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Thread: 4-stage cascade

  1. #1
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    4-stage cascade



    Finally, I've decided not to go for an autocascade but a 4-stager unit.

    I've already prepared drawnings with expected size for pipes, item locations, etc.

    Here's the check list. I'm now waiting for the needed parts.




    Steps

    1. Empirical agencement of parts following drawing expectations
    2. Inter-parts piping
    3. Case building (as expected or revised thanks to step 1)
    4. Paintings (both case and compressors)
    5. Modding TXVs (one for R1150 and one for R14)
    6. Installation of parts into the case + brazing of prepared pipes
    7. Empirical realization of a bench station on top of the case + evaporators piping
    8. Finishing insulation
    9. Vaccuming all stages + filling them with R290
    10. Vaccuming again
    11. Charging and testing
    Last edited by before; 05-06-2009 at 03:51 PM.



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    Re: 4-stage cascade

    Started the work about a week ago.

    I'm currently trying to put parts as in the drawings to be sure everything fit prior to work on the case.









    I'll have to paint the compressors as soon as possible because they are really dirty. :shock:

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    Re: 4-stage cascade

    Yesterday's work.





    Today's work.



    R50 evap in front of R14 evap (to be finished)

    Captube won't act as an expansion metric... but as a hand controlled bypass to put some hot refrigerant into the evap if needed to fight CPU cold-bug.



    HX pressure testing.




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    Re: 4-stage cascade

    Hello. May not be the condenser to be a little undersized when all stages engage?

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    Re: 4-stage cascade

    Well I don't think so. This is a 5.2kW; looks huge to me (49cm*38cm*26cm)

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    Re: 4-stage cascade

    Fine, very meticulous work, indeed. What is the full compressors' capacity?

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    Re: 4-stage cascade

    Thanks

    Do you mean cooling capacity wattage, btu/hr, or motor input wattage?

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    Re: 4-stage cascade

    I am an electrician working in HVAC for several years and my very very rough correlation is 1 kWe, 3 kW cool, 9 000 BTU.

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    Re: 4-stage cascade

    3 kW caloric equals, more precisely, not 9000 Btu/h but 10242.
    Your compressors are 46000 Btu, that is 13,5 kW. Is not that much for 5,2kW condenser (at full load)?

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    Re: 4-stage cascade

    Ok I see.

    Well, as far as I understand the condenser will be loaded by compressor motor input wattage, i.e. 4.4kW here (752+923+923+1800). I could be wrong, you know, because I'm not a professional, just an amateur.

    Furthermore, heat load produced by the compressors will be partly eliminated by oil separators. To my own experience a great part of it is dropped out by oil separators.

    This condenser was used into a big 2-stager unit build with a 25,000btu/hr and a 22,000btu/hr compressors.

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    Re: 4-stage cascade

    You may not add all the compressors together in a cascade system. The condenser will only have to remove the heat from the highest stage, that's all.
    The heat from the other stages is 'removed' with the compressor from the lower stages.
    Keep up the postings, I'm interested.
    Yuri B., this is indeed a very rough calculation not useful for this application. Your rough calculation is only valid for AC's - and even then - but certainly not for freezer and not talking about cascade.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: 4-stage cascade

    I agree. Why there are so many solenoid valves - 6 - and will there be back valves on the discharge sides?

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    Re: 4-stage cascade

    By the way, a rough calculation to go by is better than no at all. Once working along with a certified ref mechanic, we ordered by phone a compressor for an AC. Only I meant el power, he - caloric. We have long faces when arrived to pick up the order. From then I have my rough calculation.

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    Re: 4-stage cascade

    Befroe, Yuri has a point, I think it can run without an SV, will save you a lot of money and it doesn't serve a purpose for me .
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: 4-stage cascade

    Quote Originally Posted by Yuri B. View Post
    By the way, a rough calculation to go by is better than no at all. Once working along with a certified ref mechanic, we ordered by phone a compressor for an AC. Only I meant el power, he - caloric. We have long faces when arrived to pick up the order. From then I have my rough calculation.
    But your caculations aren't valid in this case, they're too far away from the real world (more then a tenfold in fact).
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: 4-stage cascade

    El power of 1 kW, for instance, in this case trasfers to approx what 30 kW, or 0,3kW caloric?

