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Hardware Forum / PC Hardware / Overclocking / December 2007Pumping Liquid Nitrogen
I have been offered a small (about the size of a water cooler) liquid nitrogen generator at an attractive price. It generates four and a half liters per day, using a gravity feed to keep a half liter dewar filled. I want to pump the liquid nitrogen into a hole drilled into the heatsinks of the CPU and GPU of a gaming PC so I can overclock them farther than otherwise possible. (This is for a a "just for fun" personal project, not for work). My question is how best to pump the liquid nitrogen. In the past I have worked with big dewars and let them self-pressurize with a relief valve on top and a feed tube going to the bottom -- sort of like an aerosol can. This doesn't look feasible in this case; the back pressure seems like it will back up the gravity feed. I think I need a small pump that can take the cold and not add too much heat to the liquid nitrogen. Any ideas? BTW, I have seven old 500 MHz. Pentium 3 systems that are ready to be scrapped that I will be doing my initial experiments on before deciding whether to risk a more modern PC.  SignatureGuy Macon <http://www.guymacon.com/> > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] > initial experiments on before deciding whether to > risk a more modern PC. Let me be the first to say, "that's going to be cool." :-) Mike > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] > initial experiments on before deciding whether to > risk a more modern PC. It would be easier to deal with the boiloff gas - it's still at 77K. Do you actually need the LN2? SignatureDirk http://www.transcendence.me.uk/ - Transcendence UK Remote Viewing classes in London >> I want to pump the liquid nitrogen into a hole drilled >> into the heatsinks of the CPU and GPU of a gaming PC >> so I can overclock them farther than otherwise possible. > >It would be easier to deal with the boiloff gas - it's still at 77K. >Do you actually need the LN2? Yup. The latent heat of evaporation for Nitrogen is 198.3 Joules per gram at one atmosphere, while the the specific heat capacity for nitrogen is only 1.006 Joules per gram per degree Kelvin. Also, liquids conduct heat far better than gasses. I don't have an uploadable cooling curve for nitrogen at hand, but take a look at the cooling curve for water: [ http://www.physchem.co.za/Heat/Graphics/Heat42.gif ]. The portion of the curve labled D shows that the energy needed to go from 99.99 degrees C to 100.01 degrees C is much larger than from 0.01 degrees C to 99.99 degrees C. This is typical of boiling liquids. SignatureGuy Macon <http://www.guymacon.com/> >>> I want to pump the liquid nitrogen into a hole drilled >>> into the heatsinks of the CPU and GPU of a gaming PC [quoted text clipped - 14 lines] > is much larger than from 0.01 degrees C to 99.99 > degrees C. This is typical of boiling liquids. The solder balls on the processor module will probably rip the pad metallization right off the CPU, but if the PC is scrap anyway, it's probably worth a try. Pumping LN2 is really hard--harder than pumping boiling water, and for the same reason, namely cavitation on the low-pressure side--so you'd be much better off just letting the dewar pressurize itself a little. You're going to run out of LN2 in a few hours anyway. Cheers, Phil Hobbs >I have been offered a small (about the size of a water >cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] >initial experiments on before deciding whether to >risk a more modern PC. The only thing that comes to mind is pumps used for liquid fuel rockets. D from BC > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 6 lines] > (This is for a a "just for fun" personal project, not > for work). What's the temperature spec on the CPU you will be using? Odds are that it won't deal with LN2 temperatures well. Consider the heat capacity of LN2 (include the heat of vaporization) compared to that of H2O. For the complexity of what you propose to do, LN2 won't buy you much more than a good heat exchanger/radiator setup. Also, keep in mind that in an enclosed space (your mom's basement? ;-)) the nitrogen gas will displace air and asphyxiate the user if not properly ventilated. SignaturePaul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ ASCII stupid question, get a stupid ANSI! >> I have been offered a small (about the size of a water >> cooler) liquid nitrogen generator at an attractive [quoted text clipped - 17 lines] >the nitrogen gas will displace air and asphyxiate the user if not >properly ventilated. http://www.youtube.com/watch?v=zUc6znC848o CPU cooling with liquid nitrogen D from BC >What's the temperature spec on the CPU you will be using? >Odds are that it won't deal with LN2 temperatures well. Others have done it without any problems. Semiconductors as a rule do not mind LN2 temperatures as long as you avoid thermal shock and icing. Besides, overclockers pretty much expect to lose a few if they push the envelope. >Consider the heat capacity of LN2 (include the heat of vaporization) >compared to that of H2O. For the complexity of what you propose to do, >LN2 won't buy you much more than a good heat exchanger/radiator setup. It will buy me minus 196 degrees, and others who have tried it have reported a stable system with a 3GHz. CPU overclocked to 5GHz. >Also, keep in mind that in an enclosed space (your mom's basement? ;-)) >the nitrogen gas will displace air and asphyxiate the user if not >properly ventilated. Nope. that's for systems with a *source* of nitrogen. A nitrogen generator takes as much out of the room air as the boiling nitrogen puts back in. (I would ventalate it anyway, but for the opposite reason; to avoid any Oxygen concentration around the generator) SignatureGuy Macon <http://www.guymacon.com/> [snip] > >Also, keep in mind that in an enclosed space (your mom's basement? ;-)) > >the nitrogen gas