Solar-Powered Water Desalination: Condensation issues

Ask questions about projects relating to: aerodynamics or hydrodynamics, astronomy, chemistry, electricity, electronics, physics, or engineering.

Moderators: AmyCowen, kgudger, bfinio, MadelineB, Moderators

Locked
amarko
Posts: 1
Joined: Thu Feb 11, 2016 9:18 am
Occupation: Teacher

Solar-Powered Water Desalination: Condensation issues

Post by amarko »

Hi, A student at my school is conducting a science experiment on water desalination following this procedure found on the Science Buddies website - https://www.sciencebuddies.org/science- ... #procedure

He is having difficulty collecting condensate. He has read through the trouble shooting section and it appears as if he is following all of the suggestions given there. Is there any way you can give us some guidance on why you think his desalination apparatus is not producing enough condensate?

Anita Marko
St. Jude School
tdaly
Former Expert
Posts: 1415
Joined: Sat Nov 08, 2003 11:27 pm
Occupation: Planetary Scientist
Project Question: N/A
Project Due Date: N/A
Project Status: Not applicable

Re: Solar-Powered Water Desalination: Condensation issues

Post by tdaly »

Hi Anita,

Is the problem that your student is collecting water in the funnel, but it isn't continuing down into the cup? That condensation is forming on the cling wrap but not falling down into the funnel? Or is the problem that very little water is condensing on the cling wrap? Each of these might have different solutions.

If the water is collecting in the funnel but not continuing down into the cup, then the problem is most likely that the straw is not sloped enough. Try making the slope of the straw steeper.

If water is condensing on the plastic wrap but not falling down into the funnel, you can try a slightly heavier washer or use a bit more cling wrap so that the cling wrap slopes more steeply down to where the washer is. Make sure, however, that you still have a good seal between the edges of the rectangular box and the cling wrap.

If very little water is condensing on the cling wrap, then I suspect you have one of two problems. First, you might have a leak between the modeling clay and the straw or between the cling wrap and the rectangular box. Triple check those connections. You could even spread a thin layer of petroleum jelly on the rim of the rectangular box and press the cling wrap against that to help make a better seal. That could get a bit messy, though, if you use too much jelly. Second, you might not be getting the water in the box hot enough. You could try starting with warm water. It's important, however, that the water in box containers be the same temperature. Starting with warm water will make it harder to see the differences between the box with black paper and the box with white paper. However, if you do a test using warmer water and do not see condensation, that strongly suggests that you have a leak somewhere where water vapor is escaping.

I hope that helps; post back with any other questions you have.
All the best,
Terik
bajanhoney
Posts: 1
Joined: Sun May 08, 2016 2:42 pm
Occupation: Parent

Re: Solar-Powered Water Desalination: Condensation issues

Post by bajanhoney »

I am doing the same experiment with my son and he is asking me the purpose for the white and black construction paper in experiment and I am having some difficulty explaining to him. He wants to be able to explain to his class what this has to do with desalination process. Can you please help me?

Struggling mom
tdaly
Former Expert
Posts: 1415
Joined: Sat Nov 08, 2003 11:27 pm
Occupation: Planetary Scientist
Project Question: N/A
Project Due Date: N/A
Project Status: Not applicable

Re: Solar-Powered Water Desalination: Condensation issues

Post by tdaly »

Hi bajanhoney,

The black and white construction paper absorb different amounts of the sunlight that hits them. The black paper absorbs more of the sun's energy that hits it than the white piece of paper absorbs. This fact helps to explain the results you should have observed during the experiment.

One that is important to note is that the color of the paper (black vs. white) is the only difference between the two desalinators that you built. Does this make the color of the paper the independent, dependent, or a controlled variable?
All the best,
Terik
Locked

Return to “Grades 6-8: Physical Science”