Joule-Thomson Cryocooler Part II (-153°C)

In this video, I'll build on my progress from the last Joule-Thomson
cryocooler video and reach a temperature of -153C on a single stage
using parts sourced from window A/C units and common/cheap substances as
refrigerants (a mixture of Propane, Ethylene, and Methane). This
temperature is low enough to condense any gas except for Hydrogen,
Helium, or Neon, at the following pressures:
Nitrogen - 25.3 barA (352 PsiG)
Air - 20.2 barA (278 PsiG)
Oxygen - 10.3 barA (135 PsiG)
Methane - 1.9 barA (13 PsiG)
I tested several different mixtures to achieve this temperature, but the
best performing I've found so far has been a 30/20/50 blend of Propane,
Ethylene, and Methane, respectively. The Propane comes from an ordinary
grilling tank, the Ethylene is produced by heating denatured alcohol
over a catalyst, and the Methane comes from residential natural gas. All
these sources are very cheap.
For a throttling valve to achieve the Joule-Thomson effect, I use a 1m
long 1mm ID capillary inline with a computer-controllable electronic
expansion valve (EEV) used for fine-tuning flow resistance. I avoid
using only an EEV due to the relatively large thermal conduction
losses experienced through the bulky metal valve body.
The system is charged with 180 PsiG (11.3 BarA). With the EEV wide open,
the high/low side pressure is ~400/65 psiG (28.6/5.5 barA) respectively.
With the EEV closed as far as possible without shutting off the flow,
the high/low side pressure is ~520/10 psiG (36.9/1.7 barA) respectively.
A temperature drop of 20-35°C across the EEV+capillary restriction is
typical.
I use a vacuum enclosure to thermally insulate the cold end of the
system, but since I can't reach a vacuum much higher than about ~2 mBar,
the vacuum isn't a very effective insulator, so I still had to pack the
enclosure and wrap the heat exchanger coil with glass wool. Research
papers on this subject claim pressures on the order of 10^-4 mBar inside
the vacuum enclosure, which I'm unable to produce.
While the temperature I've achieved is low enough to make liquid
nitrogen / oxygen / methane under pressure, the heat exchanger I
assembled to do so on the cold end was ineffective, so I didn't liquify
any gas in this video.
In the next part of this series, I'll focus on mixture optimization (by
adding varying percentages of Butane and Nitrogen or Argon to the mix),
increasing cooler power / temperature drop by use of a pre-cooler, and
construction of a cold head that incorporates a large "reservoir" for
accumulating several hundred CC of liquified gas before discharge to
atmospheric pressure.
If this project is succesful in producing decent quantities of liquid
Nitrogen, I'll turn my focus toward production of Liquid Hydrogen using
a Joule-Thomson system with LN2 pre-cooling.

[@HyperspacePirate]

The EEV's are Chinese units I got for $25 from eBay. As far as I can tell, they don't have a problem with extreme low temperatures as long as there's no moisture in the stream. I've busted a few of them by applying too much heat by brazing, so that's the main thing to watch for. www.ebay.com/itm/155538290835

[@godofplumbing]

Your electronic txv valve hates Oxide scale. You need to purge nitrogen when brazing

[@BVN-TEXAS]

Instead of brazing on the EEV, just cut the swaged ends off and flare them and use some NYLOG sealant. To keep it from getting clogged you need to put a Filter drier that’s got flare fittings and hook it to the inlet at the drier. It will keep all the debris out of them. I deal with them daily working on Heatcraft brand systems like the Beacon II. What’s great is when you can get a pressure transducer and thermistor to control your EEV. I think one issue you have is too small of compressor. You are running up against volumetric efficiency with such a large compression ratio.

[@mikewallace8087]

There is Heat Sink RediWhip available or the standard wet dish cloth.

[@orlandotech]

