4-stage cascade

[before]

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

[before]

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:

[before]

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.

[Yuri B.]

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

[before]

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

[Yuri B.]

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

[before]

Thanks

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

[Yuri B.]

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.

[Yuri B.]

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)?

[before]

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.

[Peter_1]

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.

[Yuri B.]

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

[Yuri B.]

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.

[Peter_1]

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 .

[Peter_1]

Originally Posted by Yuri B.

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).

[Yuri B.]

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

[before]

Originally Posted by Peter_1

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.

Originally Posted by Yuri B.

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.

[before]

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.

[Yuri B.]

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?

[before]

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.

[Yuri B.]

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

[before]

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.

[Dualist]

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.

[before]

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

[r1ch]

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

[before]

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.

[before]

A bit more.

[before]

[Foamy]

Those aluminum tubes are those dampers? Against vibration?

Monstreous cascade

[before]

Thanks dude Yes you're right.

[before]

A bit more.

[pina]

Please I´m 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?

[before]

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

[before]

A bit more.

[before]

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

[tanguintel]

perfect =)

[cadillackid]

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

[Pyr0Beast]

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

[before]

just having fun

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

[before]

[cadillackid]

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

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