CryoBUG is Back

[mytekcontrols]

Oh, and i don't know if I mentioned, but the twin phase sep was all about R14. Oil separation seems to be a nightmare with that gas, so a series oilsep configuration may be the best way to keep that in check, even though I've seen some serious oilseps slowly fail, the oil creeping through.

Yep R14 isn't really an HFC (hydrofluorocarbons) like some people think, but more accurately a PFC (perfluorocarbons) or sometimes also simply called an FC (fluorocarbons). So although the HFC's are readily miscible with POE, I'm not sure if the same can be said for R14. Although with POE you'll stand a better chance, then with AB or Mineral oil.

At one of the places I work, it is standard practice to retrofit dual or even triple series fed oil separators in units that have been experiencing oil freeze-up problems.

[[XC] gomeler]

This thread makes me happy. Still casually searching for a place to build at in my new town. One day I'll get to tinker again and try these things

[Gray Mole]

2) I want to keep all the refrigerants ozone friendly and non-flammable (HFC).
3) I want to avoid using a mixture in an AutoC that is covered by Brooks/Polcold's patent #6502410, which pretty much covers what would be an ideal mixture using HFC's.

BTW I made it down into the -130's yesterday by using a combination of R134a, R23, R14, and Argon.



Yep, for now it sounds like my approach isn't really suitable.

Beyond that, depending on regulations, a hydrocarbon based fridge isn't really marketable.

Nice result though -130 is good, shows you're getting at least a little of the highest pressure gas condensing.

As always, the best mixtures are 'taken' and coming up with a new mix that works well is a lot of trial and error.

If you're condensing close to the end of the captube you will see a rise in HP and the temp will rise, as well as you've said if you don't have the mass flow to cool the compressor it's going to burn on you. Bit of a tightrope.

What do you figure you've got for %'s now? (though you may want to keep that to yourself if you're shooting for a marketable mixture)

Damn you though, now this project is stuck in my head again. I'd left it since I didn't see a real likelyhood of success for higher loads, but from a low temp low load fridge perspective it's worth pursuing if temp drop speed is a need.

So I'll likely drag out my notes and start making the V2 of mine.

Curious, what's your target temp?

Gray

Oh, and hey Gomeler nice to see the weird stuff come back. Maybe not so much for PC cooling, but R&D is what makes refrigeration a lot of fun for some.

[mytekcontrols]

This thread makes me happy. Still casually searching for a place to build at in my new town. One day I'll get to tinker again and try these things

And that's what I live for
If Gom is happy, then something good must be in the works

[Buckeye]

This thread makes me happy.

Agreed !

I love watching you guys build these things
Nice blog site also Mytech !

[mytekcontrols]

What do you figure you've got for %'s now? (though you may want to keep that to yourself if you're shooting for a marketable mixture)

Curious, what's your target temp?

Here's where I think I'm at with the charge (I was chasing it towards the end, and not always being good about weighing the additions):

130 Grams R-134a
50 Grams R-14
40 Grams R-23
5-10 Grams Argon

My goal is to hit a solid -150C average across the evaporator. And here's where I'm at:

Green = Evap-Out, Blue = Evap-In

Damn you though, now this project is stuck in my head again. I'd left it since I didn't see a real likelyhood of success for higher loads, but from a low temp low load fridge perspective it's worth pursuing if temp drop speed is a need.

So I'll likely drag out my notes and start making the V2 of mine.

Fantastic

The more people tweaking and sharing stuff, the more fun it will be for everyone. It seems like this forum has lost some of this lately, and it's nice to see it coming back to life.

[n00b 0f l337]

I was thinking on the pulldown time issue. It seems better insulation and lower mass HX's are the only way to go. Lower mass HX's aren't necesarily a good idea though.
Might be nice to try the vacuumed out evaporator Mytek. It's just hard to maintain.

[Gray Mole]

Well you're not far off that -150 and your pressures are actually quite good. Do you see much spiking on 'changeover' when you start the HP gasses condensing?