will displace air and asphyxiate the user if not [quoted text clipped - 4 lines] > puts back in. (I would ventalate it anyway, but for the opposite > reason; to avoid any Oxygen concentration around the generator) True. Some time ago, I had to stop someone from setting up a refrigeration system with the LN2 generator located in a different area. It made too much noise. SignaturePaul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Do not mold, findle or sputilate. >>What's the temperature spec on the CPU you will be using? >>Odds are that it won't deal with LN2 temperatures well. [quoted text clipped - 19 lines] >puts back in. (I would ventalate it anyway, but for the opposite >reason; to avoid any Oxygen concentration around the generator) That makes me wonder. You are in fact creating some sort of heat-pump which doesn't sound very efficient (you will be heating the room!). Isn't it easier to use a modified air-conditioner? All you need is to evaporate gas in the CPU's heatsink and chipset's heatsink. SignatureReply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl 'Guy Macon' wrote, in part: | I have been offered a small (about the size of a water | cooler) liquid nitrogen generator at an attractive | price. It generates four and a half liters per day, | using a gravity feed to keep a half liter dewar filled. _____ You could just Google a search string that includes [ overclocking CPU liquid Nitrogen ] and get over 94,000 hits. Most (if not all) these Rube Goldberg devices just build a tank around the CPU heatsink, fill the tank with liquid Nitrogen and let it boil off as it may. For actually pumping liquid nitrogen you could contact NASA for a few tips... especially safety tips. Taking a flyer with a Pentium III is hardly worth the effort. One possibility for a more or less continuously operating cooler would be to use the boil-off of liquid nitrogen to chill an anti-freeze mixture (propylene glycol & water ~ 50:50 should be good to below - 40) that you could then pump through a more or less stock CPU water block. Phil Weldon | I want to pump the liquid nitrogen into a hole drilled | into the heatsinks of the CPU and GPU of a gaming PC [quoted text clipped - 15 lines] | initial experiments on before deciding whether to | risk a more modern PC. A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on Usenet? >For actually pumping liquid nitrogen you could contact NASA >for a few tips... especially safety tips. You are talking to the person who taught the cryogenic safety classes for Parker Hannifin on the space shuttle 17 inch disconnect project -- under contract with NASA. >Taking a flyer with a Pentium III is hardly worth the effort. You prefer I ruin a few Core Duos while I experiment? >One possibility for a more or less continuously operating >cooler would be to use the boil-off of liquid nitrogen to >chill an anti-freeze mixture (propylene glycol & water >~ 50:50 should be good to below - 40) that you could then >pump through a more or less stock CPU water block. I don't want minus 40. I want minus 196. SignatureGuy Macon <http://www.guymacon.com/> Somewhere on teh intarweb "Guy Macon" typed: > A: Because it messes up the order in which people normally read text. > [quoted text clipped - 3 lines] > > Q: What is the most annoying thing on Usenet? Ohhh! Original. You come into our house asking advice and act like this? Good luck with that. >> For actually pumping liquid nitrogen you could contact NASA >> for a few tips... especially safety tips. > > You are talking to the person who taught the cryogenic > safety classes for Parker Hannifin on the space shuttle > 17 inch disconnect project -- under contract with NASA. And you're asking your questions here because all those contacts you made are ob holiday? >> Taking a flyer with a Pentium III is hardly worth the effort. > > You prefer I ruin a few Core Duos while I experiment? Sure, with the money you made from a morning's teaching cryogenic safety classes you could ruin a few Core Quads. After all, you can afford a liquid nitrogen generator, what's a few hundred bucks worth of CPUs? Trying it with a PIII is like learning to drag-race in a pedal-car. >> One possibility for a more or less continuously operating >> cooler would be to use the boil-off of liquid nitrogen to [quoted text clipped - 3 lines] > > I don't want minus 40. I want minus 196. Well Mr. Cryo-teacher, be sure to let us know how it works out for you. Or not. SignatureTTFN, Shaun. >>> For actually pumping liquid nitrogen you could contact NASA >>> for a few tips... especially safety tips. [quoted text clipped - 5 lines] >And you're asking your questions here because all those >contacts you made are ob holiday? Experience designing the 17 inch wide valve that connects the external tank to the space shuttle doesn't apply much to the problem of finding a small, cheap pump for less than a liter per hour of liquid nitrogen. >>> Taking a flyer with a Pentium III is hardly worth the effort. >> >> You prefer I ruin a few Core Duos while I experiment? > >Sure, with the money you made from a morning's teaching cryogenic >safety classes The word "taught" is past tense. I no longer work for Parker. The Jamboree Blvd. plant closed down quite some time ago. >you could ruin a few Core Quads. After all, you can afford >a liquid nitrogen generator, what's a few hundred bucks >worth of CPUs? Trying it with a PIII is like learning to >drag-race in a pedal-car. If I was thinking of trying something that could burn out my expensive drag racer, I might very well try it on a few pedal cars first. Even if I could afford to destroy multiple race cars. >>> One possibility for a more or less continuously operating >>> cooler would be to use the boil-off of liquid nitrogen to [quoted text clipped - 6 lines] >Well Mr. Cryo-teacher, be sure to let us know how it works >out for you. Or not. "Arguing with anonymous strangers on the Internet is a sucker's game because