Autocascade Drawings

[n00b 0f l337]

I think cryo-tek has discussed over 2500watts of heat on multi-stage autocascades.

EDIT: What length capillary though for the wierd tube?

[s7e9h3n]

@cryo-tek do you think it is possible for an autocascade to remove huge loads withouht a sharp rise in pressures. Lets say to cool a constant load of 500Watt or maybe more.

And if it is possible what are the recommended gas,compressor size and heat exchanger designs to remove such huge loads.
not intending to build it of course, just an itch to get to know how industrial autocascade builders do their work.

I've spoken to cryo-tek and he tells me it's possible to build a 5hp autocascade capable of removing (iirc) 1500W of heat the size of my polycold - basically the size of a large stereo cabinet

[cryo-tek]

@cryo-tek do you think it is possible for an autocascade to remove huge loads withouht a sharp rise in pressures. Lets say to cool a constant load of 500Watt or maybe more.

And if it is possible what are the recommended gas,compressor size and heat exchanger designs to remove such huge loads.
not intending to build it of course, just an itch to get to know how industrial autocascade builders do their work.

Nyx, The load is half of the question, the second half of the question gives the desired temperature.
500 watts at –100c could be done with about 3 hp compressor. But if you want –130, that could take a 5 hp compressor.
How big you asked. Do you want to build it with Tube in shell or flatplate heat exchangers? I think that a tube in shell, 3 stage autocascade for a 3 hp compressor could fit into a 2-foot cube with working room. A flatplate heatexchanger would fit in half that. Swep makes some nice flatplate heatexchangers if you want to spend the money.

There are companies that make 5 hp units that are the size of a home refrigerator. One company makes a system that is the size of a small refrigerator that uses 2 Copeland ZF33 scrolls. This thing can handle over 3500 watts. Did you ask your self the second half of the question? At what temperature? They do 3500 watts at around the –120c range. I know someone’s reading this and asking “is that at the inlet or outlet of the evaporator?� They tend to use an average of the inlet and the outlet with a maximum delta.

Choosing your refrigerant is a topic for its own thread. Am I rambling? Sorry, it’s cold here and there’s no one to talk cryo with.

[Xeon th MG Pony]

I like wet jacket style exchangers personally remind me of the good ol camp days, but I definitely want to get a hold of a plat exchanger for experimenting purposes.

[Nyx]

1 Word IMPRESSIVE !!!!!

I am really lost for words. Except to say YOU ARE XTREME......

[Blaster]

Nyx, The load is half of the question, the second half of the question gives the desired temperature.
500 watts at –100c could be done with about 3 hp compressor. But if you want –130, that could take a 5 hp compressor.
How big you asked. Do you want to build it with Tube in shell or flatplate heat exchangers? I think that a tube in shell, 3 stage autocascade for a 3 hp compressor could fit into a 2-foot cube with working room. A flatplate heatexchanger would fit in half that. Swep makes some nice flatplate heatexchangers if you want to spend the money.

There are companies that make 5 hp units that are the size of a home refrigerator. One company makes a system that is the size of a small refrigerator that uses 2 Copeland ZF33 scrolls. This thing can handle over 3500 watts. Did you ask your self the second half of the question? At what temperature? They do 3500 watts at around the –120c range. I know someone’s reading this and asking “is that at the inlet or outlet of the evaporator?” They tend to use an average of the inlet and the outlet with a maximum delta.

The evaporators we use on the systems we build here are rather small compared to the phase systems that the companies you mentioned use. As it has to fit the CPU head of the computer.

What are your thoughts about using such small evaps on Auto-Cs ?

Heres an example of a CPU evaporator

[kayl]

cryo-tek you really should show us some pics, i love autoC's.
their a pain to build though with smaller compressors.

[cryo-tek]

The evaporators we use on the systems we build here are rather small compared to the phase systems that the companies you mentioned use. As it has to fit the CPU head of the computer.

