DIY Cascade Refrigeration System (Part I)

Big thanks to Exotic Chem Lab for providing lots of guidance / info on this project. Check out his channel at:
/ @exotic_chem_lab
In this video I'll be building on the work I did in my last 2 videos (DIY vapor compression refrigeration & Ethylene Production) to create a 2-stage or "cascade" vapor compression refrigeration system that uses propylene (aka MAPP gas) in the first stage, and Ethylene (R1150) in the second stage. The goal of the project is to hit -100C.
A major snag i ran into was that I wasn't getting the temperature drop I thought i'd be getting from my Ethylene refrigerant. Running the second stage condenser below -30C and 400 psi, no condensation was occuring, despite the fact that my Ethylene should have begun condensing around ~300 psi. After some investigation, it figured out that the Ethylene refrigerant was highly contaminated (about 30%) with Hydrogen gas from running the catalyst too hot during the production process. This resulting in the partial pressure of Ethylene being reduced to the point that condensation couldn't be achieved at a reasonable total pressure.
Using a converted ice maker, i built a second cascade system where the second stage was essentially static, as opposed to a continuous loop. The purpose of this was to collect my ethylene and get it to the lowest possible temperature and condense it under pressure, then release it and hopefully allow the hydrogen to be purged out by phase separation. This allowed me to analyze the behavior of my gas mixture, and i found that at -38C, the mixture that should have condensed at around ~16 bar actually required ~23 bar to condense. This information is what allowed me to make a rough determination of the Ethylene's purity (around 70%).
Unfortunately, my attempt to purify the Ethylene through phase separation simply resulted in all of it boiling off because my flow rate was so high. However, in the process, I did manage to capture a temperature drop on my thermocouple of as low as -83C, meaning Ethylene did in fact condense in my icemaker unit and then evaporate again, so while I technically achieved cascade refrigeration, there's more work that has to be done before I can get continuous refrigeration down to -100C, which will be the focus of my next video. The two main areas of improvement are:
-Making Ethylene of a significantly higher purity (95% or higher)
-Fine tuning the second stage flow resistance / high side volume / low side volume for optimal flow rate / pressure drop
Once temperatures of -100C can be consistently achieved, it will become possible to produce Liquid Methane (or LNG), such as what's used in modern rocket engines like the SpaceX Raptor. This will be done by using a third compressor to take natural gas from a residential source and condense it at a pressure of 26 bar (370 psig) at -100C. When expanded back to 1 bar, the temperature will drop to -162C.
Music:
Kevin MacLeod - George Street Shuffle

[@mathildadeer]

"I never thought I'd see a refrigeration cascade, let alone create one!"

[@HitoPrl]

We tried to warn them!

[@PsychoBelka]

But the Administrator assured us it was the purest sample yet...

[@DrenImeraj]

We boosted the anti-mass spectrometer 105%. Bit of a gamble, but we need the extra resolution.

[@hughjanes4883]

"Im no sure sure i want to get to the surface, what if they find what we were cooling down here"

[@arealhumanname4150]

I predicted all of this, you know...

[@AllanDeal]

I’ve learned more about refrigeration systems from this guy than I thought I would ever be interested in I think it’s because it’s a crossover between the diy chemistry that’s been created from scratch and then with some home made janky engineering made on the cheap at home is just brilliant. The only one way you learn something sometimes is just go do it yourself

[@derkeksinator17]

I hated thermodynamics (the subject) but this is a lot of fun!

[@TheMinecraftACMan]

As not only an air conditioning technician, but an avid experimenter, watching you answer so many "what ifs" as you engineer your way through DIYing something this complicated is fascinating in the best possible way. I even learned something today, which was your explanation of why impure refrigerant (something us A/C guys refer to as "non-condensibles") raises the pressure on the high side. That being the law of partial pressures.

[@scottcarr1563]

Industrial refrigeration expert here. Very nicely done. My personal preference for calculating refrigeration cycles is Danfoss Coolselector. It makes quick work of determining discharge temperatures and other refrigeration properties and is quick to populator PT refrigeration cycle diagrams. At first I was worried that you were picking up heat from your aftercooler instead of rejecting heat but then I ran some numbers and it looks like your discharge temp from your compressor should be around 100°C. Those little scroll compressors don't like much above those temps and mineral oil can start carburizing so I would be mindful of that. Try and get your high stage evaporation temp lower to help with this as ethylene has a ton of heat when it is compressed, unlike propane which stays pretty cool.

