AP Physics Solar Water Distillation Project

Description:  Students will design and construct a solar thermal powered still.

1.   The device will change dirty salty water into clean pure drinkable water of low conductivity as measured by a conductivity probe.

2.    Grading will be based upon a 24 hour test period of 90% sun starting June 10th in a secure area on campus.  In the event of clouding a second test will be performed June 11th, or when sun is available.

3.  The total area of collector may not exceed 0.36 square meters.

4.  80% of the materials by weight must be  post consumer materials  such as used food containers, cardboard, worn tires,   construction debris, etc.

5.  Value:  This project is valued at 100 points.

6.  The test will be done on grass in the courtyard.

7.  Your project is required to have wind protection for winds up to 30 miles per hour.  There is  10 point deduction for designs without wind protection.  If ballast is your plan you are required to use at least 10 pounds.

8.  The reliance on tape to remove your clean water  will result in a 10 point deduction.  This is an inferior material for a project that generates steam.  Do not tape your glazing to your project body.

9.  A deduction of 10 points will result if your project requires more than 5 minutes to add dirty water, secure the glazing and stake down for wind protection.

10.  Grading will be based upon the production of clean water in mls.

300 ml =  A

200 ml = B

100 ml = C

50 ml = D

Less than 50 ml = F

Suggested design elements:

1.  Research the best orientation for capturing maximum sun in our latitude

2.  Do not allow vaporized clean water to escape from your project

3.  Keeping mass low will allow for quick temperature increases.

4.  Selective insulation can prevent heat loss through radiation back into the environment

5.  Some glazing will prevent light transmission.  This is to be avoided

6.  To maximize condensation your condensation surface must be cooler than the vapor inside your project

7.  Here is a link to a small still made from some recycled components