What are your thoughts about using such small evaps on Auto-Cs ?

Heres an example of a CPU evaporator

Now that’s a nice piece. How big is this? Small evaporators are fine if there is enough surface area to remove the heat load. You have the same issues with a traditional cascade. Man that’s nice!!

I assume that there is another hole in the top for the return and a Cu sleeve.

[Xeon th MG Pony]

ya that is definatly the best designed block I've seen, loads of surface area.

[cryo-tek]

cryo-tek you really should show us some pics, i love autoC's.
their a pain to build though with smaller compressors.

First I need to get the pictures from the camera to my computer then figuer out how to post them. DON’T LAUGH ! I’m only an Autocascade Geek. Soon!

[cryo-tek]

cryo-tek you really should show us some pics, i love autoC's.
their a pain to build though with smaller compressors.

kayl, I think I did it I started a thread and posted some pictures of a 2 stage autocascade that I'm putting in an old test chamber. I want to do some cryo treating of steel bits and blades.

[Blaster]

Now that’s a nice piece. How big is this? Small evaporators are fine if there is enough surface area to remove the heat load. You have the same issues with a traditional cascade. Man that’s nice!!
I assume that there is another hole in the top for the return and a Cu sleeve.

Theres many nice evap designs more or less like this one, i do try to increase surface area with the grooves.

cap tube is drilled from top till base and a Cu sleeve is brazed. Dimensions are 40mm diameter, 33mm height. So the surface are in contact with cpu head is about 12cm^2

[kayl]

kayl, I think I did it I started a thread and posted some pictures of a 2 stage autocascade that I'm putting in an old test chamber. I want to do some cryo treating of steel bits and blades.

thanxs man. we love cold things here also

[chilly1]

Block Assembly... Original..

[Revv23]

Block Assembly... Original..

And there is the best one.

[mytekcontrols]

To add some clarification to what cryo-tek has proposed in his earlier piping schematic, I offer the following additional information:

Cap Tube Phase Separation Overview

In the diagram above, a method is presented by which partial phase separation is achieved through creating a "back-up" or restricted area immediately following a cap tube soldered into the discharge line within a tube-in-tube heat exchanger.

Cap Tube Separation Detail

When the two phase refrigerant flowing through the discharge line of the heat exchanger encounters the restricted area formed by a combination of the pinch point in the tubing, and the body of the cap tube. A back wash occurs as the liquid part of the refrigerant mix trys to squeeze through. Some of the liquid refrigerant bounces backwards and/or builds up, thus feeding the cap tube.

Advantages to such a system:

• Greatly simplified construction
• No phase separators required
• Single inner & outer tube creates multi-stage autocascade
• Heat exchanger can be used as interconnecting line between condensing unit and evaporator
• Lends itself to creating a very small package

By having the captube live within the suction side tube of the heat exchanger, the cap tube automatically gets sub-cooled by the expanding refrigerant returning from the evaporator and succeeding stages. To improve performance of the system, additional captube separators may be required as compared to a system that utilizes actual phase separators between heat exchangers.

This idea is based on an actual product that was produced in the 80's by a company called Polycold Systems, and utilized a mixture of R-11, R-13 (CFC's), and was later abandoned when they encountered difficulty in creating an HFC replacement charge. Although the design was patented, this has long since run out its 17 year period. The product was called a P-20, and utilized the "serial" heat exchanger as a bendable armaflex covered line connecting the condensing unit to the evaporator.

I was involved in the development of the original P-20 proto-type, and can attest that the system worked quite well, achieving temperatures down to about -80C (low load) and -65C under 200 watts. The P-20 was based on a 3 cap tube design similar to what cryo-tek showed in his last piping schematic.

I'm sure that with a little bit of experimentation, this design could be made to work with a combination of perhaps R-22, R-123, and R-23. And if oil problems are encountered, adding an oil separator to the condensing unit, or the addition of some propane would probably cure it.