they almost always turn out to be -- or to be indistinguishable from -- self-righteous sixteen-year-olds possessing infinite amounts of free time." -Neil Stephenson, _Cryptonomicon_ *plonk* > "Arguing with anonymous strangers on the Internet is a sucker's > game because they almost always turn out to be -- or to be [quoted text clipped - 3 lines] > > *plonk* Wouldn't your time be better spent correcting the it's/its errors on your site, beard-boy? "Before examining Structured Engineering, it is instructive to examine it's predecessor," Argh. Anyways, go spend some time with a woman this Christmas instead of an inert box of crap that only excites teenagers and 45 year old teenagers. With horror-beards. At least it's not a neck beard, I suppose. > >>> For actually pumping liquid nitrogen you could contact NASA > >>> for a few tips... especially safety tips. [quoted text clipped - 47 lines] > possessing infinite amounts of free time." > -Neil Stephenson, _Cryptonomicon_ Resistor maybe. Evaporate a little nitrogen, use the pressure to move the rest. Use the exhausted nitrogen from the other end to keep the rest of the box cool and dry. Robert SignaturePosted via a free Usenet account from http://www.teranews.com >Evaporate a little nitrogen, use the pressure to move the rest. >Use the exhausted nitrogen from the other end to keep the >rest of the box cool and dry. That was my original thought as well, and is the method I have used in larger cryogenic systems. There is even an outfit that will sell you a microcontroller-operated sensor/valve that you put on the gas vent to regulate flow through the liquid output -- sort of like an aerosol can that never loses pressure. The problem is that those systems all depebded on deliveries of liquid nitrogen, so getting a full dewar to self-pressurize was no problem. The system I am looking at here generates liquid nitrogen from the air (it was originally used in a medical office) and gravity-fills a half liter dewar. I am pretty sure that if I let it self-pressurize the gas will escape through the intake tube rather than by forcing liquid out through the output tube. thus the question about a pump. SignatureGuy Macon <http://www.guymacon.com/> > >Evaporate a little nitrogen, use the pressure to move the rest. > >Use the exhausted nitrogen from the other end to keep the [quoted text clipped - 14 lines] > escape through the intake tube rather than by forcing liquid > out through the output tube. thus the question about a pump. Ah, any reason you need continuous flow? Pressurize to pump, let off pressure to let accumulated liquid nitrogen into the dewar. You'd need check valves on the inlet an outlet lines. I rather like the percolator idea as well but isn;t the surface tension of liquid nitrogen rather low compared to water? You might just end up with a stream of cool nitrogen vapour coming up the tube. Robert SignaturePosted via a free Usenet account from http://www.teranews.com >> >Evaporate a little nitrogen, use the pressure to move the rest. >> >Use the exhausted nitrogen from the other end to keep the [quoted text clipped - 19 lines] >Pressurize to pump, let off pressure to let accumulated liquid nitrogen >into the dewar. You'd need check valves on the inlet an outlet lines. I would have to either shut down the PC or drop the clock rate on the CPU and GPU. It wouldn't take long to burn up a 3GHz proessor overclocked to 5GHz. Then again, I probably need a shutdown on loss of coolant anyway. I was envisioning a constant flow with a simple servo to hold a certain CPU temperature. A put-put variation as in a percolator or pistom pump wouldn't be too bad, but an interuprtion long enough to refill a dewar seems like it would be a problem. >I rather like the percolator idea as well but isn;t the surface tension >of liquid nitrogen rather low compared to water? You might just end up >with a stream of cool nitrogen vapour coming up the tube. I am beginning to think that designing a LN2 perolator might be the part that I find to be the most fun. :) SignatureGuy Macon <http://www.guymacon.com/> > >> >Evaporate a little nitrogen, use the pressure to move the rest. > >> >Use the exhausted nitrogen from the other end to keep the [quoted text clipped - 24 lines] > overclocked to 5GHz. Then again, I probably need a shutdown on loss > of coolant anyway. I was thinking the off portion would be a second or two. Not enough to fill the Dewar, just let in whatever has been generated. I was assuming there would be enough of a head on the nitrogen to handle a short off period. A nice wide input valve and a short off cycle. > >I rather like the percolator idea as well but isn;t the surface tension > >of liquid nitrogen rather low compared to water? You might just end up > >with a stream of cool nitrogen vapour coming up the tube. > > I am beginning to think that designing a LN2 perolator might be the > part that I find to be the most fun. :) Well, there is that :) Robert SignaturePosted via a free Usenet account from http://www.teranews.com >> >Evaporate a little nitrogen, use the pressure to move the rest. >> >Use the exhausted nitrogen from the other end to keep the [quoted text clipped - 25 lines] > >Robert The percolator pump can work well with LN2, for instance a percolator pump is used for a 6 foot lift in one air separation plant I know of. Air separation plants and bottle filling facilities generally fill high pressure bottles from low pressure liquid storage tanks by perssurizing the liquid to 3000+ PSI, evaporating the HP liquid in those ice covered towers you see outside at these facilities, and filling the tanks with warmed HP gas. It takes a lot less energy to pressurize liquid than gas. The pumps are simple piston pumps with extra long insulated parts, but hardly worth it for moving a few liters a few feet. Somewhere on teh intarweb "Glen Walpert" typed: > It takes a lot less energy to > pressurize liquid than gas. Wow! Things