Looking at the figures I'd say if anything is giving compressor strain it'd be the R23. I found exactly that on my first attempt way back (7 years maybe) and R23 was my only HP gas. Seemed like no matter how little I had compressor strain like crazy. R23's pretty heavy that way.

So I'd pull back with that but at the same time, it's the link you need too. Not much for pure gasses that give a go-between except R22 and that's being phased out soon.

R125 would be a great gas if you can get it, ideal for blending and tends to be a great 'linking' gas. I know Air Liquide can get it, but never checked on price.

[Gray Mole]

Wow, XS is being weird with posts. I lost some of mine

I was saying, something like 35% 134a / 25% R125 / 15% R23 / 15% R14 / 10% Argon should be a lighter mix, but still get the ultimate low temp you'd be after. Heavier HP/Low temp gasses tend to need a bit less for this kind of low load application.

[Gray Mole]

Come to think of it, you could use 404a (which has 1/2 143 1/2 125 with a bit of 134a) and just add 134a to bring it to the %'s you want. Both of the primary's in 404 are around the -47 mark BP and 404a is cheap.

Gray

[mytekcontrols]

Come to think of it, you could use 404a (which has 1/2 143 1/2 125 with a bit of 134a) and just add 134a to bring it to the %'s you want. Both of the primary's in 404 are around the -47 mark BP and 404a is cheap.

The problem with R125 by itself is that it tends to be a very high pressure if you got any liquid sitting around. Not sure about R404a, but I think R507 has the lowest vapor pressure for a R125 blend, and still gives you good temps. However As per my 3 part list of what I want to do from a refrigerant standpoint, I don't really want to use R125 (or any blend that uses it) because it possibly gets me patent problems with Polycold's HFC charge. Not a problem on a personal level, but you never know if something like this has commercial possibilities (courts still out on that one).

Note: It's not R125 by itself that causes the patent issue, but more the combination of ingredients that also include it, and that are used in an AutoC.

[mytekcontrols]

Well you're not far off that -150 and your pressures are actually quite good. Do you see much spiking on 'changeover' when you start the HP gasses condensing?

Not sure I exactly know what you mean by 'changeover', but Argon does the most damage to my head pressure, which is to be expected. It also causes quite a shift in the compressor's audible frequency when I add it. But boy does it give you some cold temps in combination with the R14.

Looking at the figures I'd say if anything is giving compressor strain it'd be the R23. I found exactly that on my first attempt way back (7 years maybe) and R23 was my only HP gas. Seemed like no matter how little I had compressor strain like crazy. R23's pretty heavy that way.

Hmm... I've never noticed a problem when adding R23. In fact if my head pressure is getting high, a lot of times by adding R23 it'll take it down a notch or two. But I do agree that something like Ethane, a hydrocarbon, works even better for keeping the discharge low, and boils a little colder as well.

[mytekcontrols]

Might be nice to try the vacuumed out evaporator Mytek. It's just hard to maintain.

When the CryoBUG gets it's Cold Head, that is exactly what I'll be doing

[mytekcontrols]

I love watching you guys build these things
Nice blog site also Mytech !

Thanks I love building them too

yeah I figured it was about time that I got my blog back up again. Although I love posting stuff here and chatting with everyone, a blog just seems like a cleaner way to document a project.

[Gray Mole]

What I mean is that at times in my setup, when cooling down or when applying load, is that I could see a spike in head pressure when the refrigerant was starting to significantly condense or stop condensing at a given load or temperature. The 'changover' from LP to HP gas condensing effect. That's all.

But my pressures seemed to remain a lot lower on average even with load, so I suppose that I would 'see' that spike more clearly.

I did a project with R134a and R23, then tried R290 and R23, and both seemed to spike serious pressure fast. I used a 3/4hp recip. Captube was just a length of .031". Even a small amount and my head pressures went very high and my compressor would kick out at around 90c and it never took long :p

That's why I avoided it, going directly to hydrocarbons for this project. But I've been playing a lot with propane for a tester and really getting a feel for how the hydrocarbons feel, behave. Something about them seems to work well for me. Bit of playing and I'm getting with Propane what I get with 507. More of the tweaks I use work well on them, where they don't give a boost on 404/507.

