this video is sponsored by Squarespace after a lot of work I've managed to build a homemade cryocooler that's capable of making liquid nitrogen nitrogen is liquid atus 196 C or 320° below 0 fah it's cold enough to make this disc of Atrium superc conduct and levitate a magnet above it it also feels really cold on my hand ouch this was done entirely with parts salvaged from old window AC units and a couple electronic parts for motorized valves no fancy Sterling cryocoolers were involved in this process it's built entirely from standard Refrigeration components this is the same machine I used in my previous video for producing liquid methane but with a few changes but in case you didn't see it I'll do a quick recap on how it works a mixture of gases is compressed then goes through a radiator that removes the heat of compression the high-press gas mixture then travels through a long counterflow heat exchanger at the bottom of the heat exchanger a very small diameter capillary tube throttles the flow and the gas expands and drops pressure as it comes out of the other side of the tube as this happens the temperature drops not by a huge amount mind you maybe 20 or 30° C depending on what gas mixture It's Made of This is called the juwel Thompson effect the cold low pressure gas rushes back up the counterflow heat exchanger which cools down the incoming High Press gas by the time it exits the heat exchanger it's at the same temperature as the incoming gas or at least within a few degrees the low pressure gas then returns to the compressor and the cycle repeats this process creates a positive feedback loop that drives the cold end of the heat exchanger down to a way lower temperature than the initial 20 30° drop that it caused lowest I've managed to get so far is minus 180c the high pressure side of the loop is about 400 PSI or 28 bar in this case the gas mixture is a combination of propane ethylene methane argon and nitrogen however I've managed to get extremely low temperatures with just archon and propane although it's not as efficient the cold low pressure gas goes through a tube inside a tank which is fed with high pressure nitrogen from a separate compressor once the system gets down to around minus 150c High Press nitrogen to begin condensing this typically occurs between 400 to 450 PSI gauge or around 28 to 30 bar absolute once the tank is full of liquid nitrogen it's discharged through a motorized needle valve into a small deir or a thermos a portion of the liquid is lost to evaporation in this process because it's above the one atmosphere boiling point for more power and efficiency a separate Vapor compression cycle is used to pre-cool the gas to around -25 to -3c before it goes into the counterflow heat exchanger the system will work without this but it provides a tremendous boost the compressors used in the process are taken from window AC units the main cycle compressor came from a 12,000 BTU unit meant for R22 refrigerant and the other two came from 5,000 BTU units meant for r410 refrigerant the main stage and the feed gas Loop there's also oil separators with motorized valves on timers connected between the oil sumps and the return lines as you can probably guess oil doesn't move so well at cryogenic temperatures so it has to be separated out as for the plum Plumbing it's all just copper tubing I got from the hardware store which is either braced together with copper phosphor rods or connected by4 in 45° flare fittings the only exception to that is the stainless steel to Copper connections on the oil separators which are AB braised using ssf6 which is a type of silver solder alloy okay so picking up where I left off in my last video I had a pretty scary explosion that happened when the liquid methane holding tank blew up well technically it ruptured because it didn't fragment and throw shrapnel everywhere but it did tear open at the braze joint so I rebuilt the tank and actually used proper end caps this time this is just a 2 and 1/2 in copper pipe with a coil of quarter inch tubing going through it to transfer the cooling from the refrigeration Loop to the liquid inside there's also a line for feed gas to come in and a siphon tube for pressurized liquid to exit and this time I actually hydr tested the tank before installing it and fortunately it didn't blow up although the previously flat endc caps were bowed a little bit after being under 400 PSI so I braced everything back up to the counterflow heat exchanger for the refrigeration Loop and submerged it in water while it was pressurized to find some leaks which it had after resolving those leaks by reflowing my brace joints I wrapped the tank and the heat exchanger tubing in a ton of foam and then plac the whole assembly in a thick foam box stuffed with fiberglass wool problem is with the big tank the system never got below