[n00b 0f l337]

Hi Mytek, you seem very knowledgeable as was Cryo-tek. I hope you like the forum here and stick around and hopefully are not scared off by any members of this forum. I hope to try the method you listed above when Cryo-tek first explained it to me, but i haven't gotten around to it just yet. The biggest problem i cannot figure out is proper length of capillary tubing for the design. Do you know of any formula's or methods to calculate the capillary length in a system like this?

[mytekcontrols]

Do you know of any formula's or methods to calculate the capillary length in a system like this?

Hi n00b,

Unfortunately I have been away from doing actual design on this stuff for so long now (20 years) that I don't recall the flow calculations that were used. Also I must admit that on several designs intuitive guesses were more the order of the day (I never was especially good with math). When I was deeply immersed in cryo system development, it almost seemed like I had a 6th sense about what would or would not work. Of course I am pretty certain that I wasn't the only one that approached this stuff in this way (just ask cryo-tek ).

Cryo-tek is still very much tuned into this stuff, so I'm sure he could give you some insight on this as well.

Sorry I couldn't provide a more specific answer to your question.

[n00b 0f l337]

Cryo-tek unfortunately does not seem to visit XS anymore, he was scared away by some members on this forum.

[mytekcontrols]

Cryo-tek unfortunately does not seem to visit XS anymore, he was scared away by some members on this forum.

Hmmm... That doesn't seem like him. To be scared away from sharing his knowledge that is (I worked with him back in the P-20 days and beyond... really great guy, went out of his way to help anyone).

So what happened?

[n00b 0f l337]

Eh its a bit unknown but can be seen in his threads that he was doubted and criticized heavily. Most likely this post even will be deleted for being off topic, but your private messaging function doesnt seem to be enabled. I'd really like to learn more of what you know though

[s7e9h3n]

Hmmm... That doesn't seem like him. To be scared away from sharing his knowledge that is (I worked with him back in the P-20 days and beyond... really great guy, went out of his way to help anyone).

So what happened?

Hey Michael,
Welcome to Xtremesystems I think I'd only need one guess to figure out your relationship with Cryo-tek Just a FYI....Cryo-tek was never "scared" off the forums. If you want to know the REAL story, drop me a PM (private message) and I'll be happy to explain. For obvious reasons, it's just better that we keep any personal info of his private. By the way, in case you haven't made the connection, it was my Polycold unit which he worked on http://www.xtremesystems.org/forums/...ad.php?t=97265

[mytekcontrols]

Not really into IM's or PM's, but if you check out my profile, you'll see a link to my website, from there just click on Contact and send me a General Inquiry message. I'll respond from my personal email account, and we can continue this conversation (I probably won't respond today, got some stuff to do, but get back to you soon).

[wdrzal]

I,m the one who questioned cryo-tec knowledge, as he never posted anything but auto cascade designs, even that he was asked to post pictures or answerers to very specific questions. Those design drawings have been available for 15 years or more. He did post the above picture of his work, the one above using fiberglass insulation. That told me he knew very little about thermodynamics or cooling in general. As moisture will pass right thru the fiberglass insulation.A professional working in cryogenic cooling would not do work like that,especially since it would be so detrimental to the outcome,you would lose much of your capacity. It sure doesn't look like the work from a professional to me.

ps: where the crimp is,that would cause a Bernoulli effect, flow would temporally speed up,while the pressure would drop in that area.

[Xeon th MG Pony]

Hmmm... That doesn't seem like him. To be scared away from sharing his knowledge that is (I worked with him back in the P-20 days and beyond... really great guy, went out of his way to help anyone).

So what happened?

He wasn't scared I'd wager royaly pi*sed at one who was scared to have a compeating knowledge to him self so acted like an A*s towards him. Rather then treating him on an equal level acted condecending (at least the un named member seems to be good at condicending)

Or so How I viewed the whole drama.