Further testing

After creating our initial prototype, we wanted to test different materials for the top of the water distiller, as well as different angles. We decided to test glass and acrylic for the tops, and made two new prototypes:

Two new prototypes with different materials for tops.
Left is acrylic and right is glass.

These prototypes have a few key differences. We decided to not cut out an angle, and instead, tilt the box to create the slope. This approach has both advantages and drawbacks, the advantage, being that it made the distillers incredibly easy to build. The drawback, however, is that the angle makes it so that the surface area of the water becomes smaller, and therefore, water is slower to evaporate. Our former prototype allowed the water to be flat, so since the water was spread out and thinner, it evaporated quite well. However, since it was such a pain to cut, we decided to try this approach.

We put in 400 mL in each box and then sealed the tops with tape. The boxes were left under the solar lights for 12 hours, and then the distilled water was measured. The undistilled water was measured as well, in order to calculate how much water was lost in this whole process. This process was repeated twice for both boxes, each time with a different angle. The angles were created by propping the boxes with wooden blocks of the same size. The blocks had a height of .75 inches. The first time, we propped the boxes with two blocks, the second time with 4 blocks... and got these results.

Our results from testing

In the first run through with two blocks, we immediately noticed some disadvantages with the plastic. It appeared that the plastic curved with the heat, and even through the top was securely taped down with lots of tape, too much water was escaping through the edges of the curves. It also pointed to the fact that the plastic could potentially degrade very easily in intense heat. In the end, it didn't produce any distilled water, and 50 mL of water was lost, as 400 mL was originally put in. The glass was noticeably heavier, and did not have any apparent curving. 35 mL of distilled water was produced, while 15 mL of water was lost in the process.

In the second run through with the four blocks, we made sure to tape the plastic extremely throughly in order prevent water loss. 22 mL of distilled water was produced, while 13 mL was lost. The glass, on the other hand, produced 37 mL of distilled water and 13 mL of water was lost as well.

Significant amount of water loss coming from the sides of the glass top box

For our testing, we had use tape/remove the tape to easily take out and measure the amount of water produced, as we did not create the mechanisms for filling and taking out the water yet. However, in our final prototype, will will glue the tops down, and this will hopefully prevent more water loss. Looking at the second run-through, it appears that glass is far more effective than plastic, as it had the same amount of water-loss, yet glass produced more distilled water. Adding more height/angle to the boxes did not appear to make a significant difference. Given that we only had two run-throughs, we may need to test more to come to more concrete conclusions. However, judging by previous water distillers that other have made, we concluded that glass does appear to be the best material for the top, and we will proceed with that.