-100c single stage

[Gray Mole]

Well it's sort of an Autocascade, and sort of not...

I have an AC window unit i got cheap and thought I'd play a bit.

Really the inspiration is Drewmeister more than anyone else. He's had a system for blending gasses that's given some amazing temps, and working in the science and medical cooling field of cooling, has the gasses and experience to make it happen.

There was a time that I wasn't a 'believer' but I realised that any limitations I placed on his work, I place on my own.


Took around 4 min to get the initial cooling working well, then a steady drop over the next 5-10 min to around -90c. Around 5 min after that, to -100c.

So this is a 1/2hp rotary, and the blend is 134a/290/1150. Enough of the lower pressure gasses to get started, and enough Ethylene to maintain the low temps.


Not pretty or even really well organised, just brazed in what was needed without a lot of fuss. Not going to be a finished unit how it is.


No load tests yet, but I'll clean up the evap and all that, get a bit better insulation, and go from there. I don't expect much, but if I can get even a 20% Ethylene 'cooling blend' to work, then that's enough to pull the temps down on load dramatically.


Currently around 1/3 of each gas, but I don't expect the Ethylene to remain at that level when it's entering the evap. Hard to explain exactly, but I am hoping that it can stay over 15% fully condensed Ethylene for actual evap cooling.


It's autocascading obviously, but not with phase separation as such. More of an enhanced blending system within the captube.

Wish I'd gotten pic of how it's been brazed, but the manifold in the pics is the start. The return gas uses it as the suction line heat exchanger, and then captube is a 2 part setup.

The Captube is coiled enough to slide into the SLHX, and 2 kinds.

First length is 1/8", around 7'. Then it's brazed into a 6" piece of 1/4" copper pipe. Then it carries on as .031" captube, around 3'.

The 1/8" and 1/4" are coiled and brazed into the SLHX and it's a fairly tight fit.

The 31 is just wrapped, and I'm thinking of brazing that to the pipe.

No flexline for this though. No intention of this being a 'unit' just some experimentation. The gas blend is pretty standard to be honest. Started with a 40psi charge of 290. Then up to 80psi with 134a. After that, around 150psi total static with the 1150.


I added another small amount of R290, but my static is still around 130psi with a cold suction line, more likely 150psi still with it warm.

But I found a good blend, and the 6" piece of pipe seems to be working the way I'd hoped, making a chamber for the liquid low pressure stuff to help the 1150 condense, and then travel into the 31.

But the numbers speak for themself so far.

I'll be playing a bit here and there with this, try to find a blend of gas and a captube setup that really makes the high pressure blending work for me.

Don't know if I'll be able to get the Ethylene to stay condensing well enough to be part of the gas that's actually cooling with higher load, but it's a fun experiment.

I enjoy the research a lot more than the 'real work'

Gray

[Gray Mole]

Got the copper manifold pic in the wrong spot for the words of course but I cut one piece from it, with 2 small barbs.

One end got crushed flat in a vise and brazed,and the other end I slid the coiled captube and 1/4" captube join/mixture chamber setup and crushed and brazed that with the inlet 1/8" and outlet 1/4" pipes sticking out.





That's a mockup of what it looks like under the insulation.
Quick Edit: The pipes I used in the actual heat exchanger setup were cleaned and slightly 'scuffed' with emery cloth and cleaned again. Trying to get the heat transfer as good as possible in there.

I just started it up again, and it starts without a problem, which is nice

Goes to -30 in less than 10 seconds, so the 134a is condensing fast. Floated there for a few seconds, then the temp went to -55 over the next 15 seconds. So it's almost like you can 'see' the gasses condensing in order.

After a minute, it was at -65c, and I came in to post. Will check again after I post this, see what it's like. Should end up being around 5-10min after startup, so I'll know whether it's a consistent result as far as 'unloaded' performance goes.

I'll go and see where it's at now. Hopefully it's working in a similar way to how it was, then I can look at some prelim load testing

Another Edit: Yup, down to -85c after around 8 minutes.

Odd though. Starts at around 0psi to -30ish, then drops to -10psi and -60 or so, thenslowly back up to 2-3psi at -80, and it's slowly crawling down to -10psi again as it's condensing the Ethylene. Really cool to see the way it works.

Gray

[johnksss]

and this is another project, correct?

[Gray Mole]

Aren't they all?

Pretty much every unit I make has a new idea or something I want to experiment with a little. Makes it at least a little challenge.

