Pulse Tube Cryocooler - Part 2 (-75C)

[@HyperspacePirate]

I've read through the comments and thought I'd address a few of them: -The 40mm piston is probably not optimally matched to the pulse tube geometry, since i optimized it for higher frequencies on the 25mm piston -For part 3 or 4 i'll probably try using Hydrogen as a working gas. It has a lower specific heat ratio than helium, but the highest thermal conductivity of any gas, so I should see an increase in performance as long as all the components are sealed well enough to avoid leakage -For part 3 I'll be looking at heat exchangers with multiple heat pipes and water cooling, as well as single tubes packed with copper wool. -I do intend to evaluate a segmented regenerator with polymer "heat breaks" to slow down axial conduction losses by breaking the continuity of the metal mesh -For higher pressures and lower temperatures, I'll be replacing the PVC with stainless steel to avoid explosion hazards. -The ESC has flyback diodes across the H-bridge MOSFETs, so any back-current from the flywheel after motor shutoff should be dissipated through those. -Multiple stages might be neccesary to reach LN2 temperatures with a DIY setup. Pulse tubes can be staged by connecting a much smaller pulse tube to the output of the compressor's aftercooler and thermally anchoring the second heat exchanger to the cold end of the first stage. Pulse tubes used for liquefying helium/hydrogen typically have 3 or 4 of these stages and can reach single-digit kelvin temperatures

[@Axman6]

I’d be really interested to see more tests with increasing the regenerator diameter so the gas flowing over the steel wool is moving at a slower velocity; if your idea about the velocity of the air getting too high is right this should help… maybe 🙃

[@BirdbrainEngineer]

- Hydrogen is incredibly difficult to keep sealed; just look at the troubles and delays with SLS - I wouldn't be so sure that you can use water cooling... wouldn't the heat exchanger itself not get cold enough at one point to freeze water inside the heat exchanger? Then you have an insulator in the pipes instead!

[@marttileppanen]

Could you add a new stage just by eg. adding a Peltier element (with a heat sink) to forcibly cool down the hot end and thus increasing the temperature difference? They're not terribly efficient, but can move tens of watts of heat without using moving parts?

[@vladovrhovsek]

You should ISOLATE ALL around the precision valve and after on the right, all the way to coper pipe and reservoar. When air from the resevoar expands through valve, it cools off, and it is good, that it is cool as posible, before expands.

[@WetDoggo]

is the volume really really low or what?

[@dr.med.janschiefer7163]

This is fascinating. The first DIY cryocooler that works sufficiently This is the first DIY project reaching really low temperatures without complicated multistage refrigerant stages.

[@AttilaBlade]

:) Not the first that works well, but with a really cool presentation!

[@Aeogenia]

This is by far, the most interesting video project recommended by KZbin in a long time. Great explanation and accurate presentation. Amazing work, keep up the good work. Hope to see -200C in a while :)

[@drezster]

I second that. Looking forward to some liquid nitrogen in the near future :)

[@pradipda3171]

So True otherwise youtube only promotes garbage and clickbait

[@xmysef4920]

Gotta agree with ya!

[@jtjames79]

I agree this is highly relevant to my interests. I've been wanting to test out instead of using heat to evaporate water from my 3D printer filament, sublimate it with cold instead. Freeze drying machines are ridiculously expensive. I could do so much science with this!

[@fickgooglefickthem6884]

In case You don't know: watch the "star in a jar" project by the plasma channel. Just a recommendation

[@VarkaTheDragon]

That's some seriously impressive data analysis and scientific method for a simple prototype! Great work - subscribed!

[@Stoneman06660]

Yeah, couldn't agree more. Often that sort of info is missed during YT content which I assume is to make it palatable to a wider audience who just want to see stuff built, tested, and completed. (Or blow up; intentionally or otherwise).

[@trustthedogsheneverlies644]

When cleaning wire wool up wrap the magnet in a rag so you can separate the captured steel wool from the magnet to dispose. Great to see an explanation of why gas-gas heat exchangers are hard to design!