aroundus 68c because the thermal inertia of all that copper was too much and or it wasn't insulated well enough and was causing a ton of losses so I stuck a much smaller tank on there using a 1-in pipe instead of a 2 and 1/2 in one I also tried using expanding foam as insulation instead of fiberglass wool but as you can see here it had a bunch of air pockets inside it also only got down to minus 153c which kind of sucks so I busted up the expanding foam and wrapped the heat exchanger tubing with rubber foam and stuffed the whole thing with fiberglass wool now that got me down to minus 172c and I started feeding in nitrogen a little over 4 50 psi now just as a side note I am using nitrogen from a tank for testing purposes but in a future video I'll show how to make it from Air however the gauge on my High Press regulator was unreliable so I transferred the nitrogen to a 10g air tank to make it easier to keep track of how much gas I had used when I fed it into the cryocooler assuming the nitrogen at room temperature is an ideal gas this makes it very easy to keep track of the mass being liquefied based on the pressure of the tank so after pumping about 100 gr of nitrogen gas I opened up the discharged valve to collect my liquid and that's it that's all I got probably less than 5 cc's there and here's attempt number two looked like there might have been one or two drops there okay so technically I made some liquid nitrogen there but uh pretty useless overall but you know what's not useless having a website for your business unless you're living in an uncontacted tribe in Papa New Guinea you're going to need this series of tubes known as the internet to do business and Squarespace has all the tools you need to do that let's f face it social media business pages are for crack addicts trying to sell their stolen copper or for your weird aunt to advertise the psychic reading she does out of her garage if you're serious about your business you're going to need a website Squarespace offers website hosting and all the tools you need to build and run a business website they provide graphic design tools that help you make a professional looking site and make it super easy to set up invoicing payment processing and appointment scheduling you can also use it to run ads for your business on social media sites and it provides all the important analytics for website traffic and sales data as well as inventory and shipping management and all that other really fancy business stuff that super important people wearing suits do go to squarespace.com for a free trial and if you want to launch a website go to squarespace.com hyperspace pirate to save 10% on your first purchase of a website or domain so anyway after this letdown I tried several other approaches to improve my yield since I was losing almost all of my liquid to evaporation I figured maybe I should have a sealed thermus attached to some sort of regenerative heat exchanger to recover all that energy that I was losing and then using it to precool the incoming nitrogen seemed good in theory but it didn't really work out I also tried reconfiguring my cryocooler as a precooler for a pure nitrogen drel Thompson cycle in theory if I precooled a 30 bar nitrogen stream to around minus 100 C it would be thermodynamically equivalent to a juel Thompson cycle with a 300 bar pressure at room temperature and so I built yet another counterflow heat exchanger and insulation for it and that didn't really work out either now it did seem like I might have some success with this really tiny counterflow heat exchanger that I put inside a thermos I managed to get it down to minus 150c with pure nitrogen which was pre-cooled to- 75c and it seemed to be steadily dropping past that but then I killed the nitrogen compressor from overheating this approach may have actually had some Merit so I'll probably revisit this in the future but anyway my schemes to improve yield seem to cause more problems than they solved so I returned to my original plan of using a high-press liquid tank the difference was that this time I'd control the discharge from an electronic expansion valve and it would be placed directly underneath the tank the needle valve I was previously using for liquid discharge would leak when I got it really cold because the Teflon seals would shrink the electronic expansion valve was all metal so it didn't have that problem also I think having several feet of tubing going out of the insulated box was causing huge losses even with all the insulation that I put around it and so I built wait for it yet another liquid tank this time with a 2-in pipe instead of a 2 and 1/2 in one hopefully this would be small enough that it wouldn't have excessive thermal inertia but large enough to have a decent storage capacity for liquid looks like it's got at least 320 CC's or