Morphing Air Conditioner into Autocascade System

[godmod]

R-152a is "extremely flamable".

[Xeon th MG Pony]

R-152a is "extremely flamable".

ya right only in liquid form, in gas form you can't get it to burn at all. and hardly extream either. It has been seriously considered for mobile systems here in Canada, but then again we use HC refrigerants in Mobile AC systems to so, take it as ye will.

[plasmatique]

Which pleasure of reading this file day apres day

[mytekcontrols]

Mytek ever look into R-152a? As any and all computer air duster cans use it!

As godmod pointed out it is flammable, and this MSDS appears to be in agreement.

Although the boiling point is almost identical to R134a (-26C), I don't see any apparent advantage. Perhaps there is a COP improvement, but I haven't looked into this. Anyway this is probably a mute point, if one is trying to compose an autocascade refrigerant blend made up of nonflammable components.

However it could be useful in a HC charge blend, since I would guess that it would do well with conventional oils.

[chilly1]

R152A appears to be ventable. (It is used to clean electronic components ) and one advantage is that it is misicible with mineral oil. it does wirk as R12 replacment but I am not sure about compatibility of material with the internal components of current and past compressors (shellac and or coating of the windings and seals and berings internal to the compressor. I have built a few systems with it and it works good as a single component refrigerant..


mytekcontrols
I have a block and kit for you to add to one of your systems if you want just give the word and I will ship it...

EDIT: Just finised catching up Great project and thanks for hte entire post here... Learned a lot abou autocascades...
I have a couple 1.5 HP Rotary horizontal's and a large selection of gasses.. ( Odd ones such as sulfer hex and iceon 89) if you want to play with the horz rotary I can also send you one of these...
First question.. have you used some of the new "Blends" (507, 89, 408,401) in autocascades.. ?

[mytekcontrols]

I have a block and kit for you to add to one of your systems if you want just give the word and I will ship it...

Wow! Thanks chilly, that's a very generous offer, but I'll have to hold off until such time (if ever) that I get into cooling CPU's. My next project as I alluded to previously, will be a repackaging of the AC-2 with added features, and a more eco-friendly refrigerant charge. It wont be suitable for the higher loads required by modern day processors.

I have a couple 1.5 HP Rotary horizontal's... if you want to play with the horz rotary I can also send you one of these...

I just might be interested; what's the voltage requirement and approximate dimensions on one of these? Make, Model?

Edit: Well after thinking about it for a minute, the voltage has got to be 220-240 VAC for a 1.5 HP compressor. Might still have a future application, but nothing in particular at the moment. So if I think of a serious endeavor for such a thing, and I think I'll have the time, I'll be sure to get back to you on this. In the meantime, can you send me a link to the specs, or give me the make and model info?

-Thanks

have you used some of the new "Blends" (507, 89, 408,401) in autocascades.. ?

No I haven't, but if my memory serves me right, some of these use R125 as one of the components, as well as HCFC's which I am now trying to avoid.

I have done some experiments with R410a which also uses R125, and found it's high vapor pressure to be a problem (increases expansion tank requirements).

Chilly thanks for jumping into this thread. You are quite the legend on this forum, and many others

[chilly1]

THanks. Well just thought you might get some inspiration having one of these olittle evaps and hold down kits setting on your shelf if nothing more than an interesting conversion piece... Ha ha just trying to see what insane machine you could get out of an evap designed for surface only cooling...
Compressor labling Wattage labling kinda got hit with oil got rough handeling getting here. 2000W/743W 115V MOdel QHR-11T Cap 50uF Lanhai Compressor company
I think it is a 743 watt motor so I think it might be only 1 hp which is about the size it is, however the company shipping it to me (Lanhai) said it was 1.5 hp but there is that Language barrier.... See I was trying to get some off the wall parts in your hands, I dont think you could let them set around without doing something off the wall with them... Haha I also have a 70K @ 40 Watt cooler here (Fugger has the pump I got the head here) (1 Watt @ 4K)

[ultralo1]

Amazing thread, and knowledge here.
I have a source for instrument grade propane (R290) at 99.2% purity.
It is Scott medical gases here is the link
http://www.scottecatalog.com/Scottgas.nsf/web/MedHome
You will have to call for a quote. I purchased a case (12X 400gram cylinders) for $170
This is what we use in the cascades I work on.

