Desalination

Description: 

The objective of this module is to build a simple solar powered device that can be used to recover fresh water from a salt water solution. You will build this using commonly available materials.

Picture/Schematic: 

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Step 6

Condenser

The air coming from the salt water tank is warm and saturated with water. There are two key ideas to keep in mind
The amount of water the air can carry is proportional to its temperature
The larger the cool surface the air comes in contact with, the more condensation can take place
So you want a cool vessel, and you want lots of contact between the gas and the solid surfaces inside. How would you design it? I can give you a few suggestions
Prevent tank from heating up from solar radiation: use plastic material, paint white, wrap with a very reflective material 
Q: Why paint white?
Q: Why wrap with reflective material?
Hint: what is reflectivity?
Q: What reflective materials can you find at home, your neighborhood, your school, at the market?
Increase condensation surface area:  Make a bed of pebbles and let the gas flow through it, what else?
Natural refrigeration: Can you use a clay vessel, or at least a specially prepared clay vessel?
Have you heard of earthen ware pots, and how your great great grand parents managed to keep water cool in hot (but preferably dry) climate? Can you apply a similar concept here?

 

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