Monday, April 27, 2015

Simple Solar Thermal Projects for Kids - Solar Updraft Tower

We're supposed to have sun for the rest of the week, but it's never good to take chances with the weather.  So, when the sun came out today, we hit the ground running with three solar thermal projects at once.

This time, instead of working with complicated, photovoltaic, solar panels, we experimented with harnessing the heat of the sun to expand air, purify water, and turn a pinwheel.  Each project was simple to put together, and provided easily observable results, but with lots of little details that could be tweaked, adjusted, or expanded.

Really I had a hard time deciding which one to write about first, finally settling on the simple solar chimney, or updraft tower we found archived on the National Research Counsel Canada website.

The chimney is made by taping together three, large, empty, clean tin cans, with the tops and bottoms removed.

A wire arch (made from an unbent paper clip) is taped across the opening of the top can...

...with a thumbtack, or straight pin, taped to the center of the arch, pointing up.

The chimney is placed on top of a couple of books, to allow air to flow in from underneath.

Finally a pinwheel - made by cutting diagonally in from the corners of a 6 inch square sheet of paper, to within a quarter inch of the center, bending the every other point from the corners to the center, and taping them in place... balanced on top of the thumbtack, taped side down.

When placed in the sunlight, the heat from the sun will warm the air inside the cans, creating a convective updraft, and spinning the pinwheel.

Questions for thought:

What would happen if the tower was not on the books?
Would a paper tower work in place of cans?
Would pinwheels made of different materials, or in different sizes spin faster?
What if the tower was painted black?
Could enough power be generated by the spinning pinwheel to turn a generator?


claireshomeeducation said...

Brilliant! My son would love to do this so I will be sharing with him. Although I'm not certain the UK ever has enough sun to do any of these projects!

Cristy said...

Man, this series is AWESOME! You've inspired me again to get going on some solar ideas I had been toying with previously.

But even if I had never thought of doing solar experiments, I would want to try the solar updraft. That is so COOL!

Thank you for sharing. I always tell people that if they are looking for hands on science projects, they can't do better than your site. :)

An Almost Unschooling Mom said...

Christy - Thanks!

Claire - We just watched Paddington Bear, and learned the English have 107 different ways to say, "it's raining". But then, I seem to remember Douglas Adams having it at 231 in one of his books.

Phyllis said...

Wow! This is fantastic!!

Ticia said...

LOVE it! Now can I successfully make it? That is the question.

MaryAnne said...

We have an excess of sun, so I really need to give this a try! Very cool experiment.

Anonymous said...

Did this for a school science fair

Anonymous said...

How does the pin wheel balance? Its just slipping straight off?

Lexy said...

How long did it take for the fan to spin?

Anonymous said...

This is cool! Might do this for my son's science project. How long did it take for the pinwheel to spin? Was that morning or afternoon sun?

An Almost Unschooling Mom said...

It was afternoon, and if I remember correctly, it took 15 to 20 minutes (but it was a while ago, so I'm not positive about the time).

mikay0918 said...

Hi, this experiment is so cool. I have also seen your science project on the solar chimney and I am so much interested to try it on a bigger perspective. I am trying to build/create a solar heat conductor to be used for my corn dryer. I wonder if you can help me out with a more effective but inexpensive project to try.

Unknown said...

Thanks! Your project sounds interesting - a little out of my range though.