[@penguiin12]

you know what else is pretty cool? deez nuts

[@derrickenbuenosaires]

I started looking into ethylene as a refrigerant since I never came across it before in the field and it's labeled as R1150 but odd thing is Danfoss won't give you low temperature evaporation pressures for R1150. I think it's maxed out somewhere around -23°C so it's all experimenting after that. Regardless he'll be evaporating below atmospheric. I thought too he might've been gaining heat from his aftercooler. I advised him to put a fan on it to help condense. It's a nifty project he got going on. On my end I probably would've tried something like 404A on the first stage and one of those butane refrigerants or even R437A (R12 replacement) on the 2nd to try out.

[@penguiin12]

@@derrickenbuenosaires you can condense these nuts in your mouth

[@scottcarr1563]

@@derrickenbuenosaires Are you sure coolselector won't do ethyleneat these target temps? I just checked on coolselector 2 and it seems to calculate it just fine.

[@derrickenbuenosaires]

@@scottcarr1563 Sorry I was using the Reftools app by Danfoss. I went into the application again and found that I can now go down to -100 C with ethynol lol might've been a glitch or something. Evap pressure should be around 4 below atmospheric if he can successfully reach -100 C.

[@DerekWoolverton]

So another approach to distilling the Ethylene could be to go down to your local weld shop and have them fill up a foam cooler with liquid nitrogen for a few bucks, then use that to chill down your mix and let all the other gasses out. Yes, I can see the irony here.

[@defenestrated23]

Important note! Most places won't let you put LN2 dewars in any kind of enclosed space. You'll need a trailer or cargo rack to transport it.

[@Skeys13]

@@defenestrated23not even in the bed of a truck?

[@DEtchells]

@@defenestrated23 Ah, interesting and good note for future reference, thanks!

[@leocurious9919]

At least he would only have to do that once, so not too bad.

[@RNA0ROGER]

Would lowering the cat heat not do the same thing at room temps. Ether boils at 35c and unless I am mistaken it could be recycled into the ethanol stream

[@Grove332]

These series are giving me newfound appreciation for HVAC. It's not just fancy plumbing anymore.

[@BVN-TEXAS]

As a industrial refrigeration tech I have to say you never cease to amaze with what you are doing. I’ve forwarded it to several co workers who watch it now.

[@blipman17]

Love it that you got yourself a copper brazed plate heat exchanger. I figured those would be pretty expensive for the budget you're building this, and I figured you'd be quite stuck after the heat exchanger issue of last video. Super cool! Edit: okay so after completing your video, you could pressurrise a balloon with the Hydrogen Ethylene mixture. Since H2 is really difficult to keep contained, it'll naturally diffuse the membrane. The Ethylene will also, but much slower since they're bigger molecules. You'd have to have some form of purity test to find out your purity of your mixture, but that doesn't sound undoable. Just very low yield. Another method is to try to bind the H2 to something like Iron Oxide and then filter out the water like you did before. Not sure if this is at all possible, or practical. Nonetheless, some cool chemical reactions with to bind hydrogen can be found here: en.m.wikipedia.org/wiki/Hydrogen_storage

[@WetDoggo]

that could work, but since he already got the high pressure condenser he could try draining the liquid ethylene straight down into another smaller vessel with a valve and disconnected, so the liquid displaces all the gas up to the valve. After disconnecting you should be left with a nice pure sample of high pressure ethylene. I didn't pay enough attention to be sure if this is a bomb, but I figure you will figure it out... before it blows up of course 😅

[@WaffleStaffel]

You can pick up a brazed plate heat exchanger for under $40 on that giant Chinese site, the one named after the Arab character and his 40 thieves.

[@leocurious9919]

Note that ethylene should also get out of the balloon fast-ish since it can fairly well dissolve into the rubber. Maybe try butane and see how fast that escapes as a comparison to hydrogen and air.

