Good looking autoc this far once again :slobber:
BTW could some of you guys add an schemastics for phase sep here (or why not directly to my pm)?
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Good looking autoc this far once again :slobber:
BTW could some of you guys add an schemastics for phase sep here (or why not directly to my pm)?
godmod -- Although I see the HPCO as strictly a redundant safety device (The buffer will keep the compressor from ever seeing such a high pressure), I do believe the rotary compressor used on the system in mind could restart at 300 psi. However, in my new system, I have the motor start circuit set-up more like a professional motor-starter. It uses a latching relay activated by a momentary switch to turn the compressor ON, with the OFF switch as well as all safeties breaking the relay coil circuit, thereby unlatching the relay. This way if a fault occurs, the system will not restart after the fault clears, but instead requires the ON button to be pushed once again.Quote:
You wrote that you set the "Compressor High Pressure Cut-Out" to 400psi cut out and 300psi cut in. Du you think the compressor will start again? I think the compressors overload protection will "click". Did you think about using a relais to combine it with the buffer valve control switch to let them open both (to make sure the compressor CAN start again)?
Yes on the AC-2 unit I used copper wool, but steel wool would also work.Quote:
next Q: have you put steel/copper wool inside the phase seperator #1?
The new project is coming together, and now pressurized for leak check. Insulation of the HXC stack should occur possibly later today.
As can be seen in the photos, there are quite a few valves involved. Here is a breakdown of their use:
- Sporlan A3F1 - Buffer Valve
- Sporlan A3F1 - Defrost Valve
- Sporlan A3F1 - HXC ByPass Valve
- Danfoss BML10 - Comp Suction Valve (hiding under solenoid valves)
The "HXC ByPass Valve" is activated during the defrost cycle at the same time as the "Defrost Valve". It's purpose is to reroute the returning hot gases from the evaporator directly to the compressor suction. This prevents heating up the HXC Stack while defrosting (allows for faster cool-down when defrost is terminated, and the unit is once again put back into cooling mode).
The "Buffer Valve" is used to dump gases from the 1st phase separator directly into the combo Buffer/Expansion Tank whenever compressor discharge pressures exceed a preset amount. These gases are then metered back into the suction via a very small captube.
The "Comp Suction Valve" allows for doing pump downs to verify the integrity of the compressor, and also to suck in a charge from a pre-mix tank. It has an extended shaft routed out to where the front panel will eventually be, to allow access.
AC3 Modes of Operation:
- Compressor ON = COOL MODE
- Compressor ON w/Defrost Valve Open = DEFROST MODE
- Compressor OFF when Defrost has completed = STANDBY MODE
There is no independent Cool Control Solenoid Valve. The ever so higher flow of the defrost circuit, effectively prevents any flow from the final evaporator captube, and thereby prevents cooling while defrosting. When defrost is done, as determined by a temperature switch monitoring the evaporator return, the compressor power is terminated. This puts the system effectively into "STANDBY MODE". Reactivating the compressor puts us back in "COOL MODE".
Eliminating the Cool Valve allows for standard refrigeration rated components to be used, and thereby keeps the cost reasonable.
Target Evaporator Temperature: -155C :up:
That looks really awesome, great job. Probably the neatest setup with that complexity that I've ever seen on here. I love the attention to detail such as the flares coming out of the HZ box so that maintenance is easier at a later date - And the little labels on everything.
Question: Why have both a Defrost valve and a HXC ByPass valve instead of just routing the Defrost valve straight to the suction line ? (I hope I haven't missed the answer to this earlier in the thread.)
Because the normal return path from the evaporator goes through the HXC Stack (passes through all the cascades and the auxiliary condenser). And the hot gas defrost is teed into the evaporator feed connection. So if I didn't bypass the returning gases around the HXC Stack during defrost, the stack would be warmed up as well.Quote:
Question: Why have both a Defrost valve and a HXC ByPass valve instead of just routing the Defrost valve straight to the suction line ?
Does that make sense? Or do I need to show a diagram? :)
Yep I can't stand having to open up a unit to verify pressure readings against a gage set, or to recharge it. It is amazing how many commercially built units completely overlook this. Especially considering the minimal cost to incorporate this added accessability.Quote:
I love the attention to detail such as the flares coming out of the HZ box so that maintenance is easier at a later date
Note: the 2 aluminum pieces holding up the manifold are temporary, they'll get removed when the front panel is installed which has the appropriate mounting holes.
