Liquid Nitrogen

[Teacher_Doug]

Just a word of caution to all you mad:mad: overclockers out there. I've read about some guys using Liquid Nitrogen (LIN) for cooling your CPUs so you can get 2Gig out of a 1Gig Athlon. Beware:
Even though LIN is pretty easy to use and inert, if you use it in a metal box, you can condense Liquid Oxygen from the air...this is not a good move, : ( as if it drips onto plastic or oil it will explode, rather violently. I've worked with LIN for many years and I suggest you treat the stuff with some degree of respect.
Keep up the good work guys, I enjoy reading about your enthusiasm and wish for death (seriously though, you pump water into and next to a 240 v power supply!!!!)

[JigPu]

Once again, more people confirming the dangers on liquid nitrogen. Lets hope some of the newbies learn to play nice with their insane cooling, and us already insane OCers remeber just what the stuff can do...

JigPu

[Yodums]

I've seen that ..

Although -74 Celius is great I just don't think its worth it and very dangerous.

I'd just go water cooling with a 220 watt peltier at the most for extreme measures if you will...

Yodums

[JFettig]

yea, but people say "diamonds are forever" and its NOT TRUE!
when you get liquid O2 itll eat a diamond up! like if youv ever seen watter and lithium or cesium! itll almost explode! its actually pretty cool!!!!

[Thelemac]

Originally posted by Yodums
I've seen that ..

Although -74 Celius is great I just don't think its worth it and very dangerous.

I'd just go water cooling with a 220 watt peltier at the most for extreme measures if you will...

Yodums

Actually, that's not so good. When you hit about -50C you're looking at the limit, since much below that will kill your chip. Maybe not right away, but it won't take too long.

[fatshlink]

im simpaly curios here not being sarcastic or anything, but how does lox condence on a metal box if lin is not as cold??:confused:

[Christoph]

Originally posted by fatshlink
im simpaly curios here not being sarcastic or anything, but how does lox condence on a metal box if lin is not as cold??:confused:

Indeed. I'd love to worry about my computer exploding, but oxygen boils at 90.2 K while nitrogen boils at 70 someting K. I suppose that if you got really cold LN, you'd have to worry about liquid O2 forming, but I'd be more worried about keeping my CPU above 50 °C.

D'oh! My bad. I just answered my own question. 70 K is colder than 90 K.

[ButcherUK]

Originally posted by Yodums

I'd just go water cooling with a 220 watt peltier at the most for extreme measures if you will...


Just you wait till I get my dual 220W rig going, then you'll see extreme. :D

[BinarySuperman]

lol i was gonna ask you guys about liquid nitrogen, does it really stay cold all the time, how does it do that, and is that the stuff the freezes body parts so much you can knock it off???

[Intraveinous]

Yes, LN2 will freeze a finger solid, I've never seen anyone try sticking a finger in and then breaking it off, but it'd prolly work... Shattered hot dogs and carnations are cool.. :D LN2 stays cold because you have something that is a gas at room temp that has phase changed into a liquid. To phase change back to a gas requires energy (heat) so as it evaporates, it draws an immense amount of energy from its surroundings.
I need to get some Liquid Helium, now you're talking... :D
Peace
John

[Teacher_Doug]

Hi again folks,
read your comments with interest, seems a few questions out there that I can help to answer.
:D
Nitrogen boils at -194 to -196 C, Oxygen boils at -181 to -183 C.
This means that Liquid Nitrogen (LIN)is colder than Liquid Oxygen (LOX). If you cool a metal container, like an Aluminium heat exchanger, with LIN, it will eventually reach the same temp. as the LIN. Any Oxygen in the air will condense at -181. Even if you don't see any actual drops fall off, the concentration of oxygen in the surrounding air will increase, so makeing an explosion/very rapid combustion more likely.
IdeaMagnate is correct in his facts about the Boiling points of the gases, but his logic reversed. If Oxygen boils at 90K and Nitrogen at 70K, then the Nitrogen will be liquid when the oxygen will be gas. Its easy to do because we're used to thinking about BOILING like water.
You've also got to think about the expansion. Nitrogen gas takes up about 600 times the volume of the LIN. So if you use 2 litres of LIN to cool, you create over 1200 litres of nitrogen gas. This fills up the room from the bottom (don't forget its still cold) and pushes the breathable air up to the roof...axphyxiation time cough...cough
:eek:
Last point. It is true you can supercool flowers and bananas so they can become brittle and snap off, but you can also pour LIN onto your hand. If you do it slowly, the heat from your hand will actually evaporate the LIN before the liquid reaches the skin.. DONT however put your hand INTO LIN, you won't be able to keep it there long because of the pain, but it won't freeze solid, just have to be amputated later when you develope 100% frostbite.

Sorry about all the tech. info, but I'm a teacher and I CAN'T STOP:burn:
If you see a light at the end of the tunnel, it probably means the tunnel's on fire.!

