It's probably the only way to make some progress here - who would have guessed that the far more professional looking stainless steel construction underperformed the PVC construction so significantly...
@Alexander Gräf I was... mostly because of heat transfer through the hardware. With the last video I was thinking about adding a heat break I. Between the hot and cold sides, a small section that is ceramic... keep the hot side hot and the cold side cold.
@@kayakMike1000 That sounds like a good idea. I personally was not able to decide whether steel would have a negative impact, seeing how heat transfer is actually wanted in certain parts. Like there's a literal heat exchange. But you're right, you want the hot and cold side not to be able to conduct to each other.
@@SamCooler 🔴 What Is Islam? 🔴 Islam is not just another religion. 🔵 It is the same message preached by Moses, Jesus and Abraham. 🔴 Islam literally means ‘submission to God’ and it teaches us to have a direct relationship with God. 🔵 It reminds us that since God created us, no one should be worshipped except God alone. 🔴 It also teaches that God is nothing like a human being or like anything that we can imagine. 🌍 The concept of God is summarized in the Quran as: 📖 { “Say, He is God, the One. God, the Absolute. He does not give birth, nor was He born, and there is nothing like Him.”} (Quran 112:1-4) 📚 🔴 Becoming a Muslim is not turning your back to Jesus. 🔵 Rather it’s going back to the original teachings of Jesus and obeying him. More ...
I noticed that the copper tubing you are using was cut with a standard tubing cutter but the ends were not de-burred. The burr formed on each tube is effectively turning your tubes into double orifices causing expansion losses at each end. And while the "orifices" are deep into the open end of the fitting they can behave like venturi tubes and waste valuable gas expansion. If you can get your hands on a 2mm swage tool so that the tube itself is the venturi instead of the ends I estimate 5 to 8% increase in capacity with the double inlet setup. Having about 1m^3/min airflow over the hot end per watt total input power will help dissipate friction loss heating significantly. My background is only phase change refrigeration and air conditioning so do with that what you will. Use of a common refrigerant like pure CO2 or 134a are my choice for hobby projects but I don't remember if you were trying to use pure air at which point I would like to point out the obvious that any moisture in the air makes all the above moot since it has a massive effect due to it's specific heat capacity. Cheers!
You are absolutely correct 9:17 all of those need to be deburred and chamfered. That will increase flow rate a bit. Should upvote this its a easy thing to forget.
@@fajile5109 You could place the fitting in a lathe and machine the tube ends flush with the fitting and perhaps even countersink then a bit with a drill bit. Great project and I hope you succeed. A potential source of Nitrogen would be the exhaust vent of a small consumer Oxygen concentrator. Having liquid nitrogen always available opens up a lot of possibilities. You can make multiple cold traps at N2(l), CO2(s), H2O(s) and perhaps a couple more phase change temperatures. Let you gain better solvent separation and freeze drying performance.
It is an absolute delight to watch a such a disciplined and thorough design process performed by somebody who is willing to go into the thermodynamics. As an engineer in a different field (comp/elec), it’s a privilege to get an inside view of a design process and issues being grappled with.
Exactly! Dude I don't know jack ish about this but following along with the math presentations, hypotheses, trials, and plot-graphing is soooo fin dope dude What a radical dude, dude...
I do hope that once you reach your goal, and you will, that the series can still continue to find efficiency gains. Making something work is always goal number one on any project starting out. Making it work well is an even longer, and just as interesting, road.
Use HELIUM instead of regular air inside your system. I have a pulse tube cryocooler that can reach -196c. I repaired and charged it with helium @265psi and it operates at 60hz. The pistons use gas-bearing tech which keeps loss and wear low. 150 watt input will lift 5 watt load at -196c. Unit was pulled from a Superconductor Technologies band-pass filter for cell tower application.
@@xDevscom_EE Yes, you are correct that the STI is a Stirling type. However, even though the term Pulse Tube refers to a specific type that does not employ a displacer, it is still often loosely used to describe any regenerative system because of the oscillatory movement of the working fluid. I will try to be more accurate.
He said in an earlier video that he knows to use helium but that he plans for that to be the last thing he does. He wants to tinker with all the other stuff as helium gets expensive.
So interesting. I hope we get to LN2 temps, and there’s an open source design that anyone can build and iterate with basically just a McMaster order. Great work!
Cylos garage has a pretty tight ultra precision lathe he's building, and I mean, like, machine an optical grade mirror using a chip making machine precision lathe.