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    Re: 4-stage cascade

    Quote Originally Posted by Peter_1 View Post
    You may not add all the compressors together in a cascade system. The condenser will only have to remove the heat from the highest stage, that's all.
    The heat from the other stages is 'removed' with the compressor from the lower stages.
    Keep up the postings, I'm interested.
    Yuri B., this is indeed a very rough calculation not useful for this application. Your rough calculation is only valid for AC's - and even then - but certainly not for freezer and not talking about cascade.
    Thank you.

    Quote Originally Posted by Yuri B. View Post
    I agree. Why there are so many solenoid valves - 6 - and will there be back valves on the discharge sides?
    In fact, each stage (lowest one excepted) will have 2 different expansion ways: one to an inter-stage HX, and another to a CPU evaporator.

    On the line after the liquid reciever I'm considering brazing 2 solenoids both wired to the same switch so that by choosing a switch position, it'll open a way while closing the other. If for instance I need -50C for CPU cooling, then I expect being able thanks to the frist stage solenoids to use only the first compressor without even turning on the lower ones. But if I need -100C, then I'll set the first stage evaporation to the inter-stage HX and the second stage evaporation to its own CPU cooler. Hopefully this unit will be all at once a single stager, 2-stager, 3-stager and even a 4-stager... depending on the need.

    Only the lowest stage, R50, won't use solenoid valves. It'll have a single expansion way to a CPU evaporator.

    I'm not considering using back valves so far. Well at least if I correctly understand. Anyway, I'm gonna use bypass hand valve at each stage.
    Last edited by before; 31-05-2009 at 04:20 PM.

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    Re: 4-stage cascade

    Today I've started working on the box for the three HX. It misses the third one; the others have been fully tested and proved to be leak free.


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    Re: 4-stage cascade

    Hello. I am not a ref engineer by trade to evaluate rightfully, but I admire the creativity of people like you.
    Do the temperatures on this device will reach as low as - 100 C?

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    Re: 4-stage cascade

    Thanks for the kind words.

    Well, to my experience I think first stage will allow -40C to -60C, second one -90C to -115C, thrid one -120C to -135C.

    Fourth one is a mystery because I've never used R50 as a fourth stage refrigerant before. It could do -160C... but -145C / -150C would be nice.

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    Re: 4-stage cascade

    Then your design must be intended for some really scientific experiments.

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    Re: 4-stage cascade

    Could be. I've to think about evaporator adapters for other needs such laser cooling.

    I've started positioning parts of the box second level.





    I'm gonna have to prepare a second insulated box for three liquid recievers.

  23. #23
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    Re: 4-stage cascade

    I'm liking the look of this Xavier, loved your build post on 'Grosse Bertha' on XS.
    I have similar compressors to these, well same as your first stage and larger than your other stages and have been thinking about building a quad stage cascade for a while.
    Watching with interest.

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    Re: 4-stage cascade

    Thanks for the kind words mate

    I've other larger compressors as well, but I'm a bit afraid of the electricity bill to be honest... That's why I've decided to go for moderately powerful rotaries.

    Good luck if you start building a 4 stager unit

  25. #25
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    Re: 4-stage cascade

    Hey before, I'm from BenchTec the same as Dualist - this looks like a very exciting build. Will be watching this one with interest.

    I don't look forward to your electricity bill though

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    Re: 4-stage cascade

    Won't be more expensive than my past units. This one uses moderately big compressors.

    Well, the garage was way too hot during the past 2 months. I didn't work on the unit.
    Time has come to continue working.



  27. #27
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    Re: 4-stage cascade

    A bit more.


















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    Re: 4-stage cascade












  29. #29
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    Re: 4-stage cascade

    Those aluminum tubes are those dampers? Against vibration?

    Monstreous cascade

  30. #30
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    Re: 4-stage cascade

    Thanks dude Yes you're right.

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    Re: 4-stage cascade

    A bit more.
















  32. #32
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    Re: 4-stage cascade

    Please Im from Brazil. I started one development cascade 2 stage, R 404 #1 st R744 #2 st. But I have some doubt. Can I used compressor unit Bitzer IV for to do it?