Michael, you never fail to impress. I'm slightly concerned about how the little blue condenser will hold up but I don't even know how much heat you are dumping, so besides pump-down it should be sufficient given a sufficiently small load. I eagerly await your analysis of the unit once it is operational, especially if you can at least share a little information on the gas blend you'll be utilizing. I ask this as you are hitting temps I'm eyeballing as I mentioned to you earlier albeit with two compressors.
I'm incredibly jealous, can't wait to see the finished product.
Michael, that is a lovely job.
What kind a fan are you using with this condenser ?
regards
I still don't quite understand the use of two valves. Here is a diagram of how I see it, but I've probably got the whole thing mixed up:
http://yngndrw.hostilezone.net/uploads/AC-2.png (Sorry about the poor diagram.)
When I said HZ box before I meant HX box (Typo) - The internal flares coming out from where the HX stack is.
He wants to also dump hot gas into the evap to warm up the evap. However since the HX stack feeds off the suction gases of the evap, he has the 2nd valve to bypass the HX stack to keep it chilled so it won't require a complete system restart and pulldown when he just wants to defrost the evap.
Ah I get it now, ignore my drawing I totally messed that one up - No idea why I had it coming from the liquid line something went (Badly) wrong in my head. :D
Sorry about that.
Beautiful as always mytekcontrols, what an awesome job you have! :D
that 80/20 sure is expensive stuff... props to you for going all out :)
Yep did that for several reasons. ease of maintenance, maintain good seal for keeping water out of insulation foam, and able to eventually create modular drop-in replacement HXC stack.Quote:
When I said HZ box before I meant HX box (Typo) - The internal flares coming out from where the HX stack is.
Quote:
I'm slightly concerned about how the little blue condenser will hold up but I don't even know how much heat you are dumping, so besides pump-down it should be sufficient given a sufficiently small load.
Yes my load will be small, probably 15-25 watts. So a large condenser shouldn't be necessary. Also keep in mind that because of my "Regenerative HXC" on the compressor discharge (for creating the hot gas defrost from the colder 1st phase sep gases), I have effectively extended the length of the air cooled condenser.Quote:
What kind a fan are you using with this condenser ?
As for fans; I am using the stock fan that comes with the Little Blue condenser, but I also intend to supplement this with an additional 120CFM fan directly behind the compressor (will be mounted to outside of the future rear panel).
Chris - I'll be using R600,R170,R14,Argon in this puppy, but unfortunately can not disclose the exact amounts of each (this unit is aimed at becoming a commercial product).Quote:
I eagerly await your analysis of the unit once it is operational, especially if you can at least share a little information on the gas blend you'll be utilizing.
wonderful work :clap:
We can soon buy....:up:
So is there any Company backing you up? Will we see some of these units on the market?Quote:
Originally Posted by mytekcontrols
Outstanding craftsmanship :clap:
Nobody is backing me at present. But I do have a company in mind for my first potential customer. As for seeing these units on the market; it wont be anything to do with PC cooling. Instead it would be something that might show up in a vacuum systems trade journal.Quote:
So is there any Company backing you up? Will we see some of these units on the market?
Sorry Plasmatique, but as I said this is not aimed at cooling a CPU (25 watts tops). Also the market price for the final version would be at least $10,000.Quote:
We can soon buy....
I had definitely understood that this systeme was not to cool down a central processing unit of treatment but principle could etre adapted... To future let us wish:)
You say apparatus for space, pump moleculaire?
Mind if I ask what this unit would be used for, if not cooling a CPU?
Or is that a trade secret?
The application (at least the intended initial one) is for cryopumping water out of an inline hard disk platter coating machine. Some of these machines use up to 24 tiny cold heads coupled with just as many turbomolecular pumps for this purpose. Each one is creating a mini environment suitable for coating the magnetic material onto the glass or aluminum disk.
One such company building these machines is Intevac.
Let me know when you need a service rep for the Southeast :D
I see you lost quite some valuable posts :(
I just wanted to say again that this build is awesome!
And thanks for replying my question.
Quote:
Can you braze in such a tight space without setting the other parts on fire?
Well actually there is a tendency for the residual foam insulation to burn, but once that's gone, no problem. Of course this wouldn't be the case for the area around the compressor and valves, so it does get tricky, and takes a lot of wet rags draped over things to keep the fire in check. I also fashion heat shields out of SST sheet that can be placed in-between things.