Mytec: please check your web site email

Thanks.

[mytekcontrols]

ultralo1 welcome to XtremeSystems, and to this thread

Also thanks for the lead on the propane, I'm sure several people around here will be most interested in getting there hands on some non camping stove R290

Here is a more direct link to the propane info page on the site: medical grade propane

It's nice that they sell it in relatively small quantities (14 ounces), since it doesn't take much to charge up the systems being built around here, and It wouldn't be cheap if you had to buy 100 lbs of the stuff.

Although I never had given it the chance it deserved, I don't see why this in combination with some good quality butane, wouldn't work well for the liquid charge in the AC-2 unit.

Obviously I got your email, and it's cool that MG Pony pointed you in my direction. When everyone finds out what you do for a living, and the access you have to some very pro chilling equipment, as well as some exotic refrigerants, they'll be picking your brain in no time.

It's great to have another experienced person on board from this field of interest

[ultralo1]

It's nice that they sell it in relatively small quantities (14 ounces), since it doesn't take much to charge up the systems being built around here, and It wouldn't be cheap if you had to buy 100 lbs of the stuff.

I use it in conjuntion with R23 mostly to aid in oil miscablity for the second stage. I usually charge from vacuum to 5psi with this. Then I will take R23 from 5psi to 65psi. This usually makes the unit reach -60 to -65c. Then I add a hose full at time to reach -85c which is design temp for the units.

i will explain the other use of it later when I have some time. We call it a "cold enema"

[ultralo1]

Let me dig up my books on Auto cascades. I think they have the msds for the different refrigerants used by Queue in it.


Found it. No percentages or wieghts were given, proprietary.
R600a
R134a
R508b
R14
R740

[wdrzal]

When does that patent expire ? I rememember seeing one from polycold somewhere around 2000-2002.
It was before they where sold iirc.

[mytekcontrols]

Walt --- It's a fairly new patent:
Patent Number: 6502410
Co-Inventor: Oleg Podtchereniaev et al.
Patent Date: January 7th, 2003

So it wont expire until 2023.

Ultralo --- That Queue charge is very interesting. I'll have to think on it a bit when I get a chance tomorrow. Thanks for sharing it.

[kayl]

THanks. Well just thought you might get some inspiration having one of these olittle evaps and hold down kits setting on your shelf if nothing more than an interesting conversion piece... Ha ha just trying to see what insane machine you could get out of an evap designed for surface only cooling...
Compressor labling Wattage labling kinda got hit with oil got rough handeling getting here. 2000W/743W 115V MOdel QHR-11T Cap 50uF Lanhai Compressor company
I think it is a 743 watt motor so I think it might be only 1 hp which is about the size it is, however the company shipping it to me (Lanhai) said it was 1.5 hp but there is that Language barrier.... See I was trying to get some off the wall parts in your hands, I dont think you could let them set around without doing something off the wall with them... Haha I also have a 70K @ 40 Watt cooler here (Fugger has the pump I got the head here) (1 Watt @ 4K)

i personally didnt like their horizontal compressors chilly1, i bought 2 and the first one i tested died on me with limited use. So i stuck to using their normal rotarty compressors, they make a really mean csacade

[mytekcontrols]

Queue's Charge:

Ultralo: Found it. No percentages or wieghts were given, proprietary.
R600a (BP = -12C)
R134a (BP = -26C)
R508b (BP = -88C)
R14 (BP = -128C)
R740 (not condensed)

The R508B is simply an HFC replacement for the formally used CFC-13 in standard cascades. It is composed of 30-50% HFC-23 and 50-70% HFC-116. I would think in an autocascade that R23 (BP = -84C) could be directly substituted, since the presence of the R14 in the blend would give you the colder temperature.

