DIY Vapor Compression Refrigeration System

In this video i'll show how to put together a single-stage vapor compression refrigeration system and explain the theory behind it. This machine uses propane (R290) as a refrigerant, because it has properties very similar to standard Hydrofluorocarbon (HFC) refrigerants, but is extremely cheap and readily available, and has almost no negative environmental effects. The obvious disadvantage is its flammability. If you're careful, though, propane or butane are perfect substances for a DIY vapor compression system.
This is still part of my long term project to build a DIY cryocooler to make my own liquid nitrogen, but I've pivoted away from gas-phase systems like stirling/GM and decided to focus more on phase change systems due to the greater availability and low cost of parts. In upcoming videos, i'll be staging multiple vapor compression loops together to get temperatures below -100C. After that, i'll use a joule-thompson cycle to make the final push down to liquid nitrogen temperatures, but will do so with a mixture of hydrocarbons rather than nitrogen.
Here's some performance specs of the device in this video:
Condenser Pressure: 10-15 bar
Condenser Temperature: 27-44 C
Evaporator Pressure: 1.2 bar
Evaporator Temperature: -37 C
Capillary tube ID: 1mm
Capillary tube length: 2m
Compressor nominal rating: 5,000 BTU
Compressor locked rotor amps: 27A
Compressor operating limit (estimated): 5.4A
Input power: 667W (529W from compressor, 138W from fans)
Refrigerant charge: ~50 grams of propane
Maximum recorded cooling power: 116W (COP 0.173)
*Note that this power was recorded by testing the temperature drop of water reservoir at room temperature with lots of heat leaks, which was a far from optimal condition.
Also, recording cooling power by multiplying the water flowrate of 13.5 grams/sec by water's heat capacity times the temperature differential across the coil of 3.3C yielded a higher cooling power of 186W.
In upcoming videos, this system will be used to cool the condensor of a second refrigeration circuit, which will then evaporate to a far colder temperature close to -100C. This requires ethylene as a refrigerant (R1150). It's pretty hard to find and expensive to buy commercially, so in the next video, i'll be showing how to make it.
Other useful tidbits:
Propane bottle NPT thread adapter:
www.amazon.com/Hooshing-Propa...
Condenser fan:
www.amazon.com/BLACKHORSE-RAC...
-Window AC unit that was stripped for condenser coil was rated at 5,000 BTU. The manufacturer/model number you use is not important as long as its sized right.
Music Used:
Kevin MacLeod - Lobby Time

[@szwiecifon]

Its 3am, yea i got 28 minutes to spare, suree

[@thetoasterisonfire2080]

“10 minutes till class starts” Yea I got time

[@ezrakornfeld8436]

Real

[@Scrap5000]

My life summed up!!

[@hughjanes4883]

Well its 2:30 for me, so ill just have this in the background till i can find a good 3am Vid

[@ericlotze7724]

Watch at 2x Speed with Closed Captions and you have even more time to spare!

[@carbontetlabs8606]

A few notes, from someone currently going to school for this: - Install your filter dryer last and change it as close to every time the system is opened as possible. Installing a filter dryer should be a very quick hot potato sort of operation, you get the pipes lined up, swaged or flared and ready, and right after popping the filter dryer caps off you stick it into the pipes and start brazing or tightening. There should also be zero temperature drop across the filter dryer (within your measurement margin of error), a temperature drop indicates the filter dryer is clogged or otherwise producing a resistance to flow. That dryer spent way too much time open to atmosphere and is unlikely to have much dry dessicant left, especially if you blew air through it testing the cap tube in that one clip - Solder, no no no. Solder can't be trusted with the sort of pressures you're working with. You should be using brazing rod, and learning to make flare fittings will do wonders for the ease of disassembly and modification of your system - Awesome work on the calculations for your capillary tube! All that homework you did is the only reason this is working at all. - Pulling a vacuum before charging is, like super duper important, not just necessary. For best results, pull a vacuum below 500 microns of mercury (about .67 mBar), break the vacuum (let

[@TheTemporalAnomaly]

You nearly got a like from me when you talked about the compressor being cooled by the refrigerant return stream and you made some good points, then you started beating on the guy! As a refrigerant engineer, have you never done anything a little naughty? The answer will be yes, we all have! This is one of the best You-tube channels, encouraging people to ask the question `how does it work` and how to modify things for other purposes. As for any perceived risks, they are very, very minimal and they are personal risks, and as such are of no concern to us. I don`t mean this to offend, I am just aware that negative comments on You-Tube (and in real life) have the potential to stop people pursuing their hobbies and vocations. In the very least, it might put someone off the idea of publishing and sharing with us.

[@JH-tc3yu]

You're massively overthinking this. SH and SC are refrigeration and application specific. One application might have 5° of superheat and another might have 30. It depends on the application. There's no rule of thumb.

