DIY Cascade Refrigeration System (Part III)

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This is part III of my video series on building a DIY vapor-compression casacade (i.e. multi-stage) refrigeration system. In the last two videos, i demonstrated the concepts needed to make a cascade system work and reached temperatures below -110C, but because i used low-powered reciprocating compressors meant for R600A, I wasn't able to build a system that ran continuously and only managed to evaporate low-temperature refrigerants in short bursts.
This time, I'm using a pair of rotary compressors extracted from 5,000 BTU window air conditioner units. The first stage will use propane (R290) as a refrigerant, and the second stage will use Ethylene (R1150). The compressors were made for R410A, so they're able to run as high as ~30 bar continuously without a problem. This will allow me to condense Ethylene at the first stage evaporator temperature of around -20C to -25C.
To extract more efficiency (and a lower temperature) out of the system, I use subcoolers on both stages; the return lines to both compressors are wrapped in capillary tubing coming from the condensers.
The lowest temperature I managed to achieve with this system was only -88C, but that's probably because I ran the second stage suction pressure relatively high (around 4-6 bar) in order to keep the mass flow rate high. Down to about -63C, the efficiency or "coefficient of performance" (COP) is about 10%, so there's definitely some room for improvement.
The best way to improve the ultimate temperature and/or thermal efficiency of this system would be to use a sub-cooler with a thermal gradient across it that looks basically identical to the regenerative heat exchanger in a joule-thomson system. When I experimented with this using my precooled joule-thomson cryocooler with 100% ethylene (effectively turning it into a cascade vapor compression system), I achieved nearly twice the thermal efficiency of the device I built for this video.
I originally planned to use this system to liquefy Methane. This is possible at -88C, but would require a very high pressure, and with the marginal cooling power at that temperature, it's probably not practical, so I'll be doing that in my next video using my joule-thomson cryocooler.
I'd also recommend using a higher-boiling refrigerant for the second stage - like R508 (if you can get it), Ethane (R170), Nitrous Oxide (R744A), or even Carbon Dioxide (R744) (although CO2 is only feasible if you keep the second stage evaporator ABOVE the -56C). The boiling points of Ethylene and Propane are far enough apart that the system is reaching pretty far.
Music Used:
Kevin MacLeod - George Street Shuffle
Kevin MacLeod - Bossa Antigua
Kevin MacLeod - Lobby Time
Kevin MacLeod - Elevator

[@HyperspacePirate]

If my voice sounded funny in this one it's cause season allergies are terrible rn. For those asking, I was originally gonna put out part III of the joule thomson series but there were some delays. It's workable right now for liquid methane, and should be usable for liquid nitrogen pretty soon.

[@TechwithStefan]

the voice is perfect! also the video, really liked the booster #69 :D

[@harriehausenman8623]

omg. I feel ya. havent had them this bad for years 🤧

[@ericbreckenkamp976]

You sounded like @andrewkleinww

[@rougechampion]

Haha I was confused at first. I thought the cascade cooler was gonna be part of the joule Thompson cooler to get you to liquid nitrogen. I was confused when you were at -80c because you had already gotten there!

[@jamest.5001]

Oh ok, I thought you may had a refrigerant leak, changing your voice a bit , kinda like helium!😆😂

[@tuskiomisham]

this guy makes nothing but refrigerator videos, and I have no clue why, but I love watching every single one.

[@loadingcylinder9067]

He’s made a homemade submarine

[@andersjjensen]

He also made a death ray lunch box. I'm not entirely sure what his end game is, but apparently you need quite a lot of advanced kit to commit piracy in hyperspace.

[@rougechampion]

@@andersjjensen we haven't even invented a craft to get to hyperspace so presumably he will do that at some point too

[@andersjjensen]

@@rougechampion I'm pretty sure that's what he needs copious amounts of liquid nitrogen for. A hyperspace drive most certainly requires superconductors, which (currently) only work at cryogenic temperatures.

[@turkeyboyjh1]

I knew nothing about refrigeration other that automotive a/c systems until I watched this channel now I’m an facilities/hvac tech at an Indian casino in northern California

[@salce_with_onion]

Honey wake up! Hyperspace Pirate uploaded! Its time to watch for 13 minutes video about refrigiretors! Yay!

[@lucasimark7992]

Yes dear

[@custos3249]

I want a divorce.

[@ctje1638]

refrigiretor! yay

[@jerbear7952]

Why is the honey wake up thing still going on

[@keepyourbilsteins]

Glad to see those R410s going to stay with their forever family.