Ultralo -- is this charge being used in the Cryostar freezers?

Interesting note; Polycold licensed their technology to Queue in the early 80's. I was directly involved with creating the first prototype chest freezer designed for -100C operation. I also remember that there was a heat up problem after extended operation, due to oil freeze up in the final captube feeding the evaporator. The charge used at the time consisted of CFC-114, CFC-13, HFC-14, and Argon (R740). Oil return was solely done via the phase separators. I would imagine that using a charge with R600a probably would have solved the oil migration/freeze up problems.

I remember we even talked about using 2 final captubes with shut-off solenoid valves. And then cycling back-and-forth, thereby allowing one captube to thaw out while using the other.

Utralo -- On the subject of using hydrocarbons as refrigerants. At an early point in time, you mentioned something about propane being used as...

We call it a "cold enema"

Are you ready to explain what and how this works?

[ultralo1]

Queue's Charge:


Ultralo -- is this charge being used in the Cryostar freezers?

Yes, this is the most current charge for -140 & -150. It is not cryostar anymore, it is now a division of ThermoFisher. They have bought all the major cascade players in the US. This division is based out of Asheville NC.

[I]Interesting note; Polycold licensed their technology to Queue in the early 80's. I was directly involved with creating the first prototype chest freezer designed for -100C operation. I also remember that there was a heat up problem after extended operation, due to oil freeze up in the final captube feeding the evaporator. The charge used at the time consisted of CFC-114, CFC-13, HFC-14, and Argon (R740). Oil return was solely done via the phase separators. I would imagine that using a charge with R600a probably would have solved the oil migration/freeze up problems.

That what I love about the cascade industry. Its a small world. I still have a few of the old queue systems on campus. I usually let the my competitor handle these as he has been in the business for 20+ years. He handled them before we had a shop so his service notes are extinsve on these systems. i have been handling the newer systems, about 1 per year. There have been some major changes to the newer units. Scroll comps, double oil seps, larger condensors, buffer tank size, etc.

The COLD ENIMA, I had forgotten about that.
With the ULT -80s we have a problem with the users warming up the cabinet above -60c. When this happens the frozen oil in the evap becomes thawed. It is still highly viscous but mobile. The refrigerant flow causes this thawed oil to move. As it refreezes it will form "lumps" of oil which reduces the diameter of the evap tube thus refrigerant flow is reduced and capacity is reduced.

This is where the cold enima comes in at. The addition of 1-2oz of R290 into the 2nd stage system will disolve these "lumps" and allow the oil coating inside the evap lines to form a more smooth surface. This returns the flow back closer to normal and capacity increases. Although you dont usually get 100% capacity restoration. The design temp is -85c after enima it usually will only make -82 or -83c.

On a personal note I try to stay away from this method. This is because you have to put line taps on the system. It has been beat into my head that "ALL VALVES LEAK", and i have found this to be true to some exstint. Also you have to be very precise in the manifold, line purging when you do this or else you introduce a hose full of moist air into the sustion side of a system that is running in a vacuum. BAD JUJU.

What would be the best way to contact you privately?

[yngndrw]

I hope you don't mind me asking a question which is slightly off the current topic but is still very much related with auto cascades:

What is the general procedure for reclaiming / reusing blended refrigerants when testing different blends ?
Do you have to reclaim and then dispose of the charge each time, as it is blended ? Can you "distil" the different refrigerants out of the blend ?

[mytekcontrols]

Ultralo, thanks for the info. Very interesting and useful.

Check your email.

What is the general procedure for reclaiming / reusing blended refrigerants when testing different blends ?
Do you have to reclaim and then dispose of the charge each time, as it is blended ? Can you "distil" the different refrigerants out of the blend ?