I doubt this will end up becoming a 'unit design' for a while. If the setup on the captube, being a 'multistage' captube setup, really works well, and ends up being able to hold load with Ethylene blending, then I may look at doing an actual unit with it.

I think that a larger Rotary is a better idea though. Being able to push and pull harder could make better use of the Ethylene and make the cooldown faster.

It's just R&D I guess. Part of what PC cooling lets you do. I mean, at work they're not going to let me sit around doing research all day (I wish) but I'd do nothing but this kind of playing around if i could

I've been playing with this thing for a while now, looking at different captube setups to help with the 'mix' part of the blend setup. This is the first really sucessful and consistent result so far, and if it will hold load and maintain the high pressure condensing, I'll start really pushing forward on making a workable unit.

This is just a mess but it's the data that I'm getting that matters. I'm really seeing a perceptible change in superheat along the return, even if I can't accurately measure subcooling.

But in the next while I'll be back with it, may end up redoing the HX setup in different ways, may look at multiple chambers to see what effect it may have.

Hell if I could get a 1/2hp compressor to deal with 300w of load at even -60 I'd be pretty stoked, but it just depends on how well I can get the Ethylene to remain condensing and cooling, as opposed to just floating through as a gas.


Gray

[Gray Mole]

And again, after around 15 minutes it's pulling down to around -12psi and -100c

So the mix is stable and pretty consistent. Just a matter of whether it'll do anything interesting with load.

I'll wait for it too warm up and get the evap prepped for load testing. I'm pretty curious about low load too, where it can keep a consistent temp. Even if it's a limit of 100w or something for the -75c or lower temps, at least it'll give me an idea of where to go with this kind of setup.

Whether it has a practical application in PC cooling or something else, at least i'm closer to a workable solution for a single compressor system for low temp.

If it were going to be any kind of permanent cooler, I'd have to change the oil over to Zerol 150 or look at oil separation since it doesn't use phase separation. The AB oil in it (according to the spec I found) will work a while but will freeze in the captube in longer durations.

Gray

[Hondacity]

wow thats perfect for my e8600

[Ian[Frozen]]

Amazing

[n00b 0f l337]

So, let me ask it this way:

Condenser --> into SLHX --> 1/8" tube 7' --> Few inches of 1/4" --> .031 3' --> Evap

If so, congrats
If I can make a pondering at what's going on, you've made a zone in between your high and low with a mid range pressure. In goes r134a and cools off the section, which really just pulls energy out of the r290 and r1150, eventually saturating the r290 with r1150 and possibly condensing some ethylene along the way. It's practically the same method as the zero-separation autocascade with multiple capillary tubes, except crammed into one operation.

If you do put her on a heatload and try and see what you get, I'd suggest starting with more r290 before throwing it all out of whack with r1150.

[tiborrr]

Well, the question is, can it hold load? Autocascade ( LPG/R744/shots of R1150) I have built hovers around -75°C idle but holds a solid ~ 280-300W load @ -60°C.

[[XC] Oj101]

Drewmeister is awesome at mixing, -62'c through Pi on a single stage (NOT autocascade) - nice unit GM and good to see an AC, I haven't seen more than a SS for a while

[Gray Mole]

Well yes and no

250w is the limit on this thing in it's current setup and around -45c.

Which is fairly mediocre but it's running 10psi low at that temp and load.

Autocascading is a better method for sure but I'm working on more of a method for blending than Auto as such.

The condensor -> 1/8 -> 1/4 -> .031 -> evaporator is how it's run with the 1/8 and 1/4 in the slhx. Slhx is just the usual from evap to compressor.

With no phase separation I've never had any real success with up blending until now and I think multiple chambers would hep so I may look to that.

But the real problem is that the jump to 1150 is just too aggressive. I need a gas or 2 in the middle.

I don't know if 'chambering' is working how I think, but this is better than I've done with previous attempts so I'll keep working it

I'd like to see about ethane and something like 410 but a bit colder and something pure if possible.

Oh and hey NOL good to see you.

Gray

[[XC] gomeler]

Curious what your highside pressure is like

[Gray Mole]

Yeah, the highside is high, but not what I'd thought it would be.

I started at 100w to get a feel, and mainly had to add 134a and 290 to keep the HX flooding. -15 measured at the middle of the HX was the bare minimum. -20 seemed much better.

So 250w is all I could get. No matter how I played with it.

But 250w at -45c 8psi low/260psi high on a 1/2hp compressor is a start. Ethylene I think is just too much. In an autocascade I'd still be struggling with it at -20HX but it's working to a certain extent.

