Pulse Tube Cryocooler - Part 1

In this video i expand on the resonant linear motor from my previous video and use it to drive a linear compressor for a pulse-tube refrigerator. A pulse tube refrigerator is used to reach cryogenic temperatures, with some going into the sub-kelvin temperature range. These are typically used in labs for scientific experiments that require extreme low temperatures, or for sensors on sattelites/spacecraft, like the optics on the James Webb Space Telescope.
From a thermodynamic standpoint, a pulse tube cryocooler is effectively the same as a Stirling or Gifford-McMahon (GM) cooling cycle, but it replaces the displacer (or expander piston in the case of an alpha-stirling) with a gas piston. With careful tuning of a needle valve, inertance tube (gas momentum tube), and buffer volume, the phase of the gas piston's motion is shifted from the pressure oscillations of the compressor (by ~60-90 degrees), allowing heat pumping to occur out of the cold end. The major advantage of this device is that it eliminates moving parts from the cold end, which would be the displacer piston in the case of a Stirling or GM cooling cycle.
While i did manage to create a working linear compressor with a tuned dynamic balancer to create pressure oscillations, the linear motor didn't seem to have enough force to create a reasonably large compression ratio, and i only managed to produce a minor temperature difference. However, actuating the piston by hand, i was able to produce a temperature drop of around 4C.
Pulse tubes are also extremely dependent on the tuning of the needle valve, inertance tube, and buffer volume, which act like an electrical RLC circuit to create a specific phase shift at a specific frequency. The pneumatic tuning in this video was far from optimal.
In the next part of this series, i'll be replacing the linear compressor with a rotary compressor that I plan to build with an air cylinder driven by a geared down brushless motor from an RC plane. I'll also be focusing heavily on tuning the inertance tube / buffer volume, and optimizing heat exchangers to remove energy from the system even at small temperature differentials.
Previous video on building a linear motor:
• Electro-Mechanical Res...
If you want to understand the basics of different cryocooler types, these articles are helpful:
www2.jpl.nasa.gov/adv_tech/co...
www2.jpl.nasa.gov/adv_tech/co...
This is a helpful overview of how different pulse tube configurations work:
large.stanford.edu/courses/200...
This paper explains more about the math in computing resistance/inertance/compliance and phase shift:
trc.nist.gov/cryogenics/Paper...
Another resource i found tremendously useful was cryocooler.org/. Under "Past Proceedings - Volumes 14 to 20" you can select a volume and under "Table of Contents" there's dozens of research papers on Stirling/GM/Pulse Tube cryocooler development.
STL Files (these are for the linear compressor with the TPU bellows piston):
www.thingiverse.com/thing:568...
Music Used:
Heatley Bros - Sunset Beach
Kevin MacLeod - George Street Shuffle
Kevin MacLeod - Lobby Time

[@HyperspacePirate]

BTW, "Sub-kelvin" isn't referring to below absolute zero (which is impossible), it refers to temperatures that are between 0 - 0.9999..... kelvin

[@friedtomatoes4946]

Something to consider is that even fully filled 3D printed parts can leak air. You may want to go onto your compressor parts and cover them in some form of sealant. To test this take one of your 3D printed parts and make like a box with a clear side and then put it in water at a certain depth if it starts to leak then you've got leaky prints. I recommend silicon and epoxy

[@Marin3r101]

Hmms so you mean a 1 is a singular value and thusly could be dropped entirely resulting in sub-kelvin?

[@horrorhotel1999]

Just for completeness sake: negative absolute temperatures i.e. temperatures "below" 0K are in fact possible but these are incredibly energetic systems and can only be achieved under very specific circumstances. A fun rabbithole to go down nonetheless if this interests you.

[@jonathany1240]

yeah i was curious about this - whoever came up with the term "sub-kelvin" gets a pass on using counter-intuitive language bc it sounds cool as hell

[@wolfy1398]

@@horrorhotel1999 Can you link something to read more about this? I'm really interested.

[@opcn18]

People have been doing this kind of thing in their garages for decades (popular mechanics had a legitimate set of plans for a build it at home electron microscope back in the day) but youtube has enabled unprecedented levels of sharing for which I am eternally grateful.

[@madeintexas3d442]

This is absolutely fascinating. This video far exceed my expectations. Your explanations and graphics made the concept really clear.

[@derrekvanee4567]

And the audio quality is great even monotone. The script isn't amzzing but not terrible, the odd breakand deceny story line.

