Solar Still Update

It didn't work. I realized that the plastic strip wasn't thick enough so I reinforced it by covering it with thicker plastic. I then realized that the water vapour was indeed getting created and being condensed by the pastic strip but not flowing to the receiver because the plastic was blocked by the edge of the box. Then I placed a small receiver inside the module, hanging by a binder clip. This collected very little water as the condensed vapour was not flowing smoothly down the plastic strip. The strip was really crooked and did not create a smooth flowing surface.

I have not substituted it for a sheet of glass (which should work), but instead emailed 'The Farm' which has a prototype design on its website: http://www.thefarm.org/charities/i4at/surv/sstill.htm

This design is expensive and tough to implement in an Indian slum, so I wanted to know if I could use local materials. i also talked to friends about what we can do. Here is the answer from The Farm:

Dear Vijai,


I agree that silicone and rubber caulking are high-tech items. I am sure there are local substitutes. Lately we have been using an elastomeric paint, but again, that would not be something easy to acquire in the poorer sections of India. Any black paint, if it is not lead-based or otherwise toxic, might work if applied with enough thickness and perhaps sealed with a clear coat of some material that would not easily melt. Perhaps if a layer of fine charcoal were laid across the bottom, no black paint would be needed and the charcoal would also filter and protect the condensate.


Good to know you are experimenting and we would be happy to publish any new designs to our site.


Albert

My friend also suggested that we add a reflector to capture as much sunlight as possible, and instead of a plastic blox use aluminum. All this will add to the cost but we need to implement it in India to actually test the results.

My friend is working on a design diagram. I will have it published when it is done!

Making a Prototype Solar Still

Solar stills may be the way forward in emerging nations like India to provide fresh water to the billion-plus populations.

This is the first phase of a working prototype for distilling brackish or unclean water. If this works well we will build a bigger better model. Under normal conditions of daylong sunlight in the summer (90-100 Fahrenheit) I should be able to collect 1 gallon of pure water for every 8 gallons of brackish water

Components: Rectangular Plastic Box, Clear Plastic Wrap, Aluminum Foil, Cardboard strips to slant the plastic top,

Begin with the plastic box as the base of the module

Align cardboard strips on the side, cut it to create a sloping roof

Cover the interior of the module with aluminum foil, fill up the module with water

Cover the top of the module with clear plastic wrap; make sure it sticks out a bit at the end to create a catchment area for the pure water





Position the catchment vessel in the catchment area