[@tomoliver8498]

@Carbon good analysis of his efforts and shortcomings. About the only thing I would add is not to use soft solder on discharge lines and original compressor is probably designed for high temp application your low superheat concerns are warranted and you are right adequate mass flo cooling capability at operating temperature is also important. You have to keep the compressor happy. (I have worked in the trade over 40 years)

[@jayfowler4747]

Agree with everything you say until your actually doing it in a time crunch especially the vacuum stuff.?😅

[@Redtooth75]

@@jayfowler4747 breaking and redoing the vacuum is really only necessary with very large systems. For light commercial and residential systems a vacuum of 500 microns is fine and no nitrogen purge is required, the manufactures don't say its necessary.

[@CharlesVanNoland]

All us fellow nerds are living vicariously through you, sir. We commend you.

[@jerbear7952]

I don't commend him. He exterminated all of my monkeys. In facts as soon as I get my last moon sapphire I will...yes we commend you yess

[@leifhietala8074]

Frost is actually pretty effective insulation, so while an HVAC guy (me) doesn't generally like to see it, you can see how it serves your purpose, preventing unnecessary heat loads migrating into the system once the layer forms.

[@smn368]

Bruuuh! Also an HVAC guy here, were you about to explode right up until he said? Oh yeah by the way I did vacuum the system down😅😂 .... The way he did it it looked like he was like. Oh yeah, I just built this compressor and evap soft soldered it and then dumped a bunch of propane in there @atmospheric pressure. I was dying for a second but also I was like there's no way he doesn't know this

[@leifhietala8074]

@@smn368 I just assumed Pirate did it. He mentions having a vac pump just laying around so while he didn't spell it out in the moment and I admit, I had a little nagging doubt, he's also pretty comprehensive about everything else so I figured he'd covered that step in its time. I threw a solder patch on a pinhole once and then forgot about it for the next five years. Don't disregard solder too quickly.

[@ShainAndrews]

Nope... All of it... nope.

[@1marcelfilms]

plus you can easily tell it is working

[@sontapaa11jokulainen94]

​@@ShainAndrews how so?

[@adrianprice-roberts9139]

You probably already know this, however you didn't mention your flow configuration in the video. Make sure you're running all your tube-in-shell heat exchangers in countercurrent flow for best heat transfer. This series is fantastic and extremely high quality, I look forward to seeing the end result.

[@michaelnonamehere9003]

Lol I work on tube in shell heat exchangers and I didn't know that.

[@BoB-Dobbs_leaning-left]

@@michaelnonamehere9003 I have often thought about this and came to that conclusion myself, it makes sense. The exchange is more efficient as the input is closer to the output in temperature. As the fluid, or gas goes through the exchanger the difference in temperature remains close and, as such, retains the efficiency.

[@XX-et9se]

Yes, noticed that the diagram had arrows going in the same direction, but counter-current is optimal in linear exchangers. Props for Adrian, and yes, props for HypPir. Good job.

[@KyleBrubakerrekaburBelyK]

I was going to mention the same. Countercurrent flow maximizes the temperature difference between the two fluids, enhancing heat transfer.

[@arfyness]

i paused to comment this too. the same flow direction will have both fluids exiting at (almost) the same temperature. opposite flow direction will much more effectively transfer (nearly) all of the temperature of one to the other, for example the hot side will exit right at the coldest part of the cold side, therefore the hot input will exit (almost) that cold.

[@LitchKB]

13:55 - Copper work-hardens, so your straightening of the coil to thread the other one through would have already hardened it, made it more difficult to re-coil (in addition to the added internal pipe). Annealing (heating and quenching) isn't really an option here either with 18ft of straight pipe, so you often need to be frugal with your manipulations, lest you end up with some really stiff pipe.

[@whatelseison8970]

Yeah that's very true. I've noticed my pipe also getting stiff when I manipulate it. 😅🤣

[@dennis-nz5im]

You can anneal it, it will be just fine with no quench .

[@custos3249]

Sigh.... Ever heard of induction heating? He could literally just run the line over a cheap induction cooker on high with one hand and use the other to drizzle a water hose.

[@LitchKB]

​@@custos3249 Wow, that's brilliant - it doesn't sound difficult and subject to having specialist equipment on hand because induction cooktops are of insufficent power and design at all. You should comment more, your input is well considered and valuable.

[@VEC7ORlt]

Good luck induction heating copper.

[@defenestrated23]

In your diagram of the coaxial heat exchanger, it shows a concurrent flow. Usually countercurrent heat exchangers are better, as they allow for more efficient heat transfer. There's other engineering reasons for concurrent flow but I don't think any apply here.

[@TheTemporalAnomaly]

You are correct, very good point!