Besides, like I said the 'Real' gasses are brutal here. All of the regular standards cost too much, R23 is around 2k a bottle on average. Ethylene, Ethane, Propane, Methane, all cheap here.

I'm finishing up the tiny cascade's case though. Just need to paint and cut the display holes and I'm done. When I get that out of the road I'll throw my project back on the bench and start going with it.

I have a cheap Rotary in the 1/2hp range sitting, so I'll just give that one a go. It's a 'Highly' cheapo rotary, 22LRA. Rated 5200btu in the crappy window AC I took it from, but it's actually rated 4k btu

So I wouldn't care if it burns.

So I'll see if I can beat you to -150 though I doubt it. Between the head start and the FAR more years of experience, I think you'll get there before I get started

Gray

[mytekcontrols]

Yeah I love hydrocarbons as well. In fact my favorites are butane (R600 not R600a) and ethylene, which work superbly in an AutoC. However as you pointed out earlier, not well accepted in the US for refrigeration systems.

Back to the R23 thing. My experience with this gas has always been related to its use within an AutoC. And as such it does very well, without the problems you described. So my question would be... When you experienced these problems with R23, was it being used in an AutoC, Cascade, or with your graduated cap tube design?

As for the spike in head pressure later in the run mode of a chiller. Also never seen this to be the case on the systems I've worked with. At least not unless the evaporator load has been intentionally increased. Usually the head pressure jumps up high on initial start, and then steadily increases for the first 5 to 10 minutes until things begin condensing, after which time the trend reverses.

So you you wanna race me to -150C? Sounds good to me, because I can always use the motivation.

[Gray Mole]

Back then was pretty early in my PC cooling experience. I'd done Automotive and some commercial for a while but the really technical stuff was still all new.

So I'd been modding a Mach2 unit trying out those kinds of variations and it didn't do well. Standard captube, non auto. I got very limited results, but I didn't use any enhanced subcooling methods, no discharge dampening or compressor protection of any kind.

I used it again in an Auto and it was ok, but my only success was in Cascades with R23 and even then it was pretty limited results. I think now I'd have a lot more success, but R23 was so cheap back then, wish it was cheaper here. The UK was a better place for getting cheap gasses. Had to know where to look, but it was around. US seems better for price too.

You need to be able to know you'll get some of the money back out I guess, or be rich enough to support the hobby.

But I figure I'll just keep saving from the stuff I build and sell here and there. I'm not a full time builder anymore though, that's for sure.

Well I'll be done today and I'll get to work today.

Shouldn't take more than a day to build the basics of my setup. It's not really complex anyway. All I'm missing is an oilsep (they're not here yet) but I'll throw one together and get to work.

I won't make it with just Ethylene, and I'm no sure I want to put Argon into my mix (I'm going to try to stay pure Hydrocarbons)

So I may see if I can do a Propane/Ethylene/Methane without the R134a. That should get to -150c given some time, and as long as I don't get overly aggressive on the Methane I should be ok. I'll stick a 375psi cutoff in the compressor wiring so I don't get a serious spike and blow a line or something. I got a box of 10 from Ebay for about 8 bucks each.

If I can't get there with that, I'll have to pick up some Ethane for the mix, but I've found that you leave those together you do get a bit of blending you might not with heavier gasses.

So it's a race, as long as you don't get done today I may have some small hope

[mytekcontrols]

Well I did get my hardware mods done yesterday, which consisted of adding another cap tube in parallel with my #1 and replacing the #2 (evaporator) cap tube with one for half as much flow. The really tricking part was drilling a hole into my first HX at about the same spot that the original internal #1 cap tube ended without punching through the inner discharge tubing. And also to get the additional parallel cap tube to sub cool, I had to braze it to outside tubing of the HX (no small feat). I'll post a picture and update my blog later today.