[@absalomdraconis]

​@@leocurious9919 : Hmm, use several diameters of rubber hose running through each other, all in turn running through a lower-leakage pipe, with lowest pressure on the outside and highest inside, and you could produce a continuous-flow fractional distiller system.

[@leocurious9919]

@@absalomdraconis As long as hydrogen is getting through the hoses at a significantly different speed: Yes, I guess so? Seems super sketchy tho. Note that it is not a fractional distillation, nothing is liquid. It is mostly diffusion.

[@Grak70]

I hate Sundays, but you’re reversing the trend for me with these videos. Thank you!

[@Assault_Butter_Knife]

What kind of a monster hates Sundays?

[@Grak70]

@@Assault_Butter_Knife the kind who hates rushing to get my shit in order before having to go back to work on Monday.

[@jamesmihalcik1310]

The importance of a home scientist should never be lost to time, nor government. Most profound discoveries were made in a garage, basement or an attic. Fantastic work!

[@AndyLowe]

In the winter of 1994 I was a freshman volunteer crawling through access tunnels stringing fiber for the new "World Wide Web" on campus. Hyperspace, you are the living embodiment of the future I was dreaming about. Well done sir.

[@joeflosion]

Since Tom shit the bed with the Cubane series this has become my new "must watch immediately" youtube binge. Love the vids my man

[@benlee4940]

You mentioned that Ethane was more complicated to produce, but I don't think it is. Look at Kolbe electrolysis, Scrap Science did a video on it recently. If you do the electrolysis, run the generated gas through a gas washing bottle (you can make one from a jam jar) with Sodium hydroxide solution in to remove the Carbon Dioxide. Add an indicator to the hydroxide to see when it's getting depleted, or you could calculate the required amount and use an excess or chain a few of them together to ensure complete removal. The collected gas should be Ethane and water vapour. The electrolysis should give quite pure gas, but will take ages to collect any decent volume. To reduce the water vapour content before collecting you could add a drying tube made from silica gel or another method. If you require a gas with no CO2, then you could run the dried gas through a tube filled with dried solid Sodium hydroxide.

[@user-wi5vi7dd3z]

My favorite series on KZbin right now. I catch myself every few days checking your channel for the next video 😂

[@davidwilliams5497]

Was literally rewatching this series going back to the pulse tube cooler eps last night. Glad to see you’re still getting closer to the goal. I’ll be anxiously awaiting the next installment.

[@tntamaster3879]

YES! I waited for this video and i swear i had rewatched all of the videos in this series at least three times, such a good quality series

[@AllanDeal]

I’ve learnt I’m really interested in refrigerated systems. Who knew

[@tulsatrash]

I love that we get to see what is being talked about using "practical effects" (actually doing it) rather than us just having to use our imaginations. There is a lot of important how-to knowledge that doesn't come from just having to imagine things.

[@Xsiondu]

I remember when this was a shake weight ductaped to a bong. Now look at you. Got a control panel and toggle switches.

[@richiec7700]

Seems like some LN2 would make purifying your Ethylene easier.

[@MarkFunderburk]

Knowing enough to generate your own refrigerant and build a 2 stage cryocooler but not having pipe dope on hand is both magnificent and terrifying. Love the videos though.

[@Puffalupagus360]

The best option for your second stage compressor would be a semi-hermetic compressor. Great flow rates and you don't have to worry as much about the compressor oil getting trapped in the low side and the windings won't be running in a vacuum.

[@r0cketplumber]

Ethane might be complicated to produce, but you can just buy it. Heck, at XCOR we used it as a rocket fuel for more than ten years and simply called up our welding supplier whenever we needed more. Amusingly, because it has modest pressure at ambient temperatures, ethane was supplied in the oldest bottles we'd ever seen, ones that had been derated due to their age. The record was a bottle that had hydrotest dates stretching back to 1915, almost a century old at the time.

[@PsRohrbaugh]

Sorry about the last minute failure. This channel is amazing. I REALLY want to do my own version of these projects and it's an amazing resource.

[@ericlotze7724]

Refreshed my KZbin Feed at JUST THE RIGHT TIME!