A couple of others have noted, and I'll add as a reminder. You are pushing into air liquification temperatures, and that will eat up a lot more power. At one atmosphere you are already hitting CO2 liquification, and at higher pressure you could be getting close to O2 liquification. And since your thermocouple is averaging the temperature over a second or two, the per cycle temperature may be oscillating above and below liquid temperatures. These rapid phase changes, many times per second, will eat up power until the bulk temperature is below the liquid temps. Probably best to switch to at least pure N2, to help mitigate the potential of phase changing. And N2 is cheaper and easier to get at welding shops then He. Great videos, and have fun exploring.
Yea i was just about to comment that that flatline he keeps hitting close to -80C makes me feel like he's coming up against a phase change or something. I'd love to see him address this concern with one of his neato charts!
Another excellent video, with great experimental planning and detailed data and discussion! As a point of reference, FYI, I have a system at work with a 2-stage Gifford-McMahon Cryocooler for condensing Helium. It has 40 W cooling capacity for stage 1 and < 1 W for stage 2. This requires a 10 HP (about 8 KW) compressor, with some serious cooling for the compressor itself. You may be running up against a compressor power constraint now. Great work, very impressive progress so far though! I can't wait to see more. Best wishes!
You hit the nail on the head with your A/C circuit analogy. I would suggest you pay mind to your pump's resonant frequency, its effect on performance and efficiency, and how you could tune that. Using the analogy again, your flywheel is like an inductor, and compressing air in the total system acts like a capacitor. This forms a resonant tank in and of itself. Adding and removing "counter springs" to your air cylinder has the analogous effect to adding and removing capacitors in parallel to the tank. You may, alternatively, wish to add or remove weight to your flywheel, and see what this does. It may not bring the system the direction you want, but it will provide useful information to be sure. 👍
Love the quick turnaround on uploads. If you have a fulltime job I have no idea how you are cranking out updates on the project so fast but I love to see it.
Fascinating..... Your willingness to try out different techniques to see how they affect your results AND document the failures as well as the successes is really refreshing! THAT is the core of science! You WONDER what this will do and what that will do.. and I WONDER right along with you.. it is exciting... and makes me want to watch more to see the outcome. I dare to say that MOST other channels likely do the same type of work that you do.. but merely issue a "This is how you do it" video.. and that's fine... But it's not entertaining.. I'm not interested in ever building a Pulse Tube Cryocooler... But i am incredibly interested in watching you go through the process of building one!
Just leaving a thumbs up seems inadequate for the quality of this series, so I just wanted to add my thanks for the amazing information and your excellent presentation!
If you need the regenerator to cause less resistance then, like last video, I suggest trying out a different regenerator construction. Take stainless steel strips/foil, press some dimples on it (apparently a sewing machine works fine for this; alternatively I'd imagine just pressing some slight sharp notches with a knife or something would also work), and then roll it up like a rolled cake. It would be like a very dense air-cooler heatsink - air can pass (relatively) unimpeded between the different fins (layers of the roll), while still exposing a large surface area for heat transfer. While I doubt a better regenerator design alone is a miracle magic bullet for the project, if it gives you another 5C gain, then that's worth it, no?
'Finally found 'SmartTube" THANK YOU !!! SUBBED Great depth, data-driven analysis and optimization. Math meets Mechanics !! I'm sure there are Fluid Dynamics factoring into the resonance such as turbulence, Reflection, standing waves etc Bring in Mr. Viktor Schauberger techniques !
Superb presentation of the data and experimental data collection.Extreemly thorough. Its lovely to see real numbers. The high static pressure with lower ripple would favour a linear electric motor where a sprung offset can be applied. Not sure how that could be done on a crank. . Fascinating. A real adventure.
I really cant wait for the next instalment of this series! Was very happy this morning when I spotted you uploaded this video. Albeit I’m somewhat versed in the technical field, this is beyond me and extremely interesting. Thank you for this contribution!
Awesome stuff! Grab bag of ideas: * You tried alternate regenerator materials but none of the ones shown were fibrous like your steel, so I think surface area : volume ratios were ruining them all. Have you tried plain old cotton balls, or the various types of fibrous insulation? * Have you thought about using insulative liners inside of metal components to get the pressure rating of metal but avoid contacting your working fluid with metal exposed to ambient? * You can DIY a super dense heat exchanger with 3D printed stamping molds and thin 1000 series aluminum (it's super soft and easy). Print a pair of dies wavy in one axis to make a tiny version of corrugated roof panels, then alternate a stack of corrugated, flat, corrugated, flat. Clamp the edges of your stack so they get good thermal contact with the outside of your housing.