Oh jesus :( This thread took a huge beating in the data loss.
lets hope the losses were just Nol's 717 posts :)ha ha haQuote:
Originally Posted by [XC] gomeler
Well as far as I can remember, we're missing posts about Mytek swapping the condensor and changing the condensor fan.Quote:
Originally Posted by EvoCarlos
Also he did some work on the discharge and liquid line piping, and removed the complete HX coil.
Unfortunately I did not save the email notifications :(
Don't worry, I'll restore what got deleted in the next week or so. Although it'll be a bit different then it was, because this server is not the only thing that suffers from memory loss :D
Edit: 8/28/2009 -- Sorry that I haven't updated as promised. Been kinda busy, and also haven't been feeling good for a while due to a sleep apnea problem, and ineffective treatment. But here is a list of what has been happening.
- Larger fan installed.
- Larger fan was not able to keep up with higher load due to increased Argon additions. Changed to water cooled condenser (10 plate -- flat plate HXC).
- Built Bong Cooling Tower for water source.
- Abandoned first HXC Stack design due to inability to go much below -100 C.
- Built new stack based on more conventional design with 2 full phase separators.
- Had cross-feed problem with stack, but was able to fix it.
- Ran out of R600 for experiments, so temporarily used HFE-7000 & R290 instead.
- Best Cold Head temperature to date is -137 C.
- Found new source of R600, and its on the way.
Anticipate even better temperatures with R600, R1150, R14, Argon blend. I will hopefully have results in a few weeks. Stay Tuned.
Just a bump on this thread to expose people to the awesomeness contained within. Going to sift through it in my sparetime and link the important posts into the sticky guides for everyone's future reference.
Turned this into a sticky, I have the next 2 days off so I'm hoping to compile it all into a novel in my spare time. Make no promises though =\
Sticky well worthed! i mean there is so much good info in this thread!!
Chris thanks for making this a sticky. I just wish I had more time to put in the updates. As for the AC-3 Prototype, it made it down to -141C with a predominately hydrocarbon based charge (and a little bit of R14). Was able to use the stock AB oil that came with the compressor, and no coalescing oil filter. The R600/R170 combination as the 1st 2 refrigerants in the mix, seemed to do just fine at pulling the oil out at the phase separators before the system had a chance to freeze it up.
Performance was good, although I did not add any heat as in a test load, I did see rapid cooling from a warm start condition. Went from a +25C Cold Head temperature down to -125C in 30 minutes, a total decrease in temperature of -150C. Took another 25 minutes to reach -140C, and leveled off at -141C in another 10 minutes.
This concludes my tests on the AC-3 Prototype for now. What's next? On to the new AC-4 design. What is that? Do the same in an even smaller package. Shooting for meeting a footprint requirement of 9" x 9" at not much more than 12" in height (although this dimension has some fudge factor).
Here's a pic of pretty much where I left off on the AC-3 Prototype:
That's awesome Michael. I see you've gone with the water cooled condenser to reduce space requirements.
Have you used plate heat exchangers in the stack this time too ?
Also sorry if this has been asked before, but what is the overall purpose for these prototypes - What will they be used for ? (Or are they just for playing with ?)
yngndrw -- No plates being used in the HXC Stack, although I did do some fiddling around in this area, and failed because of my lack of experience with the strict orientation requirements (vertical is best).
As for what are these prototypes to be used for: My ultimate goal is to produce a product that serves the need of water vapor cryopumping in the Hard Disk manufacturing arena. Several of the specialized coating machines designed for this specific application use a series of very small low heat load cold heads, one per coating cell. Currently they use very large power hungry (10 HP) Polycold autocascades to do this, with one Polycold feeding 5 cold heads in series. My proposal is to create a small enough unit with a cold head directly exiting the side, that each Hard Disk coating cell will have its own cryopump. Since some applications have the cold heads spaced at 9" apart, the unit's footprint will also need to meet this requirement (very small indeed).
So the AC-3 unit was an early prototype aimed at this application, but one that had an unacceptable footprint. Essentially it helped me prove out some concepts such as providing a hot gas defrost without the need for a coalescing oil filter, develop a mostly hydrocarbon based mixed refrigerant charge, and establishing the minimum number of HXC stages required to meet my temperature requirements. It also showed me some alternative construction techniques.
Well you're well on your way to meeting your goal and it looks great so far. Good luck with the project. :)
man you developed an incredible project! congratulations
Mytekcontrols, any update man???
I'm bored with all the normal cascades around here:)
The autocascade is so much beter than a normal cascade i feel sorrow for myself for having a normal cascade:shakes:
....
..
.