[@derpuck9769]

After 30 seconds of watching I was subscribed Great stuff

[@rockpadstudios]

it's cool

[@munxprojectsalternative]

Thanks for saying this; saved my thinking out the same :D -Good work

[@MrSomethingdark]

This is that STEM education we always wanted. Ties in so many field together. Makes me want to rise up to your level. Thank you so much good sir wherever you are

[@GerinoMorn]

I recognized the Stirling cycle, the adiabatic etc. etc. from my HS physics course. It took me weeks to get my head around it, and this video probably would do it in, well, 18 minutes :D

[@Vshamann336]

bling bling, that stem a char lmao! He wants us to believe that he is building a pulse tube cryocooler, but what he is really doing is solving that huge problem, the problem of a dead lighter. lmao

[@EricDalgetty]

Hey I actually just started at a company that makes Gifford McMahon coolers! I think you understand this a lot better than I do, but if you have any questions, I am surrounded by experts on the topic and would be happy to ask them for you. Keep up the good work!

[@xDevscom_EE]

Good luck with your goals! I have big 0.7W 4K cooler from MRI machine, but only 1kW He compressor. Question to answer would be if there is any chance to make big cooler functional with much smaller compressor, given that I can accept much lower heat lift capacity, but keep low temperature at very light load.

[@GudLawdHammercy]

@@xDevscom_EE It is possible to use a smaller compressor with a larger cooler, but the cooling capacity of the system will be reduced, meaning that it will take longer to cool down and will not be able to handle as much heat. The ability to maintain a low temperature at light loads will depend on the specific requirements of your cooling application and the thermal properties of the materials being cooled.

[@xDevscom_EE]

@@GudLawdHammercylonger cooldown time is expected, as well as limited capacity. It is just temperature that I am after. I haven't find any research papers or reports yet showing performance limits of such system, with large (>0.5W @ 4K, like PT407) head used with small compressor (1-2kW power in) and concerned if heat loss and mass flow required for large head make this unworkable. I guess I should just try to run it and see what happens...

[@Cineenvenordquist]

Hey, do pulse tubes not work at higher T? I guess there are pulse rockets, but not pulse high pressure superheated water generator ones, which might be nice to get once you've desalinated some water or rainwater... I'm going, why aren't there more conc. solar steam power things, maybe powered from steam off PV covers but sent off to condensed and hi-press lines...

[@ericlotze7724]

Really neat, and props to you for posting the project and all that, even if it wasn’t 100% successful. Even though it may not get all those views and whatnot, documenting the full development process and all that failures/things learned along the way is important and neat!

[@Kotesu]

I don't think I've subbed anything as hard as I just have right now. Incredible work!

[@ugurunver2403]

The theory and the scientific facts behind the mechanism are well explained. You started with a great design and you iterated it to better forms by using feedbacks and new ideas. The balance between the theory and the building process is right on the optimal point. I already knew something about ultrasonic cooling/heating but the concepts in your video (vibration cancelling/phase shifting etc) are really new for me and there are really cool concepts. And there will be a really cool end result which you can use it for doing real science. I mean, liquidifying the nitrogen is a real deal. So, in conclusion, i really appreciate your work. This project and the presentaion are beyond my expectation from internet. I honestly wanted to thank you.

[@en2oh]

most importantly, you didn't give up! as Edison once said "you didn't fail a bunch of times - you successfully found a bunch of ways that didn't work!"

[@atarisidequest]

Very cool project! If I could make a suggestion or two: that resonant balancer is neat but super lossy. It'll be sapping a lot of your energy. The simplest and least interesting solution is to bolt the entire device to a heavy metal base, but there are also better and more interesting solutions. You could swap your moving mass with your static mass - a fixed magnet and moving coil (essentially a voice coil) using aluminium wire wound on a former would be much lower mass. Or you could use two motors diametrically opposed and in phase to cancel out the vibration - you'd need to match their resonant frequencies. Finally you could use two motors 180° out of phase and a manifold to couple the gas - the same resonant frequency matching would apply but note that some torsional forces be present somewhere between the two motors causing some vibration. I hope this was helpful in some way and can 't wait to see where this little project goes!

[@AdvancedTinkering]

Such a great and interesting video! I can't wait to see your next version!

[@bolwem50]

Best explanation of the Stirling cycle I've seen anywhere.

[@beautifulsmall]

I was telling a colleague yesterday how I'd always wanted to build a cryocooler so super happy to see this project. Subscribed. Fascinating. Hot is easy, cold is such an unexplored world. Inspiring.

[@jimviau327]

I can't wait for part 2. Fascinating!

[@maxxotic1]

This is impressive. Great work. The balancer is genius.