Can't tell you how much I enjoy seeing real engineering presented with clarity and precision. Thank you so much for this series! I can't wait for the next installment. Incidentally, the "t" in Carnot is silent (it's French).
This is the best content on RUclips. Looking forward to every and any video in this series. I hope that when you reach -196 C you will continue the development so that I one day can have a flashlight sized HPGe-detector in my pocket.
This is a great series, thanks very much. I suggest you try operating with the unit vertical in gravity, with the cold end of the pulse tube down, to avoid gravitationally-driven convection in the pulse tube, which will be present even despite the oscillating flow.
Two years ago I was playing with different mixtures of propane and butane to see how well heat pipes worked. We think very much alike. But you make videos about it. Okay - I will focus...
I've worked with pulses tubes few month ago, I'm not an expert but I may have some idea to improve your system! You can use silica aerogel as insulator. It's way better than glass wool. You can increase the surface area of your heat exchanger with heat pipe(cuts both ends and use it like a copper pipe). I've heard that regenerator is often made of stainless steel or small lead balls which have a high thermal capacity and doesn't reduce the flow too much! Commercial pulses tubes use helium mostly because it liquidized at 4K but I'll recommend you to use at least really dry air, any water vapor can drop the efficiency! Edit: typo and french
Very well documented progress! Another thing I'd look at is whether the water vapor in your gas causes a significant decrease in performance. It should be relatively easy to compare the performance with regular compressed air and some form of drying(even a pipe full of baked silica gel will do).
Amazing video as always! You can definitely get better performance and lower temps with helium or argon especially under pressure. It would also be very interesting to see a dry vs humid air performance chart. You could start playing with these once you've honed down the parameters you're already tracking. Also the regenerator may be packed too tightly and the 8g vs 2g is not very conclusive since 2g is too little material and would underperform anyway. You could try 4g or 6g steel wool in the same space or even 8g but in more space. Can't wait for the next part in the series!
excellent job! Thanks for sharing your project with us. I can't wait until you cool the hot end! Hopefully you can calculate the total cooling capacity for this beast! Amazing work!
I come from a background of tinkering with heat-engines and it's pretty typical with many engines that the designer worries greatly about the hot-end, and pays little attention to the cold. There's often worthwhile gains to be found with a decent cooling system,. It will certainly help to keep all your nice graphs lined up if you were to use a consistent hot-end temp for baseline. I suggest an ice-water bath, as it'll provide a rock-solid repeatable temp near freezing, and should get you down to dry-ice temps with ease. Pressurising with nitrogen would also be worthwhile, it works well for engines turning heat flux into power, I can't see why it wouldn't work the other way around! of course, you'll need to use the stainless setup as PVC can be a bit dicey under pressure, but with some proper insulation and cooling where appropriate, it's quite do-able. nitrogen's cheap after all!
Great video (as always). Respect. Consider achieving Your temperature goal by magnetocaloric effect of gadolinium. It can be easier than pulse tube. Good luck!
If i may make a suggestion for heat extraction, LED lamps are often cooled with an extruded tubular heat sink with a significant number of fins on the outside. If you arrange this heat sink within another pipe and run coolant through the middle with your gas in the space between the two pipes you would have an incredible amount of surface area in play.
Thanks for the videos :) I heard pulse tube coolers efficiency is effected by pulse tube orientation. I dont know would it be practical to make pulse tube vertical (cold head down) but I saw like %15 efficiency difference compared to horizontal orientation. may be another point.. about phase shift mechanism.. may be you already considered but, I like the idea to actively control phase difference by another compressor piston (or 2 more aditional solenoid valve from same air compressor; 4 valve system). I dont know if it would increase the performance but may be it help to manipulate the phase difference better. I cannot guess how did copper tube extension to heat exchanger effected the gas flow resistance but may be in this new setup with air compressor, compressor can also cool the gas to ambient temperature itself, so may be it worth a try with and without copper tube extensions to heat exchangers?
I'm about to finish my single stage precooled joule thompson cryocooler tomorrow. Wish me luck. Will soon share the details about it. It's using a mix of ethylene and nitrogen 60:40 as working fluid.