Full disclosure: none of the links are affiliate links. They are posted for information purposes. You should look into StayBrite 8 solder and the good “Stay Clean” flux. It’s a silver bearing tin filler material that is very similar to plumbers solder but since it has the silver (6% by weight) it allows it to stick better and gives it a melting range vs. a melting point. The range for StayBrite 8 is Solidus 430°F (221°C) Liquids’ 535°F (279°C). It also has a 14K psi burst, 10k shear psi rating too since the lower heat doesn’t anneal the copper (it’s also a lot more friendly towards heat sensitive devices and parts like the TXV and EEV’s) plus you nearly eliminate the oxides buildup inside the tubing due to the lower heat. The decent failure ratings also gives it good resistance to vibration stress failures. So in short, it’s the best thing to use for delicate work and doesn’t require as much prep in regards to sweeping the system with nitrogen (but those are the best workmanship practices to use). There is a simple nitrogen purge regulator that attaches normally to a standard 20 or 40 cu.ft bottle (normal portable HVAC size bottle). It’s made by Western Enterprises, model VN-650 (link: westernenterprises.com/wp-content/uploads/2013/06/HVAC-VN.pdf ). It has a hand tight regulator attachment knob, 3 settings (test 650psi, purge, braze, Off) and has a compact size so it doesn’t take up much room/ harder to destroy it with daily thrashing, etc. Best type of torch to use for this soldering work would be a “B tank” acetylene torch with a “Turbo” tip. It uses only the acetylene gas and air (single hose). The turbo style handle/ tip introduces air into it and swirls it up for a good, clean, even burn. If you have a small acetylene/ oxy rig that’s common to HVAC you would want to turn the heat way down (mostly acetylene with some oxygen to keep the soot “bats” away) and keep the torch tip pulled back some to evenly heat the joint to the middle of the melting range. You’ll see it start to get shiny and almost right after start to soften up like warmed butter. Then you sort of sweep the heat all around the joint to help pull it down into the joint socket better as you add some to cap it off. Those StayBrite 8 joints will kinda have a MIG welded look to the bead when it’s done and hasn’t been heated too much. If it’s heated too much it makes the solder really watery similar to plumbers solder. PRO tip: if you have some excess on or around the joint (usually called puppy balls. Lol) you can wipe it with only a Dry cotton rag to remove the excess. Work quickly, gently, and carefully when wiping it so you don’t disturb the joint while it’s still hot. It will just leave a residue of the solder behind when you’re done almost like it was plated. Old school name for a similar technique was called “lead wiping” for direct burial high voltage (and later on) telephone cable splices. There’s a bunch of decent StayBrite 8 soldering vids out there plus the techniques you would use to solder plumbing pipes/ fittings are nearly identical for this HVAC use. The B tank rig IS a plumbers torch anyway. Lol Here’s the tech sheet/ MSDS from Harris Products for StayBrite 8: ch-delivery.lincolnelectric.com/api/public/content/e521e75f45b741e58940da1988c2976d?v=a156575a Sorry if all of this seems to jump around. I was trying to get all of the info down for ya as it came to me. Hope this helps!

[@Squidly_Venture]

let’s go it’s fridge guy!!!

[@domergan6195]

💀

[@kernealalpiniste6293]

Nooooo 🤣🤣🤣

[@pissmilker2313]

Refrigerator man!

[@RinceCochon]

Exactly what my mind yelled at me xD

[@EtherTheReal]

Bro, fridge guy? Dont do my man like that💀

[@Produkt_R]

We live in a day and age that scientific stuff is presented mixed with loads of memes. I do like this period in time.

[@snowdaysrule]

What do you mean memes that last clip was actual footage from the US Army of nuclear test Castle Bravo in 1953, colorized.

[@GeorgeTsiros]

Humor is one of the best ways to create interest in learning!

[@Tuckobi]

This man is able to monolog for 14 minutes and expound so profusely that his spell bound audience craves more and celebrates the arrival of each installment.

[@rick.mz29]

From rediculous tesla coils to fridges on steriods. This man is a techincal marvel

[@ruben_balea]

Maybe aliens abducted him to make fridges on *asteroids* 😁

[@carbontetlabs8606]

AS someone who's been educated in HVAC/R, this man is a menace, did you even see what he did to that poor EEV? Absolutely unhinged

[@jhoughjr1]

Sometimes u just gotta try. He also has the time and space

[@leviblack7036]

​@@jhoughjr1and he can get as much space as he wants with the aliens.

[@orlandotech]

Being a commercial refrigeration tech I’ve been following you along all of your cryogenic and refrigeration projects as they come up in my feed. I think the progress you have achieved so far is awesome! I kinda wish we were neighbors or lived closer (I live in central florida and I believe you’re on the east coast) because I could probably help you out greatly with some of the hurdles you’re experiencing. The “precooler” unit is going to be essential to your cryogenic goals. It’s normally called a subcooler as it increases the subcooling of the liquid refrigerant. I believe the rough gains for a subcooler are, for every degree colder you drop the liquid temp below the saturated condensing temp, you gain 2% increase in refrigeration capacity pound for pound of refrigerant. The subcoolers are used a lot in commercial refrigeration where the medium temp parallel racks (normal refrigerated food) have a subcooler unit piped to it to help drop the liquid temp on the low temp parallel racks (frozen temp food). You do hit a wall eventually where the energy cost to drop it past a certain temp is too much for the little amount of gains. This “magic” temperature is 45* for standard refrigeration systems. I’m sure with ultra low temp or cryogenics there is a magic number as well but I’m not too familiar with those sectors of the trade. Oil control is essential for what you’re doing too as it starts to get as thick as molasses as temps drop down deep into the negatives. Also, when the refrigerant is passing through a metering device at really low temps, if too much oil is mixed in along with the refrigerant it will inhibit the unit from dropping down as easily. This is because the oil (that doesn’t flash off and evaporate) takes up some of the room in the metering device that the refrigerant (that does flash off and evaporate) could be using to do more of it’s work. That’s why the commercial cryogenic machines have multiple oil separators in series. The more oil you remove (down to 100% of it) the better and more efficient the unit becomes up to a point. The part of the video where you had to wait for the temp to flatten out to adjust the refrigerant flow can be attributed to superheat management. If you had a digital controller managing that part it should be able to keep things under control to have a nice sweeping graph down to setpoint. Anyway, I love the videos you’re doing and look forward to watching the new videos as they’re published. It’s the same sort of “hobby work” that I would want to do if I had the time to tinker around with things as i’ve got a bunch of old spare parts or stuff that was removed due to being unreliable but still decent for a little project or personal thing that’s not considered “mission critical”. Maybe one day….. (I’ll get to play around) lol.