[@gotbread2]

Absolutely awesome. I looked into these coolers a bit and am intrigued to build one. Looking forward to part 2!

[@RCrosbyLyles]

Absolutely brilliant work! Well done! Relating cooler parts to inductors, resistors, and capacitors is interesting.

[@ThomasGrillo]

Very cool. Was interesting to see the device translating across the desk. Reminded me of a space propulsion concept which inchworms it's way through space by shoving a mass forward, and then the rest of the ship moves forward. Frankly, I didn't thing that could work, until I saw your cooling device moving along.

[@vintyprod]

So glad I found this channel.

[@fr3zer677]

Your videos make my day! Thank you for providing us with this quality engineering content

[@snowdaysrule]

This is the greatest home-engineering thermodynamics related video I've ever seen!

[@willturner2202]

Fascinating video! I just finished a circuit theory course in college so i absolutely love the comparisons of the various parts to electric components. Helped me understand so much more how everything worked.

[@lucaayfmlyysiaejdsrtnnervd4646]

I have no idea what's going on, but I am here for it!

[@yiyou6529]

It has been a long while since I saw and deeply enjoyed a video last time. Man, you take me all the way back to school. I like it a lot.

[@alirezatanehkar2009]

One of the most amazing and informative video in the history of the KZbin. Please continue!!

[@sazafrass]

The lack of snicker shame in this video is upsetting. Great video and interesting project. Can't wait to see more and be shamed for it.

[@en2oh]

if only these tools were available when I was in grad school! Your engineering/thermodynamics skills are amazing! Thanks for sharing this. Doug

[@alex4alexn]

very pumped to see the next iteration

[@harriehausenman8623]

This is so cool! 🥶 Never heard of these devices before and still trying to wrap my head around it. Thanks for the explanations, looking forward to many more parts!

[@Vinzmannn]

I'm watching all your videos rn. This is so great.

[@knallpistol]

I've always wanted to build a cryo cooler, just for fun. You take this up a notch! Coolest thing I've ever seen. Subscribed! Can't wait to see if you find a way to build your own cooler. Also liked that you did research on different forms of cryocoolers. Wich one of these are the quietest?

[@scienceandmathHandle]

Great effort on this attempt, you are really making me feel like I need to use my 3d printer more. So I used to work in a thin passive component fab and we used cryopumps on almost everything that didn't involve Silane(a super scary gas). A cryopump is just a cryocooler with basically a heat sink on the cold end that gas would freeze to and pump out the cavity. I think we had around 30 cryopumps and would re-build a couple a year. They were all of the Stirling style where the regenerator was stacked mesh in the displacer. They all had large compressors and used a valve cycle style setup. Typically our pumps would run somewhere around 8-12 Kelvins(when they were at running well). Once I got to look inside one when it running and had the baffles off; the frozen gas on the carbon heat sink looked just like water frost might look even though it was just frozen air at 10s of Kelvins.

[@rubenhayastan4854]

Блин, открытие века )))))) Такая хрень использовалась для подкачки воздуха в аквариумах ,уже лет сто .

[@HuskyMachining]

This is so cool! I have always wanted to build a LN generator. I'm glad I found this channel

[@MaximumBan]

It was fun to see your linear motor's, the mass dumper's and camera shutter's speeds all sync up.

[@VexMexIndustries]

i never eim amazed Simply amazed by how incredible your work already is and the explanations that are actually understandable !

[@hinz1]

Great project and awesome presentation, more intuitive than my thermodynamics professor at university!

[@Moist_yet_Crispy]

Loved the video! Looking forward to part 2!

[@asmotaku]

Really nice projects ! Thank you for your hard work and dedication !

[@valyushalee2320]

Brilliant video especially with the electronic analogies

[@andrew051968]

This video really excited me, I’ve been looking for a used cryocooler for ages but they’re not easy to find cheaply in Australia. You’ve given me hope that they may actually be able to be built by amateurs !

[@abrahamvarghesein]

Really good description of the principle of cryo cooler. I liked the practicals ❤

[@Some_Beach]

I knew something like this had to be coming when you mentioned the vibration stabilizers. Cold finger FTW

[@vincenttwin3890]

It's funny how with enough insight and ingenuity, even things like cryocoolers or EM resonant oscillators can be built using 3D printed parts and hobby-grade electronics. Is it as effective as something like a professional cryocooler - probably not, but the fact that it could be close with enough time and tuning is amazing to see. Gonna have to keep my eye on this project!

[@Darkbob-ew1lk]

This is a superb work of engineering, your work is inspiring

[@alejandronan607]

Channels like this is why the average youtube session lasts many hours....bravo you got my subscription :)

[@jessiejanson1528]

vary neat, cant wait for part 2.