have sure changed since I studied physics. You can pressurize liquids now? Easier than gas no less! I guess that means my car brakes aren't going to work anymore. Thanks for the heads-up, I could have been killed. SignatureTTFN, Shaun. "another academic failure.... trying to prove that your smart" 'blanking', nz.comp, 20 Dec 2007. "your so predictable misfit" 'blanking', nz.comp, 21 Dec 2007. >Somewhere on teh intarweb "Glen Walpert" typed: > [quoted text clipped - 5 lines] >aren't going to work anymore. Thanks for the heads-up, I could have been >killed. Do you know the difference between "pressurize" and "compress"? Best regards, Spehro Pefhany Signature"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Somewhere on teh intarweb "Spehro Pefhany" typed: >> Somewhere on teh intarweb "Glen Walpert" typed: >> [quoted text clipped - 7 lines] > > Do you know the difference between "pressurize" and "compress"? Sometimes. Obviously this wasn't one of them. ;-) SignatureTTFN, Shaun. "another academic failure.... trying to prove that your smart" 'blanking', nz.comp, 20 Dec 2007. "your so predictable misfit" 'blanking', nz.comp, 21 Dec 2007. > >I rather like the percolator idea as well but isn;t the surface tension > >of liquid nitrogen rather low compared to water? You might just end up > >with a stream of cool nitrogen vapour coming up the tube. > > The percolator pump can work well with LN2, for instance a percolator > pump is used for a 6 foot lift in one air separation plant I know of. There we go. How large is the diameter of the pipes in the percolator? Robert SignaturePosted via a free Usenet account from http://www.teranews.com >> >I rather like the percolator idea as well but isn;t the surface tension >> >of liquid nitrogen rather low compared to water? You might just end up [quoted text clipped - 6 lines] > >How large is the diameter of the pipes in the percolator? I don't recall the pipe size anymore but it was way too big for just a few liters per day. You could calculate the optimal diameter using the rather complicated methods described in "Two Phase Flows and Heat Transfer" by Ginoux, or you could wing it and try 1/4" OD 3/16" ID tubing or therabouts. Effective insulation will be the hard part. Having once spent 3 days on a single cryo transfer choking calculation, I suggest the "wing it" approach :-). >>Evaporate a little nitrogen, use the pressure to move the rest. Use the >>exhausted nitrogen from the other end to keep the rest of the box cool [quoted text clipped - 13 lines] > will escape through the intake tube rather than by forcing liquid out > through the output tube. thus the question about a pump. Hey, Guy, am I on plonk again, or what? I suggested that if you have your own place, and two stories to work with, just make a 15 foot tall dewar, and gravity feed the stuff from the second floor. I mean, it makes as much sense as tracking down and buying a rocket fuel pump. And the fact that you want to chill your CPU to LN2 temperatures is prima facie evidence that you're already quite insane, so what the hell, go for it! ;-D Cheers! Rich Somewhere on teh intarweb "Guy Macon" typed: >>>> For actually pumping liquid nitrogen you could contact NASA >>>> for a few tips... especially safety tips. [quoted text clipped - 49 lines] > > *plonk* Indeed, what one would expect from someone with little grasp of the English language. I'm a great believer in the passage that you quoted above. That's why I don't engage in *arguments* "on the internet". (Hint: Look up the word, re-read my post...) Oh, and from your website: "HARDWARE DESIGN; I am an *expert* in *all areas* of electronics, including analog, digital, microcontroller, high-power, low-power, high volume, aerospace and consumer electronics." (My ** emphasis) Seems that you should be helping us instead of only coming here for help. Mr. Expert. Buh-bye. SignatureTTFN, Shaun. "another academic failure.... trying to prove that your smart" 'blanking', nz.comp, 20 Dec 2007. 'Guy Macon' wrote, in part: | A: Because it messes up the order in which people normally read text. | [quoted text clipped - 3 lines] | | Q: What is the most annoying thing on Usenet? ______ Being that you are more interested in heat than light, why the post on liquid Nitrogen in the first place? Phil Weldon | A: Because it messes up the order in which people normally read text. | [quoted text clipped - 22 lines] | | I don't want minus 40. I want minus 196. How about a percolator arrangement; can't get much simpler and no moving parts? I think that if you submerge one end of a piece of tubing in the LN2 you will get spurts of LN2 forced up the tube. I don't know what geometry would be best but I think a few small entrance holes with area a good bit less than the inside cross sectional area of the tubing. Maybe look online at pulse jets for ideas, or your oldfashioned coffee pot :-). -- Regards, Carl Ijames carl dott ijames aat verizon dott net (remove nospm or make the obvious changes before replying) >How about a percolator arrangement; can't get much simpler and no moving >parts? I think that if you submerge one end of a piece of tubing in the [quoted text clipped - 3 lines] >Maybe look online at pulse jets for ideas, or your oldfashioned coffee >pot :-). That's a really good idea! If the percolator doesn'y do it, I could also use check valves; I haven't found a suitible pump, but small teflon check valves are easy to get. A resistor controoled by a BasicX controller (www.basicx.com) could provide a pulsing heat source if needed. Thanks! I will let you know if I can make that work. SignatureGuy Macon <http://www.guymacon.com/> > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] > initial experiments on before deciding whether to > risk a more modern PC. There is a whole forum devoted to LN2 and dry ice here. Maybe someone here will have an answer. http://www.xtremesystems.org/forums/forumdisplay.php?f=156 Paul > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 24 lines] > Guy Macon > <http://www.guymacon.com/> That's wonderful; how are you going to deal with frost? Where's this water gonna go when it melts? >That's wonderful; how are you going to deal with frost? >Where's this water gonna go when it melts? Frost comes from condensation. Condensation comes from moisture in the air (humidity). Boiling liquid Nitrogen produces a gas that has no moisture in it -- it is completely dry -- and will fill the enclosure if I make it so that all fans recirculate instead on exhausting. I will have to worry about the outside of the case dripping, though. I wouldn't want it to drip on to the internal circuitry. SignatureGuy Macon <http://www.guymacon.com/> > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 8 lines] > > My question is how best to pump the liquid nitrogen. You can use a simple piston pump for the actual pumping. The motor should be connected via a very long non conducting rod. The construction of the pump can use Teflon parts where things need to slide and silicone parts where a little springiness is needed. The idea, however is quite insane. The thermal stress will break things in the computer. > In the past I have worked with big dewars and let them > self-pressurize with a relief valve on top and a feed [quoted text clipped - 12 lines] > Guy Macon > <http://www.guymacon.com/> >The thermal stress will break things in the computer. A slow cool down is needed to avoid thermal shock. SignatureGuy Macon <http://www.guymacon.com/> >I have been offered a small (about the size of a water >cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] >initial experiments on before deciding whether to >risk a more modern PC. You could be shooting yourself in the foot. I think the self pressuring with a dip tube in the flask is the way to go. Back pressure? Where is that coming from? Plan to regulate the boil off at the outlet of the Pentium heat sink? The gas is much less dense than liquid to it should get through the heat sink without much back pressure . The foot wound - check the low temp specs on the Pentium before you go all out on this. Transistor gain goes way down at cryogenic temperatures. -- > I have been offered a small (about the size of a water cooler) liquid > nitrogen generator at an attractive price. It generates four and a half [quoted text clipped - 16 lines] > scrapped that I will be doing my initial experiments on before deciding > whether to risk a more modern PC. Notwithstanding the "it's _TOO_ cold!" warnings, if you own your own house, you could use plain ol' gravity feed - just put the generator on the floor above the comp, with a very tall dewar between. Of course, that depends on whether modifying the house is cheaper than a(an?) LN2 pump. ;-) Good Luck! Rich > > I have been offered a small (about the size of a water cooler) liquid > > nitrogen generator at an attractive price. It generates four and a half [quoted text clipped - 26 lines] > Good Luck! > Rich Yup, gravity feed was exactly my thinking as I read through this thread. Let me just add: Keep the liquid nitrogen BELOW eyelevel. Think about not only spills, but drops spattering about. (Imagine grease or water in a hot frying pan. That's what liquid nitrogen does when it hits "hot" room temperature objects). Mark p.s. that being said, I will mention that I violated the "eye level rule" back in grad school. The main point is to be careful while still having fun. > I have been offered a small (about the size of a water > cooler)liquidnitrogengenerator at an attractive [quoted text clipped - 24 lines] > Guy Macon > <http://www.guymacon.com/> I just got involved with cooling a microscope chamber. The first design, not by me, was a failure in every respect. Trying to cool a copper chamber by a copper pipe about a foot long, from a thermos filled around the end coil of the copper tubing. Gas was allowed to go through the tube. Temp drop after several minutes was a couple degrees below room temp. Next design gets the fluid right around the chamber. I also recently was working with a pumped unit, rather expensive, out of date, and didn't work right. Sometimes these things are not repairable or is too costly. I would be interested in knowing what type of pumps are suitable for moving the fluid around. greg >I have been offered a small (about the size of a water >cooler) liquid nitrogen generator at an attractive [quoted text clipped - 20 lines] >initial experiments on before deciding whether to >risk a more modern PC. How about a magnetically coupled centrifugal pump. A magnet in a rotor can be spun by a magnet on a motor or by coils that emulate a rotating mag field. This is not too different than my interest in magnetic stirrers. (See DIY Magnetic Stirrer post and my posts on etchant pumps.) Some liquid nitrogen can probably be fed to the field inductors to enhance the drive performance. Likewise I think the rotor magnet gets a boost too from the cold temperature. (I can't recall what magnets do when super cooled.) I"ve been tempted to design a pump like this, but it would be to pump etchant. If you make one, let me know.. :) D from BC > >I have been offered a small (about the size of a water > >cooler) liquid nitrogen generator at an attractive [quoted text clipped - 30 lines] > Likewise I think the rotor magnet gets a boost too from the cold > temperature. (I can't recall what magnets do when super cooled.) I don't think motors mind low temperatures too much as long as the materials tolerate them (I'm thinking about bearing lubricants, brittle insulation, etc.) Some superconductors don't do too well in high magnetic fields, but I think that is a problem with the older generation type. Superconducting rotating machines are a very interesting field of R&D. As long as the motor doesn't depend on superconduction properties at LN2 temps, it should run fine. There are quite a few pump designs (both centrifugal and others) in which the impeller, bearings, rotors, etc. are immersed in the pumped fluid. The stator windings are potted to keep the fluid out. Small water pumps and immersed gasoline pumps in your car's tank are built this way. With an LN2 environment, the rotor and stator might shrink a bit, so the design should account for a slightly larger air gap than at room temperature. > I"ve been tempted to design a pump like this, but it would be to pump > etchant. If you make one, let me know.. :) > > D from BC SignaturePaul Hovnanian paul@hovnanian.com ----------------------------------------------------------------------- Procrastinators: The leaders for tomorrow. > With an LN2 environment, the rotor and stator might shrink a bit, so the ^^^ > design should account for a slightly larger air gap than at room > temperature. You mean smaller gap? Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms > > With an LN2 environment, the rotor and stator might shrink a bit, so the > ^^^ > > design should account for a slightly larger air gap than at room > > temperature. > > You mean smaller gap? I think if the rotor and stator shrink, the gap gets larger. > Tim > > -- > Deep Fryer: A very philosophical monk. > Website @ http://webpages.charter.net/dawill/tmoranwms SignaturePaul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ The Three Laws of Thermodynamics: 1) You can't win. 2) You can't break even. 3) You can't quit the game. > > > With an LN2 environment, the rotor and stator might shrink a bit, so the > > ^^^ [quoted text clipped - 4 lines] > > I think if the rotor and stator shrink, the gap gets larger. Everything shrinks proportionally in all dimension. "Everything" includes the gap. Somewhere on teh intarweb "Richard Henry" typed: >>>> With an LN2 environment, the rotor and stator might shrink a bit, >>>> so the ^^^ design should account for a slightly larger air gap [quoted text clipped - 6 lines] > Everything shrinks proportionally in all dimension. "Everything" > includes the gap. Assuming similar materials for rotor and stator (housing). SignatureTTFN, Shaun. "another academic failure.... trying to prove that your smart" 'blanking', nz.comp, 20 Dec 2007. "your so predictable misfit" 'blanking', nz.comp, 21 Dec 2007. > Somewhere on teh intarweb "Richard Henry" typed: > [quoted text clipped - 20 lines] > "your so predictable misfit" > 'blanking', nz.comp, 21 Dec 2007. True, but the difference in shrinkage betwen the rotor and stator would have to be greater that the shrinkage of the stator in order for the gap to become larger. > > > > With an LN2 environment, the rotor and stator might shrink a bit, so the > > > ^^^ [quoted text clipped - 7 lines] > Everything shrinks proportionally in all dimension. "Everything" > includes the gap. Lets see: The rotor gets smaller. The stator gets thinner and its circumference decreases. Unlike a solid ring, the interior of a rotor is (usually) slotted, so its circumferential shrinkage doesn't reduce the ID in the same manner as with a solid ring. The pole pieces do shrink in length, increasing the stator ID. I've seen the results of the reverse problem, heating a motor with a very small air gap to the point that the rotor hit the poles. SignaturePaul Hovnanian paul@hovnanian.com ----------------------------------------------------------------------- Procrastinators: The leaders for tomorrow. > Lets see: The rotor gets smaller. The stator gets thinner and its > circumference decreases. The circumference, inside and out, decreases. It gets thinner, but the inside diameter does not increase; that would be absurd. If the rotor and stator are made of the same material (they are in an induction motor, made of laminated steel) and are the same temperature, then the gap will get smaller as the temperature decreases. If the materials are not equal (e.g., aluminum housing or rotor, permanent magnets, etc.), behavior may differ. Most likely, in a DC motor, the rotor heats up more than the stator/housing, so the gap will tend to shrink, regardless of the outside air temperature. Different types of induction motors (wound, fixed and permanent rotors, etc.) may behave differently. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms > > Lets see: The rotor gets smaller. The stator gets thinner and its > > circumference decreases. > > The circumference, inside and out, decreases. It gets thinner, but the > inside diameter does not increase; that would be absurd. Absurd? That's how one gets a press fit bearing race on a shaft (by heating it). > If the rotor and stator are made of the same material (they are in an > induction motor, made of laminated steel) and are the same temperature, > then the gap will get smaller as the temperature decreases. > > If the materials are not equal (e.g., aluminum housing or rotor, permanent > magnets, etc.), behavior may differ. That may be the case. I've seen generators fail at high temps by rubbing the rotor/stator due to decreased clearance. At first, it seemed to be counter intuitive. > Most likely, in a DC motor, the rotor heats up more than the > stator/housing, so the gap will tend to shrink, regardless of the outside > air temperature. Different types of induction motors (wound, fixed and > permanent rotors, etc.) may behave differently. That's possible as well. Behavior of a stator and rotor in contact with LN2 may have different effects than a machine cooled mainly from the outside. > Tim > > -- > Deep Fryer: A very philosophical monk. > Website @ http://webpages.charter.net/dawill/tmoranwms SignaturePaul Hovnanian paul@hovnanian.com ----------------------------------------------------------------------- Procrastinators: The leaders for tomorrow. > Absurd? That's how one gets a press fit bearing race on a shaft (by > heating it). Not simultaneously. The bearing (or other socket) is kept at room temperature or heated, while the shaft (or peg, or...) is cooled or kept at room temperature, respectively. Heat makes the inner diameter expand, not cold. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms >> Absurd? That's how one gets a press fit bearing race on a shaft (by >> heating it). [quoted text clipped - 3 lines] >room temperature, respectively. Heat makes the inner diameter expand, not >cold. And you have exactly one chance to get them into the correct position before the temperature equalizes... Best regards, Spehro Pefhany Signature"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com > > Absurd? That's how one gets a press fit bearing race on a shaft (by > > heating it). [quoted text clipped - 3 lines] > room temperature, respectively. Heat makes the inner diameter expand, not > cold. That's how you get a press fit bearing race _off_ a shaft as well. Not much chance of maintaining a temp difference between them in this case. SignaturePaul Hovnanian paul@hovnanian.com ----------------------------------------------------------------------- Procrastinators: The leaders for tomorrow. > That's how you get a press fit bearing race _off_ a shaft as well. Not > much chance of maintaining a temp difference between them in this case. Except for certain circumstances: I've heard of CNC heads which have ferrite transformers in the cutting head to inductively heat the spindle, expanding it away from the cutter's shank quickly. Sweet! Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms >> > > With an LN2 environment, the rotor and stator might shrink a bit, so >> > > the [quoted text clipped - 8 lines] > Everything shrinks proportionally in all dimension. "Everything" > includes the gap. Pretty much, but it still depends on the materials TCE. SignatureJosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive > price. It generates four and a half liters per day, > using a gravity feed to keep a half liter dewar filled. Lucky bastard! That what I want for chrismas. > I think I need a small pump that can take the cold and > not add too much heat to the liquid nitrogen. Any ideas? How about a "bubble pump" or "vapour lift pump"? Basically the principle used by aquariums. That way you "only" need to pump very cold nitrogen gas - which could be the gas boiled off from the CPU cooler > I have been offered a small (about the size of a water > cooler) liquid nitrogen generator at an attractive [quoted text clipped - 24 lines] > Guy Macon > <http://www.guymacon.com/> How about pushing the liquid nitrogen instead of pumping it? Imagine an insulated chamber, half-filled with liquid nitrogen, having a lid with two holes. One hole is for the nitrogen output tube, which goes all the way from the lid down to within say 1/8 inch from the bottom of the chamber. The other hole is for the input tube, which is just a short tube. This is where you blow. Now you just need a way to blow measured amounts of gas into the short tube, pushing the liquid nitrogen up the output tube. Compressed air tank with a needle valve... aquarium pump... CO2 gun cylinders... ? Have fun Michael >> I have been offered a small (about the size of a water >> cooler) liquid nitrogen generator at an attractive [quoted text clipped - 42 lines] > >Michael With that idea, I think the LN2 could pump itself.. How about using gas pressure regulator. Feed the 'exhaust' N2 gas back to pressurize the tank. Excess pressure is vented. D from BC > With that idea, I think the LN2 could pump itself.. > How about using gas pressure regulator. > Feed the 'exhaust' N2 gas back to pressurize the tank. > Excess pressure is vented. So where does the pressure come from? If I could pull my emitter follower up entirely by its boostraps, I wouldn't need a battery anymore. :-) Maybe with a seperate expansion chamber and keen connections, but offhand, it doesn't work: internal pressure is internal pressure. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms >> With that idea, I think the LN2 could pump itself.. >> How about using gas pressure regulator. [quoted text clipped - 10 lines] > >Tim A nice demo of pressure from nitrogen. Bottle blowing up from liquid nitrogen http://www.youtube.com/watch?v=zCNn2hXJPcg I was thinking this.. Release +-----------------------+ Valve ||<----+A |+---------------------+| +---------||-----||----||-+ || | N2 pressure | || |~~~~~~~~~~~~~~~~~~~~~~~~ | B || | LN2 +->-----------------|| +--------------------------->------------------+ ~CPU~ 'A' is a pressure sensor which operates an electrically controlled valve. 'B' is a one way valve. After awhile, the LN2 eventually disappears and the system blows up. :) D from BC >I was thinking this.. > [quoted text clipped - 10 lines] >valve. >'B' is a one way valve. The above system has equal pressure at all points and thus will not do any pumping. You would have to do this instead: Release Valve ||<----+A +--------||-----||--------+ Vent To | N2 pressure | Room Air |~~~~~~~~~~~~~~~~~~~~~~~~ | | | | LN2 +------------------+ | +----------------------------------------------+ ~CPU~ Alas, you left out the part that caused me to ask this question: +------------+ | Liquid | | Nitrogen | | Generator | +----+ +-----+ | | C--->| | Release | | Valve | | ||<----+A +--+ +---||-----||--------+ Vent To | N2 pressure | Room Air |~~~~~~~~~~~~~~~~~~~~~~~~ | | | | LN2 +-------------------+ | +-----------------------------------------------+ ~CPU~ "C" is whatever pressure the liquid Nitrogen generator puts out. If C has enough pressure to fill the tank, I can replace the avove system with: +------------+ | Liquid | | Nitrogen | | Generator | Vent To +----+ +-----+ Room Air | | | | | | | +--------------+ | +------------------+ ~CPU~ If C does not have enough pressure to fill the tank, the tank will run out of liquid and my liquid Nitrogen generator might as well be something inert and useless, like an engineering manager. SignatureGuy Macon <http://www.guymacon.com/> >>I was thinking this.. >> [quoted text clipped - 13 lines] >The above system has equal pressure