[@MysticalDork]

Hydrogen has two spin states, ortho and para. Parahydrogen is in a lower energy state than is orthohydrogen. At room temperature and thermal equilibrium, thermal excitation causes hydrogen to consist of approximately 75% orthohydrogen and 25% parahydrogen. When hydrogen is liquified at low temperature, there is a slow spontaneous transition to a predominantly para ratio, with the released energy having implications for storage, namely the spin conversion will release enough energy to boil off all your precious liquid hydrogen. A hydrous ferric oxide catalyst can speed up the conversion to allow the heat to be rejected during the cooling, rather than after.

[@samblackstone3400]

Wow that’s insane. I wouldn’t even think the angular momentum of a hydrogen molecule would be enough to cause a phase change

[@riccardoorlando2262]

@@samblackstone3400 Hydrogen is very light. In fact, it's almost a single proton.

[@Jefferson-ly5qe]

Never heard of this effect. Cryogenics are amazing

[@mduckernz]

@@samblackstone3400​​⁠ It can be surprising at first, but it makes a ton of sense in hindsight: as the other person said, it’s the fact that hydrogen is so light that makes this such a noticeable effect - the energy that is available needs only be applied to so little mass, it ends up being significant :)

[@peterirvin7121]

I remember reading about this in Ignition. Very good point, could lead to explosion.

[@tntamaster3879]

Liquid hydrogen? That is fucking insane! I love this content and it was well worth the wait.

[@JJayzX]

We're going to the moon!

[@letsburn00]

Hydrogen is extremely hard to liquefy. It has no JT cooling.

[@antoniobragancamartins3165]

Guy, not hydrogen! He said nitrogen!

[@tntamaster3879]

​@@antoniobragancamartins3165at about 13:36 it is mentioned.

[@fire17102]

​@@antoniobragancamartins3165actually he did say hydrogen ftw 13:30

[@5ilverstreak854]

We’re making it out of the compressor with this one! 🗣️🔥💯

[@FreejackVesa]

Hey dude, love your stuff. Not a lot of DIY cryo stuff going online. Whenever you've got it all set to move on to the superconducting portion of your project, I'm respectfully suggesting that you finalize and harden your cryocooler process (put it all together, take care of any minor issues, modularize it so you can put it in storage when not in use, etc) and most importantly document it. I've done a bunch of projects in order to create the needed precursors for bigger projects and making some paper documentation to go along with my mechanism really helped after I needed to use it after some time had passed. It's a real pain having to re-educate yourself, look up important values and figures, and remind yourself about the optimal process in order to use it. I suppose you could just watch your own videos, but having some concise and complete paper documentation on hand is way better. Keep up the great videos.

[@maciejpieskasta493]

Dude, you just gave me an answer to some of my problems

[@FreejackVesa]

@@maciejpieskasta493 well thanks! I'm glad I was able to help. Take care and good luck

[@flomojo2u]

I have an unfortunate amount of experience trying to skip steps and use RTV adhesive/siilcone in vacuum systems, and I have one word: DON'T. Anything that sets without a catalyst has a chemical compound that reacts with moisture/oxygen to cure, generating an additional substance as it cures-- either acetic acid or methanol for RTV silicone, depending on the type. It's impossible to get rid of all that substance, it is bound up with the silicone and will slowly leak out under vacuum, creating "virtual leaks" that are impossible to patch. It's too bad that the stuff won't work since it's incredibly tempting and cheap to slather a bunch into gaps to seal things, however it will never give a good enough seal to get to a very good vacuum (Especially if you're trying to use the vacuum as thermal insulation, which requires a *very* good vacuum for significant effects) , and the last thing you need is more leaks in addition to the ones you haven't found yet. The best types of gaskets are made from fluoropolymers like Viton, however you can get away with things like neoprene if you're not trying to reach high vacuums-- it depends on the cross-section of the seal that's exposed to the vacuum. Vacuum grease is also handy for plugging extremely small holes and helping to prevent leaks, though it's not an actual sealant and is more to keep gases from sneaking through microscopic gaps. Really looking forward to your next videos!

[@PsRohrbaugh]

Isn't the best option copper gaskets between stainless parts?