[@maqabayker]

Gas-to-gas heat exchangers are much harder than the other because overall heat transfer coefficient is substantially low that you need very large equipment for that. Because of that, the diameter and length of the heat exchanger gets larger and larger. If you intend to do gas to liquid heat exchanger, it is far worse than it seems, because the liquid will have higher conductivity while gas will have very low conductivity which makes a lot of problems on the design process. Other than this, the pressure drop across the heat exchanger will be very high for gas effluent (because of high velocities) depending on what type of heat exchanger and which side you intend to have liquid flowing (if it is shell and tube heat exchanger of course) In my process design course, I had a lot of problems with superheated vapor stream and it was a nightmare to get the correct design values.

[@kitemanmusic]

Great suggestion. Could use a vacuum cleaner or a small brush.

[@mrf4549]

Instead of a rag you can also use a sandwich bag but the rag works well too.

[@beckettevans7228]

I use a ziploc bag, inside out... and then boom I flip it around and now I have all my chips!

[@odw32]

The clarity & detail in your explanations is absolutely amazing, the collected data and visualizations really help to make this more intuitive. You're a great teacher!

[@kellenfoore5182]

This is the best thing that KZbin has sent my way in a LONG time. Thank you so much for the amazingly well made video, and I can't wait for the next part!

[@origamerking6927]

this is incredible you are the only youtuber that shows how to make a cryocooler keep this up

[@hectorgarcia1326]

I love how far diy projects have come since the early days of KZbin a decade ago which were 90% LED projects keep up the good work

[@sachitdaniel6688]

The use of the scaling exponents to predict the behaviour, along with the brute force empirical parameter sweep was beautiful ❤️ I wanted to click like so many times in this video but sadly I am limited to just one. This is so beautiful.

[@rorypenstock1763]

I just want to say that in terms of video produciton, you've done an excellent job in the treatment of the calculations and design considerations. You've somehow kept your explanations concise without glossing over anything big, and made it accessible without dumbing it down. Your channel is the best one KZbin has recommended me in a long time.

[@dannyneumann4547]

Love this series, seriously. I feel like I understand now how “real” engineering is done. Keep the videos coming!

[@user-nj9mh7ly2n]

And he's using the correct units! +10 points!

[@EricGardnerTX]

So, I don't comment often, but you are fantastic. This is such a great example of scientific and data driven innovation. Finding ways to isolate, measure and iterate individual components is the name of the game, and you have done it wonderfully.

[@un65tube]

I more or less stumbled by accident over your videos, but the subject is very fascinating and they are one of the best youtube videos I ever saw up to now that combine practical use with scientific background. Wish my scool lessons in physics or thermodynamic would have been so interesting! As already said by others, you would be a very good teacher! Many greetings from Germany and all the best for upcoming 2023! 😃

[@davidmclean5067]

This is excellent! Having scratch-built several high temperature Stirling engines, I very much appreciate your approach to this.

[@mikeconnery4652]

Were you thinking of using the waste heat. Also, would a sterling engine make a good power source on the moon?

[@timothysands5537]

Your channel is a goldmine for us mechanical engineering students. Thank you for the detailed content!

[@TopiasKorpiTK]

You could try to improve regenerator performance by using several "sub-regenerators" to prevent heat conduction axially. In practice, instead of making one blob of steel wool, make several and stack them inside the tube.

[@mitchellstrobbe7779]

I wonder if adding an insulator material or air gap between them would help as well

[@TopiasKorpiTK]

@@mitchellstrobbe7779 What I've read, having an air gap or insulator material between sub-regenerators does not improve the perfomance much at all. Axial discontinuity in the regenerator should be enough to prevent axial conduction.

[@kreynolds1123]

Try a stack of stainless steel filter mesh. Not only does stainless steel have a much lower thermal conductivity than the steel in steel wool, but heat has to flow laterally along the before reaching a contact point where it can flow axially to the next screen. The second part contrast with the random orientations allowing comparitivly faster axial heat conduction with steel wool.