at least that's what I dumped out of it it also doesn't explode so that's a plus so I installed the tank the same way I did the other two I showed earlier and while I was at it I built a movable bench to put all this equipment on to keep things more organized the main compressor and pre-cooler on the top and the nitrogen feed compressor is on the bottom I also raised up the cold box so I could fit the thermos underneath it to collect the liquid nitrogen instead of running long tubes out of the insulation that would cause a lot of losses later I'll use this 3 lit deir for that purpose after about an hour of runtime I got down to minus 177c and then went about pumping in nitrogen gas to liquify it I originally set up this rotary compressor in a cooling water bath to feed nitrogen but it died pretty quickly even though it wasn't overheating I think it may have been an oiling issue so I switch back to this little fridge compressor that I've been using for gas transfer since I started this project I take nitrogen in from my 10g tank and pump up the cold tank in the cryocooler until it's at about 450 PSI which is pretty much right at the critical point for nitrogen now there's no reason I couldn't go beyond the critical point of nitrogen but pushing the compressor past 500 PSI would probably damage it then I shut off the compressor and give the liquid several minutes to cool until the pressure drops to around 250 psi then I start pumping again I think the compressor runs less than 30% duty cycle in this case I repeat this process several times until my 10 gallon tank goes from 120 PSI to about 30 PSI this should be the mass of nitrogen required to completely fill the coal tank as liquid which is around 260 g i short the terminals on my board to trigger the Valve controller to open I need to get around to wiring up a button for that and there it goes we've got some liquid coming out the kype thermocouple output gets a little fuzzy at this temperature and it'll read between - 194 to - 1996 but yeah we've definitely got liquid nitrogen now my thermos weighs 562 G versus 454 when it's empty so I've made 108 G when I dump it into a little plastic cup on a scale you can see how quickly it loses Mass to evaporation without any insulation [Music] it's pretty cold on my hand but doesn't give me frostbite because of the laden Frost effect which is where a vapor boundary layer slows down heat transfer you can see that effect a little better in this demo where the liquid sort of clumps up into blobs that Glide across the garage floor The Vapor boundary layer acts as a sort of bearing kind of like on an air hockey table let's try this on a superconductor I bought a little puck of ybco that should allow a small magnet to levitate over it once it's at liquid nitrogen temperature and it works although the magnet it's levitating is pretty tiny I tried to float the ybco itself over a big magnet and it floated for a second or two before it warmed up and lost super conductivity now minus 196c isn't cold enough to make copper super conduct but it should theoretically drop its resistance to to about 10% that of room temperature let's try cooling this little electromagnet at room temperature it's 26 1/2 ohms but when I dunk it in the liquid nitrogen you can see the resistance start to drop it only went down to around 7 and 1/2 ohms but I was expecting 2 and A2 I guess I didn't have enough liquid left anyway that's still a major change and the metal shell was actually cold enough to leave little freeze burns on my fingers when I pinched it it stayed cold for quite a while too here's the magnet after about 15 minutes let's try freezing this Orange very nice how about cooling off the salad oh yeah by the way you can actually liquefy argon with this cryocooler too which is actually easier because it has a boiling point that's 10° higher than nitrogen minus 186 okay so that's how I did a year and a half of engineering to produce a liquid that can make little magnets float or ruin food for fun the whole system consumes about 1,400 watts and produces around 130 CCC per hour of liquid nitrogen which is not great but the energy only cost me a buck 29 per liter whereas the gas gas supply place in town charges me $5 per liter for liquid nitrogen although with a little bit more optimization I'm pretty sure I can bump that number up to two or 300 CC per hour which would actually make this a pretty useful machine I'm also using nitrogen that I bought from a tank but in a future video I'll show how to extract pure nitrogen from the air with pressure swing absorption and use that as a feed gas I'll probably do the same thing with oxygen which is also easier to liquefy than nitrogen but requires some extra safety precautions because it's an absolutely monstrous fire hazard anyway thanks for watching hope you lik my thing bye