Mytekcontrols did a outstanding job on this auto cascade project,not only building but in the support he gave for auto-C's advancement to the Xs community. :up:. I think this build thread was the first to truely autocascade all the gases. :yepp:Quote:
Originally Posted by quintus
But Mytek will even tell you it was for a low wattage ,50 watts iirc. and he has a lifetime in experience behind him.
Going from 50 watts to 300watts is going to be diffucult especially for a DIY builder.
Many others who tried auto-c's failed or only got them to partly autocascade. I don't recommend one at all unless you well versed & experienced and have a very complete shop full of tools,most never even get mentioned on XS.
These are for the very experienced, I warned severial people in pm to stay away from auto-c's and they lost their a$$ and reputation when they couldn't deliver.They are much more technicaly diffucult than a classic interstaged cascade.
Mytekcontrols if you disagree with my opinion please feel free to point out where I,m wrong.
I hate to see guys attempt a project and in the end have one that doesn't do the job. Now if you want to start with myteks design and progress it to a higher wattage ,great,but be prepared for one step forward and two steps back. But if you have the desire & funds,by all means give it a try.
Yep I agree with you Walt. And yes the last design (AC-2) based on the oblong coiled HXC's worked very well, and actually out did my next design (AC-3) which had a higher CFM compressor.
Although I learned a lot from the AC-3 design, I ended up abandoning it, and have since been making plans for the next version AC-4 (albeit I must admit much slower than I originally thought).
I also agree with Walt on taking what I did with the AC-2 design, and scaling it up for 300 watts might be the way to go for your guys end application. Of course winding the HXC's in an oblong fashion would not be necessary, if tube-in-tube coaxial HXC's were to still be used. A scaled up design would also benefit from flat plate HXC's to keep the package size reasonable.
But be prepared to spend quite a bit of time and money undertaking such a project.
As for refrigerant charge, I think the following components would be appropriate, as based on my AC-3 tests.
-130C Charge (or better with increased Argon)
- R600 (Nbutane)
- R170 (ethane)
- R14
- Argon
-80C Charge
- R600 (Nbutane)
- R1150 (ethylene)
Keep in mind that there is a tremendous difference in required compressor mass flow requirements and number of stages required to go from -80C versus -130C or colder. I would say that the AC-2 design, which was based on a 6500 btu compressor, would stand a pretty good chance at coming close to -80C operation at up to 200 watts, assuming that the last stage was removed (eliminate Cascade Condenser #3, its associated phase separator, and increase flow in the final cap tube proportionally).
However if you are shooting for a comfortable -140C @300 watts, be prepared to bump up the compressor to something approaching 4 horsepower, and requiring 3 phase power.
mytekcontrols,
What method did you follow when you made your tube-in-tube HX?
Do you have a way to estimate heat exchange?
Also, I tried to make one and I ran into trouble trying to insert the smaller tube into the larger... I ended straightening the tubes out, making the insertion and re-coiling.
Surely there's a better way.
Thanks,
-AC_Hacker
Well other than using a prefabricated HXC such as a flat plate type, the DIY tube-in-tube coaxial is going to be a bit of a challenge to make. However with that said, there is at least one trick to make this process much easier. And that is to pay particular attention to keeping the tubing very straight when rolling it out (prior to doing the insertion of one tube into the other).Quote:
I ran into trouble trying to insert the smaller tube into the larger... I ended straightening the tubes out, making the insertion and re-coiling. Surely there's a better way.
So my method involves:
- Begin by anchoring one end of tubing, using either a heavy weight, or someone standing on it.
- Take your time, and roll the tubing out very straight.
- If the outer and inner pieces have a curve, then line them up together, prior to stuffing one into the other.
- Finally, make absolutely sure that the outer tubing has been reamed out on both ends (using a tapered reamer), back to it's original ID (tubing cutters tend to crimp down the tubing). Making sure to do this step, will allow the inner tube to slide much easier into the outer one.
I can't stress this enough: KEEP THE TUBING STRAIGHT
Another trick, although much more involved, is to securely anchor one end of the tubing (clamp it to something very solid and immovable), and attach a hydraulic puller to the other end to both pull and slightly stretch the tubing. This will make the tubing extremely straight as a result (good method to implement for full production, just be absolutely sure that the ends of the tubing are clamped really good before stretching).
I hope that helps, and good luck on your project AC_Hacker :)
Hey Michael! (Popped you an email a while ago)
I also found as a cheap method, is to use a square steel tube and a steel angle. By rolling out a tube against the inner curve of the angle, you can press it down flat with the square to really get it nice and straight. That helped me roll 40' of 3/16" into a 3/8" tube with minimal discomfort.
