Rotary 2 stager with metal case and some extras

[Cronos]

100-110*C compressors' top, so to hotest place .

Isn't this too much? Reliability may be affected.

What about sound level? Is it acceptable for the 24/7 use? And overall, is it possible to use that unit for 24/7 operation?

[n00b 0f l337]

I have a feeling she's loud, might just be the 120mm fans, or the two rotarys, but its a feeling. Might just be me feeling the vibration of him using the unit over there in Europe
As for compressor temperature, I think they could use a bit more cooling, and lower compression ratio, but thats less performance. So its a balance.

[Blaster]

Guys, its a cascade! Its not to be used 24/7, its not built for that.

Of course its loud, all rotarys builds are loud.

[Cronos]

Blaster
I thought rotaries and scrolls supposed to be more quiet than pistons?
Less moving parts and so on..

If i were to build 24/7 cascade chiller, what compressors should i choose?
Provided i want acceptable sound level and reliable operation.

[Clemmaster]

There's nothing more quiet than danfoss piston's compressors for a power-rating. The SCxx are quiet, the noisiest may be scrolls compressors (I had 2 scroll compressors at school that were very noisy ).

What coolant would you use with a cascade chiller tell me?
Under -40° you must do your own coolant with ethylenglycol and I'm sure about its viscosity under theses temps ...

Be aware that you can't use ethylen for that purpose but R23/R508/R170 as you'd be working with very high pressures (or maybe use a little compressor on 2nd stage with very short captube but that's not advised)

[Cronos]

Clemmaster
It is offtopic here, i am afraid, but liquid will be pure ethanol pumped by positive displacement pump (micropump series probably). The pump is the main problem, actually, it is rated to -46C. I wonder will it work at -90-100C?

Lets get back somewhat to the topic, i'd like to ask is it possible/advantages
to use electronic valves on the second stage?
I want to use electronic valves with stepper motor everywhere and largely oversized condenser on first stage and plate HX on second.

[piotres]

I don't think 110*C is too much for rotaries . I've heard that 130*C is safety limit for them .

Like Blaster said - almost all rotary build are loudly . But cascades can be used 24/7, why not .

About Danfoss SC series and loud ..owner of that cascade : http://www.xtremesystems.org/forums/...highlight=tiny said me that single-stage with SC21CL and 230v fan on condensor has been more loudly that this cascade, so 2 rotaries .

Thanks
Peter

[n00b 0f l337]

Heh, as long as the thermal overload doesnt trip.

[Jort]

Hey peter,

i do not advise to use that shock absorber in that position.

It's ment to be used straight afaik.

For the rest you made a really nice cascade!!! :o

[Clemmaster]

I've got a SC18B and it's quiet

[Xeon th MG Pony]

Perhaps I'm being picky but it isn't a shock absorber at all, rather vibration dampener, and jort you are quite correct, they are meant to be straight and level. In the position OP has it in it has a greatly increased risk of forming leaks.

[Jort]

Perhaps I'm being picky but it isn't a shock absorber at all, rather vibration dampener, and jort you are quite correct, they are meant to be straight and level. In the position OP has it in it has a greatly increased risk of forming leaks.

Tnx for the verification

[Blaster]

Blaster
I thought rotaries and scrolls supposed to be more quiet than pistons?
Less moving parts and so on..

In the size engine we use for cpu cooling piston are quieter, for high power, scrolls become more efficient and quiet, an equivalent scroll to this one would be quieter.

If i were to build 24/7 cascade chiller, what compressors should i choose?
Provided i want acceptable sound level and reliable operation

depends what temp and capacity you wanted, and what you think its acceptable sound level
maybe best option would be to put chiller at distance

[V2-V3]

Congrats on the -100C, I must say your box is one fine looking machine!

[kayl]

I don't think 110*C is too much for rotaries . I've heard that 130*C is safety limit for them .
Like Blaster said - almost all rotary build are loudly . But cascades can be used 24/7, why not .
About Danfoss SC series and loud ..owner of that cascade : http://www.xtremesystems.org/forums/...highlight=tiny said me that single-stage with SC21CL and 230v fan on condensor has been more loudly that this cascade, so 2 rotaries .
Thanks
Peter

110c is ment to be close to max running temp, but as the guys say cascades are for benching. If the compressor does get too hot they shut down anyways. Ya can normally get atleast 4hours benching though no trouble

[Brettbeck]

Nice build Piotres!

Guys, its a cascade! Its not to be used 24/7, its not built for that.

lol I remember FUGGER saying at an exhibition he went to he left his cascade running for several days (IIRC) and it ran perfect.

[n00b 0f l337]

Those weren't rotarys either, and they were pretty well cooled if I recall. Triple SC12MLX I beleive.

[Brettbeck]

Yeah I think it was at CES, so probably air conditioned in the room.

[n00b 0f l337]

Eh not as much as the reciprocatings run at lower temperatures, and without accumulators they get plenty of cooling, and sometimes floodback. But even a 120mm fan can cool em down. I've found that most rotarys if you put a fan above them blowing down, they cool down quite well.

[Brettbeck]

Ahh that's a point. I remember him saying when the unit was built the compressors didn't even get warm at all. The returning gas probably still cool.

[n00b 0f l337]

Yep, though something like r11 would probably be used in the industry, or often in a autocascade that needs compressor cooling badly.

[Moc]

Yep, though something like r11 would probably be used in the industry, or often in a autocascade that needs compressor cooling badly.

Nowadays, R123 is the substitute for R11 .

[n00b 0f l337]

Yes it is, but you use whatcha got
Not to mention its pretty hard to find non-barreled r11 or r123, small quantities are more expensive and annoying.

[SoddemFX]

NoL,

Or could it be that a 12cc LBP/MPB recip doesn't have a 1KW+ motor in a rotary designed for HBP A/C...

Ethylene is a hot discharge gas, you'll have a high superheat on ST2 and you've got a lot of motor power going into the system, it'll be hot.

Nice cascade, very compact

Tom

[Clemmaster]

+1 Tom, with R22 ethylen is a gas that involve a very high discharge pressure, you must take care about that effect, that's probably the cause of such hot compressor on 2nd stage