[@leocurious9919]

Never heard "concurrent" before, I only knew it as cocurrent or co-current. Are your sure that the n is supposed to be there?

[@TheTemporalAnomaly]

@@leocurious9919 Concurrent means at the same time or in this case it means in the same direction, so his choice of word is correct. Incidentally, I don`t approve of this `nit picking` I does nothing to encourage conversation or understanding.

[@ianicus123]

Correct

[@leocurious9919]

@@TheTemporalAnomaly It does help to "nit pick" something like that. It could be wrong or it could be a new term to learn for people like me. Either case is a win for me.

[@blakes8901]

this series has been so much fun to watch so far. really looking forward to seeing how everything eventually pans out.

[@GatorGlider]

Like half this stuff is well beyond me, but it's so interesting to watch you methodically go through, explain everything, not dumb it down, and then actually put it in practice. Can't wait to see the next vid!

[@TheTemporalAnomaly]

Don`t underestimate your knowledge Sir, It`s a great time to be living in, with all the information anyone could need just a button push away! Anything you don`t immediately understand can be put right with a few clicks, all you need is a desire to learn. The internet has made it possible for anyone to have access to all this wonderful technology. I am involved in R&D, but before the internet was available, it used to take me ages to do the necessary research, but now it`s all right in front of us! (Scientific papers etc). Channels like this are great because they get people asking `how` and `why` things work.

[@SoloRenegade]

it's not actually as complicated as it looks. it's intimidating, but if you take the time to learn pieces of it, break it down into smaller chunks, you can learn it. This is basically a thermodynamics class, which is not actually as hard as people claim. Probably some free courses online somewhere if you were interested enough in learning more. But even if you're not that interested, doesn't mean you're not capable of learning and understanding it.

[@xXx-yv7vg]

@@SoloRenegade do you have any recommendations of where one could learn this?

[@SoloRenegade]

@@xXx-yv7vg Search the internet, KZbin videos/lectures, and find books on topics such as; Thermodynamics (refrigeration cycle) Heat Transfer (Conduction, Convection, heat sinks) HVAC, Refrigeration and Air Conditioning Pumps, valves, plumbing Tons of good books, lectures, and such on these various topics.

[@jerbear7952]

​@@TheTemporalAnomalyevery single day I say this too myself at some point. I was pretty smart back in the day, now I am like the new guy every single day and I can accomplish so much more. Even if I don't fully understand it it is just like baking a cake. Which I can also do now. 😊

[@flomojo2u]

While it's easier to just buy an A/C unit, seeing a system built from the ground up was really cool (ha ha). Vapor phase refrigeration systems were always a little mysterious to me, the many unstated details necessary to make one work, so seeing one built from scratch was really appreciated.

[@umutk5614]

I love your approach, calculations, tolerances, etc... That is pure engineering in my opinion. Looking forward to the second stage.

[@JoseOliveira-lz1up]

Pass the capillary tube around the suction line, it will increase your compressor life and COP by overheating the gas exiting the evaporator and undercooling the liquid exiting the condenser.

[@rushoffman2364]

I'm so excited for the next part, this is easily becoming my favorite series

[@tobyoverton_hvacr]

Dude, as a refrigeration mechanic myself, I gotta say, your content and understanding of the refrigeration theory is fantastic. Keep doing what you do! I’m very impressed

[@genjitsu7448]

This was well presented, takes me back to school days...but what I like about this better is the actual build that has gone with the discussion. Nicely done! Cheers.

[@bluejayfabrications2216]

The quality and humour in something that could be presented so blandly is very much appreciated

[@CARLSFAB2016]

I’m taking thermodynamics right now in college. I really love the class and the math that comes with it so watching this and seeing someone design a refrigeration cycle is awesome. It really helps show how what I’m currently doing in school applies to real world design challenges. This was really cool to watch. Phenomenal job sir!

[@enotdetcelfer]

Segmented capillary tubes in series and parallel with bypass valves at convenient intervals would allow you to have a digital adjustment without much more complexity. Great project, your insights are helping with the ship repairs, thank you.

[@ProtozoanKid]

I finally realized that the structure of your videos is a near-perfect example of an experiment report. Actually seeing one in video format like this has already helped me figure out how to make my reports for work so much better. Thank you.

[@knallpistol]

I love the humor and production in this video. I've wanted to build a cryocooler for the longest time. Have no background in engineering, and no use for one other than I've always wanted one.

[@gooball2005]

Very impressive results! I absolutely love this series on compressor-based cooling systems, would you mind creating a playlist of these videos on your channel? As always, great stuff. Cheers

[@Skulljeep00]

Being EPA certified in this stuff, I say keep up the good work! I made my own wonky system to run in my computer for super cooling before. And I've got a project or 2 for the books for problems that aren't really problems. But this is awesome! 😊

[@Psrj-ad]

This is the first video iv found of someone actually making a phase-change system from scratch like this. Iv been fascinated with heat-pumps for a while now so this channael is a blessing.