[@Shazzamm1971]

From someone who has built and operated cryo hydrogen systems, craftsmanship counts. When you make liquid air are you prepared for the fun that will bring to even what you touched your connection points with. Where is the JT valve? Use the pressure drop that provides to force the phase change at the HE. Matching the flow needed and where your system deviates from everything from surface area of everything. Compressor flow, pipe, where is your jacketed piping? Losing before measurement? Joules Thompson valve and that flow pulling it through the latent heat zone. Vacuum, gravity, and even a simulation run fifty ways on the computer are your friend. Good call on the toxicity of the flourene solder. In industry you wouldn’t believe the risks others love to put the guy commissioning.

[@beguilingfire]

You might be able to get purer ethylene by refluxing ethanol with phosphoric acid - the only product is ethylene. I don't think it's quite as continuous as your alumina catalyst process though, which could therefore be faffier

[@3089io]

I've been hacking towards some things for about a decade that line up pretty well with the stuff you post videos about. You've really inspired me to push harder on quite a few projects I have back burnered and given my a TON of information to jump start them. Thank you. This in particular. Yeah. Solving this problem is huge. You've done a fantastic job.

[@olduhfguy]

I am intrigued by your experiences with a DIY cascade refrigeration system. I took the 'easy' way out and found a commercial used/surplus one on Ebay that produces -110c temps. In the event it ever fails I will use the knowledge I have picked up watching your videos.

[@skenzyme81]

This will be great. That Ethylene video was BANANAS. 🍌🍌🍌

[@mike25620]

ive been checking everyday for the last week for this video

[@J.Darwin]

Was suprised to learn that the capillary length influences the pressure, very cool.

[@-r-495]

Wow! We tore out out cascade cooling systems as they weren‘t very reliable. One can drive compressors near their limit/just outside it by replacing the valve plates (higher compression, higher wear) and with R404 you‘d reach similar temperature differentials. Or go cheap and use a Mayekawa screw compressor 😅 -100C with their Pascal Air. I salute your efforts, this is so good because I had forgotten why you want to reach these low temperatures!

[@-r-495]

About leaks: Leak testers for hydrocarbons like propane could work for you too. They have a flexible sniffer that can reach the spots where the leaks usually occur (the least accessible point of failure).

[@weedium]

I get enjoyment out of visualizing the refrigeration cycle, it started when I was a a boy and continues to this day. I have always wanted to try this.

[@Gabriel-yd4bq]

The background song in the intro brings back memories

[@rodjownsu]

Years ago I used to fill balloons with HHO and blow them up, if the balloon stayed pressurised for too long though all the hydrogen would escape as the molecule was so small, the balloon was essentially acting as a molecular sieve. Filling a large balloon up with your contaminated ethylene+ hydrogen may filter out the hydrogen component, probably not air though... Just a thought ;) love your work man! Been watching every video with massive interest as I love refrigeration!

[@vikenemesh]

Nice thought. Working with ~200L gas in ballons at 1atm is not totally impossible, but a garage full of ballons leaking hydrogen sounds like a REALLY fun insurance case :D

[@rodjownsu]

@@vikenemesh haha true, guess that will motivate him to ensure it's relatively pure in the first place ;)

[@chemholio8700]

Nice mention on Hackaday…👏👏👏

[@garrettmandujano2996]

You’re so close man! Can’t wait to see your cryo-cooler

[@AiOinc1]

Seriously, never have I understood so little yet been so entertained

[@bungalowjuice7225]

Chilling story. You're a cool guy.

[@Aasishsapkota2059]

been waiting for this video so long that i forget about this

[@arthurlondero7036]

I watched the video as soon as it came out, and I'm coming back here daily waiting for the update, amazing project, and amazing channel.

[@tootalldan5702]

I'm glad you shared your "lessons learned" about your progress. I didn't think the hydrogen would be saturated in the Ethylene

[@Moist_yet_Crispy]

These episodes are always a treat. Looking forward to the next one.