Interesting technique. Kinda reminds me of something that a guy I work with showed me. In his case, he would lay the tubing on a very smooth cement floor, and then stand on the tubing while sliding his feet sideways across it back and forth. The end result was amazingly straight tubing, almost as if it had started out life as rigid tubing.Quote:
By rolling out a tube against the inner curve of the angle, you can press it down flat with the square to really get it nice and straight. That helped me roll 40' of 3/16" into a 3/8" tube with minimal discomfort.
Mind dropping me a message? I'm getting a bounce back from your old email.
I was looking through my test notes the other day using hydrocarbons on my AutoC and came across what I think was my most promising blend. This was tested in my last design iteration of the AC-3 unit, which was essentially a 4 stage AutoC (Aux Condenser, 3 Cascade Condensers, 3 Phase Separators), having a 6500 BTU/hr Rotary Compressor, and a 3"x9" expansion tank (with head pressure activated Buffer Valve set to 350 psig).
Charging was done via tank transfer, where an independent tank (5lb propane cylinder) is evacuated, and then the liquid is first added while weighing the tank with an electronic scale. This is then followed by adding the gases one-by-one based on their additive pressure, starting with the initial vapor pressure of the liquid alone (method was previously described in an earlier post to this thread).
CHARGE
R600 (Nbutane): 2.5 ounces (10-15 psig vapor pressure)
R1150 (ethylene): 90 psi
R14: 25 psi
Argon: 30 psi
Tank B.P. = 155-160 psig
Unit balance pressure (B.P.) after charged from tank and allowed to "soak-in" for 12 hours = 210-215 psig
Note: This unit had a suction cut-off hand valve, which allowed isolating the compressor from the heat exchanger stack during the charging process, thus allowing the compressor to "suck-in" and fully evacuate the charging tank, thereby transferring the entire charge from the tank into the unit. Also important; the liquid butane was first allowed to charge into the discharge circuit only by inverting the charging tank, and letting the gases push it into the unit (only the discharge side of a connected gauge set/charging manifold was open). Afterwards the connected charging tank and unit were allowed to balance out for several minutes, then the manifold's discharge valve was closed, the manifold's suction valve was opened, the unit's suction cut-off hand valve was closed, and the compressor was started and allowed to run until the suction gauge no longer dropped in pressure.
With this charge I saw a very rapid cool-down (+20C to -125C in 30 minutes @30 watt static load), and an ultimate temperature of -140C within 2 hours. Only buffered 4 times within the first 15 minutes. For higher loads I would recommend reducing the Argon and boosting the R14.
5 lb Propane cylinder used as Charge Transfer Tank (with suitable adapter)
So it works :)
Now to get a decent way to access butane instead of those damn pop top cans.
Any load figures yet?
Michael, what hardware and software did you use to monitor/data log all of your thermal couples on the AC-2 project?
It looks like a Measurement Computing, but I wasn't sure.
Regards
And have you considered Methane to replace R14/Argon?
To be clear to all that may read this... These results are from nearly a year ago, and pertain to the 3rd prototype in the "AC" series units, a project that I have for the most part abandoned.Quote:
So it works
No I never did set-up a way to actually load the evaporator on this unit, so the test results shown were just based on an estimated static heat load of approximately 25-30 watts (1/4"id x 2' Feed & Return flex lines w/1.5" thick insulation, solid machined copper vacuum insulated cold head --- see images below).Quote:
Any load figures yet?
Yes and no. But I would first have to get my hands on some, which in my case means spending some $$$. And on my next prototype (AC-4) I plan to go back to a non-flammable charge based predominately on HFC's.Quote:
And have you considered Methane to replace R14/Argon?
Sgrios you are correct on the hardware, and semi correct on the software. My brother wrote a chart recorder application in Delphi using the Measurement Computing supplied drivers, which was far superior to the TracerDAQ program that comes with the USB-TC hardware.Quote:
Michael, what hardware and software did you use to monitor/data log all of your thermal couples on the AC-2 project?
It looks like a Measurement Computing, but I wasn't sure.
Can't beat it when it comes to a fairly inexpensive way to accurately monitor 8 thermocouples down into the cryogenic range.
