Ethylene and Auto-c (big discussion about safety,refrigerants,argon + R14 blend etc)

[liquidcooled]

what do you look for in a gas?

[LukeXE]

It depends on unit, for autocascade R23 is really safe and it has low boiling temp (-82).

For cascade the best refrigerant is ethylene (-103*C)

BTW, I changed thread title, hope it`s "on place"

[404Power]

We need a professional autocascade engineer in here

We had one! ... Anyone knows where he went (cryo-tek)??

[n00b 0f l337]

Some other members, who are pretty easy to notice, scared him away.

[Unknown_road]

Some other members, who are pretty easy to notice, scared him away.

since when is asking questions scaring away. He didn't give 1 answer when questions became a little harder then standard refrigeration questions, he just didn't know. When he tried to explain it, it was wrong. pretty logical that some people found that a weird caracteristic for an "expert". The fact that he could fill up an autocascade was more routine then knowledge I think. This doesn't mean I have a problem with cryo (can't blame him for not knowing something) but I'm getting tired of fanboy'ism.

[Blaster]

dont bother trying argon on ethilene, it doesnt work

just swapped the oil sep on my cascade, will try adding r14 to ethilene, with the slhx it should give some result

[n00b 0f l337]

Hahaha did someone say 740 + 1150? Missed it then, yeah that won't help, only works with r14 as far as I know.

[wdrzal]

It depends on unit, for autocascade R23 is really safe and it has low boiling temp (-82).

For cascade the best refrigerant is ethylene (-103*C)

BTW, I changed thread title, hope it`s "on place"

r23 has a vapor pressure of 686psi @ 25 c. thats beyond most standard refrigeration components design pressure.

Not safe

[LukeXE]

r23 has a vapor pressure of 686psi @ 25 c. thats beyond most standard refrigeration components design pressure.

Not safe

But nobody normal won`t use R23 in normal SS stage, in cascade or auto-c R23 is very easy to condense...and for cascade it`s safe, more safe than CO2

[eshbach]

r23 has a vapor pressure of 686psi @ 25 c. thats beyond most standard refrigeration components design pressure.

Not safe

what conditions would have to arise for that amount of pressure to build though?

i mean, I've run the second stage of my R1150 cascade without the first stage running when I was trying to push oil out of the evap, and the pressure went up to like ~460psi and sat there... there wasn't enough restriction in the system for the compressor to build any more pressure...

i'm not saying we can ignore pressures high pressures, that would be a terrible suggestion, but realistically, a reasonably well-built unit with R23 (cascade or auto-c) is not going to get anywhere near 600 psi...

[LukeXE]

... a reasonably well-built unit with R23 (cascade or auto-c) is not going to get anywhere near 600 psi...

...or even 250-300PSI when running with load. R23 doesn`t need super low temps to condense (about -20@15bar), so too high discharge pressure is just...impossible !

[eshbach]

460PSI is realy not sensible. What was the cascade pressure tested to..???

When you're not condensing the pressure will mainly depend on how much gas the compressor can compress (the size of the compressor) and the restriction you have at the other end. The pressure of the discharge will rise until you have equilibrium with gas flow through the restriction and the amount of gas the compressor can move. If your compressor was larger or your restriction was greater the pressure would be higher.

Not to mention that the compressor is also heating the gas so you'll be going above normal vapour pressure temperature.

When you brase your pipework you're annealing the copper making it softer. The first thing to go will be homemade oil separators due to the high surface area subject to high discharge pressure. The soft copper pipe will balloon, as it does this it'll work harden making it stronger, but as its expanded you now have more surface area under high pressure, pressure continues to rise, brased joints fail. Kaboom.

It's not realy comparable, but i've worked with a pneumatic system at 700+PSI acting on a 8" x 3" cylinder which was designed to vent very, very quickly (although still not as fast as a brased joint blowing could do). When that vented it has the same audio volume as a 12 bore shotgun being fired.

The energy stored in an average oil separator at 500PSI is huge.

Tom

I'm not saying anyone should ever run with that kind of pressure, as that's probably too dangerous and too close to the limit of the components. I was just using it as an example of "worst case scenario" for one of our units... an R1150 system with 1/2 hp compressors running with NO first stage. That's basically the worst thing that could happen, as far as I can tell. The only thing that would have made it worse would have been a bigger compressor. But even in my situation, nothing bad happened, none of my pipes ballooned, my oil sep (which was home made) is fine, and my cascade still works.