When I was brazing the cap tube to the outside of the HX I could see a bit of smoke coming out of the free end of the cap tube as well as some oil dripping out (being forced out by my nitrogen purge). This got me thinking that I was probably changing the composition of any residual oil coating the inside walls of the HX I was torching on. And so after I finished the brazing, I sucked up some Acetone in a tank, pressurized it with nitrogen, and forced it through the discharge side of my HX stack (fairly easy to do with the stack disconnected from my condensing unit). I then followed this up with high pressure nitrogen to blast out the Acetone. Repeated this process a couple of times, and then evacuated the stack by itself with a vacuum pump before reconnecting it to my compressor/condenser.

It appears that I pushed out some oil in my Acetone flush, and assuming I left some behind in the Window AC that the compressor was removed from, I think I might add back in about 2 ounces of new oil before I recharge the system.

Gray -- Not sure if I'll get it recharged today, but I doubt that I'll be running before tomorrow. So that should buy you some time.

[ultralo1]

Glad to see you guys doing this and posting about it. It is making me scratch my head and google some of the stuff. I am not sure I understand your diagram in the beginning but still studying it. Could have some applications on my end.

Micheal, as for the hydrocarbon acceptance here in the US, I think you are going to see that change in the near future (5-10yrs). I had a face to face with some factory engineers about the future products, HCs seem to be the future that they are envisioning at the moment. HFOs were also talked about but are cost prohibitive at this time.

[tiborrr]

I am again the one who is going to make mytek's design for PC chip cooling? Cmon guys, I don't have time for this

P.S.: Fantastic work mytek and thank you for sharing your knowledge with our community.

[mytekcontrols]

Glad to see you guys doing this and posting about it. It is making me scratch my head and google some of the stuff. I am not sure I understand your diagram in the beginning but still studying it. Could have some applications on my end.

Yeah I'll have to do a better job on that diagram. Probably be easier to understand if I draw it in a cut-away style. I'll get to work on that tomorrow (I'm on my iPad right now, and it sucks to draw on).

tiboor -- Yep it'll be up to you to work some PC cooling magic out all this. Adam could do it, but he'd rather be a doctor. And Gray's busy stringing cap tubes together to put around his Christmas tree hoping to freeze Santa in the act. And me, my wife took over my PC (that's why I'm pecking away writing this on my iPad), and she don't need over clocking for FaceBook.

[Gray Mole]

Yeah I'll have to do a better job on that diagram. Probably be easier to understand if I draw it in a cut-away style. I'll get to work on that tomorrow (I'm on my iPad right now, and it sucks to draw on).

tiboor -- Yep it'll be up to you to work some PC cooling magic out all this. Adam could do it, but he'd rather be a doctor. And Gray's busy stringing cap tubes together to put around his Christmas tree hoping to freeze Santa in the act. And me, my wife took over my PC (that's why I'm pecking away writing this on my iPad), and she don't need over clocking for FaceBook.

Bastard better bundle up REAL warm this year

Got nothing done on my project today Xmas means doing every little thing you're asked to do, and not be able to complain about it.

Did get the cascade boxed up though. Gonna go and post some pics. That 'should' mean I'm on to other things tomorrow

Merry yeah yeah yeah

[kang-China]

Hi,why i don't see your blog picture, about you new idea.

In your blog the letter is ok ,but the picture none showing

[mytekcontrols]

Hi,why i don't see your blog picture, about you new idea.

In your blog the letter is ok ,but the picture none showing

It seems to be working on my devices ok (PC Linux-Chrome, iPad Safari). I'll check it out later on my Win7 laptop with both IE and FireFox to see if this works as well. So no explanation yet for why you can't view the photos.

[Gray Mole]

Hey, who's that good lookin' guy in the pics? You get a 'stand-in' for the photos?

Stack looks great btw. I like your use of the brazed captube for subcooling. I started using that myself on most systems so I could get a nicer tuning charge.

For this I think it's crucial, and it should take less HP charge to get effective condensing which could hopefully keep lowering the head pressure and CT.

Pics work from here too though, not sure what's up at Kang's end