[@THarSul]

@@PsRohrbaugh indium is another option that sees use for gaskets in high pressure experiments, as it is more ductile than copper and doesn’t form oxides unless exposed to extreme heat and specific chemicals

[@TiSapph]

@@PsRohrbaugh Yeah CF flanges are copper or aluminium gaskets with knife-edges on the flanges that cut into the gasket. But it's a bit overkill. Something similar to KF flanges would be fine. Essentially just a big O-ring squeezed between two flat and smooth metal surfaces. A little vacuum grease helps with sealing, but is often not necessary. Flange material is usually Nitrile, Viton, or Kalrez.

[@dsfs17987]

@@PsRohrbaugh it's not practical for development, not necessary at these vacuum levels, once he figures everything out and makes a somewhat final setup, then you can go copper, but I have couple pieces of equipment that go to 10-6 torr (and slightly more), and they have been working just fine for 20 years with viton seals, I replaced the first ones when the unit was 10 years in service already, there was a small leak that I was trying to find, and in the end fault was not with the rubber seals at all, so who knows how long they last, and the unit has rotating and moving elements that are sealed by these orings, so that adds risk compared to a totally static design p.s. use _very_ little vacuum grease whenever necessary, making a rubber seal look wet is enough, more = bad in this application p.s.s. this probably is design specific, in my case I have around 1.5kw total power diffusion pumps running all the time + vane vacuum pump to make it work, but even after shutting everything down for a week, most of time the vacuum stays basically at the level the unit was turned off

[@TiSapph]

​@@dsfs17987 That's a good point, low leak rates don't matter if you have enough pumping rate. I've taken KF seals down to below 10^-8 mbar, not hard with a big ol' turbo pump and large tubing. Only reason I see to get low leak rates in this case is to not have to re-pump so often. If the temperatures go low enough his cold-end will become a sorption pump anyway :)

[@dingolovethrob]

your perseverance is admirable and your videos are brilliant.

[@rufuslastname9121]

In regards to the "slow leak" in your vacuum insulation enclosure, might it be outgassing from the flex seal due to the low pressure? Probably not terribly important but it could lead to seal degradation.

[@Tera_Hai]

Honestly what I was thinking

[@bnarit]

Silicon can let oxygen pass thought due to its chemical structure, especially in an ultra vacuum. Use Poly urethan or rubber instead.

[@spacejunky4380]

​@bnarit how does the chemical structure make the gas leak out?

[@FlaccidFrog]

I’d also suggest stycast 2850 epoxy for sealing things for this reason among others. We have used it on several liquid hydrogen applications. One thing to look out for is its high rate of thermal contraction as it likes to shrink more than metal and will pull away if you use it to fill the end of a pipe or something similar.

[@tobyoverton_hvacr]

YES FINALLY 🙌🏻

[@daretodreamtofly3288]

Hi new here. As someone who gets to hang out next to freezer units that store dry ice and other things at very cold Temps between -180 and -218 depending on what they are storing, I find it incredibly cool to see other people who are building these types of systems. My main goal is LOX with a Helium cooler.

[@kasuraga]

Nice! I've been wanting to see more of your cryocooler videos

[@instazx2]

1:45 -- Center-tapped unipolar steppers are easily converted to bipolars by tracking down that center tap and cutting it. I've converted those ubiquitious 28BYJ steppers into bipolar by cutting a trace on their PCB (under the blue cap), and then you can drive them from A4988's. They get a lot faster and more powerful when doing that.

[@orlandotech]

Oh damn! This is a good “life hack” if you’re life is consumed by refrigeration tech or tech stuff in general (like me). Thx so much! Question? Doesn’t a unipolar have a torque advantage over a bi-polar but the bi-polar has better speed/ lower torque lock to lock? I think that is the trade off but it could be flipped around too. I remember reading something way back about that in a pro/ con list. Bad thing is that with certain types of stepper motors used in the refrigeration industry the motors, to improve reliability, are hermetically sealed (Sporlan CDS evaporator pressure regulator valves). Those happen to be the bi-polar type anyway (4 conductor) so the cutting of that certain trace isn’t necessary. I believe with an earlier design they did use a unipolar type or some other manufacturer did. They are still used by some but I believe the bi-polar are more common. I could be dead wrong as my exposure to this tech is limited to what the supermarket chain I do repair work for specs for their systems or some engineers spec out. They use Sporlan products for most refrigerant controls/ device hard parts. The E2 is the standard controller platform in almost all stores but they have been starting to use the Danfoss platform with some new construction projects. I’m more familiar and comfortable with the E2 and would rather continue to see it used exclusively but I’m no where near an important enough person to have any influence for that stuff. Lol

[@TimNeumann]

