Hi, I am Sahas Chitlange , aging 14 , from India . Here's my new innovation on fridge from clay. Its very easy and cheap to build and very cheap. In india the cost is about Rs. 300 only. The project's principle is based on evaporation. you can take this system for camping where you need a fridge to keep your cokes cool. The materials required for making this easy fridge are:
1) Clay pots
2) some sand
For the first time to get the cooling effect you need to wait for 10-12 hrs. The thing you need to remember is adding water after a day.
Step 1: Chose correct pots
You need to chose correct size pots so that they go into each other easily. Prefer new ones because old ones have their pores blocked. This affects cooling.
Step 2: Adding sand
Add some sand in the base of the larger pot. You may close the pot holes. I did not. You may also heat the sand strongly to kill the germs as in India you get the sand on roadsides!
Step 3: Insert the smaller pot
Now insert the smaller pot in the larger one. Take care you may get your hands jammed during this process. I got once, Very painfull...
Also see that you have some gap left on the sides , you need to add sand there later.
Step 4: Add sand to the sides
Carefully add sand on the sides of the pot. Avoid spilling it into the smaller pot , its very difficult to get that stuff out once spilled in ! Also add some water after you add sand.
Step 5: Cover it
You can make a cover out of old pots as i did or simply cover it with a damp cloth.
Step 6: Enjoy cooling
Its the time to enjoy cooling.