[@graealex]

Simplest way to give these 3D printed parts better performance and tolerances is to press in some bushings, typically made from brass. It works similar to putting in inserts, heating them up and then just pushing. Bushings are very often the better solution compared to roller or ball bearings anyway.

[@dustinbrueggemann1875]

Bushings are only really significantly better if you're worried about contaminant intrusions into the race or concentricity. For a continuous low speed, ambient temperature, high torque system in an open and dry environment, ball bearings are pretty much perfect. A bushing would need much more careful tolerances for the shafts and alignment. If he were working with hydrogen gas you might have an argument though.

[@graealex]

@@dustinbrueggemann1875 Yes yes, high torque like here lol. It's low-torque, low-load, low-speed, and very limited operating hours, so the main argument for bushings is the fact that they're low profile. Which I guess is the reason he didn't install ball bearings in the first iteration of the rod, as there wasn't enough space.

[@amannarwal7032]

Truly remarkable in my whole life as an engineer to this date it's the first time I realised how difficult it is to build something when you are dealing with multiple variables

[@krystianstolarczyk4544]

Once you can turn air to liquid i know this channel is gonna blow up. Great editing, the graphs are sweet. I'm getting ready to follow along.

[@RocketkidDesigns]

This is super cool, I went down a rabbit hole of research into cryocoolers about 6 months ago but never found anyone else doing it DIY. I'm glad you took it to the next step and built it!

[@drfoop]

That I could understand this using memories of high school physics from the distant past speaks volumes for your presentation skills. The KZbin recommendation engine has a success for once. Excellent video.

[@mohammadkahil8255]

This id one of the best documented experiment with best scientific illustration, salutes

[@jillianonthehudson1739]

One of the most underrated channels on KZbin

[@BloodyMobile]

4:00 this is a very well done explaination for a really complex system that throws numbers and formula symbols at you like a gatling.

[@R290s_biggest_fan]

This is the best fluid dynamics lesson I've ever had

[@thonkingintensifies9510]

Brother what the hell did you study to all know all this, not only physics but your grasp on electricity is also astonishing, keep making videos love this stuff

[@vernonzehr]

I recently signed up for Paramount+ and was watching "The Love Boat" before I clicked on this video. My GOD, the vast difference in the intelligent content between these two programs is astounding. I believe they are fighting for control of my brain (it didn't matter so much back in the 70s and 80s). I'm not sure if this could cause some sort of brain damage. Like a kind of "content intelligence quotient whiplash".

[@ChrisContin]

Great idea! The functional part of “cold effect” you’re using is the guarantee of all potential energy lost in a cold stuff. To amplify your effect discover ways of reducing potential energy in the material used. Specific heat is one, or the ability of a material to regain heat. Isolate the chamber in all directions except one (or so) and draw it through a salt-water bath, which is notoriously disconductive of heat. Hope to see Part 3!

[@chemicalcookie7546]

Awesome video. I have been intrigued by pulse tube coolers since I heard about it on JWST, so to see a functional DIY build is astounding. Great work, looking forward to part 3!

[@udovan]

Great video. One bonus for your tip for the cleanup of steel wool with a magnet, is to put the magnet into a plastic bag first. Then when you're done you can just fold over the bag and remove the clean magnet :)

[@AttilaBlade]

It was a great presentation again! Congratulation! DELTA EC program from Penn State University could help a lot to you in the next steps. There is possible variations of heat engines and heat pumps from simple alpha Stirling to pulse tube via thermoacoustics. The resonant frequency of the system is one of the main thing to increase the performance with a better performance of HX & regenerator also with changed basic parameters. Try to abstract from the pressure ratio a bit, because ThermoAcoustic systems could rich this temperature range easily with low compression ratio, typically under 10%. These materials that you used are enough good for a trial run where you can see the effect basically, but with this density, wire diameter and thermal properties of the regenerator just with a bit poor performance. The Achilles-heel the HX parts in every "homemade" heat pump. (I think it again, because maybe just we've made this type of unit in public...) I know you've learnt a lot about this unit, I'm impressed!, so I just suggest to you look around the thermal penetration depth for better performance of heat exchangers. The regenerator density is not a big problem here, that will create a phase shift too, when it will dense enough so try to not worry about it too much. The moisture is a real problem, because the ice could block the gaps. Alpha Stirling has a high compression ratio but if you can hit the -100 degrees Celsius you will experience strange things with sealing, or around the solid material when you want to going under. BLADE SPS: Sorry for the essay!