[@dirtbikenrcman]

I needed these videos to learn how to work on Thermotron environmental chambers. The old guys(massive respect for them) spoke in frost patterns and qualitative methods, and I became great tech with numbers and quantitative measurements. And thanks to your videos, I'm finally getting the numbers and science I need.

[@samuelb6960]

For filling large soldering gaps Sil-Fos brazing rods work awesome. For pipe threads rector seal tru-blue works great for refrigeration.

[@TheBauwssss]

Bro, these vids are like CRACK to me, every time I see you've posted a new video I instantly binge and rewatch it a couple times for good measure ☺️ Aside from your epic and super interesting project, all the refrigeration knowledge you're pumping directly into my eyeballs is seriously informative, and I'm now finally starting to understand why my first air conditioner unit failed with the entire thing feeling 80 deg C on the outside with the lack of noise waking me up deep in the night when I panicked from the external plastic casing temperature and immediately turned the thing off. I haven't dated turn it back on ever since, and I was fiddling with the starter capacitor because I though that was the cause of the issue, but now I'm starting to doubt that. Thanks to your videos I really feel like I'm finally learning enough about this topic to be able to fix the thing myself in the future (I hope!!). thanks for your epic vids, AWRRRRRR MATEY! I really appreciate all the effort and hard work you out into these super educational videos of yours! ♥️

[@MrHichammohsen1]

This series just keeps getting better and better!

[@TheGiantHog]

I really really appreciate you referring to pressure by gauge or absolute, much more clear

[@rob647]

The cool video series continues!

[@wesameldinelshafey3032]

I really can't find words to express how amazing you are in so many aspects Since my childhood, I have been working in the refrigeration and air conditioning departments for nearly thirty years. I know very well and appreciate the enormous amount of effort that you have made in these experiments. Much more than wonderful I would like us to meet, but there are many obstacles, but I will write to you by mail, and this is my pleasure and happiness I was impressed, enjoyed and honored to see you My sincere wishes for all success and I would like if I can help you Sorry for the inaccuracy of the expression, I use a translator👍👍👍

[@zenmark42]

I really appreciate this whole deep dive into esoteric cooling technologies and seeing how you're going about modifying stuff. I'm a big proponent of DIYing glycol chillers for homebrewing and I usually just take a whole AC unit and bend it for my purposes. I've been thinking about ways to get creative with using liquid cooling to eliminate the fan noise, or... oh shit I just realized that fridge hot coils are passive! That's a huge benefit for doing some DIYing on what I'm planning...

[@MrGatlin98]

I was waiting for the propane and propane accessories reference. Wasn't disappointed.

[@aiden1838]

First, I think your channel is probably the best on KZbin for inventing/engineering discussions that show the actual process of trial/evaluation/retrial of ideas. Keep up the excellent work. However, a few points that are likely also being made by other commenters: Soldering propane connections is unsafe and prohibited by the gas code (at least where I'm from). The connections at the end of your evaporator/heat exchanger are very sketchy. The wetted surface area of your soldered joint is very small, and will be subjected to substantial thermal stress. Don't be surprised if it starts to leak. If you rebuild it, I would strongly reccomend you use a reducing tee instead of a 90. You can find models that are AxBxB sized where you can have a sidearm and one through connection at the smaller tubing size, with the second through connection larger. You then file/grind/drill out the stop inside the smaller through connection and can run your smaller tubing right through the tee. This allows a full sized brazed or soldered joint on all three pipe connections. The home distilling community has lots of examples of condensers made this way. You might also want to consider using a small brazed plate exchanger instead of a tube-in-tube. You can get these quite cheaply in the usual spots online, and they're often rated for refrigerants and their working pressures.

[@TheTemporalAnomaly]

To get the centre pipe through the heat exchanger, you might want to send a flexible piece of plastic through first, then attach the copper. That way you can `pull` the copper through and it will be much easier. To clean the `fuel` type propane up, I have a tank that contains a few pounds of activated charcoal, I transfer a quantity of of propane and let it sit for a day or so. This will absorb most of the stenching agent. This is needed for a long term unit as the stencher is rather corrosive to some materials. Lastly, the soft solder is not suited to long term operation in a unit like this. Some people think it`s not suitable for the pressure, this is incorrect though. The real reason that it is not suitable is that after many cycles of hot, cold, it begins to crack. You will most likely see this effect where the layer of solder is thickest, like in the connection to the capillary tube. Great video series, watching with interest!

[@FrainFreeze]

Your channel is so good I keep your homepage open in a pinned tab at all times.