Cooldown is amazingly fast to -60 now, so that's where I do like how it's working, and the load temp for a 1/2hp is resonable. Just wish it had more capacity in it.

Which brings me back to Ethane.

I need the gasses to mix well, and not be a 'stepping stone' system. Finding enough to work a really long glide is going to be my best bet if it's going to be a system that works.

So I'll be reworking another SLHX at some point, maybe with 2 or 3 chambers to see if that actually does anything. I think it does assist the mix. Time will tell.

Ethane (I'm hoping) should be low enough pressure to do more. Lowest temp will be higher, but I need more of the lowtemp gas to condense. I'm getting there though, R23 never did a lot for me, and I feel that it's because of the weight of it.

Ethylene and Ethane are very light, and they tend to mix really well with most things, especially other hydrocarbons.

So I'll probably leave out the Ethylene on the next one, see if it works better without, then try a small addition and see if I can make the glide even longer, or if it's just out of reach.

Potentially a second SLHX but I don't see a benefit outside of an Auto. I just need to maintain a really cold slhx and with more 'room' to condense it may be more effective.

But that's where I'm at. HP is high, but still within a workable system.

So I'm happy enough with this project, until I get some Ethane to test next.


Gray

[Gray Mole]

Oh yeah, the way it responds to going over the limit of capacity is odd.

The pressure drops dramatically, from around 8psi down to -10 and the temps rise pretty fast.

When I go back under the 250w (especially if I just cut off the load completely) the lowside pressure goes up a lot, to around 20 - 25psi. The highside is up too, at around 325psi. This lasts for around 15 seconds, then it settles as it's cooling, back to 4 or 5 psi unloaded as it drops, and 275psi settling to 260spi or so.

So I don't think it's 'running out' of gas as such.

I think the high pressure might get high enough to create an actual 'block' of condensed refrigerant. I'm still looking at the numbers but it's one theory I'll look at. Maybe it's just when the evap's load is high enough it can't maintain the HX temp and everything falls apart.

I'm not sure yet, it's a fast drop and hard to 'read' just yet.

But I'm hoping that Ethane will end up allowing a better and more reliable mix for slightly higher load, and if I can get a higher % of the Ethane to remain condensed, then both higher load and lower load temp could be achievable.


Gray

[Tetrafluorometh]

Hi Gray,

I have no idea on any of this but i am looking on in aww. I have a 4Kw Luve condenser here and 3 12000 BTU Rotary compressor.

How many BTU is your in this test project?

Any need for an expansion tank maybe?

You say your using 134a/290/1150. I guess the R134a is take everything down a bit which is easy to do. R290 helps with oil, it's free almost and easy to condense and gives a good temp. R1150 which is the daddy of it all gives the biggest drop.

So would R404a or 507a (there is extra R134a i think) between one of them help at all? Using less R290 just to carry oil?

Failing that what about R600a or R22 (well a replacment)?

To have a -100c blend singe stage would be amazing and i would really like to replicate your project into something working.

I have some good parts already, Luve 4kw, 12K BTU rotary (option of 3), Poitres 54mm evap 2m lineset, Danfoss KP15 (bit of saftey), so i think a nice looking safe high load uber cold unit could be built

[Gray Mole]

Hey

Well this is just a start, and to be honest a completely -100c single stage isn't very likely, but it's the potential that I'm looking at for getting a lot lower with a blend of some kind.

Now, when I used R23 for the low temp 'additive' it wouldn't work at all. At no load, it would condense just a bit, but any load just reverted back to the lower pressure refrigerants.

It seems like 1150 should be even more difficult but there are 2 main reasons I see for the minor success here.

1. Weight. 1150 is very light, as far as it's mass goes. So maybe I can't get it all to condense but being as light as it is, at least some is getting there. So that's a good sign.

2. Hydrocarbon. They mix. They mix with anything, really, but with each other they mix amazingly well. That's the reason for R290 most of all. I don't know if I could get it to work as well with another midrange gas.

So that's where I'm looking towards Ethane instead. Still pretty light, still a hydrocarbon.

I can't find much in between though, but with a bit of luck, I'll see more success there, and see a higher % of the Ethane condensing than the Ethylene. If I'm very lucky a small mix of Ethylene will work too, and that's somewhat hopeful with it working a bit in this setup.

A more powerful compresser is key though, I think. 1/2hp in a rotary is ok, but more HS pressure consistently, and pulling hard enough to get a much colder LS result could be enough to make the difference.

Like I'd said though, it's an Autocascade...and it isn't. Similar rules apply, as far as heat exchange to assist the HP gas to condense.

