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Conductive liquids

by Shelnutt2
Tags: conductive, liquids
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Shelnutt2
#1
Jun19-07, 10:11 PM
P: 57
I'm working on a project and right now my idea fluid is to use Gallium, a liquid metal. Only major issue is its currently about $1000 USD for 1kg of this stuff!So I can't afford gallium. Mercury isn't that cheap either and its a bit dangerous if not handled properly.

What about other fluids? I know salt water is conductive but its not conductive enough for me. What I am doing is building a MHD generator, it runs by moving a fluid around the magnetic field instead of a solid piece of copper wire. Therefore I need a fluid that is more conductive than copper but about as cheap as copper.

Thanks
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mrjeffy321
#2
Jun19-07, 11:02 PM
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There is a metal alloy called "Wood's metal" which melts in hot water (about 70 C) which might be a possibility for you. It is made from base metals such as Tin, Lead, Bismuth, and Cadmium, but you should be able to buy some pre-made.
I dont know if a 70 C melting point will work for your application, it might be too high.

There is an alloy of Sodium and Potassium metals which is liquid at room temperature. But this is almost certainly not a possibility for your application.
JGM_14
#3
Jun19-07, 11:18 PM
P: 158
there aren't many materials that are more conductive than copper, aside from superconductors. you could try gallium aluminum alloy or sodium potassium alloy but the price of these metals (except aluminum) are quite high. The sodium potassium aloy reacts very violently with air when heated but otherwise it forms an oxide coating that protects it from further oxidation like aluminum the galium aluminum alloy reacts violenty with water because the galium prevents an oxide coating from forming and it will continue reacting unil all the aluminum is gone this also releases hydrogen gas

Shelnutt2
#4
Jun20-07, 05:02 PM
P: 57
Conductive liquids

Quote Quote by mrjeffy321 View Post
There is a metal alloy called "Wood's metal" which melts in hot water (about 70 C) which might be a possibility for you. It is made from base metals such as Tin, Lead, Bismuth, and Cadmium, but you should be able to buy some pre-made.
I dont know if a 70 C melting point will work for your application, it might be too high.

There is an alloy of Sodium and Potassium metals which is liquid at room temperature. But this is almost certainly not a possibility for your application.
Woods metal. Woods metal looks interesting and its not too expensive either. The 70C melting temp is a bit much though. I was really hoping for something that is liquid under 40C. I was planning to use PVC or CPVC for my casing, and that melts at 60/93C...
chemisttree
#5
Jun20-07, 06:10 PM
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Quote Quote by Shelnutt2 View Post
I was planning to use PVC or CPVC for my casing, and that melts at 60/93C...
Thats incompatible with NaK as well. Would ionic liquids work for you?
Shelnutt2
#6
Jun20-07, 07:52 PM
P: 57
Quote Quote by chemisttree View Post
Thats incompatible with NaK as well. Would ionic liquids work for you?

Ionic liquids would be great. They are full of electrical charge, which is what I need.
chemisttree
#7
Jun21-07, 08:19 AM
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Try saltwater.
mrjeffy321
#8
Jun21-07, 08:42 AM
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If Sodium Chloride salt water is not conductive enough for you, then perhaps you should try another type of salt.
Calcium Chloride is even more soluble in water than Sodium Chloride and will disassociate into 3 moles of ions per mole of CaCl2 compared to only 2 moles of ions per mole of NaCl. More ions should mean a higher conductivity.
chemisttree
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Jun21-07, 09:05 AM
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Or 30% sulfuric acid?
Shelnutt2
#10
Jun22-07, 10:02 AM
P: 57
Quote Quote by mrjeffy321 View Post
If Sodium Chloride salt water is not conductive enough for you, then perhaps you should try another type of salt.
Calcium Chloride is even more soluble in water than Sodium Chloride and will disassociate into 3 moles of ions per mole of CaCl2 compared to only 2 moles of ions per mole of NaCl. More ions should mean a higher conductivity.
Calcium Chloride. That sounds like a good solution. Its 50% more conductive than regular salt water!
chemisttree
#11
Jun22-07, 03:34 PM
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Calcium chloride might be more soluble than sodium chloride, but what is important is how many charges are produced. This is related to the activity coefficient. I think you will find that there is no significant advantage to using calcium chloride vs. sodium chloride but there is a huge advantage to using sulfuric acid.
Shelnutt2
#12
Jul8-07, 11:18 PM
P: 57
Well, I ran into a huge issue. I forgot about a little thing called electrolysis.

I'll recap what happened today.
I've got my 3rd revision of my experiment underway, this one is made up of CPVC and one piece of copper piping. I heat the whole experiment up via the copper piping, and the hot water rises and I cool it off at the top and it falls down the outer pipes.

Well I think I have a working design, and I have 4 holes drilled into the CPVC where I have JB-Quicked wires so I can messure the voltage I produce. One side leaked so I used great stuff (gap filler) to close the hole. After the propane touch is heating it, I start trying to meassure the voltage. When I touched 2 of the wires on the right side, the left side pipe, start leaking around the joints of the wires. We decide to keep going. I go to check the voltage again, and now the drizzle turns into a stream on the left pipe, and my friend saw a small thing of smoke start to rise from the right side where I am measuring the voltage.

I go to check the voltage one more time, and I look for the smoke this time. That was a mistake. There was a spark, water shot out of the left pipe, enough water that it broke the wire loose and put out the propane tourch..

So lesson learned, was that electrolysis happens no matter. I was lucky I didn't gap fill the left pipe too. It might have exploded both sides then.

I'm sure the continuous flame didn't help either...


So I need a new conductive fluid, that will not seperate when intoduced to DC current. Can be heated up.

Or I need another method of making the salt water flow, that doesn't involve a pump.
JGM_14
#13
Jul9-07, 10:21 PM
P: 158
use a vent for the gases or a pressure relief valve
use the same concept but instead of flame use sunlight and a parabolic mirror
J.ofalltrades
#14
Nov10-09, 11:06 AM
P: 16
You need a relief chamber that cools the liquid. You need a setup like an air conditioner unit, but it sounds like you will want something that doesn't need power for pumps and such. So, no condenser or evaporator. Could try a chamber lined with heat dissipating fins, a one way valve into the chamber at the top or end. lower the other end so that the liquid condenses and drips down to circle back into the heating chamber. To accomplish that, the cooling chamber would need to be higher than the heating chamber, one way valve releases steam into cooling chamber, then liquid runs down chamber into a tube or hose equipped with a one way valve at the heating chamber. when enough liquid gets backed up, pushes valve open, releases liquid back into heating chamber. That might not work, depending on how much pressure is in the heating chamber compared to how much push the liquid exerts. Closed loop systems are hard to keep balanced, but its done everyday in your radiator and air conditioner, shouldn't be any reason you can't do it without power, if you fine tune it enough.


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