Pulse Tube Cryocooler - Part 2 (-75C)

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Part 1:
• Pulse Tube Cryocooler ...
This is the second part of my video series on attempting to build a Pulse Tube cryocooler. I managed to make significant progress by removing the linear motor and using a conventional rotary motor with a large gear reduction ratio and a flywheel to produce the larger forces needed for higher compression ratios.
For pistons, I used pneumatic actuators. I evaluated a 25mm bore and a 40mm bore piston, both with a 50mm stroke. Pneumatic actuators have more friction than conventional pistons due to their rubber lip seals, but theoretically have zero blowby, so they hold pressure, which makes them more effective for low frequency applications.
Here are some specifications for the cooler:
Pipe diameter: 18mm
Regenerator Length: 30mm
Regenerator Material: Fine steel wool
Pulse Tube Length: 100mm
Flow resistance source: 1/8 NPT needle valve
Inertance Tube Length: 10' (~3m)
Inertance Tube Diameter: 4.4mm
Buffer Tank Volume: 2L
Piston Swept volume (25mm): 23CC
Piston Swept volume (40mm): 57CC
Compression Ratio (25mm): 1.4
Compression Ratio (40mm): 2.0
Maximum Frequency: 15 Hz
Motor KV: 750
Motor Voltage: 16V
Motor reduction ratio: 5:1
Flywheel moment of Inertia: 0.012 kgm^2
Maximum recorded temperature drop below ambient: -91C
Lowest recorded temperature: -75C
I think with some more optimization, this system can probably reach -100C, although without helium or hydrogen as a working fluid, I think it's unlikely that I'll reach cold enough temperatures to liquefy oxygen/nitrogen.
In part 3 of this video, I'll do more investigation into hot-end heat exchanger design, regenerator design, and the effect of increasing the power density of the system by pressurizing it. I'll also be comparing the pulse tube performance to a similar spec alpha stirling cooler.
Links for parts:
Motor:
www.amazon.com/dp/B084QCLTM1?...
25: and 40mm pistons:
www.amazon.com/gp/product/B08...
www.amazon.com/dp/B08YYQZ5CQ?...
Music Used:
Kevin MacLeod - Lobby Time
Kevin MacLeod - Groove Groove

Опубликовано:

26 дек 2022

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Комментарии : 651

@HyperspacePirate Год назад

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 Год назад

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 Год назад

- 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 Год назад

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 Год назад

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 Год назад

is the volume really really low or what?

@Aeogenia Год назад

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

@drezster Год назад

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

@pradipda3171 Год назад

So True otherwise youtube only promotes garbage and clickbait

@xmysef4920 Год назад

Gotta agree with ya!

@jtjames79 Год назад

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 Год назад

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

@dr.med.janschiefer7163 Год назад

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 Год назад

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

@VarkaTheDragon Год назад

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

@Stoneman06660 Год назад

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 Год назад

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 Год назад

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 Год назад

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

@mrf4549 Год назад

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

@origamerking6927 Год назад

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

@odw32 Год назад

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 Год назад

This is the best thing that RU-vid 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!

@sachitdaniel6688 Год назад

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.

@hectorgarcia1326 6 месяцев назад

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

@dannyneumann4547 Год назад

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

@un65tube Год назад

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! 😃

@rorypenstock1763 Год назад

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 RU-vid has recommended me in a long time.

@lidamullendore6166 Год назад

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

@davidmclean5067 Год назад

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

@mikeconnery4652 Год назад

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

@chemicalcookie7546 Год назад

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!

@krystianstolarczyk4544 Год назад

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.

@Rocketkid2121 Год назад

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!

@NiphanosTheLost Год назад

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

@Betruet Год назад

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

@timothysands5537 Год назад

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

@JuniorJunison Год назад

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.

@1weck1 Год назад

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

@mohammadkahil8255 Год назад

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

@drfoop Год назад

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

@EricGardnerTX Год назад

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.

@amannarwal7032 Год назад

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

@boltonky Год назад

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

@nolanmods7172 Год назад

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

@mikaellavoie6811 Год назад

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

@R290s_biggest_fan Год назад

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

@ivprojects8143 Год назад

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

@hiphopalest6295 Год назад

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

@LassIV Год назад

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

@fr3zer677 Год назад

Can't wait for the next video! Very nice job!