I’ll be honest, most of this mini series is way more complex than what I can understand but I think you mentioned in the first episode needing more surface area on the internal diameter of the cooper pipes so I thought I’d suggest trying sintered copper heat pipes. They are really common in pc coolers and can be purchased relatively easily.
This stuff is pretty epic. I wish I could monitor the entire system and take a bunch of pictures with a nice thermal camera so you can see the entire system thermodynamics
Yes Impedance is key to almost all magic when it comes to acoustics. Just as electrical circuits can do seemingly amazing things when resonance is properly matched acoustics are in similar.
if you think its the heat exchanger then put a fan or water cool it. 7:52 13:47 what are your thoughts on trying a smaller piston? 17:11 What? if waiting for temp to normalize for a record isn't cheating neither is a fan or watercooling... 17:46 Oh nevermind. lol. great video! The impedance matching sounds like a very tricky problem, verifying iterative predictions is so slow in meat space .. (good computer modeling software would be great for that! and bad computer molding would be exposed by the same :)
Try to get a beefy subwoofer speaker and convert it into a membrane piston. Theoretically if you pressurize both sides of the membrane you should be able to run at higher pressures too. With a smart driver you should be able to precisely control the pressure wave. Maybe it is even possible to autodetect the best resonances with it.
Two ideas. 1) Possibly adding an insulating coating to the inside of some of the metal components. Maybe just a bit of epoxy mixed with with a fine power that could offer a thin thermal barrier. 2) The heat exchanger might be affected by the void near the entry point of the tubes. This area is effectively a capacitor preventing flow from entering the tubes, but could also be adding the the turbulence. That could be good (for transfer), or bad. But filling that area with something easily removed (like Play-Doh or something) could provide more data.
I love the systematic scientific evaluation of this DIY project.
It's probably the only way to make some progress here - who would have guessed that the far more professional looking stainless steel construction underperformed the PVC construction so significantly...
@Alexander Gräf I was... mostly because of heat transfer through the hardware. With the last video I was thinking about adding a heat break I. Between the hot and cold sides, a small section that is ceramic... keep the hot side hot and the cold side cold.
@@kayakMike1000 That sounds like a good idea.
I personally was not able to decide whether steel would have a negative impact, seeing how heat transfer is actually wanted in certain parts. Like there's a literal heat exchange. But you're right, you want the hot and cold side not to be able to conduct to each other.
You've consistently been one of the most fascinating channels I've seen. Good job!
Amennnn
Yeah! There are very few "maker" channels that also have a high-level engineering/physics approach like this. Love it!
@@SamCooler 🔴 What Is Islam?
🔴 Islam is not just another religion.
🔵 It is the same message preached by Moses, Jesus and Abraham.
🔴 Islam literally means ‘submission to God’ and it teaches us to have a direct relationship with God.
🔵 It reminds us that since God created us, no one should be worshipped except God alone.
🔴 It also teaches that God is nothing like a human being or like anything that we can imagine.
🌍 The concept of God is summarized in the Quran as:
📖 { “Say, He is God, the One. God, the Absolute. He does not give birth, nor was He born, and there is nothing like Him.”} (Quran 112:1-4) 📚
🔴 Becoming a Muslim is not turning your back to Jesus.
🔵 Rather it’s going back to the original teachings of Jesus and obeying him.
More ...
What would happen if you placed the whole system into a vacuum chamber?
This is an excellent project. Thanks for sharing your work and making it easy on those who will recreate it in the future.
Love your vids, would like to see you try this
I noticed that the copper tubing you are using was cut with a standard tubing cutter but the ends were not de-burred. The burr formed on each tube is effectively turning your tubes into double orifices causing expansion losses at each end. And while the "orifices" are deep into the open end of the fitting they can behave like venturi tubes and waste valuable gas expansion. If you can get your hands on a 2mm swage tool so that the tube itself is the venturi instead of the ends I estimate 5 to 8% increase in capacity with the double inlet setup. Having about 1m^3/min airflow over the hot end per watt total input power will help dissipate friction loss heating significantly.
My background is only phase change refrigeration and air conditioning so do with that what you will. Use of a common refrigerant like pure CO2 or 134a are my choice for hobby projects but I don't remember if you were trying to use pure air at which point I would like to point out the obvious that any moisture in the air makes all the above moot since it has a massive effect due to it's specific heat capacity. Cheers!
You are absolutely correct 9:17 all of those need to be deburred and chamfered. That will increase flow rate a bit. Should upvote this its a easy thing to forget.