at all points and thus >will not do any pumping. You would have to do this instead: k.. gonna go back to the electronics..cause my gas/liquid physics sucks.. :) > Release > Valve [quoted text clipped - 45 lines] >be something inert and useless, like an >engineering manager. D from BC > +------------+ > | Liquid | [quoted text clipped - 10 lines] > out of liquid and my liquid Nitrogen generator might as well be > something inert and useless, like an engineering manager. You've just drawn the diagram I was too lazy to draw. ;-) Just insulate the bejabbers out of the CPU, and use that container as your dewar, with room for extra as needed. :-) Would using the exhaust N2 enhance the operation of the genny? It's sure to be quite cold, you know. :-) Have Fun! Rich >Would using the exhaust N2 enhance the operation of the genny? >It's sure to be quite cold, you know. :-) ...and the N2 generator has to strip out the O2, CO2 and H2O, so feeding it dry, cold N2 gas instead of air would seem to be something it would like. I wonder if a watt-meter on the power cord will register a difference? SignatureGuy Macon <http://www.guymacon.com/> >So where does the pressure come from? The loquid N2 boiling off. >Maybe with a seperate expansion chamber and keen connections, but offhand, >it doesn't work: internal pressure is internal pressure. You put one end of a pipe down into the liquid. The other end goes up above the tank you want to get the N2 into. There is a lid on the storage tank that is sealed against the outside of the pipe. The internal pressure will push the liquid up into the pipe. (If there isn't enough pressure, the weight of the column of N2 will ballance the pressure and nothing will flow.) The inside of the pipe is a hole through the wall of the storage tank. SignatureThese are my opinions, not necessarily my employer's. I hate spam. > "D from BC" <myrealaddress@comic.com> wrote in message > [quoted text clipped - 9 lines] > Maybe with a seperate expansion chamber and keen connections, but > offhand, it doesn't work: internal pressure is internal pressure. How about two dewars? One gets filled while the other drains onto the heat sink. They just have to be higher than the computer - I wonder how big this LN2 genny is? It would have to be on a top shelf, but from there gravity should do all the work that's needed. And if the CPU is insulated from air properly, once it's chilled, the boil-off rate should decrease some. Cheers! Rich >How about two dewars? One gets filled while the other drains onto >the heat sink. *There's* that Rich Grise thinking out of the box that we all know and love! As with most great ideas, my first thought was that I should have thought of that -- but I didn't. :( The one being filled can be vented to the room. No back pressure. The one cooling the CPU can be vented through a standard pneumatic pressure regulator, and thus the 2nd dewar will self-pressurize to achieve whatever flow rate I choose. Even the switching is easy; there are many small hydraulic valves with teflon interiors that can handle liquid Nitrogen. Brilliant! Somebody give that man a $200,000 a year job inventing things... :) SignatureGuy Macon <http://www.guymacon.com/> >> I have been offered a small (about the size of a water >> cooler) liquid nitrogen generator at an attractive [quoted text clipped - 34 lines] >Compressed air tank with a needle valve... aquarium pump... CO2 gun >cylinders... ? I believe that the back pressure would stop the LN2 generator from putting any LN2 into the dewar flask. The above scheme cannot result in liquid going out of the output tube at a higher pressure than the liquid coming in to the input tube, and thuse is not actually a pump. SignatureGuy Macon <http://www.guymacon.com/> > mrdarr...@gmail.com wrote: > [quoted text clipped - 46 lines] > Guy Macon > <http://www.guymacon.com/> Do you have the specs on what back-pressure the LN2 generator can tolerate? Michael >Do you have the specs on what back-pressure the LN2 generator can >tolerate? I have a request in to the manufacturer. They appear to be out until 02 January. SignatureGuy Macon <http://www.guymacon.com/> >>Do you have the specs on what back-pressure the LN2 generator can >>tolerate? > > I have a request in to the manufacturer. They appear to be out until 02 > January. Got pix? Or any other kind of specs? Thanks, Rich > > mrdarr...@gmail.com wrote: > [quoted text clipped - 8 lines] > Thanks, > Rich Or even the manufacturer? M On Dec 27, 2:25 pm, mrdarr...@gmail.com wrote: > > > mrdarr...@gmail.com wrote: > [quoted text clipped - 12 lines] > > M This wouldn't happen to be similar, would it? http://www.elan-2.com/ M >Got pix? Or any other kind of specs? http://www.elan-2.com/products.asp $9,500 new for the elan2 Office Liquid Nitrogen Generator without Autotransfer Half to a quarter that used if you find a doctor that is getting rid of one. SignatureGuy Macon <http://www.guymacon.com/> > I believe that the back pressure would stop the LN2 generator from > putting any LN2 into the dewar flask. The above scheme cannot result in > liquid going out of the output tube at a higher pressure than the liquid > coming in to the input tube, and thuse is not actually a pump. LN2 drip ======== \\ || ______ || ______ | | || | | | | | | | | | | | | | | | | | | | | | | | | | | | | cold N2 | | | | | | | | | | | |~~~~~~~~~| | | | | | | | | | | | LN2 | | | | | | | | | | <- Styrofoam | | | | _______| | | |_______ | | | | | | CPU | | | | ======= | | ==================================================== PCB | | | | <- more Styrofoam | | |_______________________________________| Cheers! Rich > LN2 drip ======== > \\ [quoted text clipped - 26 lines] > | | > |_______________________________________| *Another* simple solution that will work great? Better make sure that brain of yours is properly cooled.. :) SignatureGuy Macon <http://www.guymacon.com/> |
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