[@jameswiz]

You can buy silver solder on a roll, with a silver solder Flux, and it's strong enough that I use it on custom length bandsaw blades

[@ratibbaker8126]

Don’t be afraid of the suction running in a vacuum! In the old days even household refrigerator/freezers ran in a vacuum! Early cascade systems used R12 for the first stage and R502 for the second stage! Note that in those systems we skip the oil separator by using pentane to keep the mineral oil flowing. Propane is less miscible in POE and therefore slightly more efficient but needs velocity to return the oil. Probably not an issue in this small close coupled system. Note that there are cascade systems that use a single compressor with two different refrigerants called an “auto cascade”!

[@The.Talent]

I am loving this series. It's like all of the good stuff and none of the mind numbing stuff from my thermodynamics classes at uni.

[@OtherWorldExplorers]

Two things One your AC guy could never pull the wool over your eyes Two it looks like you have about $4,000 worth of copper. That was more or less just an observation Awesome as always

[@crackedemerald4930]

This is one of my favorite ongoing animes

[@karstens7893]

This is sick! Excited to see the final product

[@kayakMike1000]

This is a master's level physics project.

[@SirCodeJunkie]

Great video. Love the mistakes with the dead pan humor. The mistakes are the real value to the experiance.

[@kid_missive]

Amazing technochemisty brought to the masses that could be utilized by the citizen scientist to unlock all kinds of high tech DIY. Great content and entertaining narration - thanks so much!

[@topfeedcoco]

This is great stuff man, I've really been enjoying the last few months and even with a little physics and a decent HVAC background I find myself rewinding, pausing and visualizing, but thank you for not dumbing it down.

[@danilofjf]

one thing that I caught myself thinking now, you have to include a safety valve in the ethylene condenser. As shown in the video, if the first stage stops and there is no cooling in the ethylene condenser, there will be nothing to prevent the pressure from continuing to rise until one of the components fails. that would cause an explosion

[@BoschPianoMusic]

Have to admit during your first video in this series, I remember thinking by myself this shouldn't be too hard I could probably do this myself. Seeing your struggles and doing everything "the hard way", I'm reconsidering those thoughts! Great videos!

[@conno7356]

Discovered your refrigeration series and may have ended up watching every video you have posted.. love what you are doing keep it up!

[@AllThingsComplex]

I love your videos on this subject, and I love that you keep on trying to find a way.

[@DEtchells]

Wow, what an incredible journey! I’m beyond impressed with the depth of your research and analysis of what’s actually happening in the system. - Not to mention the level of focus and sheer energy you’ve brought to the project. Two thumbs way up, I can’t wait for the next chapter! (I’ve been watching all of your vids from start to finish the moment I see them in my feed 👍👍😁

[@zorangeblaze01-nt2xj]

Love the boot- strap approach. Thank you for sharing.

[@robertpoynton9923]

I have no idea what this guy is saying but it's super interesting. I need this video dumbed down even more 😅

[@mystamo]

This channel and the person behind it are legendary.

[@CriticoolHit]

I can't wait to see you get this working properly. I want to see it run as planned.

[@RebuildRoger]

Every thing going above my head but still watching your videos (refrigeration series) 😅

[@weeb3277]

We'll reach Cascadia soon.

[@miklov]

This is great stuff! Whenever something doesn't pan out I like to see that as gaining wisdom. Sure, it can be quite frustrating to put a ton of work into something and it doesn't work, but then eventually you get to the bottom of it and it does work. When that happens, it may be even more rewarding than if it had worked out great the first time around. At least that is what I keep telling myself. Thank you for inspiring and informative content!

[@rushoffman965]

I cannot wait for the next part!

[@wtechboy18]

this entire project is super interesting to follow. Best of luck with your ethylene problems.

[@Lukesab3r]

Really enjoying this series It's been a ride, for sure!!!! Thanks for playing out what went wrong - so often we see content creators just telling success ... We learn from trial and error, and experimentation! Keep up the awesome sauce, can't wait to see the next!!