[@HunterHerbst]

Yeah the EPA joke had me in stitches

[@storminmormin14]

The concept of people doing high tech things with low tech gear is deeply satisfying.

[@steampunksystems1969]

Love the dry humor in these videos!

[@NikKappa]

Cold*

[@II_xD_II]

Cryo*

[@Thefreakyfreek]

Freeze dried

[@Thefreakyfreek]

Ms freeze

[@samuelberghuvud5527]

Like dry ice

[@owenrichmond1696]

Definitely my favorite KZbin series. Not even close. Honestly this is what I thought engineering would be when I started, turns out most of us have boring jobs at defense companies. Living the dream man, keep it up!!

[@IFRYRCE]

Tell mama Lockheed and papa Martin I said hi

[@Ammoniummetavanadate]

That and I am stealing all his R&D to build myself an off-grid argon generator

[@wertacus]

Yup. All those Autocad classes where I imagined myself building bridges and space elevators when reality is just locating toilets so the cabinets don't hit them 😅

[@babyeatingpsychopath]

This has become my favorite series now that @ExtractionsAndIre has finished Cubane.

[@nextjaeger9271]

Now that i started to have thermodynamics classes in uni this is even more interesting.

[@nilamotk]

I have a real 2 stage cascade system on my shelf here from a -80c fridge. The second stage has 2 large resevoirs on the low side that add volume to the system when its off to reduce the standing pressure when its at room temperature. Just a tbought for ya. Then it can have more liquid available when its running, possible moving highter BTUH, and at the same time not exploding when its on the shelf warm. Also, if your in Canada (gta) I'm in the hvac industry and can get you compressors and what-not used.. slightly abused.. for free.. lol Edit: I should watch the whole video before commenting 😂

[@Ammoniummetavanadate]

I wish he was, I have a giant compressor off a laboratory glove box refrigerator that is sitting around. I guess I will have to use it instead.

[@henryj.8528]

You've made a lot of videos on refrigeration and I haven't watched them all so I don't know if these comments are relevant, so these are offered FWIW.... It is necessary to remove moisture from the sealed system. A filter-dryier helps but only has limited capacity. You should put the entire system on a vacuum pump and pump it down to less than 500 microns--and hold it on vacuum for a half hour or so. This will remove most of the moisture and non-condensibles (mostly nitrogen and CO2). The capacity of a filter-drier assumes this was done. For maximum efficiency, you should do a "triple evac." This means pulling a vacuum down to 500 microns or less (and making sure it holds) and then breaking the vacuum with a small amount of the intended refrigerant. Doing this three times makes sure that when you charge the system, the only thing that remains in there is refrigerant. The oil in the compressor is chosen for its compatibility with the refrigerant (which is why compressors are labeled for "R-134s, 410a, R-22, etc.). The compressor doesn't care what the refrigerant is but the label is there to indicate of what type of oil is in the compressor (PAG, POE, mineral oil, etc.). The refrigerant and type of oil have to be compatible. I'm not sure that's the case here (but I haven't looked it up). Soldering is not used much any more in HVAC-R because of leaks, vibrational cracks, call backs and so forth, but is fine (if the pressures are not too high and you don't mind finding and fixing occasional leaks). Sta Brite 8 is a silver-based solder. It's expensive, but it works. I use silphos brazing material but it really requires brazing temps (oxy acetylene). For copper/copper connections, the phosphorus serves as the flux. Some installers use MAPP gas but IMO the joints have to be heated too long when brazing with anything other than oxy/acetylene.. With oxy/acetylene you can get in and get out without ruining components nearby. For that reason, it's a good idea to protect other components by spraying them with cooling gel (or using wet rags)--and being fast--to prevent heat from damaging valve seats and other stuff downstream. Damage to valves and other components from overheating may not be obvious at first.

[@i_might_be_lying]

It's always a good day when Hyperspace Pirate uploads a video!

[@Electrically-Electronic]

Yes for sure.

[@MrMaxymoo22]

I used to build very large cascade refrigeration test chambers. Every bit from the structural steel frame to the copper brazing of the loops. I didn't do any of the electronics outside of mounting them and didn't ever run or setup the cooling systems outside of testing when it was done. I really enjoy this series because it helps me to better understand what I used to build.

[@jeffevarts8757]

I congratulate you on moving forward. In the space of time since you started, many KZbinrs have started their channel, made some cool videos, hit their first "peak", then burnt out and quit. I think KZbin should reward guys like you, who KEEP producing consistent content. Just my opinion, but hey... Good job!