What I don't want, and why it's less an auto, is for the gasses to be separated. I don't think the 134a is going to be a 'true' mixer with the others, but a certain amount. In a way, it dropping the temp and flooding the HX a bit on it's own is a good thing.

So if you're going to try it, then you're entirely welcome just be careful. Remember that as far as the HP gas goes, less is definitely more. Getting a blend that's going to stay well under 350psi is a good idea. I'd like to see 300psi as a max myself, since that's the limit on most commercial AC/R stuff I've been working with.

If you're using a flex (I'm only using copper pipe in testing, so my Static isn't the same issue) then keep it to 200 max if you can. Use braided flex rated for double that at a minimum.

Even the copper braided flex has a MWP of 400/burst is usually 1000psi, so I wouldn't go less.

For the low gasses, you may be right with R600/R290/Ethane being a choice. Potentially a blend that's somewhat stable could come of that. Maybe not a -100 SS but I'd love to see -60 under 300w of load.

Next one for me will be with a 3/4hp or better compressor, and with the changes in the captube/HX I mentioned.

Good luck with yours

Gray

[n00b 0f l337]

I've got twenty pounds of r23 I got on the ebay for $45, I'll give it a shot next week.

[Gray Mole]

Nice

I think if you're using one type of refrigerant, just stick to that for the blend. R23 wasn't the best 'mixer' for me, but if you use it with other Halo's maybe that would work better.

I wasn't doing what I am now for subcooling either, and that could make the real difference too.

But it's a heavy weight of gas by comparison, so possibly less would be good.

worth a try for sure though, and at very low load it should work well. It's just the challenge of keeping it condensing at high load without the HP skyrocketing.

Gray

[piotres]

Gray, You're crazy ! BTW don't You plan to buy better camera ?

Nevertheless IMO -100c shoot can be done with the simplest SS with pure R507, rotary around 2-2.5HP and CPEV . I make -88C/pure R507 shoot with 9000BTU rotary ...

Good luck
Peter

[Gray Mole]

2.5hp on an SS?? You're calling ME crazy??

Yeah, I know my pics suck, but even with a good camera they still suck. A photographer, I am not.

But the real challenge is the load.

I mean, the whole -100c SS thing is more of a joke than a real thing. It can be done by anyone really. It's getting the load to hold and keep that second stage gas condensing in a single stage.

I get bored easy. I've gotten where I can with a single gas, and I don't see any huge gains without larger compressors.

So this is just something to keep my brain going, and if I'm really lucky, to see a better temp (especially with higher load) without the big compressors.

1/2hp rotary and -45c 250w load is a start, and while not hugely better than say, R410 it's just a stepping stone.

One day I'll run out of things that I can try and maybe along the way I'll find something really cool I can share that no one else has yet. It's not the temps or the load, but the getting there that's fun


Gray

[piotres]

That's not photographer fault, but his camera fault for sure . Please do it , Your topics then will be much more nice to read .

I'm also not a good photographer , I have old Canon A85 (good quality camer and cost me only 25 eur ) and pictures in mine topics are enought good quality.

[Tetrafluorometh]

Peter has a Point Gray.

He's photos are clear, bright and show us everything.

Think you said your using an iPhone 3G which can be okay if the light is right. I say get on eBay and get a cheap cam, 6mp are easy to get

[Gray Mole]

Well I appreciate your faith in my abilities

I'll get a camera and you're right, just an iPhone right now.

It's not even the cost, I just don't take pictures other than the coolers. Seems like such a waste to buy a good camera. But if I buy a camera, I'm always looking at good ones

Besides, if I buy a good camera and my pics still suck, then it just confirms that I'm a terrible photographer

[Tetrafluorometh]

Well I appreciate your faith in my abilities

I'll get a camera and you're right, just an iPhone right now.

It's not even the cost, I just don't take pictures other than the coolers. Seems like such a waste to buy a good camera. But if I buy a camera, I'm always looking at good ones

Besides, if I buy a good camera and my pics still suck, then it just confirms that I'm a terrible photographer

Nah man, just go with the flow when taking a shot.

Make sure its like your builds.

Clean, simple, spaced, well lit, focused, working, tidy, mint

Breath in deeply then hit the button and exhale after it's done.

Use the Auto settings can get good shoots alone with that.

take loads of photos to play with and you'll master the skills, point here the auto focus beeps and shoot, job done

[Tetrafluorometh]

Any update or better photos? I'm selling my DSLR setup which you would love, shame were across the pond. I'd of swaped units!