@@fajile5109 You could place the fitting in a lathe and machine the tube ends flush with the fitting and perhaps even countersink then a bit with a drill bit.
Great project and I hope you succeed. A potential source of Nitrogen would be the exhaust vent of a small consumer Oxygen concentrator. Having liquid nitrogen always available opens up a lot of possibilities. You can make multiple cold traps at N2(l), CO2(s), H2O(s) and perhaps a couple more phase change temperatures. Let you gain better solvent separation and freeze drying performance.
I was thinking the same thing. Also he could put a larger copper pipe over the hot side and phase change cool it
It is an absolute delight to watch a such a disciplined and thorough design process performed by somebody who is willing to go into the thermodynamics. As an engineer in a different field (comp/elec), it’s a privilege to get an inside view of a design process and issues being grappled with.
Exactly! Dude I don't know jack ish about this but following along with the math presentations, hypotheses, trials, and plot-graphing is soooo fin dope dude
What a radical dude, dude...
I do hope that once you reach your goal, and you will, that the series can still continue to find efficiency gains. Making something work is always goal number one on any project starting out. Making it work well is an even longer, and just as interesting, road.
Use HELIUM instead of regular air inside your system. I have a pulse tube cryocooler that can reach -196c. I repaired and charged it with helium @265psi and it operates at 60hz. The pistons use gas-bearing tech which keeps loss and wear low. 150 watt input will lift 5 watt load at -196c. Unit was pulled from a Superconductor Technologies band-pass filter for cell tower application.
Might be interesting to try neon, or nitrogen, instead of air. We'll be out of helium pretty soon.
STI Sapphire cooler is not pulse tube, but Stirling type cooler, so different system altogether :).
@@xDevscom_EE Yes, you are correct that the STI is a Stirling type. However, even though the term Pulse Tube refers to a specific type that does not employ a displacer, it is still often loosely used to describe any regenerative system because of the oscillatory movement of the working fluid. I will try to be more accurate.
He said in an earlier video that he knows to use helium but that he plans for that to be the last thing he does. He wants to tinker with all the other stuff as helium gets expensive.
@canonicaltom we can produce helium from fusion reactors.
So interesting. I hope we get to LN2 temps, and there’s an open source design that anyone can build and iterate with basically just a McMaster order. Great work!
I've always wanted to make my own LN2!
Yes!!! This is one of the two RUclips projects I’ve been so excited for. This and Callum Long’s mini liquid rocket engine. Keep killing it!!
lol same here
Cylos garage has a pretty tight ultra precision lathe he's building, and I mean, like, machine an optical grade mirror using a chip making machine precision lathe.
A couple of others have noted, and I'll add as a reminder. You are pushing into air liquification temperatures, and that will eat up a lot more power. At one atmosphere you are already hitting CO2 liquification, and at higher pressure you could be getting close to O2 liquification. And since your thermocouple is averaging the temperature over a second or two, the per cycle temperature may be oscillating above and below liquid temperatures. These rapid phase changes, many times per second, will eat up power until the bulk temperature is below the liquid temps.
Probably best to switch to at least pure N2, to help mitigate the potential of phase changing. And N2 is cheaper and easier to get at welding shops then He.
Great videos, and have fun exploring.
Yea i was just about to comment that that flatline he keeps hitting close to -80C makes me feel like he's coming up against a phase change or something. I'd love to see him address this concern with one of his neato charts!
Another excellent video, with great experimental planning and detailed data and discussion! As a point of reference, FYI, I have a system at work with a 2-stage Gifford-McMahon Cryocooler for condensing Helium. It has 40 W cooling capacity for stage 1 and < 1 W for stage 2. This requires a 10 HP (about 8 KW) compressor, with some serious cooling for the compressor itself. You may be running up against a compressor power constraint now. Great work, very impressive progress so far though! I can't wait to see more. Best wishes!
This project is insane! Keep it coming man, I am staying updated! :)
You hit the nail on the head with your A/C circuit analogy. I would suggest you pay mind to your pump's resonant frequency, its effect on performance and efficiency, and how you could tune that. Using the analogy again, your flywheel is like an inductor, and compressing air in the total system acts like a capacitor. This forms a resonant tank in and of itself. Adding and removing "counter springs" to your air cylinder has the analogous effect to adding and removing capacitors in parallel to the tank. You may, alternatively, wish to add or remove weight to your flywheel, and see what this does. It may not bring the system the direction you want, but it will provide useful information to be sure. 👍
I can't wait to see where this journey is going! Great video!