[@tenns]

What do you mean I'm not HVAC certified, don't worry about the leaks, if the refrigerant wants to stay, it can come back on its own

[@per995]

Nice set up. Remind me on some cold traps we sold some 30 years ago. All time running at -104C and stayed alive for 15-20 years. Much simpler set up using a single small condenser . Used an insulated evaporator flattened coil outside the drum. Not a storage tank for the low stage Ethen, just the system volume was enough. The oil separator was just a vertical placed small strainer with a microscopically bored cap tube for oil return for an all time oil return. They brazed the discharge line into the side of the strainer and placed the capillary tube in the bottom, worked well. Look forward to your next step 😊

[@Wazzup142400]

Really awesome stuff, cool to see what can be done with parts ripped out of window units and some forethought. You clearly have done your homework but for brazing I would highly recommend having a flow of nitrogen gas through any of the fittings and areas you're sweating. The black copper scale you see on the outside of the tubing is also present inside, and with the solvent nature of refrigerants and oils, can be dissolved or broken up making its way into the compressor and/or metering devices. This could cause issues with your capillary tubes, and as others have mentioned pulling a vacuum and ensuring you hold below 500 microns for a decent amount of time could avoid some other problems with moisture and refrigerant acidification. All in all, really good work!

[@gergelybencsik8626]

Hey, I see you took my advice on pull down resistors! I'm deeply honored.

[@realvanman1]

The problem with using a heat exchanger on the suction line to subcool the liquid side is that it raises suction superheat. The higher the suction superheat, the lower the efficiency and the lower the system capacity. Ideally you'd want a thermostatic expansion valve on each stage to keep superheat of each as low as possible.

[@Earth_to_Kensho...ComeInKensho]

Many HVAC techs can't wrap their head around cascade system design but now that CO2 systems are catching on they'll have to. This video is actually very cool. ❤️💥🙏

[@KingJellyfishII]

THE FRIDGE DUDE IS BACK!! exciting stuff

[@jerbear7952]

Can you imagine having an amazing dynamic life and yet to an enormous number of people you are fridge dude 😎 that's how it goes

[@KingJellyfishII]

@@jerbear7952 lol i would say the fridges in question are about as amazing and dynamic as they get

[@toygartumer7385]

you are my favorite channel on youtube

[@storbytronics]

Oh hey another *COOL* video from Hyperspace Pirate!

[@Tomas3966]

Hi there. I have some good memories regarding building cascade systems for computer cooling (overclocking). I would advise to use a thermostatic expansion valve on the first stage, the advantage of it self adjusting to the load is too great. Once you set it up it's more or less a done deal, it will do the work for you. As for the second stage, I have found that for my particular niche that constant pressure expansion valves were the best for the second stage. They offered very fine manual controll. The oil separator will work best after the pre-cooler, regarding your problems with capilary tubes for flow controll- use a small filter like in a fridge, it will take care of the debris. Also add a tapered section on the inlet. The flow from the small pipe is high velocity and will spit oil droplets that can pass through. A very small amount of propane I'm the second stage will take care of the oil that manages to pass the oil separator, think of it as a solvent/thinner for the clogging oil. I would advise to use bigger diameter pipes on the suction side, make them match the compressors suction side. Insulation is your friend, it's free performance 😂 I have found that even with a tight, compact system, when I thought that it was enough, adding more was beneficial.

[@IanGrams]

Thanks Tomas, I really appreciate people like yourself who learn a ton about a relatively niche subject and then take the time to help others learn about it too. I hope he sees this, so I'm offering this comment and a like to the altar of the algorithm in hopes of increasing the odds of that 😁

[@crackedemerald4930]

i feel like i get lost a lot when you quickly explain how your system works

[@BVN-TEXAS]

I think your issue with your 2nd stage is you need a bigger compressor. The lower the suction pressure the less dense the vapor returning. You get into volumetric efficiency. Also I would look into using a TXV on your second stage to allow your compressor to stay as efficient as possible.

[@Exotic_Chem_Lab]

second stage should always be smaller than first stage

[@BVN-TEXAS]

@@Exotic_Chem_Lab I think I may have the 1 and 2nd mixed up. The lower temp system is what I meant to say needs to be bigger in the scope of the rated BTU compressor he is using. yes in the scope of overall BTUs. BUT the rating of BTUs of his compressor is rated at AC service with 40F evap and 120F condenser. As the evaporator temp drops so does the BTU/H that the compressor is moving. So that 5,000 BTU AC compressor is going to have a much lower BTU/H when in used in the low temp stage. The amount of BTU/H the the high temp needs to handle from the low temp is heat removed + heat of motor + heat of compression. The low temp compressor needs to be upsized is what I meant to say.

