So, has anyone made a working autocascade yet?

[aenigma]

It has been many years since I've been here and the place seems pretty dead, but I'm curious if anyone else has designed and built a working autocascade? I'm also curious if any of the regulars from that time are around? For example: russell_hq, berkut, bowman1964, gary lloyd and captaincascade? I doubt anyone remembers me since it has been so long and I kind of lost interest since I stopped overclocking.

[aenigma]

Well I guess the old school guys from when I was around are gone, but if anyone wants to discuss refrigeration just pm me. I've been tinkering with another autocascade I threw together out of junk so it got me back into it. The P/T relationship has always been a downfall with the refrigerants I use since they form a blend. If only I could get some ethylene instead of nitrous and propane...

[Charles Wirth]

I have a working autocascade with dual heads. The heads both have bypass valves so they can be controlled independently or both together.

It is running the polycold blend that was modified for higher capacity, not sure of exact blend. The compressor I think is 2 or 2.5hp 220v with excellent capacity @ -100c.

It originally came as a single head "Polycold" and it was modified by Chilly1 for dual linesets with blocks. They mount to all sockets so far.

After Chilly1 modified it he could not get gas blend correct and it was re charged by mytekcontrols iirc, I also think he worked for Polycold.

Thanks S7ev3n, the previous owner of the Polycold.

PCIce made an auto, I don't think it had much capacity but he did show that it worked.

http://www.xtremesystems.org/forums/...-mytekcontrols

Check out his threads

[aenigma]

Oh right on thanks for the reply FUGGER, nice to see someone I recognize from the good old days! That sounds like a beast, I'd love to have the equipment and refrigerants available to make something like that.

Being stuck with nitrous oxide is a pain, it's a pretty lousy 2nd stage refrigerant, but it's what I've been using since me and captaincascade were trying to see who would be the first to make the first working autocascade. I never did make a thread or post any pictures for some reason, just mentioned it in a few threads. I still have it around, but something heavy fell on it and bent a line which broke when I tried to straighten it, so it isn't charged, but it worked pretty good. Well, it did before I accidentally broke my CPEV and went to cap tube on the plate HX. It used to handle around 200-300w at maybe -80 or -90c, I can't remember. Coldest it got was about -102c i believe. It has a 1HP copeland that captaincascade sent me. These autocascades need a lot of compressor power.

I have a tandem compressor setup on the latest one I've been toying with with a small 1/3hp copeland from 1989 and some kind of old rotary compressor from a small window unit and it does about -90c on average. No idea of load capability since it's just a coiled 1/4" evap so I can chill a beer in a hurry lol

They're a headache to fine tune, but that's the fun part. When it's working right then it's boring haha.

Thanks again for the reply, I'll check his threads out, although it seems like none of the pictures work on xtreme anymore.

<edit> Oh yeah, I remember him starting that autocascade back after I made mine, it turned into quite a machine! Those guys work for polycold and with autocascades for a living, that's like cheating :P

[zanzabar]

is that something we will see at IDF?

[aenigma]

What is IDF?

[zanzabar]

What is IDF?

intel developers forum. fugger goes every year and overclocks for them.

[aenigma]

Ahh gotcha, very cool! I haven't done any serious overclocking in years. I'm still on an old P5K with an E8600 3.33 that I would occasionally overclock to something like 3.6 or 4, I can't remember, just a standard overclock though. I did it so I could play FSX or P3D since they are very processor dependent simulators! It just has a heatpipe heatsink, never felt like taking the time to insulate and use my autocascade on it which is why I only used a load tester. This used to be a great computer, it's in the death throes now.

[Charles Wirth]

I also have a tandem compressor unit that hits -60c, it is charged with Iceon89

I am not doing IDF this year, but I should be back next year.

Elmor is doing the OC demo this year with Asus.

Did you want to get your cascade fixed? Needed parts?

[aenigma]

I can fix it if I ever get the ambition to bring it in and work on it, mostly just a matter of straightening a bit of tubing, recharging it and hoping the digital thermometer that was laying on it didn't break. For the time being I'm just playing with the hobbled together autocascade I made. I'd love to see what these would do with ethylene instead of nitrous. Considering that it runs at about -94c to -96c with nitrous I know ethylene would get me below -100c easy. Too bad it's impossible to find, and will most likely cost an arm and a leg.