[@Al5052H32]

Would a phasor diagram be of help here? I have been led to assume that mass flow is king. Edit: also that the goal of a phasor diagram is to balance the diagram on the middle of the regenerator. Would this be correct?

[@mikeconnery4652]

Thank you for the essay

[@TheoLubbe]

I understood 100% of ±1% of the physics/maths involved, but man was this video fascinating!

[@victoryfirst2878]

I have to say your logic in doing this project is right on. Have to admit you and I are brothers from the same mother. Look forward to your videos that take my imagination of making things to another level for sure. Keep up the great work fella.

[@lidamullendore6166]

Fantastic progress!!! I admire your bravery to take on such a challenging problem. Can't wait for part 3. Thank you so much! 😘

[@BirdbrainEngineer]

For the regenerator I recommend looking into a foil-based regenerator. The video here (starts at timestamp): kzbin.info/www/bejne/f5i6eaiei8h_gaM ,shows how a strip of stainless steel foil, would have small dimples stamped into it, so that when it is wrapped around itself, it makes for nice small airgaps between the wounds of the foil. Apparently at least for Stirling engines, it's one of the better types of regenerators to use.

[@kenmercer2721]

I was reading a lot about Stirling refrigeration in the early 80's and the "standard" regenerator consisted of a stack of fine wire mesh disks. The stack naturally has poor thermal conductivity down it's length, as required. I think copper was preferred but brass was acceptable and easier to obtain. The mesh is easy to cut with scissors. I've not seen the foil approach but it looks interesting and am left wondering how the dead space, axial conductivity and other properties compare to mesh.

[@darkwolf1328]

This is incredible! One piece of advice though, PVC is not usually rated for a load. You appear to know what you are doing, but there are a lot of people every year from the PVC in their potato cannon (and similar projects) exploding under pressure. I don't know too much about it but it might be something to look into if you didn't know about it (especially since plastic becomes even more brittle the colder it gets). It would be a shame if this project was never finished because of a material mishap

[@1weck1]

The explanations, calculations, and even concept presentation in this video is top notch. I’m learning and enjoying it

[@hiphopalest6295]

Well I must say, this is my new favorite channel. I love the inclusion of the formulas. Thanks!

[@IsiahShelton-tt9zd]

I was kind of getting board of all the math then... "my homemade CNC Mill"! I was instantly paying 100% attention. Great Video Man!

[@SocktheWorm]

I love the intelligent and thoughtful community you've fostered, I scroll down and all I see is intelligent and thoughtful comments instead of my first instinct which was laughing at the robo pubes at 8:45

[@JuniorJunison]

What a magnificent video. I love how well you are keeping track of all the variables and then plotting them on a graph, it's a very nice tool to have when trying to optimize such a system. Well done.

[@Vinzmannn]

Man, refrigeration is such a cool topic. Thank you for this video.

[@Barnaclebeard]

linear motor as a marital aid, that's an excellent attitude

[@miltonbradley4249]

I wish my professors were as good as you and your explanation. VERY WELL DONE

[@ThePowerofElectricity]

I think you just gave me an idea to rescue my old GM-Cryo system... Great video, excited to see where your journey will continue to go!

[@GautamSharmaCA]

Bravo! Looking at your channel - all the videos you have made - you should have at least a few million followers! You indeed, are one of the few.

[@Betruet]

Man, I loved the last video and this one didn't disappoint. Great job I'll be watching for updates.