[@user-cj4zm1se6m]

This is super practical and educational. I really like where you compare BTU, COp etc to watts ratings and wish you can do more videos on that. As a solar engineer it's hard sometimes estimating the watts of some AC units during a site audit.

[@Rukkus333]

Idea for the capillary tube: You could put a few taps in it like you would for a transformer. That'll give you a couple of "gears" to switch through. ie: Every couple of turns you could attach a valve and then depending on the length you want, open that valve. it'd be a bit of work but it would give you some variability.

[@GoDamit1000]

I was doing this 15 years ago for cooling CPUs, I still have a mostly full D sized cylinder of ethylene. Pro tip, get your hands on a plate heat exchanger for the interstage, they have incredible performance for their tiny size and are easier to insulate.

[@jantrammelant]

When I did this 25 years ago. People said I was insane for putting propane in a cooling system. I repaired an old Pepsi cool box. Whit just propane that was for the bbq. It is still working. Now all fridges are filled whit propane

[@spenny3403]

Wow this dude is extremely technical, great work man and great job putting the video together!

[@ADPuckey]

Man I love this content. I'm mostly a software guy and kinda an electronics guy, so mechanical / thermodynamic stuff is way out of my wheelhouse, but you do a great job of explaining things and I learn so much from each of your videos. It's super satisfying. Also the Denver gag was hilarious. Keep it coming boss

[@AiOinc1]

The really cool new YF refrigerant is actually explosive under pressure, so it's nice that they put it at the front of cars where you might potentially hit something and cause your air conditioning system to violently combust.

[@gregorymalchuk272]

It's not even remotely as explosive as the propane and butane being used in all new refrigerators due to global warming. Fridges are exploding with force of about a stick and a half of dynamite, an old lady and her kitchen just got blown up a day or two ago. Thank the government for banning r-134a in fridges and mandating explosive refrigerants over global warming.

[@JH-tc3yu]

There's a few hundred grams. Not enough to be dangerous.

[@theradioweyr]

But during that explosion/fire it can create hydrogen fluoride gas and has been known to etch the glass on windshields. When I am upside down in my burning car I don't want to add inhalation of that to my concerns about getting out.

[@gregorymalchuk272]

@@theradioweyr All of the fluorinated refrigerants, insuring good old R-22, release hydrofluoric acid on high temperature combustion. My problem with the HFOs isn't that they're combustible (they aren't), it's that they're all on-patent and cost hundreds of dollars for a few pounds.

[@theradioweyr]

@@gregorymalchuk272 I was not aware of the R-22/varients producing that (HF gas), thanks, I was under the mistaken assumption that that was unique to 1234yf. Yes, from an ethics issue and adoption/distribution, the patents, conveniently lobbied and written into Orwellian law with every generation of accepted refrigerants in spite of better options being available, it is patently (no pun intended) obvious they want us to use their slightly less efficient more environmentally damaging gases for they care nothing about the environment and want to ensure that they can sell completely new systems every half generation that require a complete replacement of every component. R-290/R-600 FTW.

[@ayydan]

My only complaint about this video series is that the videos have to end

[@dakotasteward4118]

I'm so glad I found this channel, great demonstrations 10/10.

[@speedbuggy16v]

Congrats its not often that a youtubers content and delivery pulls me in enough to subscribe in under 4 minutes.

[@Berkana]

12:37 shouldn't the flows be going in opposite directions? The on-screen graphic shows the flow going in the same direction. Counter-flow heat exchange is what enables you to get the most heat exchange. Parallel flow heat exchange will only ever approach meeting in the weighted average temperatjre of the two (with heat capacity considered), but counter-flow heat exchangers have the possibility of heating the target fluid hotter than the outlet of the heating fluid.

[@TheThomaslala]

I was reading trough the comments not to post this same concern. I also think this will make a huge difference.

[@PrefabQuasar]

Could use a resistor low-voltage start to keep inrush current down on the fan

[@vickidang8768]

Thank you. This video answered all my free ac project solution

[@BreakingBarriers2DIY]

“…pressure gage had a leak” Crying laughing at the subtle flex. This video is so full of wisdom I’m going to be rewatching it repeatedly over the next two years. You are so kind to share.

[@samuelb6960]

I was using a roofing torch while wearing shorts the 20lb tank was rubbing against my leg as I was carrying it around it caused a patch of frostbite that took about a month to heal so yeah it gets cold.

[@htomerif]

About the ethylene side: since your cooling efficiency is bad, keep in mind that the cold (ethylene) stage compressor is going to be dumping its entire heat budget into the hot (butane) stage if you use a sealed compressor unit. So your hot stage cooling power needs to be at least as much as the cold stage total power. And good luck finding a liquid lubricant that doesn't freeze at -100C (in the cold stage evaporator) or boil at room temperature. An oil separator doesn't really matter here if your lubricant has turned into a gas anyway and is spread through the whole line. Oh, also, maybe just stick the whole hot stage evaporator in a cheap styrofoam cooler for now? Its way easier than having to foam and tape everything. Also also, you might find that those $2 mylar emergency blankets are a lot more manageable than aluminum foil. I used those two things to make a passive sky freezer that gets down to -40C at night when it isn't too humid.