Just wondering, how hot does the second compressor in your tandem rig run? Mine is a small rotary that has been open to the air for the last 10+ years and I used to use as a vacuum pump, it's hot enough to burn me which is a bit worrying. Amazing it still works after all it has been through without even an oil change, so I'm sure it can handle it. This autocascade also sat outside with open lines for years getting rained on and baked by the sun before I even added the second compressor. I expected worse moisture and oil waxing issues, but only had a clogging problem with some cap tube where I spliced 2 pieces together and it's fine now.

[Buckeye]

I also have a tandem compressor unit that hits -60c, it is charged with Iceon89

I am not doing IDF this year, but I should be back next year.

Elmor is doing the OC demo this year with Asus.

Did you want to get your cascade fixed? Needed parts?

Oh your not going this year
I am only for opening day.

[Charles Wirth]

Americold compressors, compressors in parallel, lineset and block swapped, removed solenoid valve, re gassed.

[aenigma]

Oh , they're in parallel, I see. Mine are tandem/serial so the compressor piped after the first is like the surface of the sun while the first stays very cool. I didn't have enough pipe and fittings to pipe them in parallel, so just working with what I have.

Working in series does really increase the performance, but that second compressor suffers. If I had some small cap tube I could use liquid injection after the desuperheater to keep it cool. But it doesn't matter, it's hideous and just to play with haha. I got to -79c idle running just propane when I was testing it, that's how well series works. Lately it seems like everyday it gets worse, I think that compressor was already pretty much dead before I put it on.

That's a very nice system you have there, very clean and professional looking! I love that aluminum case for it. I've always been function over aesthetics, mostly because it's cheaper that way. :P

I just remembered I had some pictures of my first autocascade on my old myspace page. It's pretty rough looking too, I always planned on making a case for it if I decided to make it look good. Let's see if this link works, haven't used myspace in years. https://myspace.com/121149822/photos

[Raziel]

I have being thinking a long time about making an auto-cascade and have being collecting materials which were thrown away at my workplace. The goal is to hit much lower than -100. I do not expect this project to start anytime soon. Since I have being working on a different project (car) for some time. sure like to read about previously built phase change, the whole auto-cascade thing sounds really tricky to me.

[aenigma]

Yes it is very tricky, but very doable if you understand it. If you want much lower than -100c you are talking 3 stages or more, I am limited to only 2 stages and with a weak 2nd stage refrigerant at that. It forms an azeotropic blend increasing the boiling point of the nitrous oxide by quite a lot, but it is all I have to work with. If you want to discuss autocascade refrigeration you can contact me on skype, my screen name is Vibrophil.

[Raziel]

I'm thinking about dividing the high stage(s) from the low stage(s).
This concept is usually done in big industrial refrigeration plants. Like in ammonia 2 stage systems with a booster compressor http://s21.postimg.org/exqadpknb/Cascade_idea.jpg , the principle used is a cascade condenser. I think this is beneficial because of the lower pressure difference between suction and discharge and the high and low side can have less refrigerants. Maybe that improves the efficiency of the compressor due to less "noncondensable" gasses. What do you guys think about that ?
Maybe this is cursing when speaking of an auto-cascade, it has was done before or it defeats the "simple" single compressor design. I haven't had the time to read everything posted.


a bit incoherent -> will update this post. and make a drawing of the idea. did that.

[aenigma]

So basically a cascade cooled autocascade? I've wondered about that myself, I imagine it would work very well by keeping a better compression ratio on the 2nd stage autocascade side. I don't have access to enough refrigerants to make it worth trying, but I have thought about cooling the r290/r744a autocascade with a high stage r290 system just to achieve a lower 2nd stage SST on the autocascade, I just haven't tried it.

[Raziel]

Yeah cascaded auto-cascade R290 is favorable for the high stage because of the low price.
I haven't crunched any numbers in excel yet. Still reading up on some research papers about auto-cascade cooling.

found this.

[aenigma]

I think you forgot to post your link haha. I haven't really read any research papers on autocascade since I never found much information about them back in about 2004 when I made my first one, so I just dived into it and figured it out.

The price of R290 is exactly why I use it, the same goes for my 2nd stage gas which is nitrous oxide. $70 for a big bottle beats $600 for ethylene even though nitrous isn't a very good refrigerant.

[Raziel]

There is allot to be read.