I use a standard recovery pump and evacuated tanks to remove the blended refrigerant. As for reclamation; sometimes I can use the recovered refrigerant as a "top-off" to bring a system's balance pressure back up to normal following a leak and subsequent repair.

It is also possible to distill out the liquid part of the charge by running it through a refrigerated vessel (cold trap) prior to entering the recovery pump, and also later when using a vacuum pump for final evacuation. Note: We are working on this.

If the conditions are consistent (fixed quantity of liquid in original charge, cold trap temperature, and ultimate vacuum level) then the recovered liquid's characteristics will also be consistent. So in other words, you'll end up with a liquid refrigerant blend which can be substituted for the individual components when making a new charge, but will require some adjustment in the proportions of some of the other components that make up the blend.

As for distilling out the individual components to their pure form; it would take some very fancy and expensive equipment to pull that one off. So from a practicality point of view, this is just not possible.

Whatever we can not recycle back into the units we service, does ultimately get picked up and disposed of by a refrigerant recovery company.

[yngndrw]

So in short you cannot fully separate the blend back into it's components, however you can "create" new blends by setting the temperature of the cold trap ? Does this not mean that you can set the cold trap to withdraw a blend which is very much like one of the components or am I misunderstanding this ?

Thanks for your explanation.

[mytekcontrols]

Yes it is possible to adjust what is reclaimed by the temperature of the cold trap. Although it'll never be 100% of any one of the refrigerants in the autocascade blend. There will always be some other refrigerant in partial solution with it.

Actually a technique I intend to try is just letting the cold trap run balls out at around -50 to -60C (no temperature regulation). Then recover the charge down to 10" Hg from a given unit into freshly evacuated recovery tanks with the cold trap in between (this also assumes that we start out with an empty cold trap). After wards; switch to a vacuum pump on the outlet of the cold trap, and allow it to pump the unit down to 500 microns or better (while using a crankcase heater on the compressor, and a heat lamp on the filter dryer).

Edit: To insure that the vacuum pump, when dropped to a low vacuum level at the end of the pump-down, doesn't begin sucking out the R22; it'll take an even lower cold trap temperature. This temperature would probably need to approach -100C or better, in order to keep the refrigerant condensed, and trapped.

When the low vacuum level has been achieved, store both the recovered gases and the liquid from the cold trap as a complete charge ready to be put back into a similar unit (liquids first into discharge, followed by gases into both the high and low side using a recovery pump in reverse).

Of course this assumes that the charge is something viable that can be reused. This procedure would work well when a very small leak needs to be repaired, or one wishes to modify the piping and/or captube flow rates, and just needs to temporarily remove the charge in order to do so.

[yngndrw]

Ah I see, that makes sense then. Thanks for that.

It seems that testing different blends in an auto-cascade is far from perfect due to the fact that you cannot accuratly reclaim the pure refrigerants, I guess that's a reason to go with a normal cascade if gasses are a problem for the builder.

[mytekcontrols]

Although I can't reveal the exact details on this project, never the less I thought you guys might like to see my new Heat Exchanger Stack aimed at producing -150C or colder.

The photo below shows the "layered" approach being used in this latest autocascade design, yielding over all dimensions of 10.5" high x 6.5" footprint. And of course there are all kinds of goodies stuffed down the center (no wasted space in this baby ).

Outer coil is 5/16" od inside of 1/2" od, inner coils are 3/16" od inside of 3/8" od.

The inner coil is broken in a few spots for insertion of tees (not visible -- on back side), and was wound in one operation following brazing of these parts.

The bullet strainer shown, is feeding both the final and subcooler captubes (yes the final part of the 3/8" coil winding is the subcooler).

[godmod]

Oh damn that looks nice and promising! Will you post the whole progress again?

[ultralo1]

Again, your work is amazing!!!!!

[Xeon th MG Pony]

I think this will be his money maker so it would be fair for him to hold back, He shared more then any could have asked for in the first project!