[@nolanmods7172]

I really think adding the second piston will yield better results! Can't wait to see the next video on this!!

[@brandonwyffels8002]

Really excited to see such great results! I definitely plan on building one for myself in the future

[@vincentli9106]

if you do it, for the love of God tell me how you did it. I can't build crap!

[@b-beluga4510]

@@vincentli9106 sit in toilet bruh

[@banalestorchid5814]

That was one of the most interesting videos I have seen in a long time. I semi-learnt a ton of things from it. I say "semi" because there was stuff in it that I didn't know I didn't know. So I didn't exactly "learn" but now I know where to start in truly understanding some of the science and engineering behind the fluid and thermo dynamics of this. Thank you, I've subscribed and look forward to the next part.

[@LassIV]

Excited to the new episode! Pretty interesting to see that actually cooling Oxigen and Argon.

[@Самоделионполезион]

Тема получение низких температур в домашних условия очень интересует меня. Ваши технические решения очень интересны и поучительны. Ваши оригинальные решения и конструкции поражают простотой. Думаю изготавливать такие устройства имея скромные возможности но возможный результат вдохновляет и даёт много возможностей получения газов и получения низких температур. Есть несколько идей в числе которых изготовления высоко вакуумного насоса схожего с вашим компрессором. Не смотря что у меня есть двухступенчатый насос вакуумный и диффузионный есть большая вероятность изготовления из простых материалов насоса высокого вакуума с производительностью не хуже чем турбомолекулярный и диффузионный. Идея в том что рассматриваю вакуумный как обратный насосу создающий давление. Использую ваши конструктивные решения думаю изготовить. Благодарю.

[@LexYeen]

This is the kind of garage science everyone should know is possible.

[@AiOinc1]

I have a ton of these types of components laying around, I have doubts I will ever get around to actually doing this but this is extremely cool. You have my respect and you have my subscription.

[@glasslinger]

I have a thermal camera that uses a cryocooler that uses a vibrating linear compressor and is small enough to fit in the palm of your hand. It is a hermetic system that uses helium as the working gas. In 30 minutes operation the cold end reaches negative 250F. I would look up cryocooler patents and see what has been done. There are fantastic systems out there!

[@sky173]

This is the 'coolest' thing I'll see today on KZbin. Thanks for sharing.

[@williamogletree4153]

PV=NRT WITH THERMAL CONDUCTANCE AND DISSIPATION... EXCELLENT VIDEO

[@williamogletree4153]

however you're not fully accounting for thermal conductance in the shotgun dissipators

[@williamogletree4153]

if you spread your thermal dissipators over the XYZ axis instead of stacking them, in other words, in a spherical configuration it should achieve much greater thermal dissipation. goes in it from the core goes out it from the outside of the sphere to rejoin to a central manifold should boost efficiency exponentially. then consider cooling the outside of the sphere with the secondary cooling system you may get within liquid nitrogen range at low energy input just a suggestion keep up the good work brother

[@mr.indian_pro_creator]

दिन की शुरुआत यदि एक अच्छे से सुविचार से की जाए तो इससे पूरा दिन ही खुशनुमा हो जाता है। कहने का तात्पर्य यह हुआ कि यदि आप अपने दिन की शुरुआत प्रेरणादायक सुविचार से करेंगे तो अवश्य ही आप पूरे दिन भी उसी प्रेरणा के अनुसार काम करेंगे। यह आपके दिन को तो अच्छा बनाएगा ही बनाएगा, साथ के साथ इससे आपको अच्छा काम करने की प्रेरणा मिलेगी।

[@namaefumei]

data analysis and scientific method is unbeliavable. Thanks a lot for sharing!

[@BrilliantDesignOnline]

As a random passerby, with science knowledge, I had no idea this was possible..Great video. Fly Wheel doesn't hurt either :-)

[@danjohnstone8196]

Nice progress. A couple of suggestions, for what they are worth: measure the impedance of the components and match, rework the regenerator for lower axial conduction. May be able to measure impedance by comparing current draw at the driving motor with load and subtract no-load. Capacitance would be decreasing in impedance with f, resistance would be flat, and inductance would increase in impedance with f. Your dogged determination is inspirational. Also makes you admire Stirling et al, and wonder how they did it.