Taking us through the hypothesis then proving or better yet, when you prove yourself wrong, is really gratifying and unique. Good work!
Been waiting for so much anticipation for part 3. I hope we get a part 4. You're amazing.
I like that you aren't dumbing down or simplifying the content and theory it makes it so much more enjoyable that way
oh yeah, I love a youtube channel with graphs and unanswered questions. can't wait for part 4
Love the quick turnaround on uploads. If you have a fulltime job I have no idea how you are cranking out updates on the project so fast but I love to see it.
Ahh, this series has got to be one the the ones Im most hyped about, not just on RUclips, but anywhere.
Fascinating..... Your willingness to try out different techniques to see how they affect your results AND document the failures as well as the successes is really refreshing! THAT is the core of science! You WONDER what this will do and what that will do.. and I WONDER right along with you.. it is exciting... and makes me want to watch more to see the outcome. I dare to say that MOST other channels likely do the same type of work that you do.. but merely issue a "This is how you do it" video.. and that's fine... But it's not entertaining.. I'm not interested in ever building a Pulse Tube Cryocooler... But i am incredibly interested in watching you go through the process of building one!
This is my favourite series on youtube.
I’m drooling over this series omg
Just leaving a thumbs up seems inadequate for the quality of this series, so I just wanted to add my thanks for the amazing information and your excellent presentation!
It's fascinating to see the inner workings of a genius's brain! Your technical analysis capabilities are unsurpassed... 👍
This video tingles my engineering bone. Can't wait for the next video.
Thank you for using metric.
I have no idea how this works even after watching all the videos, but it's very interesting.
It's not often that the first attempt is so effective. But you still managed to learn from it and improve design. Impressive
I mean this in the best way possible, but these are the best videos to fall asleep to. Also very educational.
If you need the regenerator to cause less resistance then, like last video, I suggest trying out a different regenerator construction. Take stainless steel strips/foil, press some dimples on it (apparently a sewing machine works fine for this; alternatively I'd imagine just pressing some slight sharp notches with a knife or something would also work), and then roll it up like a rolled cake. It would be like a very dense air-cooler heatsink - air can pass (relatively) unimpeded between the different fins (layers of the roll), while still exposing a large surface area for heat transfer.
While I doubt a better regenerator design alone is a miracle magic bullet for the project, if it gives you another 5C gain, then that's worth it, no?
This series is why i'm hitting the bell notification button.
One of the Best RUclips channels ever! Im learning real stuff!
This here is definately my new favorite channel
can i just say thankyou for using °C much love from the rest of the world ❤❤
I didn't know I liked watching thermo acoustic videos. But you did. Thank you for letting me know.
Looking good! I can't wait to follow you down this rabbit hole
Damn! Impressed again. Had to share this video with some people thats probably interested.
Love this! When it comes to dissipating heat. Perhaps a simple convection or even pumped liquiding of the pipes would fix things?
Wow, that is everything i could hope for regarding cryocoolers, thanks for you great work, looking forward for next video!
'Finally found 'SmartTube" THANK YOU !!! SUBBED
Great depth, data-driven analysis and optimization. Math meets Mechanics !!
I'm sure there are Fluid Dynamics factoring into the resonance such as turbulence, Reflection, standing waves etc
Bring in Mr. Viktor Schauberger techniques !
I'm glad that I found this channel, awesome content
I am truly baffled by the quality of your work, it's a pleasure to follow your project. thank you !
Superb presentation of the data and experimental data collection.Extreemly thorough. Its lovely to see real numbers. The high static pressure with lower ripple would favour a linear electric motor where a sprung offset can be applied. Not sure how that could be done on a crank. . Fascinating. A real adventure.
By pressurizing the crank case
Great work, sound experimental findings leading to incremental discovery and improvements!
Great data set. It makes clear explanation why commercial PTR and GM coolers have very thin stainless steel outer housings.
I really cant wait for the next instalment of this series! Was very happy this morning when I spotted you uploaded this video. Albeit I’m somewhat versed in the technical field, this is beyond me and extremely interesting. Thank you for this contribution!
I appreciate you being so open and sharing your journey. You are becoming one of my favorite creators. Keep going my friend. 🙏
Awesome stuff! Grab bag of ideas:
* You tried alternate regenerator materials but none of the ones shown were fibrous like your steel, so I think surface area : volume ratios were ruining them all. Have you tried plain old cotton balls, or the various types of fibrous insulation?