[Christoph]

Originally posted by drobb2
...
IdeaMagnate is correct in his facts about the Boiling points of the gases, but his logic reversed. If Oxygen boils at 90K and Nitrogen at 70K, then the Nitrogen will be liquid when the oxygen will be gas. Its easy to do because we're used to thinking about BOILING like water.
...



Lysdexia.

Welcome to the forums! I was just wondering if there were any teachers around here.

[Teacher_Doug]

Read Tiger's interesting article on cooling, especially the bits about specific heat capacity (SHC) and thermal transfer rates. The prob with LIN is even though its very cold it's still a gas and has a low specific heat capacity, so you'll need a lot to keep the sink cold. Has anyone tried dry ice (CO2 solid), it has a higher SHC, is easier to buy, safer to use, and you can do away with any pumps etc. by just shovelling in a bunch of pellets when you need to.

Thanks for the welcome IdeaMagnate, enjoy reading any forum where there's real enthusiasm. I've got a Masters in Computing and a BSc in Microbiology, but I'm always learning, especially from you experts. :)

[BinarySuperman]

k so if we took some LIN and put it into a copper heatsink type box like a hollow cube, with LIN inside then how could the lin leak and explode???

[Teacher_Doug]

k so if we took some LIN and put it into a copper heatsink type box like a hollow cube, with LIN inside then how could the lin leak and explode???

s'easy...if the temp of the metal box comes down to -193C (the temp of LIN) then any oxygen in the air (about 20%) in contact with the box also starts to cool down, When the temp. of the oxygen reaches about -183C then it changes phase from a gas to a liquid. (like condensation on a cold beer glass)
:beer:
Its the liquid oxygen that is made from the super cool box which is dangerous, not the LIN itself (well not very much)

[Crash893]

you should use mercury in combo with the liquid nitrogen im pretty sure it stays fluid in that cold a condition.

( wait till i hear how dangorus this is)

[Teacher_Doug]

Oh wow Crash it'll cause a cold fusion reaction between the metal, the mercury and the LIN, all life as we know it will cease.:eek:

Actually the mercury will freeze solid, see http://www.chemicalelements.com/elements/hg.html

Remember Terminator II when the terminator 2000 froze and broke apart in the liquid nitrogen, mercury will go like that.

More seriously though, mercury does give off poisonous vapour, which can cause serious and irreversible brain damage. It aslo forms a type of compound (amalgam) with most metals, that react in odd ways (think of fulminate of mercury in blasting caps)

Have a nice day now

[Jester]

Just out of curiousity, is LiN that easy to get a hold of? I've never seen down at the corner store or anything.

[Teacher_Doug]

You can buy it from any industrial gas company, like Messer Greischam, Air Products, Aire Liquide, AGA Gas, BOC. Use a standard vacuum flask to collect it, there are no restrictions as far as I know. You're better to make a small hole in the cap of the flask, to allow for gaseous expansion, it stops it from blowing the flask apart

[UserName]

Dear doug;
Is repeting yourself a habit from being a teacher? :D

I think LIN is a liquid. That's how it gets it's name LIquid Nitrogen.

It has a lower Specific Heat than water but a much higher SH than nitrogen gas. Also remember the heat of fusion. That is really why it is great at cooling.

[Kent]

Liquid Nitrogen? Now that's INSANE cooling! :)

[ButcherUK]

Better to hire a container for the LN2 from the gas co. than to take your own as it will cause less heat loss and therefore less loss of LN2 than a normal thermos.

[Teacher_Doug]

:o sorry username, a class just came in and I must have clicked the submit button twice :o

but yes repeating IS part of a teacher's role...when I'm trying to teach a class of 20 12 year old basic spreadsheet use, I have to repeat some instructions about 15 times..some kids just don't listen..I don't mind, just part of the job. It's worthwhile when they get it and can start solving problems themselves.

Back to LIN, yes it is a liquid as long as it stays below -193 C, but as it equilibrates with the much warmer environment, it starts to boil. Quite cool,:D , you can drop an ice cube into LIN, and the HEAT of the ice makes the LIN start to boil.
Nitrogen only has one specific heat, but don't forget, the LIN is 600 times denser than the gas phase, so it seems to have higher SHC than the gas phase. Units of SHC are Joules / gram / degree
You are correct in thinking about the heat of fusion though. That's why LIN is used industrially as a rapid cooling agent.

As far as Butcher's comment on the thermos is concerned, I partly agree. If you have a stainless steel vacuum flask, it is almost identical to the smallest industrial LIN container, used by surgeons to freeze off warts:eek:
In the UK a company called Cryoservice, based in Worcester will sell you any amount of LIn, from 100ml to 50,000 litres.

[UserName]

I belive every elements specific heat changes with pressure and heat. Specific Heat units are J/kg per degree at Standard Atmosphere.
I also belive specific heat changes with a phase change.