[@poprawa]

This project is as mental, as impressive. I love it

[@JuulCPH]

Great project! Here's a tip: Put your neodymium magnet in a plastic bag. Makes removing the metal bits a lot simpler :)

[@lambdaprog]

This video is a good reference for engineers.

[@ytuat]

This is amazingly thorough and well thought out. Congrats on the Hackaday link too.

[@crusiethmaximuss]

Just found this channel via KZbin recommendations, and I must say, I am thoroughly enjoying it. Subscribed.

[@ivprojects8143]

Very impressive! It's clear you put a ton of effort into both the project itself and the video. Thanks for sharing!

[@beatrute2677]

I don’t understand much of it, but I can appreciate and enjoy it, thanks man

[@1111Syl]

You have gotten a great deal of positive remarks in the comments and that is well deserved. Very scientific and a high llvel of curiosity in exploring the possibilities and also with a good intuition as where to go next. The material is clearly well understood and very well explained. You are talented! A few suggestions: Using matt black plating for internal parts in the hot zone may help in capturing some of the IR radiation of the heat and liquid cooling on the outside seems obvious to you already. Your idea of pressurizing the system looks promissing but at the cost of added complexity. If this works, a duall piston system (opposed) may help in balancing the forces especially at start up. I have seen the comment about using bushing inserts as they are cheap and easy to use (good idea). I have used ball bearings as inserts in 3D parts as well and that works well (relatively inexpensive). Just a thought: stacking pellets of perforated sheet metal with the correct size, apperture, colour and conductivity may help in capturing the heat in the hot zone. Good luck with your project.

[@JCGver]

Tips for cleaning up after steelwool: put something around the magnet, like a it of paper. After you got all the fibers on the magnet, you can remove the paper with the fibers and not have the hassle of cleaning the magnet of fibers.

[@alexscarbro796]

A tip I like for cleaning up ferrous metal swarf. Put the magnet in a bag. Swipe it over the swarf, then turn the bag inside out. The magnet remains clean and the swarf stays inside the bag.

[@alex4alexn]

Dang it, i cant wait for the next one, these are so cool and i really enjoying seeing what you build and your thought process, cant wait to see you get some liquids dropping out of that baby, cheers

[@dave4882]

My understanding of the physics behind this are a bit sketchy, but I do know that if you are using the aluminum blocks to dissipate heat, then adding a small fan to blow air over them will increase their ability to dissipate heat into the air. Putting them into like an ice bath will help even more. That way the delta T of the inside should be higher, and therefore improve heat conduction. You may want too inspect the inside of your air cylinder to make sure the piston is going all the way to the end of the tube to the the largest compression you can get. There may be a bolt on the end of the piston or weird cutouts in the head. My other suggestion is to increase the stroke length and use both motors to drive the crank. One from each end.

[@clive4500]

Very impressive and a joy to watch journey of Discovery💯 ps high-quality glass syringes. Would be a good possibility for the pistons. Easy way to get hold of Close tolerance. Displacement could be increased by using more than one of these syringes

[@nitromeano]

I love your content, it is a beautiful example for everything engineering stands for, thank you for producing it.

[@dn275]

Really excellent presentation. I’m looking forward to seeing more of your work! Success or failure, both will be a fascinating learning experience.

[@giovanni4151]

amazing video thanks. i study engineering and watching this video was way more clear then many labs experiences in my uni

[@RumoredAtmos]

Very cool video. I liked how you showed the math and explained the relations between things such as the effect of the diameter of the copper or the differences in surface area used in the regenerator. You got my sub

[@paulbrouyere1735]

Very interesting project. This can definitely be used with renewable energy.