[@henrycarstensen]

I like the sudden turn from science to the crude hitting of frozen fruits. Humans are interesting.

[@divlles]

Not going to lie I look forward to seeing your videos every time they come out because they're very educational also funny dry humor or not they're great unlike Caitlyn Jenner's frosted mini-wheats those were terrible now I know what happens if you eat your Wheaties your entire life

[@ottersmeep25]

These videos are helping me immensely with my ice cream machine project, thanks!

[@andersjjensen]

If you follow this guy's lead you'll end up with ice cream so hard that people will either get their tongue stuck, or with shattered teeth :P

[@ottersmeep25]

@@andersjjensen I'm using this more to learn about refrigerant lol

[@abitofabitofabit4404]

@@andersjjensen hasn't had LN2 ice cream

[@jaaossa]

If only someone could love me the way this guy loves refrigeration systems

[@hassmakki]

I've never been so captivated like I have been with this series. The way you explain it makes me feel like you're successes are mine as well 😊

[@alwaysthinking614]

your builds getting alot more refined looking. Awesome to see man

[@filiono9211]

Rubbing alcohol is actually really hard to get to solidify, due to the fact that a system of alcochol and water can't form a stable enough crystall lattice, because alchol messes up water's hydrogen bonding. So, this syrupy heterogenous stuff is probably a lot of ice crystalls and a gooey liquid alcohol/water mix. The ethylene glycol/water mixes are used as an antifreeze for the same reason. Anyway, it was really interesting to watch all the 3 parts, thanks for good content!

[@lucachacha71]

That's why chemistry is all about!I love it!

[@Hootie811]

You should use home assistant to log and graph data from an esp device running esphome, there are loads of esp relay boards and all sorts of sensors that would be perfect for what your building. Keep up the awesome work, really look forward to your videos

[@bitnertinkers]

Love your videos! Thanks for all the information you've shared over the years

[@rafaelguida2317]

These videos keep getting cooler

[@thomasvnl]

Hello there Mr Hyperspace Pirate!

[@jackimo22]

Hey babe, WAKE UP! Hyperspace Pirate uploaded a new cryo-cooling video!!

[@Marty_Destroyer_of_Worlds]

this channel really is the best

[@almosthuman4457]

Thank you so much for making this series and presenting it in an interesting way. I always learn something when I watch your videos and they make me smile at the same time. Thanks for giving me the feeling that I'm sitting in class with the fun teacher again.

[@MrHichammohsen1]

I say it again, this is the funniest channel on youtube! Thank you so much for this.

[@memejeff]

Epic video man. Been eagerly waiting.

[@TheLastWolfBane]

I never miss a new video, awsome as always. Im willing to skip school for this. Funny and doesnt talk a dumbass

[@Mr_Wh1]

4:09 - dude, you need to join the crimping tool master-race.

[@0Arcoverde]

My favorite series

[@oooooooooooooooooooooooo-jf2bp]

Hello from Russia. Good luck promoting the video. I love you.

[@captainobvious9188]

I remember reading about a refrigeration hacking forever ago where they had to purify the propane first by letting the butane and other things boil off by controlling the temperature.

[@Fosuya]

Damn Sporlan would be a great sponsor for this project 😅

[@Frank-bc8gg]

yay, more adventures in refrigeration!

[@abludungeonmaster5817]

Always a good day when you upload

[@danielpetrino4129]

I don't see it, but try adding active cooling to your condensers. I went to school for this and worked on a lot of cascades in hospitals and labs if you were curious.

[@pineapple6862]

Liked it before watching, knew it was gonna be fire

[@herzogsbuick]

until you said "refrigeration content", i had never noticed that i love refrigeration youtube

[@corruptedant1613]

one of the series that is an instant click for me

[@The.Heart.Unceasing]

hell yeah, MattKC and Hyperspace Pirate uploaded today ! 'tis a good day !

[@andresyesidmorenovilla7888]

I love your videos! Keep up the great work!

[@Lukesab3r]

Dude awesome. I've been looking forward to this for a while!!

[@Pulverrostmannen]

There's a lot of dry humor about ice in this video... LOL. love it

[@htygygtgfttggyyvhh]

I love dry dry ice humor.