[Crash893]

Originally posted by drobb2
Oh wow Crash it'll cause a cold fusion reaction between the metal, the mercury and the LIN, all life as we know it will cease.:eek:

Actually the mercury will freeze solid, see http://www.chemicalelements.com/elements/hg.html

Remember Terminator II when the terminator 2000 froze and broke apart in the liquid nitrogen, mercury will go like that.

More seriously though, mercury does give off poisonous vapour, which can cause serious and irreversible brain damage. It aslo forms a type of compound (amalgam) with most metals, that react in odd ways (think of fulminate of mercury in blasting caps)

Have a nice day now

oh i know one time i proposed a mecurury cooling system i got like 1000 posts saying id kill my self

( i just like thowing gas on flames)

[Teacher_Doug]

I've never really thought about changes to the specific heat capacity with phase change. In the cooling industry, gas phase is never really used, only LIN due to (as you mentioned earlier) the energy absorbtion of the heat of fusion. I suspect that it is an elemental constant, unchanging with phase.
Anyway, nobody answered my earlier question about using Dry Ice (solid CO2), has anybody tried it?

[Coolio]

I don't think that Dry Ice or LIN are feesable. (spelling) How is one supposed to monitor the amount left and replace it periodically. You would need to replenish you supply and going out to get some would be a pain everytime.

[Teacher_Doug]

Coolio I don't think that Dry Ice or LIN are feesable.
I'm pretty sure that LIN systems are used professionaly in supercomputers, but I take your point. However the dry ice should be easier and safer to use. Because it's solid its easier to handle and to store (keeps for quite a few days in a domestic
-20C freezer) A vertical polycarbonate tube could act as a reservoir over a heat exchange block, top up as required, probably every 1-2 hours

[UserName]

I was tiold LIN systems use a pressure based system. If the system warms up the pressure incresses so a blow off vallve opens and more liquid enters from the tank.

Specific Heat is not an elemental constant. It changes with tempature and pressure. Mostly it don't change much so to not confuse the kids they say it's a constant, but its not. Just like they teach kids to round numbers off wrong, to keep it simple.

[Teacher_Doug]

I was tiold LIN systems use a pressure based system. If the system warms up the pressure incresses so a blow off vallve opens and more liquid enters from the tank.

You can use LIN this way. If you are using a closed system, you MUST have a blow off or relief valve to vent gaseous nitrogen. Most systems, especially home built systems use a slow drip feed, open to the atmosphere, so are self regulating, but this can cause fluctuations in the chip temp

[Holst]

Thanks for teaching us Doug.

I dont think im insane enough for LIN cooling.

Maybee Dry ice though.

Where could I buy dry ice in the UK ?

Ive got a old socket A board and a duron id quite like to sacrifice (sorry experiment with)

Dry Ice would be a ideal way to see if going to a peltier on my watercooling would give significant gains or not.

I saw some piccs that macci (i think it was him) took when he used dry ice to cool his system and I think I could do the same.

Could I just desolve the dry ice into a copper beaker fixed to the core filled with glycol.

What temperature would glycol freeze ?

EDIT- My typing skills are dreadfull

[Samzik]

- 40 (http://forums.overclockers.ws/vb/showthread.php?threadid=47387) thers an idea how u can sefly cool ur system down with good bandwith.

[Teacher_Doug]

You can buy dry ice from BOC, ICI or Air Products in the UK. Check your yellow pages for the nearest depot. It shouldn't be too expensive. Sometimes theatrical suppliers can supply or give info (they use it to make stage fog).
Theoretically, you can just dump it onto your athlon, the dry ice sublimates straight to vapour, and as long as ther's no water ice on it, it shouldn't cause any probs. You can test the dryness by putting some onto kitchen towel, if it gets damp, then there's water present.
You can always try putting some in warm water or a glass of coke, it produces foggy bubbles, looks really creepy. NOTE after use, check your chips are all firmly seated, thermal expansion/contraction can make them become loose, connectors for IDE cables also.
I'm not sure about he glycol. The dry ice wont dissolve (I think), but you will get supercooled glycol

[Vega]

i've always wanted to some LIN.

So i can just buy it as joe public. Is it expensive.

U can turn bananas into hammers with that stuff can't you?

mmmmmmmmm....................

[Teacher_Doug]

So i can just buy it as joe public. Is it expensive.

Not really, cost (in UK) about £5 for 1 litre. Check your phone book for BOC, Cryoservice (I think there's one near you)or Air Products. Bring a stainless steel vacuum flask, or you can normally rent one from the company. The actual cost of the stuff is pennies, (about 12p/litre), but as you'll have to cool down the flask first, you'll be charged for the extra time. There are no real legal restrictions, but the companies normally won't sell it to juveniles. It is used occaisionaly by mechanics, to shrink fit compression rings. If you have any friends/family working in hospital/university, you might be able to get a free sample