Heliotracker idea problem

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Avin
Posts: 1
Joined: Sat Feb 03, 2018 5:49 am
Occupation: Student

Heliotracker idea problem

Post by Avin »

Hi
I'm Avin. I'm working on Hydraulic Helio tracker but I'm stuck in one part and it's the liquid which has to expand and push the piston in my combination!! I've used ethanol and acetone but none of them expanded in my syringe to flow through the tube to get to the desired point. My question is what liquid should I use in there?

Thanks in advanced
Avin
eedoherty
Former Expert
Posts: 52
Joined: Thu Aug 31, 2017 11:36 am
Occupation: Other Adult

Re: Heliotracker idea problem

Post by eedoherty »

Hi Avin,

I found a reference to the original project which was a California State Science fair submission, that says isopropyl alcohol was used.

Here is the reference: http://cssf.usc.edu/History/2009/Projects/S0217.pdf

Let me know if that doesn't work out for you!

-Erin
rpeteranderl
Posts: 14
Joined: Sun Dec 03, 2017 5:02 pm
Occupation: Teacher

Re: Heliotracker idea problem

Post by rpeteranderl »

Hi Avin -

This might be too late to help you with your project, but in a nutshell, you should pick the liquid with the highest thermal expansion coefficient that you can find. Here's a link https://www.engineeringtoolbox.com/cubi ... _1262.html with some values. Your choices were all very good, but you might run into technical difficulties.
The expansion coefficients are around 0.001 /K, which means that if you had a 1000 mL reservoir that you heat up, you would get a 1 ml expansion per ºC. But if your reservoir is made of polyethylene (Which I am assuming, since you are using a syringe), the expansion of the reservoir would increase its volume by 3 to 6 ml (The coefficient of expansion for PE is around 1 - 2•10^4 m/m K, so the reservoir would increase from 10 cm cubed to about 10.02 cm cubed. See https://www.engineeringtoolbox.com/line ... -d_95.html for more data). All the expansion would be compensated for by the expansion of the reservoir, and your actuator piston would not be moved.
Your odds might be better if you were to use a pyrex test tube as a reservoir. It's expansion (linear and volumetric) is much smaller that that of plastic
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