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Re: 3-stage cascade
Firstly, I've charged a bit of refrigerant into each stage and then adjusted under load. :)
I'm using this cascade frequently and get -110C and -120C under huge CPU loads.
The only matter so far is 3rd stage because I can't really play with the CPEV. I think that need a liquid reciever here. :)
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Re: 3-stage cascade
Very impressive system you've built, albeit as I'm sure you know, strangely piped. I try and autocad or 3d model in other forms my entire system before I even pick up the pipe bender. Try it sometime! The effort before makes beauty in the end.
Your results are great. If you ever have any problems with r14 on its own, a good method is an ounce or two of r600 or r290, plus a double volume oil separator. Something like the Temprite 901 or 902 will be helpful. Assuming your rotarys are not meant for this application and are simply charged with AB, try charging the oil separator with Zerol 150.
Also with r14, your going to want a nicely sized expansion tank for sure. Not sure if you've used one on this system. Oh and really your stuck to captube, so keep your liquid line very short, and attempt to get very good contact between your post-evaporator and capillary tube.
Hope some of that helps!
(Other option is to autocascade the final stage, you certainly have the compressor size, and you can reduce some load from your 2nd stage, something like R123, R22, R14, argon will allow you much lower temperatures with a subcooler. The r14 could reach loads towards -140C that way. R123 and R22 will chill the flow before it reaches your 2nd stages evaporator and help alot!)
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Re: 3-stage cascade
Thank you! :)
Well, I was very rookie (and didn't had so much tools) at piping when I started working on this cascade. I would probably do way better now, and to be honest I'm thinking about disasembling it to rebuild it sometimes. :)
I'm not using captubes anymore here but CPEVs at each level. Well, I'm using captubes only to connect 3rd stage expansion tanks to succion side (black cylinders on the left).
I've already thought about using another oil sep for R14, but this ShineYear isn't too bad I think. The cascade can handle about -125C during hours without issues.
The only matter is, well at least I guess, the 2nd stage. I'm not sure R1150 is really appropriate here. I'm waiting for a bottle of R23; it might be better.
Refrigerants are R290, R1150 and R14. Well, R1150 is a bit hard to use here. It needs a quite low temperature to condensate, not easily achieved with R290 under load, and when condensated it goes down to a very low temperature, may be too low for R14 to work appropriately.
R290, R23 and R14 should be better.
:)
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Re: 3-stage cascade
I've done some work yesterday. I have now to finish re-insulating.
- R23 replacing R1150 at 2nd stage
- Expansion device entirely re-done at 3rd stage
- About -123C (probe) to -126C (mano) unloaded with 3/4 opened CPEV
- About -122C (probe) after 10mins with a 1200w hair drier next to the evap with 3/4 opened CPEV and massive flow into compressor suc
http://img8.imageshack.us/img8/8100/img8245zg4.jpg
http://img8.imageshack.us/img8/4209/img8248kl1.jpg
http://img156.imageshack.us/img156/7671/img8250xh2.jpg
http://img156.imageshack.us/img156/3905/img8251ou0.jpg
http://img187.imageshack.us/img187/7183/img8252lo7.jpg
http://img156.imageshack.us/img156/9467/img8253mb6.jpg
http://img8.imageshack.us/img8/9245/img8254yg4.jpg
Can't wait for testing under CPU loads.
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Re: 3-stage cascade
I've lost some R14 a small leak. Well, I've repaired it and moved back to R1150 at 2nd stage.
- Fully opened CPEV
- Evap at -131C probe (manometer indicates a bit less than that).
- Evap at -129C probe after 15mins heating with hair drier. (not a fine load tester BTW, but loosing only 2 degrees here is not so bad actually)
http://img293.imageshack.us/img293/466/img8316eg1.jpg
http://img293.imageshack.us/img293/2023/img8306pi2.jpg
The HSP of R14 is very low. 5bars (not 4, gauge is wrong).
http://img511.imageshack.us/img511/4200/img8307vn3.jpg
http://img293.imageshack.us/img293/5211/img8300ne3.jpg
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Re: 3-stage cascade
what is the pcb for ? have u ever thought about just using a helium system
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Re: 3-stage cascade
The PCB is to attached the evaporator over a CPU.
Well, a Liquid Helium sys would be way too low. Not all CPUs can do -130C or even -100C.
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Re: 3-stage cascade
I've started working on a HX to help condensing at first stage.
http://img244.imageshack.us/img244/3958/img8344.jpg