Reflection

Our hypothesis stated that Tue insulation would keep the oven from catching fire while allowing heat in to cook the food. During the cook off, our success was limited due to the top of the oven we placed and less light was let in. However, light did get to the magnifying glasses and melt the chocolate and cook the marshmallow. Our temperature increased good, but not exponentially like we predicted. However, our hypothesis was correct because the insulation kept the oven from catching fire.

We had only one limitation during the cook off. This limitation was the amount of light we let in to the oven. We could have gotten the temperature higher if we had let more light in, especially with the magnification. If we let more light in, we could have cooked from all sides, but ran the risk of letting more light be wasted. Nevertheless, it could've been worth the risk in the end.

If we had unlimited resources then we could have made a better oven by using heat absorbent material to attract the sun towards the oven. Also we could have used metal to also absorb more heat to make the oven hotter. All of this would have been possible if we had unlimited supplies and resources.

The Cookoff

Here are the five pictures of the other solar ovens

Our solar oven worked very well and we did not expect this. We ended up putting the magnifying glasses on the bowl to keep the heat inside the bowl. This worked out very well and we successfully made a s'more.

Temperature Increase Test

To start off, we did an indoor, test, as discussed earlier. Not much temperature increase was recorded, so we made some modifications so it would hold more heat. We opened the flaps and put a layer of mylar on top of the flaps. We cut holes in the mylar for the magnifying glasses and we put saran wrap on the top of the bowl so the bowl would hold more heat. We then tested the oven outside. We started at an initial temperature of 24 degrees Celsius.


After the test, there really was no temperature increase, but we think the results will be different once we actually go outside to test, because the sun will be coming from all directions, not just directly on top of the box. Data shown below.

Picture Before Test:

Picture After Test:

Our efficiency was obviously zero since the temperature was the exact same as started, so the input and output would be the same, and the equation would end up at zero.

Construction

 First, we cut off two flaps of both the big box and the small box to reduce labor in cutting more holes for the magnifying glasses.

Next, we worked on the actual oven. We took a bowl and wrapped both the inside and outside with aluminum foil. To allow light inside the oven, we poked many small holes in the covering.

Next, we painted the outside of the big box black, so it could absorb more heat and cook from the outside as well as the inside.

 This step had multiple parts. First, we filled the small box with packing peanuts. We placed the bowl in the small box and filled the rest of the small box to the brim with peanuts. Then, we filled the big box with peanuts about 2 inches. We then placed the small box in the big box and filled the rest of the way with the peanuts. This provided proper insulation for the bowl to keep it as warm as possible.

Lastly, we covered the flaps of the small and big box with aluminum foil. We then cut holes in the flaps to allow light in to the oven. We placed magnifying glasses on top of the box where the holes were. This will increase the heat drastically and heat the oven a lot faster and to a lot higher of a temperature.

Indoor Test

In order to perform at maximum potential, we performed 3 indoor tests consisting of 20 minutes each. We recorded the temperatures in 10 minute intervals.

The first test we did was our initial plan: top box to small box to covered bowl. However, we didn't get the expected temperature, so for the second test we tried opening the big box and putting the magnifying glasses on the small box. That didn't work any better, so we took the cover of the bowl off. That test did better than the first two, so we decided to scratch the cover of the bowl. The maximum temperature we reached was 28 Degrees Celsius.

Procedure

How to Build:

Step 1: Paint both boxes black both inside and outside.

Step 2: Cut the flaps off of the smaller box.

Step 3: Wrap the bowl neatly in tin foil and put tin foil on the flaps and the sides of the bigger box (Shiny side facing into the box).

Step 4: Place the small box in the center of the big box, and pack the area around the small box with packing peanuts.

Step 5: Place the aluminum bowl in the smaller box and pack any remaining space with packing peanuts.

Step 6: Close the flaps of the big box and cut 2 4-inch diameter circles in the center of the big box on the top of the flaps. These holes should be aligned with the inside of the aluminum-wrapped bowl when cut. Also, cut a 1-2 cm hole in the big box, so that we can fit a thermometer in the hole to measure temperature.

Step 7: Place 2 magnifying glasses on top of the two holes. This will magnify the light source and concentrate the light more on the inside of the box.

Data Table:

This data table is based off of time. We expect to be outside for an hour at least, so we set our max time at 70 minutes. We want to know how hot the oven gets, so we will measure the temperature with a thermometer every 10 minutes to see how well our oven works. To answer our hypothesis, every ten minutes we will also check to see if it has caught fire or not.

Graphs and the Trends:

This graph is demonstrating the predicted temperature from the time allotted. We predict that our temperature will increase exponentially, since our oven is predicted to be so efficient. The light trapped in the oven combined with the light still entering the oven will greatly increase the temperature of the oven, especially since the light is highly concentrated.

This graph shows our predicted flammability as time goes on. We predict that as time increases, especially into the over 100 degrees Celsius, the light will get so concentrated that the cardboard will catch fire. This is a possibility, although we don't think it will happen. We have researched out hypothesis and have taken all the precautionary measures to keep this from happening. Nevertheless, it can still happen, and this is where we predict the probability (in percentage) that the oven will catch fire as time goes on and the temperature increases.