[@jbrownson]

Excellent visuals, thanks!

[@akzorz9197]

First time watching and wow.. I am just so impressed. Everything was explained fully including the math behind it and your thought processes are fun to follow. Keep up the good work!

[@LucasRamog]

Great explanation! Learned a lot, thanks!

[@fishyerik]

Most interesting youtube video I've seen in a very long time. A separate compressor with valves to create the oscillations also makes it easy to get rid of the initial compression heat. Correct me if I'm wrong, but I think just adiabatic expansion from 0.9 MPa which a cheap off the shelf garage compressor can produce, and room temperature to 0.1 MPa takes you well over halfway from room temp to boiling point of nitrogen at 0.1 MPa, in temperature, obviously the easiest part, but still... On that note, if the goal is just to produce liquid nitrogen, compressors able to produce 30 MPa are available for a few hundred dollars, adiabatic expansion from there, and room temperature, would get you below the boiling point of nitrogen at 0.1 MPa if it weren't for the energy released from the oxygen condensation. So you would have to use the low temperature released air to pre-cool the compressed air, but then you should be able to get liquid nitrogen relatively easy. Using "pure" nitrogen would make things easier, regardless of which technique you use. Just to be able to get nitrogen to condensate from air you have to remove a lot of heat released by the oxygen condensation, and that removal has to happen at just a little higher temperature than you need to get the nitrogen to condensate. I wonder if it is even realistic to get significant amount of nitrogen to condensate with a diy oscillating cooler using air without using separate compressor and high pressure air from which the compression heat has been dissipated because the condensation and vaporization of the oxygen takes up a lot of the potential change without changing temperature. Both heat and volume. All this assuming I haven't got something completely wrong, or missed something important. I'm not trying to explain basic physics here, just some of my thoughts about some aspects, that might be relevant, or not. And, my suggested "shortcut" using a scuba tank type compressor and pre-cooling the compressed air with the expansion assumes that the only important goal was to create liquid nitrogen, and not also using some specific technology.

[@horrorhotel1999]

I got an old commercial pulse tube cryocooler I got from a recycling center in california. Had to vacuum bake and refill it before it worked again. It works on 28-30bars of >99.999% pure Helium

[@lavy9740]

We love you Mr. Pirate. Godspeed

[@goranjosic]

Cant wait to see continuation of this project!

[@ivprojects8143]

Really interesting! Thanks for sharing.

[@thedotjake7189]

This is what youtube is all about. Super smart people making stuff that they find extremely interesting. this is some Newton and Einstein stuff right here. never stopping for obstacles

[@rodrigograve6931]

What an amazing project!

[@ekkekrosing8454]

Finally! Just the video I needed!

[@alexandrosfilth7042]

Thank you for the parallel circuit explanations. I have been thinking about materials science this way for years and no one seems to get it. The universe is electric. Everything is a circuit. This also explained how part of my fusion reactor design works, through absorption.

[@rovhalgrencparselstedt8343]

I built a pulse tube cooler around 12-15 years ago that was based around a air compresor block that i mounted the pulse tube setup on top of, for the inertance tube i used a capillary tube from some thermostat and a starting fluid spray can as the buffer tank. For the regenerator i used steel stove scrubbers shoved into plastic electrical conduit, and the cold end i fashioned out of a piece of copper heatsink. The whole setup was ran by a three phase motor and a VFD and it worked surprisingly well for something i just randomly threw together having had zero calculations done, it got cold enough to completely frost up the cold end and block off the regenerator with a plug of frost/ice in just 10-15 minutes. I may still have a video of it somewhere.

[@HyperspacePirate]

I'd be interested to see that. There's very few videos on the internet of anything other than commercial models

[@meep282]

Such a interesting project and a great video!

[@alexlabs4858]

Super cool. Excited to follow this

[@portalvujijaina]

I saw this part in action, I knew it was going to revolutionize the adult industry.

[@caseyspiegelberg8689]

you're content is great glad I found this ill be following from now on. PS- I appreciate you reducing the noise of the motor in post - I think most headphone user's would agree

[@SchwaAlien]

That’s really cool, several years ago I saw a clip on TV that was highlighting a refrigeration system that didn’t use refrigerant running freezers in an ice cream shop - it must have been related to this design because it used very powerful speakers enclosed in a tube that was able to pump heat, didn’t give much detail but I remember being quite inspired by the innovation.

[@rocketman475]

- Accoustic refrigeration -

[@experimentalcyborg]

air is the refrigerant.