[@Caliboy90045]

I’m retired now but I worked on cascade systems and I charged my 1st circuit 12 subcooling. With -10 to 12 superheat. At 100%. My second stage I charged to 12 subcooling and and 12-13 superheat but you can go as low as 10 due to low oil return from evap. Note you must lower oil viscosity on second circuit. Note that high head with low suction may be txv issue or restriction on a cap tube. Hope this helps always pull a vacuum lol

[@joshwasho9110]

I love what youre doing man, every time you post I stop what I'm doing to watch! Keep up the good work

[@yasirrakhurrafat1142]

Been waiting for this to drop!!! Now this is an artist makin dope art here!

[@dennisdecoene]

Not a fail, many lessons learned. Keep'it coming it is so interesting to follow this project!

[@hectoralmonte3629]

This is the neighbor you want in a disaster or zombie apocalypse.

[@dumahh]

This is good stuff. I work everyday with cascade systems and compound cooling and I find this very entertaining

[@KevinAshcraft]

SO FREAKING COOL!! GL ON PART II

[@JoseSilveira-newhandleforYT]

Fascinating, this project of yours! Also, a load of good information is flushed on the viewers - many pauses needed 🙂

[@AjinkyaMahajan]

I wanna learn more about this cooling technology. Thanks for sharing

[@Nobe_Oddy]

This is INTENSE! You are a friggin GENIUS!

[@firefox1136]

its 1:24 am and I have school tomorrow but I have to watch this. How bad could 20min less sleep be 🫠

[@danielbuckman2727]

Awesome video! Thanks for sharing.

[@Vinzmannn]

Oh man "loaded with flammable gas". European legislation for automotive heat pumps will likely limit refrigerant charges for propane systems to 150 g max. R1234yf which is currently in use regularly has charges of over four and a half times that. Now I hear some say: "yes, but this is good because propane is flammable, I use it in my grill". R1234yf is also flammable and at that additionally produces HF when cumbusting. So it will not just burn your face off like propane, it will also make an acid which s so corrosive it attacks glass. Just because people have heard about something, it is not automatically more dangerous. Great video, love your stuff.

[@JohnBoen]

I am following along in this project... I have been playing with refrigeration since late January. Today I am using my CNC to put grooves on both sides of a copper plate. This will fit between two water sprays... trying to make q cheap heat exchanger... Even these little scraps of copper are going to be stuffed back inside the grooves. Much fun watching your approach :)

[@fburton8]

This is such a cool project!

[@justineloi1234]

This chanel is gold! Keep up the good work man !

[@Aaku13]

dude I love your videos. thanks so much for producing these videos. I feel like I learn so much everytime.

[@markhonea2461]

Yes , one would measure the inlet and the outlet. Really the outlet reflects the numbers that correspond to what is actually happening in the condensor.

[@vesivanov5706]

Great video, I'll be looking forward to see the following one!

[@jeffflanagan2814]

Loving these video's, learning a lot!

[@WetDoggo]

Try draining the liquid ethylene straight down into another smaller vessel with a valve and disconnected, so the liquid displaces all the gas up to the valve. After disconnecting you should be left with a nice pure sample of high pressure ethylene. I didn't pay enough attention to be sure if this is a bomb, but I figure you will figure it out... before it blows up of course 😅

[@jasonmawdsley4139]

Man I'm loving these videos

[@AlessioSangalli]

I've been waiting so much for this

[@neatoelectro3687]

This is insane work man! Good stuff.

[@wanttoseemore4596]

This is awesome thank you for sharing

[@raptorjesus3396]

High quality unsolicited fridge pic video

[@alex4alexn]

i love this series, cant wait for the next episode

[@SunriseCrawlers]

This is very neat I'm learning alot from it. I'm wanting to try and use some of this to make a 12v system for my truck. Aka a 12v ac unit for lunch time. Having a hard time finding a proper pump for this

[@mattholmes8214]

Highly recommend leak lock thread sealant

[@lumotroph]

Incredible project! Clicked in a microsecond. Keep going! 🎉

[@retrofitter]

I was thinking about how to more evenly heat the catalyst chamber last episode. It will be interesting to see what you come up with

[@joshua-the-seer8494]

Hvac tech here : you need to pull a deep vacuum everytime you open the refrigeration circuit to atmosphere. Otherwise you won't have pure Refrigerant in there. You'll have "non condensables" which eventually will destroy the compressor. Also, the P/T charts won't be accurate. Otherwise, great job!