[@brianwelch1579]

My understanding is that other refrigerants are used as lubrication on cryogenic systems - like propane or butane for example.

[@htomerif]

@@brianwelch1579 Let me explain myself a little more clearly. Almost without exception, "refrigerants" are just alkanes or alkenes or halogenated (fluoro, chloro, bromo) alkanes and alkenes. When you're dealing with a normal compressor being used normally, it gets really hot and it never gets super cold, so you could use something like decane which boils at 170C and freezes at -30C. The compressor will never not be in that range. It stays solidly at 50C-80C (ish). For cryocooling, you're not just dealing with -40C for boiling and -100C for freezing. You're dealing with 30C for not boiling (if you don't want it to get into the evaporator coil) and -100C (more actually, if you don't want it to freeze in the evaporator coil). The problem is that these refrigerants almost always form azeotropes so if you're using a higher boiling point refrigerant as a lubricant, some of it will end up in the evaporator, even if its only when everything is brought up to room temperature. Frozen oil in your evaporator can be terminal for your whole cooling system. When you're talking about industrial cryocooling, you're usually talking about one of two mechanisms: stirling cycle coolers and turboexpanders. I don't know what lubricant is used in either one, but I think its "none" in the cold end of a stirling cooler and in a turboexpander it could literally be a gas bearing. They're so expensive and/or slow that the few university things I've had experience with have either been LN2 based or dry ice based. Anyway, he might want to look at 1-butene, which goes from -180C to -6C as lubricant? At least it won't freeze in the evaporator and at a few bar it might stay a liquid at room temperature too. Worth shot I guess. I'll try to read through the list of hundreds of coolants that might work as a lubricant for what he's trying to do later. 1-butene was just a shot in the dark that looks kinda ok.

[@Blaxkor]

@@htomerif All of these systems just use an oil separator after the compressor to return the oil to the crankcase or suction line since the only purpose the oil serves is lubricating the compressor. If you needed very low temperature refrigeration oil for some reason such as poor oil separation then there are oils such as zerol 150 with a floc point below -100. Apparently propane also greatly increases the oil carrying capacity which helps oil return to the compressor when in the refrigerant blend.

[@htomerif]

@@Blaxkor Don't try to BS me. I noticed you didn't put a unit on that "-100". I know why. You wanna edit that comment again? I mean I'll be fair. That could just be a mistake on your part but it looks like intentional misinformation.

[@hfitfxhfhfufgugugu6589]

Big respect for building all this yourself.

[@mediumsmoke7823]

This channel is simply awesome…could watch for hours

[@teresashinkansen9402]

Ive used propylene and it gets you down to -40C° to -45C°

[@Berkana]

14:17 Take a look at this arrangement of tubing for a VCC system in a modern regenerative VCC refrigerator, linked below. In this design, the capillary tube itself is used in the heat exchanger, and the heat exchanger is in a counter-flow arrangement, which should yield higher efficiency. I linked straight to the timestamp where the coaxial capillary tube and gas return tube (which is effectively a heat exchanger) is explained. Modern refrigerators explained (timestamp links to introduction of the coaxial capillary tube + evaporator vapor return tube, which acts as a recuperator. Hot condensate is used to warm up cold vapor/cold vapor is used to cool down hot condensate, making the whole system more efficient, as less refrigerant needs to be evaporated to cool the remaining refrigerant to your target temperature. ) kzbin.info/www/bejne/bX_aqYCvprqsgNk This arrangement would save you a good bit of flow friction losses, and would perhaps perform better than the design you showed in this video.

[@brianwelch1579]

This indeed increases efficiency but it impacts absolute temperature IME. I did this on some "early models" of my freeze dryer.

[@shinigamineko333]

OMG.. so cool, project getting more and more difficulties. Don't stop, you're marvelous!

[@dyl1828]

This seems all very interesting and I'll be keeping an eye out on your follow up video.

[@ericlotze7724]

@Hyperspace Pirate *Granted* this is a low TRL as of now and you are still figuring out what works, let alone polishing it, **BUT**: Can you optimize this for Off the Shelf (OTS) Parts / “Clean” Design? Basically what you did with the 3D Printed Parts but on Steroids. Use reliably sourced OTS parts, have there be like a pallet sized (heck even (plastic) pallet mounted) module for each “stage” and have the fittings all in a standard spot, then make a “shell” enclosure if you are feeling REALLY fancy? It would be a PILE of work, but i feel that if you get this project working, then do that, we could have an Open Source, Modular Refrigeration System that could be used as is for a water chiller etc, or be cascaded like you are doing and get cryogenic levels of cold! Granted again this is asking a lot, and worse case scenario others and i could iterate of tour work, but i feel like that would be an AMAZING application of this project. That’s my rant lol, and thanks for reading this far. What do you think of all this?

