In many third world countries, such as Afghanistan, families burn wood and other fuels indoors. This creates many health issues such as pneumonia, and children are made to gather the fuel, rather than go to school. Solar cookers are an integral part to the future of third world countries and the families within them.
Step 1: Materials
A weight or something heavy
Step 2: Poster Board
Grab some poster board of reasonable length (around 52" long by 17" wide or bigger - this is the size we used)
Step 3: Creating Holes
In each corner of the poster board, poke a hole with a pen - do not make the hole too big, or else it will be too difficult to insert the string. Make the hole an inch away from the side (see picture)
Step 4: Reinforcing the Poster Board
Because the string will be pulling on the poster board, it exerts a lot of force onto the millimeter holes. In order for this solar cooker to be effective, the holes need to be reinforced. Take some metal washers and tape them onto the holes on each side of the cardboard. This will be able to sustain against the force from the string. Make sure to tape the washers down and that the hole is easily accessible.
Step 5: Inserting String
Insert an end of a string into one hole, and then knot it. Make the knot in the same place around three times so that it does not slip out. To get the string in the whole, use a pen or safety pin to push it in. Feed the string into another hole and repeat the process.
(We forgot to place the metal washers on. Our bad.)
Step 6: Poster Board and String
This is what the poster board should look like. Read annotations for clarification on step 3. The washers should also be present at the holes in this step.
Step 7: Make-shift Stand
For our design, we want our reflective surface to face the sun, so we built a stand to hold one side up. Take two stands of whatever kind and attach them into a cardboard tube. We drilled two holes into the cardboard and stuck the stands in. However, any type of design can work for this step as long as it keeps one side of the cooker up.
Step 8: Attaching the Posterboard to the Makeshift Stand
To make sure that the cooker is held up by the stand, make sure to properly duct tape the cardboard to the cardboard tube. Duct tape should suffice to attach the two together.
This is probably the most important step for the project. Lay the cardboard down on the floor and use adhesive spray to glue the aluminum foil onto the cardboard. Make sure to only spray in increments of one foot each time. It would be more efficient to use a straight object and smooth it out like when applying a phone screen cover. Trim any excess foil. The less creases the better.
Step 10: Finished Product
After placing the solar cooker in a position facing the sun, use cinder blocks to adjust the poster board. Place the chicken wire on top of the cinder blocks and weigh it down. Place the tray on the wire and adjust the poster board so that the focal point hits the tray. This increases the efficiency of the solar cooker.
Step 11: Physics Explanation
The main component in our project was the glued-on foil. The metallic properties were responsible for reflecting the sunlight onto a focal point. Once angled correctly, all the sunlight will focus onto our black tray. Because it’s black, the tray will more easily attract the heat because black has no color. The tray has the absorptive qualities because all the colors from the sunlight will enter the black color. Furthermore, the parabolic shape will allow the sunlight to all reflect onto the tray. Once the tray is exposed for a couple minutes, it should reach over 100 degrees fahrenheit.