Single-stage auto-cascade build

[Dualist]

Bloody awesome work there mate

I feel inspired to something similar

[tiborrr]

Thank you, buddy! I think I'm gonna try to see how it does with my HD4890

[SAE]

Don't forget to post results.

[[XC] gomeler]

Nicely done. Looking forward to seeing what you can manage with R1150. How long is the pulldown on this thing and do you have a way to combat the initial high-side pressure spike?

[piotres]

Do You have dummyload ?

[teyber]

holy smokes complete success!!!

[tiborrr]

Nicely done. Looking forward to seeing what you can manage with R1150. How long is the pulldown on this thing and do you have a way to combat the initial high-side pressure spike?

Thank you buddy. No, no issues with this refrigerant combo. Highest peak is at 15.5bar, I have never used bypass to date. Static @ 25°C is 7.5bar, goes to 9bar instantly and then creeps to 15-15.5bar for the next 15 minutes. Then it need around 10 minutes to pull back to ~ 8-10bar (depends on ambient temperature). So, pulldown takes about 20-25 minutes from the warm start I think.

@Pieter: No sorry, I don't cool resistors! But, for the sake of easier tuning I have to persuade my electrical buddies to assemble one for me. No need to drag the computer around.

@teyber: Thanks buddy! I'm quite satisfied, but another 10°C lower full load temperature (courtesy of ethylene R-1150) will make me a happy camper!

Best Regards,
Niko

[Postal Dude]

Very happy to see all your hard work come into fruition. Very nice job. Good to see any shadows of doubt regarding load holding have been well and truley discounted.

I think i need to go shopping

[tiborrr]

Thanks Postal Dude for your kind words! At the moment I am a bit jammed with the faculty related study/work (I'm away from home during this and upcoming weeks) so the ethylene experiment will have to wait another weekend.

Thanks for your support guys!

Best Regards,
niko

[clear cmos]

hi tiborrr can u pm me your autocascade diagram

and what is the black tank near phase separator

[tiborrr]

Hi clear cmos,

will draw schematics of it tommorrow. The black tank is the expansion tank for the refrigerant which helps reducing the static pressure and start-up spikes when the unit is turned off.

Best Regards,
N.

[mytekcontrols]

Very very COOL!!! (sorry I'm a little late getting into the game)

Simple, elegant, compact, fantastic execution. I can't wait to see your future test results with additional gases such as R1150.

BTW; At some point you may wish to "water seal" the outside of your poly foam insulation. I know its closed cell, but believe it or not, water will find its way in, eventually. Keep in mind that you have over 100 C difference in temperature from the outside world as compared to the coldest part of the HXC stack. This has substantial "drawing" power on any moisture in the surrounding air. On the Polycold units that I work with, we have had tremendous problems with the poly foam becoming water saturated over time. Even 3-5mil plastic sheeting is not enough (plastics are slightly porous). Of course all this assumes that the unit will be run for extended periods of time (months-years). Probably the best water seal is like what they do on refrigerators, using welded metal sheeting. Although any paintable product designed to keep moisture from leaking through roofs or into basements would work fine.

[[486]]

Don't know, but do you think If I rather go a bit easier on the CO2 charge and add some R-1150? I think I could get into -85°C league with some positive back pressure, what are your thoughts on this charge?

I know, replying to an old post, thread necromancy and all that But anyways...

If you have R1150, why not go with a charge of R290 and R1150? No worries about dry ice, and pressures shouldn't be a problem. Remembering stuff I read a while ago some refrigerants will dissolve into others and lower the boiling point of the higher boiling one. One would think that 1150 and 290 would do this well, being that both are hydrocarbon refrigerants. The SLHX might even condense a portion of the 1150 into it's liquid state before the phase sep and then it'll be in the "1st stage" half of the auto, cooling off the rest of the 1150 in the "second stage" half.

You've probably moved on from this build by now though...

[n00b 0f l337]

Would work well with R600 or R600a in the mix, as that will further sponge.

[cdolphin]

NOL, not to thread crap, but what does it mean for a gas to 'sponge'?
Anyone know any good reading sources on auto-cascades in general? I am not planning to build one obviously, just trying to understand...
Cheers guys, and great thread, OP.

[ultralo1]

NOL, not to thread crap, but what does it mean for a gas to 'sponge'?
Anyone know any good reading sources on auto-cascades in general? I am not planning to build one obviously, just trying to understand...
Cheers guys, and great thread, OP.

The only comprehensive guide to autoC on the net is the sticky here at XS. Its Mytekcontrols thread about converting a window unit into an AutoC.

[sdumper]

You've probably moved on from this build by now though...

This was completed and sold already...

It was a very slick project and turned out beautiful.

[cdolphin]

The only comprehensive guide to autoC on the net is the sticky here at XS. Its Mytekcontrols thread about converting a window unit into an AutoC.

Brilliant,
Thanks!
/Cory.

[[486]]

NOL, not to thread crap, but what does it mean for a gas to 'sponge'?

The gasses sort of dissolve into each other, like CO2 into a can of soda. When a low boiling point gas dissolves into a higher boiling one it lowers the boiling point of the higher one without raising pressures much.
I wish more people on the 'net worked on autocascades, they're awfully interesting.

This was completed and sold already...

Oh...

[n00b 0f l337]

Part of the issue has been securing the gases. Even amongst the r600a/r290/r1150 build idea, the isobutane is not easy to get in a compatible form to be put into a refrigeration unit. That liquid charge amount has to be fairly on target, so a scale is also required.

[ultralo1]

I wish more people on the 'net worked on autocascades, they're awfully interesting.

Oh...

In the refirgeration world, Cascades are considered the formula one level of refrigeration. Autocascades are considered Apollo moon missions in comparison to the cascades. There are very few individuals that can service the commercial autoCs, and even fewer that understand what is happening inside the system. As an example my bosses boss is a registared Proffesional engineer in HVAC/R. He cannot understand how an AutoC works. He just accepts that it does and that I am not pulling his leg when I explain the theory of operation.

[[486]]

So we're ahead of the curve in the fact that we have multiple people here that understand them? Dangit, I'm getting the urge to either finish my unfinished one [unlikely as it has been sitting open for a while now, it's mineral oil, but still...], or build a new one from the broken dehumidifier I've happened into [it had a leaky evaporator]. I just gotta find a use for one so that I can justify the cost.

[ultralo1]

So we're ahead of the curve in the fact that we have multiple people here that understand them

You want find better info any where else.

I just gotta find a use for one so that I can justify the cost.

Build it then find a use for it.

[tiborrr]

I've recieved this autocascade back into my hands therefore I quickly did a recharge job. Straight R-600a & R-1150. A bit risky on paper but it works wonderfully. First charge contained a bit too much R-600a which had a warming effect on my final temperatures. I've vented some of the gas and recharged some more R-1150. Final charge of ~ -90°C (7.5barg HP/0.4barg LP) was achieved eventually.

Pulldown time from warm idle to -90°C is about 12-12 minutes. I've also added some pour-foam insulation which will need to be cut with wire tomorrow.

-90°C on a single-stage auto-cascade ain't too bad I think!

Charging:


First tuning on R-600a/R-1150. Added too much isobutane:


Final charge later that day:


New super compact auto-cascade in the making!


Best regards,
Niko

[n00b 0f l337]

Very nice sir, hows the load?
Good to see the r600a/r1150 in action. It's incredible to watch if you have a pile of thermocouples on the stack