Hello @Hyperspace Pirate I am currently working with an EEV on my DIY (water to water) AC unit. I'm using a similar model as you and you can definitely run these with a regular stepper driver by connecting the outer wires (not the middle one). I use a TMC2208. Microstepping also works. My EEV has 2.5 turns to close completely. With the stepper driver I have 4200 steps to set the position. With 12 DS18B20 temperature sensors, 2 electrical (analog) pressure sensors, 2 water flow sensors on 2 plate heat exchangers, and an EPS32 (running a web server where parameters can be viewed and changed), I can measure the current cooling and heating capacity. With a wattmeter I can even measure the COP (almost) in real time. I have written a simple algorithm that keeps the subcooling constant, for example. By automatically switching the EEV from open to closed in about 1 hour and recording all temperatures and pressures, I was able to determine the optimal performance for a given environment. I also tried different gas mixtures and gas charges. I found that if you go for maximum cooling capacity, you need more gas in the system, but the pressure at the compressor outlet is quite high (20-40 K above the condensation point). The compressor gets very hot (as in your case), up to 96°C and more (until my code opens the compressor line relay at 98°C). However, if you reduce the amount of gas, you can get a better COP, and my compressor temps dropped by 10-15K. I also thought about putting my compressor in the water cooling loop, but I don't want to dump it in the water. Instead, I could wrap it with a copper coil or pvc tube, but I'm afraid that the heat conduction might be poor. Therefore, I am currently opting for a better COP :)

[@Fluxkompressor]

4:20 Use Automotive coolant instead of distilled water It has rust prohibitiors anti bacteria and whatnot in it which is ideal for your setup of about every material you could possibly put together in one giant galvanic cell

[@TheTemporalAnomaly]

His use of distilled water is to reduce the problems of the motor electrical terminals being in the water. Distilled water has a very high electrical resistance when pure. Ordinary water or the solution you describe, would lead to corrosion and eventual failure of the motors electrical feed-through contacts because compared to distilled water, its electrical conductivity is high.

[@Fluxkompressor]

@@TheTemporalAnomalyYou would be surprised how quickly the distilled water becomes a good conductor The little amount of dirt that is everywhere other than a clean room makes the water slightly conductive. This induces a current flow (if the water level reaches the contacts, which I believe it does not since they are on top of the compressor) This current produces all kinds of nasty stuff to be dissolved into the water from electrolysis which itself makes the water more and more conductive. Try this out for example: Dip bare ends of wire with mains voltage into some distilled water. I bet you about 10 minutes later you have a brown boiling poisonous cocktail

[@TheTemporalAnomaly]

@@Fluxkompressor You are in a way correct but it`s not as quick as you imagine. I was only explaining `why` he used distilled water and not the technicalities. It would be just fine for a few hours to a day. Hell, even with tap water and 110 vac you would only get a little fizzing and slow corrosion! With distilled water cooling, if you want long run times, you circulate the water through a `polisher` which is a resin filter stack to remove ions. The man doing these experiments will be well aware of this method. And,, as far as the mains wires being dipped in distilled water water, nothing would happen for many hours! I used to work with this stuff at a facility that needed tens of kilowatts of rf power, it was generated by power tubes (valves) operating at 35kv dc. These tubes were cooled by distilled water, with no problems. They, of course used a water polisher for long term operation.

[@Doktoreq]

Bit of a tip from former ref-tech - you can determine the proper liquid refrigerant amount in your final heat exchanger (and so the proper flow rate of the system) by measuring the difference between theoretical evaporation temperature of the refrigerant behind your expansion device (determined from the pressure) and temperature on the heat exchanger outlet. When that difference hits 0 you have a fully flooded heat exchanger which also indicates that you're running at its max capacity. Technically 0 superheating is bad for the compressor as you run into risk involved with hydrolocking it if you don't have a liquid trap on the compressor inlet. The thing is you can automate the process of tweaking the flow and expansion rates for the heat load using two temperature sensors connected to your Arduino. You stick one sensor right after the expansion device (should give you close enough temperature to the theoretical one) and the other one after the heat exchanger. You measure both temperatures, calculate the difference and open or close the expansion valve accordingly. A simple PID loop should do it. This is basically how all professional EEV controllers work. The other thing about your compressor getting hot. Those are designed to be cooled by cold refrigerant coming from your low side heat exchanger and have as little heat transfer through the casing as possible so sticking them in a water bucket might not fix your overheating problems. Basically speaking they are designed so X volumetric flow of refrigerant takes Y Joules of heat from internals and carries it to be dissipated in the condenser. So if you do changes to the system that affect the cooling process you're going to end up with a hard to cool overheating compressor and a lot of extra heat to remove from discharge gas which might necessitate a bigger condenser or in your case a bigger upper stage. Also a bit of practical tip - don't chase temperature as you might be thrown off trying to troubleshoot the thing. If you have your heat transfer rates figured correctly the temperature will be there.

[@rodjownsu]

Tech ingredients did a great video on vacuums, they also explained different amounts of degassing etc, apparently even epoxy de-gasses as really low pressures. From memory I think it was the video where they were making ampules that fluoresce under HV fields, they also mentioned a suitable pressure to get down to appropriately low vacuums, it's a relatively cheap 2 stage compressor, I think less than $200. I'm not sure if pre-cooling the system with some purchased LN2 and performing some measurements could help discover where inefficiencies lie? When I was attempting a JT cooler, I considered pre-cooling using LN2 just to see whether once at equilibrium, the system would continue to liquify air given the temperature drop during expansion is so much higher when already at a low temperature. Keep up the amazing work! I think you're bringing a lot of joy and excitement to your community each time you post an update!