Some links on scientific research
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf
http://eprints.whiterose.ac.uk/95741...erator_HMT.pdf
http://www.zju.edu.cn/jzus/oldversio.../jzus.A1000050

More info on stirling cooling
http://sunpowerinc.com/wp-content/up...ing-System.pdf
http://www.stirlingultracold.com/lib...r13-vF-web.pdf

some data
http://www.icecoldcomputing.com/libr...g_Data_Sum.pdf

I feel that somehow the auto-cascade hype has seen it's glory days. around 2008-9 most forums halt on this topic. Got the idea to make one 11 years ago. But I had to much other stuff going on back then to do this, and I now have the ability to buy directly from huge distributors.
Building a Auto-cascade is on my project bucket list. Though I still have my other project building a 400 hp turbo car, which still needs a substantial cash injection..

-->Added you to skype Aenigma<--

You mentioned ethylene would be better instead of nitrous oxide. Could there be a way to make this yourself? on the internet I find that this can be synthesised by dehydrating ethanol (ethyl alcohol) with sulfuric acid.
Both chemicals could be obtained easily. https://en.wikipedia.org/wiki/Ethylene

[aenigma]

Yeah, seems like there is a lot of information out there on autocascades now, I just didn't find much when I made my first autocascade. Granted I didn't look very hard for it since I wanted to figure it out myself rather than just copying a schematic or something.

I am sure one could make it themselves but it would be a lot of time and money to get a significant amount. Even ripening bananas produce it which is why some places call it banana gas since it aids in ripening fruits, although it is not pure ethylene as they mix it with co2 or nitrogen I believe.

[bthom]

I'm new to this subject but also very interested. Is an autocascade the same thing as a full two-stage cascade (two compressors with a refrigerant-refrigerant heat exchanger in the middle)?

Regarding ethylene I believe it's used for fruit ripening the other way around, meaning added to the fruit's atmosphere to make them ripen faster but it may also be produced by the fruit itself, not sure. I might even have some. Need to put a regulator on it to see if the cyl is full, empty, or somewhere in the middle.

In any case, I'm very interested in doing a two-stage cascade just for educational purposes. Trying to teach myself some thermodynamics and see how cold I can make an evaporator just using two old compressors.

[aenigma]

An autocascade is one compresor with mixed refrigerants. It is like a casade, but it uses mixed refrigerants and separates them in a phase separator so your high temp refrigerant boils in the 1st stage of the interstage heat exchanger while the low temp refrigerant condenses in the 2nd stage of the interstage heat exchanger, to put it simply.

That is what I meant with the ethylene, it is used to riped fruits, but bananas naturally produce. For example you can put tomatoes in a bag with bananas to ripen the tomatoes faster. If you have a tank of ethylene and want to use it as a refrigerant you better make sure it is pure ethylene and not a mixture with co2 or nitrogen.

[bthom]

Thanks, that makes sense on both accounts. The cyl I have is definitely just pure ethylene assuming the cyl isn't empty. Looks to be an 80cf half-height cyl with proper labels. No exact idea on age but definitely not recent. The last hydro test should be stamped on the cyl so that should put it within a few years or so. I'll take a look. I was google searching for some R23 or R508 in order to keep everything non-flammable. Ordering looks expensive though given it's just a self educational experiment, so ethylene may be a good option.

Does anyone know if there are any major concerns with using ethylene (or any other flammable refrigerant) other than the obvious that a circuit leak mixed with atmospheric oxygen plus a spark equals fire?

Regarding nitrous oxide, I thought about that as well. The temperature values look good but it's a strong oxidizer which most likely means what was clean on the inside of the circuit won't be clean for very long assuming regular copper tubing.

[aenigma]

That would be perfect if you have ethylene, I would love to have some ethylene, you're lucky! It's about $600 to get a cylinder here. Ethylene is safe enough if you take the necessary precautions. The biggest concern would be a big leak possibly causing a fire and that would be very rare. Getting enough air in the system to actually make it ignite is more than unlikely. You would have to let the system be running in a vacuum with the low side open to get enough to possibly create a flammable mixture, and then be unlucky enough to have a winding short out and spark. I have been using propane as a refrigerant for over 10 years without any problems.

Nitrous oxide is inert, it is only an oxidizer if it is heated above 577c which is when it decomposes into about 70% nitrogen and 30% oxygen which is why it works well for drag racing. It has worked fine in my autocascades since i made my first one in 2004. It is only automotive grade nitrous though, so it's not that good. My biggest problem with the nitrous I have is that it boils at -88c but when it fractionates with the propane that boiling point is about 10 degrees warmer. It also has a melting point of -90c, so when I get to -100c I start running into the nitrous oxide freezing and blocking the cap tube until the temperature or pressure increases on the low side. I usually run around -80c to -90c anyway, so not a big deal. It does good for how cheap and easy it is to get.