In normal use, the worst thing that could happen would be the first stage compressor failing, but even then the heat exchanger is already cold and the pressure would build slowly enough for the user to turn off the system before it got to dangerous levels (if it even could get to dangerous levels... as you said, it depends on the size of the compressor, the volume of gas, and the restriction of the system).

That doesn't mean you can be careless, of course. If you don't follow safety procedures when building or charging the system, then all bets are off. an incorrectly built system can definately be dangerous...

[the_new_guy]

how is r170 lower vapor pressure than r23, higer latent heat of vaporization and lower boiling point.

[LukeXE]

The worst thing that could happen would be an obstruction blocking the capillary tube when the system is opperating, and the system then being powered off in the normal way. If the oil sep had a hand valve you could relieve pressure into the low side via the oil line if you "saw" what was happening in time, in a fully automatic system you'd have problems.

Maybe it didn't harm you, but the danger is that someone else reads this and thinks its "ok". It's realy not, and if people copy what you did sooner or later someone will get hurt...

Tom

Tom, you`re writing about me ?

[goranm]

Safety "valve" whit destroyable Cu membrane (one membrane, one use) is wery small and cheap
2$ for membrane, and 5-6$ for it's housing. Every CO2 bottle is equipped whit such safety "valve". It's very interesting to see CO2 bottle when safety "valve" fire away entire bottle in 30 seconds (summer at +40C in shade)
Safety first!!!

Sorry for my bad english

[eshbach]

The worst thing that could happen would be an obstruction blocking the capillary tube when the system is opperating, and the system then being powered off in the normal way. If the oil sep had a hand valve you could relieve pressure into the low side via the oil line if you "saw" what was happening in time, in a fully automatic system you'd have problems.

Maybe it didn't harm you, but the danger is that someone else reads this and thinks its "ok". It's realy not, and if people copy what you did sooner or later someone will get hurt...

Tom

I don't disagree with you, I would never reccommend my foolish methods to anyone... I probably should have found another way to illustrate my point.

[LukeXE]

:p


I tried today R290/CO2/R1150 with small 6800btu rotary compressor, small main HX + small hx before phase separator.

My results so far (unloaded, tomorrow loaded temps):

-87,4*C @ + 0,1bar suction // 11bar discharge

Can`t go lower, with deep vacuum I can hit -100*C without problems, but then it won`t hold any load. Hmmm, must find way to have at least -95*C@0bar autocascading.

[n00b 0f l337]

Eh I think you need to add another stage. The more stages, if the compressor can provide the mass flow, the better your efficiency. 0 bar autocascading low side won't happen though.

[LukeXE]

Eh, tried with more stages, but I had worse results. Fu*king circle...

tomorrow I will test it under load, i`ve got 160W dummy, -70C will make smile on my face.

[Blaster]

loose teh co2, get some r23

and you need a high boiler

[n00b 0f l337]

Isobutanes amazing and easy to get.

[LukeXE]

I will buy some izobutane for tests.

[Shingoshi]

I've read through this to learn as much as I could. But I would really like to know what was the end result of the testing. What I have learned, is to investigate the use of R-14 for my own project.

Shingoshi

[SoddemFX]

But I would really like to know what was the end result

I believe jinu117 disappeared with several unfulfilled orders only to come back with some sad story and subsequently disappear again.

LukeXE took many thousands of Euros from various people around the globe, he then produced for them goods ranging from "thin air" to the mangled wreckage from an automobile accident.

n00b_0f_l33t did much the same on a smaller scale, although generated proportionally more bullsh*t along the way.

I have received emails from two people asking if i knew the whereabouts of Gray Mole and another from a poor old chap who had paid in advance for a system from Blaster.

chilly1 shows up on these forums every now and again, even after 3+ years he still owes ten of thousands of dollars to members of the extreme community.

But why am i telling you this Shingoshi?

It is because the vapour compression cooling forum on xtremesystems has for many years been plagued by bullsh*tters and con artists. The management of the cooling forums has demonstrated time and time again that it is unable to police the forum for the benefit of the community, as many of people mentioned above have held positions of Administrator, Moderator or XIP.

As a reflex action, the knowledgeable members that are left have become wary to anyone smelling slightly more "fruity" than normal.

Believe it or not, 2 - 3 years ago this forums was the de-facto vapour CPU compression cooling forum with a highly active very close knit sub-community.

I hope you have enjoyed our history lesson today - history is a very important subject because by studying the past you can predict the future.

Tom

[teyber]

I've read through this to learn as much as I could. But I would really like to know what was the end result of the testing. What I have learned, is to investigate the use of R-14 for my own project.

Shingoshi

why the hell was a pm not satisfactory