[@natester155]

Have you ever looked into magnetic cooling? There is a lab at my university which is currently using the magnetocaloric effect to liquify hydrogen.

[@sumguysr]

If you get 3 liters/day of LN2 it'd be cool to do some experiments on cryogenic treatment of metals, strength and wear resistance.

[@eastonjanecek9802]

Loads of documents tell you what you want to see

[@patrickd9551]

Not to mention the fact that its way cheaper to just buy 3 liters of liquid nitrogen. The electricity costs alone are immense for running such a system all day for just a few liters

[@sumguysr]

@@patrickd9551 There's a cryogenic treatment company in Chicago that claims a full 24 hour soak is far more effective than briefly bringing steel to temperature.

[@orlandotech]

@@patrickd9551 buying shit premade takes a lot of the fun out of making it yourself through trial and error

[@PsRohrbaugh]

I cannot express how awesome this series is.

[@microwave221]

Its amazing watching how this develops

[@elitearbor]

I am greatly enjoying your videos on this entire iterative process. Keep up the great work!

[@Seoup]

thank you for indulging your curiosity and bringing us along. I love this series, I've learned so much.

[@MooreAnalytical]

This is one of the best series on KZbin. Well done!

[@goober-ll1wx]

I like the juxtaposition of science with the somewhat hacky nature of the execution this channel has to offer....

[@jaythatguyyouknow5135]

When videos like this come across my screen, I can only think we are living in the best timeline.

[@zuthalsoraniz6764]

6:30 The reason that a larger pore size requires lower pressure is that vacuum insulation depends on increasing the mean free path, which is inversely proportional to gas pressure, to well above the pore size

[@TiSapph]

To expand on this, it's because at lower pressures the hot gas molecules coming from the hot surfaces can go much further before colliding with another molecule. Meaning they reach the cold side faster on average. So while there's fewer molecules, they transfer heat more efficiently. The effects cancel out until the mean free path gets larger than the gap between the surfaces. Then the heat transfer "efficiency" is essentialy fixed at maximum and further decrease of pressure only reduces the number of heat carrying molecules, so thermal conductivity drops. However the thermal resistance also depends on total insulation thickness, so a little wider gap of the same pressure should still be better no matter what. I think stuffing the chamber with something like fiberglass should still work though, as it helps randomise the direction of the hot molecules and thus reduces the heat transfer speed. Effectively it limits the mean free path to the average fiber spacing.

[@testpilotmafia862]

More animations !

[@mph8759]

Awesome, love the project, especially that you go through the effort of optimising the valve type and configuration as well as the gas mix and plot everything on charts or in tables to empirically show what/how it works. I’m looking forward to the next video!

[@Redstonmaster]

Man I love this cryocooler series!

[@sudhirpandey2109]

Was binging through the cryo cooler videos and was looking for the next one not realizing this was uploaded ten hours ago. Real good stuff and super well explained. Throughly enjoyed.

[@destroyer4416]

please keep doing this its beyond words how much joy you bring me

[@TiSapph]

Your local vacuum/cryo friend here, maybe I can give some advise. Not all might be necessary since you aren't going for the lowest possible pressure, but it might still be interesting :3 1. Many people already pointed out why the thermal conductivity doesn't reduce until very low pressure. Stuffing with something like glass-wool might help due to randomising the direction of the residual molecules. However that will only work if the average distance between the fibers is less than the mean free path. For 2mbar that's something like 35um, so glass wool would probably not help. You would need decently lower pressure, probably at least 0.1-0.01 mbar, to get vacuum insulation with ~1mm fiber separation. There's cheapish (few hundred) mechanical vacuum pumps that can do that. However the conductivity of the glass itself might make things worse. That said, usually a lower pressure helps at least somewhat due to less convection. 2. At low pressures you need large tubing to get good flow. At really low pressures (10cm in diameter and still get a factor 10 or greater pressure difference over just a meter! Use as large tubing as practical. Maybe look into KF flange components, they aren't too expensive and very easy to work with. 3. DON'T use single component silicone as sealant. It outgasses like crazy. You might be best off doing what the KF flanges do and just use a large Viton O-ring. That might need some machining but is defo worth it. The metal surfaces need to be fairly smooth, but not polished. Just no deep scratches. Maybe also get some vacuum grease and use a *little* to wet the ring. You can use Vacseal to make sure all connections/feedthroughs are tight. Epoxy might work too, there's some low outgassing ones available. Don't use cyanoacrylate glue. 4. Ideally get a turbomolecular pump, but yeah they are expensive. But you are in luck: if you get good enough insulation from the shitty vacuum to go below -200C, your cold-end itself will turn into a sorption pump! If you add a little cage of activated charcoal or zeolite to the coldest part, it will absorb water and at least partially nitrogen to give a much better vacuum. You might have to heat the material now and then to drive off the adsorbed gasses. Ideally you do that in the shitty vacuum with the mechanical pumps running and don't expose the material to air after baking. A heating element with connections to the outside should work. At some point you might even get better pressure with the mechanical pumps disconnected from the chamber. 5. It might help to "bake" the chamber. Essentially just heating up the entire vacuum chamber to 150C or so for a few hours with the pumps running. That's mostly to get the water adsorbed on the surfaces to come off and be pumped away. However once you expose the surfaces to air again you will have to bake again. This will only make sense if your chamber isn't leaky and you don't have a silicone seal outgassing stupid amounts of water. 6. Thermal radiation might be compromising your thermal insulation. In the lab we gold-coat everything and have multiple radiation shield to reduce the effect. That's a bit overkill here. Aluminium coated Mylar foil (space blanket) might do the trick. Don't use kitchen aluminium foil, it's covered in oil. UHV aluminium foil exists but is stupid expensive. 7. No oils and generally keep the chamber clean. It doesn't matter so much on the cold parts, but the warm walls should be free of residue. Maybe wipe them down with isopropanol. You won't notice at 2mbar, but you absolutely will once you go to 1e-3 and below.