[@HyperspacePirate]

This is a prototype for one piece of a larger project, but i'm thinking of doing something similar to that when the project is done, so that people can build their own cryocoolers

[@ericlotze7724]

@@HyperspacePirate sounds great!, and no need to rush as even this level of work *and* documentation is a MAJOR help. I’m excited to see what happens in the “next episode” !

[@Hxkhxh]

Hey Hyperspace Pirate, i am watching you since a long time. I want to ask , are you a college student or a research scholar? I am in high school and always want to do such projects by myself...😊

[@HyperspacePirate]

Neither. I just like to build things

[@systemloc]

You don't have to have a job that matches your hobby. Just go tinker with stuff. I used to pick trash in high school for free parts to play with stuff like this.

[@Rowow]

OMG each time you scratch the ice with your finger gives me chills. As a Floridian I am not used to that LOL

[@Eli-kr5bm]

I was looking for all this LPG gas refrigeration information and couldn’t find anything, thank you 🤠

[@ericlotze7724]

It’s probably in the charts somewhere (“read the fucking manual” moment), but at what level would using CO2 as the Refrigerant make sense? I know it is used commercially, and is kind of the “latest and greatest” / non Fluorocarbon/ Chlorocarbon / CFC options, along with Ammonia, Butane/Ethane, and DME. I haven’t taken an HVACR class yet though, and don’t remember the papers, so does it require obscene pressure and/or stainless steel or inconel pipes? If not that would be a great option. Cheap and Non-Flammable.

[@hunterlang578]

co2 is gaining popularity as a refrigerant. It has good properties, the only downside is that is has very high working pressures, so systems cannot be constructed in the traditional HVAC fashion

[@rhamph]

Significantly higher pressures. I'm seeing around 35 bar on the condenser for a regular system or maybe 90 bar for a transcritical system. Transcritical CO2 is a beast of its own though, as it sounds like it's not stable when turned off (pressure spikes dangerously as it returns to ambient, requiring venting and making the whole system non-functional).

[@Doktoreq]

@@rhamph Worked on trans-critical systems. The rule to live by is never shut of any part of the system completely without evacuating or pressure relief valve present. The moment the flow stops the CO2 starts expanding rapidly.

[@rhamph]

@@Doktoreq Even getting the pressure relief valves right sounds finicky. "Rule to live by" is poignant.

[@brianwelch1579]

At no level, if you want a *cold* box. It works great in cars for AC but forms dry ice snow around -30C and clogs the orifice. Plus crazy high pressures.

[@leozendo3500]

that is so much copper

[@-r-495]

Cascade coolers can be iffy. I am very, very happy you published this. Thank you

[@thelred-ph3lq]

Nice, clear, easy to understand speech. Thank you!

[@drsemiauto4215]

can't wait for the next video! can't get enough of refrigerating refrigerants with more refrigerants!

[@kioliex]

Great video. I had something similar planed 15-20 years ago, but stopped because people said I should not use propane... I might take this project up again...

[@omsingharjit]

Wow my all technical Doubts are cleared here very Nice explanation of thermodynamics and refrigeration system.

[@dkjoses12]

As an HVAC tech I love this can't wait for part 2

[@KageShi]

I saw the title and instantly remembered a PC case I had back in the day with a vapor chiller. It was a special edition ThermalTake and had a proper multistage fridge compressor for extreme overclocking. I used it to push a Phenom

[@PeterMilanovski]

Seeing it fire up through a thermal imaging camera would have been awesome 👍 Great job 👏

[@Skeys13]

Babe wake up, the new diy cryocooler video came out

[@andrewsvaz]

Just discovered your channel. One word about it: GREAT. Thanks for the knowledge. One more subscriber on your list.

[@revmsj]

I want to make a cryocooler one day so this is good info. Thanks, brotha

[@slacky4358]

As a hvac tech I really enjoyed this video

[@DEtchells]

You’ve probably already thought of this, but it’s really important to make sure no liquid refrigerant gets into the suction line of the pump; that’s called “slugging” and will ruin a pump in short order. Absolutely fantastic series!