@user-nj9mh7ly2n 6 месяцев назад

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

@AiOinc1 Год назад

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.

@namaefumei Год назад

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

@TopiasKorpiTK Год назад

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 Год назад

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

@TopiasKorpiTK Год назад

@@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 Год назад

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.

@banalestorchid5814 Год назад

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.

@brandonwyffels8002 Год назад

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

@vincentli9106 Год назад

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

@b-beluga4510 Год назад

@@vincentli9106 sit in toilet bruh

@ThePowerofElectricity 2 месяца назад

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!

@scottneels2628 Год назад

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

@GautamSharmaCA 7 месяцев назад

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.

@SignalDitch Год назад

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

@alex4alexn Год назад

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

@victoryfirst2878 Год назад

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.

@oddzc Год назад

Cant wait to see part 3, great stuff

@BloodyMobile Год назад

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.

@sky173 Год назад

This is the 'coolest' thing I'll see today on RU-vid. Thanks for sharing.

@Vinzmannn Год назад

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

@poprawa Год назад

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

@corey736 Год назад

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

@unicornadrian1358 Год назад

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

@nitromeano Год назад

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

@LexYeen Год назад

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

@adrian5895 Год назад

Thanks for your videos! I really enjoy them.

@grahamehadden4320 Год назад

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

@graealex Год назад

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 Год назад

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 Год назад

@@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.

@dn275 Год назад

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

@AttilaBlade Год назад

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 Год назад

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 Год назад

Thank you for the essay

@jillianonthehudson1739 Год назад

One of the most underrated channels on RU-vid

@thonkingintensifies9510 Год назад

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

@crusiethmaximuss Год назад

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

@beatrute2677 Год назад

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

@flomojo2u Год назад

Great work!! Very exciting performance for very modest materials, I'm really looking forward to your next video.

@abeleski Год назад

Love these beginner videos. Thank you.🥸

@Julian_Kulenkampff Год назад

This is so cool! Please keep going! I really like the optimizing approach you took :D

@rockyrivermushrooms529 Год назад

Im glad I found your channel. So cool!

@IsiahShelton-tt9zd 2 месяца назад

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

@poldiderbus3330 Год назад

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

@DavoodAnsariOgholBeig Год назад

Amazing piece of work. Really impressed!

@davida1hiwaaynet Год назад

Very interesting! Thanks for making these videos.

@herzogsbuick Год назад

This is great. Can't wait for part 3

@drpwnage23 Год назад

This is fascinating, Excellent video

@bobedwards8896 Год назад

This is so cool, thanks for uploading it

@ChrisContin Год назад

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!

@camfocus8888 Год назад

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

@Moist_yet_Crispy Год назад

Really loving these videos. Great work and learning a lot.

@jorgegalindo658 Год назад

woooow great job this is awesame i understand 20% what you talk but with all thge eefort to explain and show results is very entertaining

@RumoredAtmos Год назад

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

@miltonbradley4249 Год назад

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

@ATomRileyA Год назад

Really enjoyed watching you experiment with the cooler, cant wait to see how it goes in the future so i subscribed.

@kknives_switzerland Год назад

Finally, a good video recommendation!

@jamescarter9147 Год назад

Really interesting, subscribed for the next one!

@1.4142 Год назад

Great job explaining the physics

@giovanni4151 Год назад

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

@Kadeshy Год назад

This is real engineering! Attaboy Pirate! 👏

@PhG1961 Год назад

Great ingenuity and an amazing project !

@klausnielsen1537 Год назад

Soo cool! Pun totally intended! One of the greatest videos I've seen for a long while. Keep it up. Please 🙏

@braspatta Год назад

Love the fly wheel!

@TheoLubbe Год назад

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

@wouterslaa2520 Год назад

Awesome series! Thanks!

@theGraphicAutist Год назад

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!

@bentomo 2 месяца назад

This stuff is fantastic and explained so well. I feel like I'm watching advanced Bill Nye the Science Guy.

@ShafaqIftikhar-pw9ld 3 месяца назад

Love the fly+wheel annotation real funny 😂❤❤❤❤

@miklov Год назад

Great work, well explained. Thank you!

@williamogletree4153 Год назад

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

@williamogletree4153 Год назад

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

@williamogletree4153 Год назад

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