* Have you thought about using insulative liners inside of metal components to get the pressure rating of metal but avoid contacting your working fluid with metal exposed to ambient?
* You can DIY a super dense heat exchanger with 3D printed stamping molds and thin 1000 series aluminum (it's super soft and easy). Print a pair of dies wavy in one axis to make a tiny version of corrugated roof panels, then alternate a stack of corrugated, flat, corrugated, flat. Clamp the edges of your stack so they get good thermal contact with the outside of your housing.
Can't tell you how much I enjoy seeing real engineering presented with clarity and precision. Thank you so much for this series! I can't wait for the next installment. Incidentally, the "t" in Carnot is silent (it's French).
That's what I was going to say.
It's "Car-no", not "Car-not."
Well, you mentioned everything I was going to suggest.
Lookin forward to the external cooling on the hotend test results.
This is really great and the graphs are very helpful to understand where there's a away from a linear response.
Can’t wait for updates on this project every time a new video drops. You’re doing great!
This is the best content on RUclips. Looking forward to every and any video in this series. I hope that when you reach -196 C you will continue the development so that I one day can have a flashlight sized HPGe-detector in my pocket.
This is a great series, thanks very much. I suggest you try operating with the unit vertical in gravity, with the cold end of the pulse tube down, to avoid gravitationally-driven convection in the pulse tube, which will be present even despite the oscillating flow.
Wow, this is very impressive! It’s amazing to see the methodical and detailed approach to solving this problem. Can’t wait to see the next video.
This is really impressive engineering, with exceptional attention to detail.
I'm green red colorblind i wouldnt have even noticed :D
I found your Channel via this project and i'm instantly hooked , great videos :)
The pragmatic and sincere methodology keeps inspiring me. Thank you for great content!
Your videos are very cool, and the things you make are always very unique
I can see how this would be frustrating, but you keep pushing ahead!, keep up the great work!
Two years ago I was playing with different mixtures of propane and butane to see how well heat pipes worked.
We think very much alike. But you make videos about it.
Okay - I will focus...
I've worked with pulses tubes few month ago, I'm not an expert but I may have some idea to improve your system!
You can use silica aerogel as insulator. It's way better than glass wool. You can increase the surface area of your heat exchanger with heat pipe(cuts both ends and use it like a copper pipe).
I've heard that regenerator is often made of stainless steel or small lead balls which have a high thermal capacity and doesn't reduce the flow too much!
Commercial pulses tubes use helium mostly because it liquidized at 4K but I'll recommend you to use at least really dry air, any water vapor can drop the efficiency!
Edit: typo and french
I searched calloducs but no results, plus "lead bids" please explain? All I get in the search is auction like results,
@@seeker1015 sorry calloducs is the french name you should search "heat pipe"
Sorry I meant balls don't know why it wrote bids
@@oneil9615 Ah, yes, I can see that now. Callo=heat, ducs=ducts/pipes. Thank you.
Nifty AF ! This series is fantastic.
Very well documented progress! Another thing I'd look at is whether the water vapor in your gas causes a significant decrease in performance. It should be relatively easy to compare the performance with regular compressed air and some form of drying(even a pipe full of baked silica gel will do).
Very neat demonstration and analysis. Will recommend this for a physics instructor to demonstrate to the class good experimental method. 🤓
Thank you Sir! 😊👍👍
Wonderful Video!
Nice weekend 🌞🌨❄
Fascinating! Thank you for all the effort you put into these projects and videos.
Amazing video as always! You can definitely get better performance and lower temps with helium or argon especially under pressure. It would also be very interesting to see a dry vs humid air performance chart. You could start playing with these once you've honed down the parameters you're already tracking. Also the regenerator may be packed too tightly and the 8g vs 2g is not very conclusive since 2g is too little material and would underperform anyway. You could try 4g or 6g steel wool in the same space or even 8g but in more space. Can't wait for the next part in the series!
Good progress, looking forward to see part 4
Loved the RCL comparison!
That flatline looks like you didn’t have the torque. Great job on these videos, you’re a genius. I love learning this stuff. Keep up the great work
excellent job! Thanks for sharing your project with us. I can't wait until you cool the hot end! Hopefully you can calculate the total cooling capacity for this beast! Amazing work!
Can't wait for part 4!
This is great, awaiting part 4 :)
Brilliant to watch! Love your videos.