[@danilofjf]

Congratulations on the progress and for your dedication to the project, I would really like you to achieve your goal. I see several opportunities for improvement in your equipment, but it is difficult to explain them through these messages, if you want we can talk about it. Perhaps the most important one is that you are probably having a serious problem with Flash-gas (refrigeration) (Wikipedia has a good definition for you to understand). Other problems have to do with the energy balance between the two stages. The first must be able to absorb all the heat rejected by the first and with two identical compressors this is not possible. As for the second stage compressor, compressors for R410a are designed for low pressure around 100psi, working with it much below that will cause efficiency problems. The ideal would be an inverter-type LP compressor so you can control it using a vfd and be able to tune the system.

[@danilofjf]

Look at the P-h chart to see how much flash you will have at the end of the capillary tube, almost 50%. The ideal would be to condense the gas in two stages, between the first and second, use a capillary tube to lower the pressure so that the condemnation temperature is just a little above the evaporation temperature of the first stage.

[@MazeFrame]

Was thinking about not having seen a video here for a while, and here we are!

[@ancientlink0]

Day 1 of asking to build a vttc or class e hfsstc💪 Love your videos

[@petomni]

Enjoyed this immensely, but for a second I thought it was JT Part III gimme gimme, I need I need!

[@realcygnus]

Nifty AF as always !

[@airtongabriel6827]

Yeahhhh new Hyper space pirate video!!!

[@chadgdry3938]

Pretty cool

[@christopherreeves6797]

I haven’t gotten this excited for a video since this old Tony started posting again

[@Space_Reptile]

What a cool video

[@Alexelectricalengineering]

That is awesome, I want to build a similar system at some point in time! Thumbs up 😎

[@aaax9410]

This is proper science 👍

[@jakubtrzpis2595]

Dzięki za świetną pracę:)

[@Khal_Rheg0]

Nice! Thanks!

[@bobsiu1]

I was waiting for that soooo long 🥹

[@-r-495]

Rumour has it that people have used refrigerants for cleaning oily motors etc. Thank you for sharing your experiences!

[@-r-495]

Python is great for validation, that has been my personal experience. Why write pseudo-code and draw blocks when ASCI-art can be used in a SMDS and using markdown in the code itself makes a nice package out of it.

[@solidacid1337]

Whoo! I've been looking forward to the next video!

[@alejandrostrass2559]

bro makes homemade liquid gas and speaks like its a normal day. i wanna be his neighbor so bad

[@edbrackin]

Building your setup should be a community college semester project.

[@sumguysr]

I'd really love to see some cryogenic metal treatment experiments.

[@xyzero1682]

nice work!

[@ae-bd5gr]

Babe wake up Hyperspace Pirate just dropped a new video

[@tomholroyd7519]

this joke got old in one day

[@pauljoly7594]

It's not the AI that become human, it's us that become robotic.

[@atntaltd]

this is literally Cool

[@AnalogDude_]

pretty cool.

[@DudeManDude-ot5fv]

What a cool video....

[@LaLaLand.Germany]

I love this stuff! "poke" Your animations are very fun and maybe once I get to play with ac´s, too.

[@Mrgehteuchnichtsan]

Great Video

[@harriehausenman8623]

cool stuff! 😎

[@jeronstevens8491]

Have you heard of an EEV? It’s like a TXV but electronically controlled. It can also automatically and precisely control the superheat in your system.

[@BinkySears]

Now that Tom's cubane series is over your garage cryocoolers are all I have left.

[@eda___6299]

Fridge man YAY

[@joejane9977]

Hyperspace Pirate just dropped a new video

[@Adrian_Fleck]

Oh man, only 13min XD your viedeos are the best so encuraging to do own diy stuff :)

[@JustJ03cool]

Keep posting!

[@rereleader]

Babe wake up, hyperspace pirate is liquifying gases again

[@oppsicle]

blud has gone down some sort of refrigeration rabbithole i mss the old high voltage days

[@michelgrenier1878]

Perhaps it would get colder with a larger and higher volume compressor on the first stage ? Fantastic work tho !

[@seanscon]

Florida man with refrigerant is back!!!!

[@mrtnsnp]

Using a banana as a hammer is also a nice party trick of frozen fruit.

[@jaredkirkland4177]

Curious why you put the oil separator on the liquid line? Standard practice is to have it on the discharge line. Awesome video man.

[@prabalkumarsamanta8333]

Most honest and preservative less ice creams (bars) of water melon, orange and strawberry flavour.😂😂

[@boostin99]

Oh yeah he's back

[@TheWiseGuyzz]

Wooo! Refrigerator guy!!