Math Equation: To find the efficiency, we need to find the energy output and energy input. The equation for efficiency is then:

          Energy Output  x100

Energy Input

Energy output will be divided by the energy input because we need to take what we got out of the oven and divide it by what we put in to the oven. The value is a decimal, so multiply by 100 to get it to a percentage. If the percentage is greater than 100, this means the output value is greater than the input value, and is therefore efficient. However, if the value is less than 100, then the input level is greater than the output level, and therefore is not efficient.

Our Design

Hypothesis: The smaller box surrounding the solar bowl and the foam insulation will keep the oven from burning down. 

Control: Cardboard in regular sunlight

Independent Variable: The amount of insulation placed around the cardboard

Dependent Variable: The flammability of the oven

Insulation is the key to keeping this design fire-proof, and we need the best insulator. After doing some research, we came to the conclusion that foam is the best insulator, and here is a video showing just how durable foam is.

http://www.youtube.com/watch?v=kcY0Bnh_wCM

This foam has also passed many flammability tests, further showing that we should use foam to keep the solar oven both insulated and fireproof.¹ The foam we are using is in the form of packing peanuts.

"Spray Foam Passes the Test for Flammability for the Second Time." Spray Foam. Web. 12 May 2015. <http://www.sprayfoam.com/newsarchives/archivedetails.cfm?id=838>.

List of Materials:

-Two boxes, one 20x20 and one 12x12
-1 industrail-sized pack of packing peanuts
-2 magnifying glasses
-1 thermometer
-1 big box of aluminum foil
-1 big bowl
-Black Spraypaint

This is a top view of our design from the outside. We would paint the whole box black to absorb more heat. Two of the four holes are for magnifying glasses. One of the other holes is for heat ventilation (this hole will be much smaller) and the other one is for a thermometer. The thermometer hole is just big enough to fit the thermometer in it.

This is the top view of the inside of our design. We would have a smaller box inside the large box. In the smaller box we would paint it black as well and put a bowl covered in tin foil in the middle. Around the smaller box we would put foam insulation to keep the box hot. On the flaps of the big box we would put tin foil on them so when the sunlight comes in it will reflect off the tin foil in the bowl to the flaps and back again.


This design will work because not only is the heat closed off, but it will not escape because of the insulation. We will reflect light back and forth and back again to make sure the design is as efficient as it can be. Since we don't have a lot of holes for light, we have to make the design very reflective on the inside to make the most of what we have. The heat of the light will also be magnified by the magnifying glasses. We will have highly concentrated light reflecting back and forth, which turns out to be a highly powerful and efficient design.

Background

Our energy source: 
The Sun

The sun is the key to most of the energy on planet Earth.

The sun is used in many different ways to produce energy. Since the sun is the reason why most things happen on Earth, there are many power sources derived from the sun. There is biomass, wind power, hydroelectric, solar power, coal, oil, natural gas, and more. However, our project is focusing mainly on solar power, which focuses on the rays of the sun directly. The rays emit heat, and that heat will be utilized to our advantage through a passive solar oven.

Since the heat is being used directly, passive solar energy is actually pretty efficient. If it is used to its maximum potential, it can be 65%-70% efficient¹, which is really good.

Advantages of Passive Solar Energy

• Low start up costs
• Eco-friendly
• Easier to set up then normal solar system

Disadvantages of Passive Solar Energy

• Takes a lot of work to implement into an apartment
• It would be hard to use the power
• You have to do ample research on the area you're in⁴

http://www.voanews.com/content/s-africas-power-crisis-sparks-interest-in-solar-power/2731328.html


This article is a good example of what we are trying to accomplish in this lab: Using the sun to our advantage. Our design in the introduction uses the light from the sun and magnifies it to produce the best effect.


Future of Passive solar energy

The European Union has realized it is time to start relying more on renewable energy sources. They have set a goal so that by 2020, the use of renewable sources will be increased by 20%, especially in solar power⁵. The power of the sun is increasing in use every day. This power source can easily be marketed since its only costs are in startup. Some projects are being designed in places where there are massive amounts of heat, such as deserts. As weird as it seems, the deserts could become the highest source of efficient energy in the world.

Sources:

"Passive Solar Heating Design." Wikipedia. N.P., N.D. Web. 6 May 2015. <http://en.wikipedia.org/wiki/Passive_solar_building_design#Efficiency_and_economics_of_passive_solar_heating>.

Sun. WIkipedia. Web. 6 May 2015. <http://en.wikipedia.org/wiki/Sun>.

"S. Africa’s Power Crisis Sparks Interest in Solar Power." Voice of America. N.P., N.D. Web. 6 May 2015. <http://en.wikipedia.org/wiki/Passive_solar_building_design#Efficiency_and_economics_of_passive_solar_heating>.

"Passive Solar Energy Pros and Cons." Clean Green Renewable Energy Passive Solar Energy Pros and Cons Comments. N.p., n.d. Web. 07 May 2015. <http://cleangreenenergyzone.com/passive-solar-energy-pros-and-cons/>.

"The Future of Solar." REC. N.p., n.d. Web. 07 May 2015. <http://www.recgroup.com/en/tech/the-future-of-solar/>.