[@htomerif]

Thanks, this took a ton of work. I've been wanting to do this myself for ln2 or lo2 but I thought I was going to have to get my hands on a turboexpander. It would really be nice if you could automatically vary elements of the system with servos or whatever so it could self-tune. None of the graphs you showed had more than one peak, so it doesn't seem like there's local minima (or maxima) to get stuck on.

[@qownson4410]

You need a patreon or something. Some people might wanna throw money at you? What you're doing is refreshing. Happy New Year.

[@theGraphicAutist]

very cool... I'm after the same thing but ur way smarter than I! I'm routing for u... and waiting impatiently for ur next video!

[@camfocus8888]

From both you and me have same nail, I believe we think the same way too! I like your idea and work as well!

[@SignalDitch]

This is a super fun project to follow, thanks for the thorough presentation!

[@irkedoff]

I see a new PC cooler. Great work. I can't wait to see more.

[@mikaellavoie6811]

Can't wait to see the sequel! Captivating work i love it!

[@Tristoo]

god damn I wish I could subscribe twice man. absolutely sick. and this video I actually understood like 95% of it. Lmao the scenario of being your roommate just came to mind and it's absolutely hilarious- +"hey man" "hey" +>looks at contraption of 3d printed stuff with bolts on it, some piston, steel wool, PVC piping, some copper tubing and some tank-like thing. can't for the life of self figure out what it could possibly be +"so you making like a kart or something?" "nope" +"steam engine?" "closer kinda" +"what is it?" "cryo cooler" +>doesn't believe random assortment of random could possibly be the type of thing used mostly in incredibly expensive industrial equipment +"no way" "way" +"so you like freezing water or something?" "that was last prototype, this is now freezing co2 " +>looks up freezing point of CO2 and realizes that's cold af +>further looks at assortment of random things bolted onto the board +"... okay now that's cool" "quite.. but still only half as much as it will be" I've had that happen before where I do something insane and people are like "no way you made that.. you made that?" - but this is on another level. Anyway, thank you for the video once more. And as always looking forward to the next one.

[@RobertA-hq3vz]

I'm not an expert in this field, and truthfully I skimmed through most of the video, but two thoughts occur to me. Instead of rhythmically activating the piston in a sinusoidal pattern, get the piston to activate then don't release it for a few seconds. This would give the the tube greater time to dissipate the heat to the environment. Secondly if the cooler gas generated was redirected back to the outside of the piston cylinder instead of a collection reservoir it would make the cylinder cooler for the next cycle. After a certain number of cycles you collect the much colder gas into a reservoir. Say 1 out of every 10 pulses. Its probably stupid, I know, but I saw this video yesterday, and today I just woke up, had my coffee to wait for my brain to come back on line, and these thoughts popped into my head.

[@boltonky]

Wicked work and for how much information you put across it doesn't get dull. Looking forward to future updates :)

[@grahamehadden4320]

A very thorough video. Made me think of poteen making.

[@poldiderbus3330]

This is kind of a project I would have expected to see from Ben / Applied Science! Really cool, great job!

[@unicornadrian1358]

Great video, love the way you document every step and show your working. 😊

[@CooperDuper3000]

This is soo cool, well not yet - but, you know... i also always wanted my own cryo cooler but these things are so expensive if you can get one in the first place. Please, please keep up your good work. Wish you all the best. Cheers.

[@hiphopalest6295]

Hey, try making the inlet slope to the exchanger 45 deg, and the outlet slope to 30 deg this should improve the turbulence in the system. It provides a trade off. In the larger diameter tube you maintain pressure as a constant. When you reduce the dia. The pressure rises increasing velocity. The 30 deg slope outlet will smoothe the air sream allowing the pressure to stabilize prior to the steel wool. I am an HVAC guy that specializes in large mechanical systems

[@80lab38]

This is Ben Krasnow level results with Big Clive level materials. Brilliant!

[@scottneels2628]

Man that's cool! I'm hooked. Can't wait for the next installment.

[@sparc5]

this is the COOLEST thing I've ever seen on KZbin.

[@g576758]

This is the my new favorite thing to watch since Mythbusters