[@craigschiller1599]

Super cool videos, very well explained. Working my way through your videos, time & effort put into these subjects is incredible. Awsome. 10/10. 👍

[@gaetano222]

Amazing! Looking forward to your next video.

[@artrock8175]

Amazing project! Thankyou for sharing! 🙏

[@Darkatlas_23]

I just discovered you today and I'd enjoy using one or two of the items you've made. I have an idea that might be beneficial for not only us but the world as a whole.

[@christomold3142]

Great job man!

[@realdbcooper3423]

Cant wait, very interested! keep up the good work.

[@Twistedmetal-qe8kx]

Awesome video, great device.

[@scootsmcgoots1]

Instant sub. This is really cool and I'm excited to see where it goes. Really well put together video with lots of great detailed explanations

[@pixel5943]

Not only interessting .. fascinating great vid 👐

[@samuelstrymish6403]

Never knew about the blowtorch trick. That is very useful.

[@verbalance5630]

I understand hardly anything, but I love it ❤

[@stopmessingwithyt]

if this contraption could talk, i think its 1st word would be "giggity"

[@manray8513]

lmfao

[@charadremur333]

The only joke like this here, everyone else (including me) is a fuckin nerd. Go science.

[@christopherkise]

HahahHa😂

[@WetDoggo]

definitely haha 😂 this could be developed further to become the most popular toy for M and F

[@devilrexx9938]

WTF!😂

[@simonlinser8286]

this channel is great

[@jesussavescars807]

A possible solution would be to use the Stirling cycle cooler to pre-cool the gas before it enters the pulse tube, which can provide additional cooling. Alternatively, the pulse tube can be used to cool down the Stirling engine itself, which can help to increase its efficiency. However, this would require careful sizing and design to ensure that the two systems can work together seamlessly.

[@paulbrouyere1735]

Wow, really! I just shared this with Robert Murray Smith from TNT. You deserve a lot of audience.

[@ReinisLusis]

WOW!!! Very nice video! Thank you!

[@bobfugazy4916]

Interesting is an understatement. Keep going friend. Thank you for educating us.

[@mrgcav]

Very interesting. Excellent video. More please more.

[@chazbarclay]

I found this massively interesting. Subbed and now watching your backlog of videos. 👍👍

[@dumbachari]

What a great video! Thank you for sharing your failures too!!!

[@constantin1004]

Great work

[@cphVlwYa]

This is extremely ambitious. But if you can get it work it will be by far one of the coolest projects I've ever seen (pun intended)

[@rinzegewoon]

very cool! I want to see more!

[@miklov]

Fascinating. Never saw your stuff before but you earned yet another subscriber =)

[@russellzauner]

This will be great for keeping my beer cool at the next campout

[@lumotroph]

This is so cool!

[@birdpump]

What a cool video, thanks!

[@hollowllif3321]

Very good explained. Fantastic. Thanks you

[@OneAverageHuman]

This is very interesting. Thanks for sharing this.

[@theLPMichi]

Nice project! But one important detail that nobody in the comments mentioned yet is a "flow straightener" for a uniform gas front so that the "gas piston" can push the gas. It's rarely mentioned in papers and scientific literature but every Pulse Tube cooler has it. It consists of several really small tubes, similar to your heat exchanger or a long extruded mesh. One is placed at each end of the Pulse Tube (after the warm heat exchanger and before the valve to the buffer tank). Should get you better results.

[@Al5052H32]

The straighteners also reduce convection losses in the PT

[@AndersonDotPro]

I'm a moron, but this was a great video because it actually improved my understanding of things even though those things are still way over my head. The video is also very well produced. Your choice of music bedding did not interfere with your words and you set the volume of it almost perfectly. Your images were clear and stable. If I was a professor I would give you an A+.

[@ManyHeavens42]

be Free

[@ManyHeavens42]

🏃🍎,?🪤🎯🔥

[@MrClickbang357]

WOW! Give an engineer a 3d printer and see what he does with it!!1 What? No useless boaty prints! I loved learning about this design from this video.

[@JoshuaRosaaen]

Wow...this was my first time seeing some of this...thank you for a new topic of interest to dive into. Got my like and subscribe. Thank you and looking forward to more of this device.

[@Enonymouse_]

Love your projects and hope to try some of them in my own shop. :)

[@stevecann3394]

Fascinating, and informative. Enjoyed the background music too👍😀

[@redsquirrelftw]

Wow that's such a cool concept. If it could be perfected and scaled higher it could essentially be used as an air conditioner without needing to deal with refrigerants or needing a license.