I come from a background of tinkering with heat-engines and it's pretty typical with many engines that the designer worries greatly about the hot-end, and pays little attention to the cold. There's often worthwhile gains to be found with a decent cooling system,.
It will certainly help to keep all your nice graphs lined up if you were to use a consistent hot-end temp for baseline. I suggest an ice-water bath, as it'll provide a rock-solid repeatable temp near freezing, and should get you down to dry-ice temps with ease.
Pressurising with nitrogen would also be worthwhile, it works well for engines turning heat flux into power, I can't see why it wouldn't work the other way around! of course, you'll need to use the stainless setup as PVC can be a bit dicey under pressure, but with some proper insulation and cooling where appropriate, it's quite do-able. nitrogen's cheap after all!
Finally, I was waiting for this...
Loving these videos, cant wait to see the next one.
Great video (as always). Respect. Consider achieving Your temperature goal by magnetocaloric effect of gadolinium. It can be easier than pulse tube. Good luck!
Great to see this much progress
If i may make a suggestion for heat extraction, LED lamps are often cooled with an extruded tubular heat sink with a significant number of fins on the outside. If you arrange this heat sink within another pipe and run coolant through the middle with your gas in the space between the two pipes you would have an incredible amount of surface area in play.
This is very cool! I'm already excited about the next part.
Can't wait for part 4
Love it! Science and engineering is amazing in practice like this!
ive been waiting for part 3 thank you
i just rewatched part 1 & 2 haha , love the project man!
Thanks for the videos :)
I heard pulse tube coolers efficiency is effected by pulse tube orientation. I dont know would it be practical to make pulse tube vertical (cold head down) but I saw like %15 efficiency difference compared to horizontal orientation.
may be another point.. about phase shift mechanism.. may be you already considered but, I like the idea to actively control phase difference by another compressor piston (or 2 more aditional solenoid valve from same air compressor; 4 valve system). I dont know if it would increase the performance but may be it help to manipulate the phase difference better.
I cannot guess how did copper tube extension to heat exchanger effected the gas flow resistance but may be in this new setup with air compressor, compressor can also cool the gas to ambient temperature itself, so may be it worth a try with and without copper tube extensions to heat exchangers?
ah man! seems like you are back in square 1. I hope you get a decent solution soon!! I am hoping to build one as well!!!
I'm about to finish my single stage precooled joule thompson cryocooler tomorrow. Wish me luck. Will soon share the details about it. It's using a mix of ethylene and nitrogen 60:40 as working fluid.
good luck!
Can’t wait fot part 4! Keep it up!
I’ll be honest, most of this mini series is way more complex than what I can understand but I think you mentioned in the first episode needing more surface area on the internal diameter of the cooper pipes so I thought I’d suggest trying sintered copper heat pipes. They are really common in pc coolers and can be purchased relatively easily.
Great scientific procedure. Congrats!
Love this series!
Nice, can't wait to try doing it!
This stuff is pretty epic. I wish I could monitor the entire system and take a bunch of pictures with a nice thermal camera so you can see the entire system thermodynamics
Yes Impedance is key to almost all magic when it comes to acoustics. Just as electrical circuits can do seemingly amazing things when resonance is properly matched acoustics are in similar.
if you think its the heat exchanger then put a fan or water cool it. 7:52
13:47 what are your thoughts on trying a smaller piston?
17:11 What? if waiting for temp to normalize for a record isn't cheating neither is a fan or watercooling...
17:46 Oh nevermind. lol.
great video!
The impedance matching sounds like a very tricky problem, verifying iterative predictions is so slow in meat space .. (good computer modeling software would be great for that! and bad computer molding would be exposed by the same :)
Try to get a beefy subwoofer speaker and convert it into a membrane piston.
Theoretically if you pressurize both sides of the membrane you should be able to run at higher pressures too.
With a smart driver you should be able to precisely control the pressure wave.
Maybe it is even possible to autodetect the best resonances with it.
I wonder if glass syringes would work better as pistons for the alpha type.
Great work. I eagerly await your next videos.
Two ideas.
1) Possibly adding an insulating coating to the inside of some of the metal components. Maybe just a bit of epoxy mixed with with a fine power that could offer a thin thermal barrier.
2) The heat exchanger might be affected by the void near the entry point of the tubes. This area is effectively a capacitor preventing flow from entering the tubes, but could also be adding the the turbulence. That could be good (for transfer), or bad. But filling that area with something easily removed (like Play-Doh or something) could provide more data.