[@nuc2726]

HVAC Tech here. You can switch "gears" by having three capillary tubes at different lengths in parallel with a valve that isolates each tube for up to 6 "gears" by opening and closing certain tubes at certain times. However, this is a lot more convoluted and expensive than simply just using a regular TXV. However, using a regular TXV is difficult because you're doing something without any engineers or refrigerant knowledge, so you won't know exactly what model of TXV you'd want (they change based on the cooling load required and the expected operating pressure range of a particular refrigerant). Your best bet is to get an EXV which uses an electromagnet to turn a magnet inside to open and close the metering device. This has an advantage that you can test where you want the EXV seated at which stage of cooling, and program it with an raspberry pi or an arduino. You'll be able to trial-and-error it to where you want it to be for a given load.

[@ZT_Performance]

Subscribed, this is so awesome, been wanting to do something similar for my own projects. I really appreciate you going over every detail and explaining theroy.

[@cantsolvesudokus]

Very interesting, can’t wait for the next part(s)! Also very nicely documented.

[@sudoboat]

was really interesting to watch as I'm in the middle of a (somewhat) similar project, building a water cooling loop for my boat using a 12v compressor :) Thank you for a great video!

[@sempertard]

This is one of those science fact-filled vids that requires several passes to absorb what the author is trying to convey. I wouldn't want it any other way. Very, very well done. Edit: Instant sub...

[@8bit711]

One smart cookie! I love that the target temp is 42. This is actually on my build list but im not quite smart enough yet but some day.

[@BRUXXUS]

I really enjoy this series! Looking forward to eventually seeing some sweet, sweet liquid air dripping into a dewar!

[@keeganplayz1875]

Very interesting video about heat pumping. Got a lot of information from this, and I even understood some of the thermochemistry going on.

[@pieterbarneveld9518]

Lpg is an amazing refrigerant . I very much enjoyed watching your video. I make all sorts of things with refrigeration equipment and just building pre heater water heater for the boat, basically using the waste heat to warm water before it goes into the hot water cylinder.

[@subhrapratimsharma2825]

I'm hoping to build this one day. Great work.

[@lorenwilson8128]

Interesting process and well-explained for the layman. To make reducers, use a cap and tee and drill a hole of the correct diameter in the cap.

[@IvanGreguricOrtolan]

Man this video was amazing, I now know how to build a fridge! You earned an happy sub!

[@WobblycogsUk]

Absolutely fascinating series. Sort of engineering meets physics meets chemistry. I had "make liquid nitrogen" on my todo list for a while, this series have convinced me it's better to just buy it.

[@TheTemporalAnomaly]

If its down to a price, then definitely buy but as a challenge, without using commercial equipment then that`s a completely different matter. In the latter case, even a few drips or a few milliliters would be a great success!

[@adrian5895]

I will never build anything similar do this but I love your videos! Thank you and please keep going

[@DAVOinIN]

Excellent video! Been thinking about building one for years and you just made my life so much easier. 😂

[@josephlieberman3027]

Fantastic, and thoroughly well presented subject matter. Thank You.

[@FirstLast-kx1gr]

This is the best video I've seen on the subject, and I've watched many. I had to make a coaxial tube heat exchanger a number of year ago... On straightening tubing: Grab one end with a vise, grab the other end tightly in a drill chuck, pull HARD and turn the drill a few revolutions until the tubing is straight. Don't overtwist the tube. Cut off the mangled ends. Annealing the tubing should not be necessary. Putting one tube inside another is quite easy when both are straightened. I learned this method from an electrician who used it to straighten solid copper wire. 🙂

[@Jim_One-wl4ke]

Awesome explanations. Love it, thank you ❤

[@hustlaz2k]

u deserved a subscribed sir! i watched tonned of how to video on how ac works.... but i dont understand why the need of filter... capillary tube and etc... from your project i understand most of it. thank u!

[@tejonBiker]

Nice video, I really like when a people make their own equipment for refrigeration/hvac, several years ago I read that the rule of thumb for max compression ratio is 1:10, out of that your efficiency is out of range, that's why cascade systems are used for deep freezing, as side note: deep freezing use R23.

[@colepaul8320]

Used this for my thermo exam thanks!

[@bilbo_gamers6417]

YES these projects are so cool! it's such a shame that people don't make more videos like this. you've earned a sub :)

[@JehuMcSpooran]

My uncle recharged his car's AC using Autogas on a few occasions (auto gas here in Australia is a propane/butane mix depending on the season). Apparently it worked really well.

[@Cyrix2k]

at around 15:00, you should pull a vacuum on the system before filling and also add a valve at the end of your fill line. Let propane out to evacuate any air in the line, then connect and fill the system. I'm not sure how much it will impact your performance but it should avoid ice crystals forming inside the loop.

[@Southghost5997]

Wow, I wanted to do this exact project and you saved me a bunch of money with trial and error 😅. Just one thing on the test water, there may be a stationary boundary layer forming on the surface of the tube wall that you're not accounting for and which causes additional insulation. It would form almost instantly. This is why continuous freeze crystallisers use scrapers on the tubes. Edit: ..hence, even more reason for a lower than expected COP