.org, n.d.
Web. 12 Oct 2010. .
LastCBS Interactive Inc., . "How much energy does the average microwave use?."
www.bestbuy.com. CBS Interactive Inc., 2008. Web. 14 Oct 2010.
5>
Sciences Education Foundation, . "The Electric Bill Project:An Elementary School Introduction
to Energy." www.sci-ed-ga.org. Sciences Education Foundation, n.d. Web. 13 Oct 2010.
.