[@klausnielsen1537]

You still do the most amazing stuff on YT and it feels like mockery that we can only press thumbs up once. Amazing work on the refrigeration and your video style and storytelling is getting more and more engaging. Well done indeed!!

[@attilagergely6734]

This is awesome! I've been eagerly anticipating the new installment in this project.

[@MRmeanmagicman]

My dude… you are pursuing the inner child in me that I miss so much. Just building shit because you can, it’s a pleasure to watch your process man, keep it up!

[@Lukesab3r]

You've come so far!! This project is no longer a cost balance issue, it's a beef issue. Push for the win!!!

[@JohnSmith-qm5xu]

Just awesome watching the process. Thanks for taking us along

[@paitti]

Frankly, your videos are one of the most interesting video series at the moment. Well explained and easy to follow even for someone with 0 knowledge in refrigeration are the key. Keep it going and good luck with the project!

[@switch2472]

You describe a Unipolar stepping motor wiring as being unusable with bipolar drivers-this is not the case. You can just ignore the center taps and drive them as bipolar stepping motors.

[@STRIKEcorperation]

I'm not certain, but I think the stepper motor will also work better when driven in a bipolar fashion because the current flows through both halves of the coil, producing a more uniform stator field.

[@hamjudo]

5-wire steppers have a single connection for both center taps. This is less than ideal when treating them as 4 wire steppers. 6 wire steppers have separate wires for the two center taps. The center tap wires can simply be ignored and it can be treated as a 4 wire stepper. The performance differences don't matter in this application, because the valve doesn't need to move very fast. The standard unipolar stepper config only uses half of each coil at any given time. Unipolar steppers date back to a time when it was cheaper to double the size of the copper coils than to use a bipolar drive circuit.

[@emanuelgoncalvessantos4499]

Thank you for share all that knowledge with us!

[@danielspiteri9018]

I work in LNG plants. The Low temp heat exchange in upside down. This allows any liquid refrigerant to leave the heat exchange and not pool.. Great work enjoy the videos

[@jacan20]

Mechanical engineering student taking Thermodynamics II, these videos are really cool demonstration of some of the things we’re taking about in class. Very cool!

[@dm3on]

Absolutely insane, and so cool!

[@HL65536]

Your wires may be where your leak is, especially if it is stranded wire. Try using magnet wire instead.

[@ATomRileyA]

Loving these videos, keep up the great work :)

[@mrgcav]

Can not wait for part Three.

[@gradertfamilymakes]

Solid re-refridgerator. 10 points to the fellowship.

[@aurora7207]

You make me believe things are possible, thank you!

[@sealpiercing8476]

That chart is accurate for *conduction* through gas. However, ordinary foam or fibrous insulation material at ambient is a little more conductive than the gas it's filled with, so cutting off convection and condensation and reaching just the conduction of the gas is already pretty good. Reducing the conduction of the gas further from that low baseline does need lower pressures. As you reduce the number of gas molecules, fewer of them collide with the surface to retrieve heat, but also they make fewer collisions with other gas molecules on the way to the other surface, and these effects almost completely cancel out until there are so few molcules that they typically go from one surface to another with

[@alexandermarsteller7848]

For usable insulation vacuum I have a figure of roughly 10^-4 mbar in mind. Getting into that range with sorption pumps in air is not easy as you need to go well below liquid nitrogen temperature, and from ~1 mbar it still is quite a bit of molecules to getter onto a pump so you would need a pump with a big capacity as well. The modern option of choice here would be a turbo molecular pump, but making one at home is probably a bit too ambitious. But an oil diffusion pump will get you there and is a lot more realistic to build.