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    Re: 4-stage cascade

    Hi; I'd say yes; but it depends on your needs I think.

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    Re: 4-stage cascade

    A bit more.












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    Re: 4-stage cascade

    I've worked a bit on suc sides from the HX today.






  36. #36
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    Re: 4-stage cascade

    perfect =)

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    Re: 4-stage cascade

    im intruiged with this...

    iver always wanted to ask about extreme O'clocking.. does your computer really run so much faster and do things faster or is it just the fun of building a kick-butt system with awesome cooling and such that people do it?

    im one to talk as my whole house is an HVAC marvel.. ive never thought about refrigerating my CPU's though...
    -Christopher

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    Re: 4-stage cascade

    Usually it is just for the purpose of breaking (more) records

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    Re: 4-stage cascade

    just having fun

    Well, I've been doing couple of stuff since last update.












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    Re: 4-stage cascade












  41. #41
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    Re: 4-stage cascade

    what do you figure the total BTU of heat moved wit hthe system?

    what will the temperature be at the CPU chip?
    -Christopher

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    Re: 4-stage cascade

    Both questions are pretty difficult to answer cause it'll depend on the number of stage(s) running at once, and how high the CPU is overclocked.

    Tuning has started.

    - 1st stage = HSP @ ~ 10bars & TEV @ -67C



    - 2nd stage = HSP @ ~ 10.5bars & modded TEV (R1150) @ -111C



    - 3rd stage = HSP @ ~ 7bars & CPEV (wide open) @ -112C



    Just for fun. 1st stage is way too cold this way. Anyway, I'm very surprised how well it actually holds to load of the running lower stages even with such a pressure.
    With the CPEV opened like this, the 3rd stage pulls down amazingly fast!!


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    Re: 4-stage cascade

    Nice Job

    You worked some time on it and wasted some amount of money, hope your wife isn't upset )

    kip us posted

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    Re: 4-stage cascade

    Wasted?
    Gained a lot of experience and mostly, this cost some money, time and effort.

    But I don't see this as a waste at all.

    It's certainly not a waste of time nor money for me.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  45. #45
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    Re: 4-stage cascade

    I've tried to mostly used "reused" parts so that the one time investment wasn't too big.

    I've played a bit with superheats to get these. (3 stages running)

    1st TEV @ -55.2C



    2nd TEV @ -101.5C



    3rd stage CPEV @ -130.7C (crap pic sorry)


  46. #46
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    Re: 4-stage cascade

    Quote Originally Posted by Peter_1 View Post
    Wasted?
    Gained a lot of experience and mostly, this cost some money, time and effort.

    But I don't see this as a waste at all.

    It's certainly not a waste of time nor money for me.
    Bad translation on my part
    i men spent (in my lang is the same word like wasted)
    And i do agree it's not wasted time or money, but the parts probably weren't for free so it depends on how cheep he got them

    and as for the time and effort it's well invested

    so .. don't get me wrong you get my respect for it

    Edit: and if u say you got mostly reused parts then it's even better
    Last edited by DEVIL; 16-12-2009 at 07:53 PM.

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    Re: 4-stage cascade

    ... It has been ages since my last update... looks like I need to finish this beast!

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    Re: 4-stage cascade

    I've repaired few small leaks; repaired the second stage TXV and now trying to get it working properly with a mixture of R23 and R1150.

    Any idea on how much pressure is usually used by manufacturers in a TXV bulb?

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    Re: 4-stage cascade

    All good. I'm adjusting the first 3 stages by playing with TXVs.

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    Re: 4-stage cascade

    I've removed the 3rd stage CPU evaporator CPEV because it was leaking by the screw, and replaced it by 1.75m of .8mm captube.

    Evap out = -129.3C; it looks fairly accurate.



    HSP: 1st stage at 10.5 bars, 2nd stage at 5 bars and 3rd stage at 13
    Probes gave -50C for the 1st stage TXV and -85C for the 2nd stage TXV.



    I don't know why, but 3rd stage evaporator takes a very long time to go down to about -117C and then looses nearly 20C within few seconds.... I'm a bit puzzled.
    Last edited by before; 10-05-2011 at 08:50 PM.

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