[@cajunsurvivor]

I could watch content like this everyday

[@ockeojoj]

Great series, looking forward to the next part. Thanks!

[@psychedelicgem]

So soon we will see videos on liquid hydrogen and it will come to completion or suddenly their will be no more postings💥 Your vids are so great. For a moment I feel smart. Your genius is contagious. Then I meditate in awe of your wit as I realise my mind wandered and missed like 15 steps of your journey. Thankyou for sharing !

[@Hsyshdhekakskshdhehbsbshseghsh]

First I love you hyper space pirate keep it coming

[@garbleduser]

Glad to see you used the needle valve on a stepper idea!

[@serhiisinilov]

Dude, you're pretty cool. I tried to find something like that in internet and you are what I was searching for. Thank for what you are doing

[@canadajim]

incredible work, really.

[@danielfernandes2813]

I can't wait for your next video.. the stuff you do is so interesting

[@xyic0re714]

absolutely my favorite channel youtube

[@beautifulsmall]

Super impressive builds and having the balls to work with high pressure flammable gasses and liquids. Juggling PTV and find a sweetspot to liquify , magical to watch how physics works and how you edge ever forward . liquid N to H . Like Prof Farnsworth, and heres my 200L Hydrogen electrolysis machine as a passing comment. That looks a sweet rig.

[@zyzzyva303]

This is so cool! ❄

[@leifhietala8074]

All this on the same forum that offers toy reviews and makeup tutorials. What a time to be alive.

[@justinc.8191]

Love your videos! Keep up the good work!

[@MarkSparks-xd9yy]

coolest video I've seen all day

[@sebastianmuller1210]

Great work. Well done.

[@jacknesbitt240]

Love this series

[@bungalowjuice7225]

I need a fridge. Thanks for the thorough guide!

[@petewright2283]

Love it. Keep up the amazing work

[@guygfm4243]

Wow that’s a lot of info, thank for sharing

[@TmanT321]

He did it! Congrats!

[@DannyBokma]

Ow man I could consume this content for so so long!

[@blakes8901]

my man finally did it. pressurized liquid nitrogen temps. excited to watch

[@bitnertinkers]

Love you videos! Thanks for content

[@littleboot_]

very cool, looking forward to the next video

[@JoseSilveira-newhandleforYT]

Excellent video! Little by little, you are getting there :-)

[@infestus5657]

I realy like your videos. This real do it yourself attitude is nice.

[@ricardoiarossi]

Best series on KZbin

[@dumle29]

I mean the uni-polar stepper can be driven with a bi-polar stepper driver, if you just ignore the center-tap. However if the center tap of the two coils are hard-wired together that's not an option.

[@LordDecapo]

this is some of my favorite stuff on YT atm

[@joeflosion]

This channel is so damn cool! Keep at it dude!

[@rodriguezfranco3839]

Now I see , it is looking good brother

[@Fir3Chi3f]

Excessively cool! Stay safe doing this

[@an_R_key]

Very exciting stuff 😀

[@herosvicentegonzalez7872]

Even if you didn't make it it is still closer to 0K than 0C,wich imo is crazy

[@AlessioSangalli]

Oh so good to see your video

[@gabrielbr1459]

I m definitely hyped to see both the part and the hydrogen gen

[@TheFarmacySeedsNetwork]

Brilliant dude!

[@TheGreatProphecy]

Now i cant wait for the next part hahaha!! Awesome stuff!

[@TheMrR9]

This is awesome.

[@everythingeverett3021]

I am stoked to see this popped up!

[@blazehenot2536]

Can't wait for more on the electrolysis rig, I've been working on various versions for over a decade at this point and would love to see what you've done with the concept

[@rizdalegend]

I understand about 10% of what your saying. And I love it!

[@peraz968]

This is super interesting! I really love to watch your hard work. Because I do also by my self all kind of experiments. Last time I got enaugh of those cars air conditioning "repair" companys. I did it all by my self, and add only propane to the system. And wola! It worked lika a dream! It pushes like a -8 degree celsius air on a hot, 32 degree celsius summer day. I can say, there is no better product for cars A/C system, than propan. At least as far as I know. It is super cheap, it is easyly available, and it works way better than the r134a. I cant see any reason why to purchase expensive "coolant gas", if you can do it all by your self, just like that with your barbeque gas and couple of meters.. So easy and simple job to do. Btw, at here in Finland, if you go to recharge your AC system, it costs like a 100€, or more. And only if it is r134a! And if you got a R1234yf, you have to pay 300€/Kg. That aint no cheap.. Not at all.. But I have to learn more and more from you! So, thank you very much for great video again!! I really apprechiate your hard work! Thanks a lot dude, and keep going!!

[@blubb7711]

Nice, I really have to try building my first heat pump.

[@todorator]

man I love your content

[@Khal_Rheg0]

Thanks for sharing!

[@toygartumer7385]

best channel on KZbin fr