Images of AC-3 unit's flex lines, cold head, and unit connection:
Thank you very much, Michael. :)Quote:
Originally Posted by mytekcontrols
Ask a question:
1. The Ar critical temp is -122.4℃,how is about the R14 evaporation temperature
2.minor details Ar evaporation temperature
where did you get those flexlines at?Quote:
Originally Posted by mytekcontrols
kang-China...Yes the critical point for Argon (-122.4℃) is fairly close to the boiling point of R14 (-128℃), but I fail to see what your actual question is. It really seems that you are simply making a statement of facts.Quote:
Ask a question:
1. The Ar critical temp is -122.4℃,how is about the R14 evaporation temperature
2.minor details Ar evaporation temperature
But if I were to make a guess at what you want to know, I would think the question would be "How can the Argon be of any use in the AutoC, when the physical properties of such (critical temperature and boiling point) would certainly suggest that a condensate could not be formed under the pressures and temperatures that are present".
To try to answer this question, I will present you with a theory. The theory consists of two different aspects.
Aspect #1: The presence of Argon gas creates a partial pressure situation in the evaporator, which allows the R14 to boil at a lower temperature than if it were doing so in a pure R14 gas environment. This is similar to how the hydrogen in a propane heated absorption refrigerator works, exerting a partial pressure on the liquid Ammonia, and allowing it to evaporate.
Aspect #2: The condensed R14 absorbs some of the Argon gas, thereby creating a version of itself that has a lower boiling point that exists somewhere between pure Argon or pure R14.
I hope that answers the question.
johnksss...Hosecraft USAQuote:
where did you get those flexlines at?
in the AutoC, your AC-2 the refrigeration is
R123
R22 what's the evaporation temperature to be used condensation R170
R170 what's the evaporation temperature to be used condensation R14
R14 what's the evaporation temperature to be used condensation Ar
Argon what's the evaporation temperature to be used in the in the evaporator .if you will use the evaporator temperature is -150 or -160
In your AC-2 or AC-3 if the Ar is not enough ,the compressor suction is ?
in the end evaporator ,what's the refrigeration R14 or Ar to we used cool
:p:
kang-China...kang-China in order to answer your extensive list of questions, I would direct you to look at the individual refrigerant pressure/temperature chart for each one of the refrigerants in your inquiry. And then compare this to the running suction pressure of the AC-2 for evaporative data, and of course the running discharge pressure for condensation data.Quote:
in the AutoC, your AC-2 the refrigeration is R123
R22 what's the evaporation temperature to be used condensation R170
R170 what's the evaporation temperature to be used condensation R14
R14 what's the evaporation temperature to be used condensation Ar
Argon what's the evaporation temperature to be used in the in the evaporator .if you will use the evaporator temperature is -150 or -160
In your AC-2 or AC-3 if the Ar is not enough ,the compressor suction is ?
in the end evaporator ,what's the refrigeration R14 or Ar to we used cool
Edit: And of course this would relate to the temperature data profile that I supplied in one of the earlier AC-2 posts.
Of course this will only give you an approximate temperature as it relates to each one of the refrigerants in question, since the blended refrigerant charge will act entirely different than if a single refrigerant were present. Basically there are just too many variables to calculate when going beyond a binary mixture. And I must admit that trying to calculate the exact nature of what is going on within an AutoC is also outside of my expertise (and I dare say, most anyone else).
Some of the things to keep in mind is that when the refigerants become sub-cooled, meaning to drop below the temperature point required for a 100% saturated liquid at a given pressure, other neighboring refrigerant gases will more readily go into solution with the sub-cooled liquid. This creates what on the surface appears to be an azeotropic blend, although in most cases it is zeotropic in nature (exhibiting a temperature glide when evaporated).
Trying to pin a number on any of this is simply out of the question for most people. However it is not impossible, since I did meet a man that could do this, but unfortunately he was never willing to share his methods, or more specifically his computer modeling program.
So I create and tune the charge for an AutoC based on my intuition gained from years of working with AutoC's, since I lack a specific tool to do this otherwise.
Edit: Since this involves extensive pattern recognition, it is not something easily taught to others who lack extensive AutoC experience.
I found this forum last year ,and look your AC-2,and AC-3.so,I don't understand this .
I have not your experience,so I ask some question to you .
so I say sorry to your
Where'd you get the butane from this time around Michael?
I keep making the calls and everyone either doesn't have or considers its so specialty they want more than the cost of R14 for it.
kang-China no reason to say your sorry, and I hope you don't think you need to from our discussion. It is just very difficult for me to provide better answers then what I have given thus far.
Nol...I got it from UltraLow. he had some extra from a Sanyo chiller that he was charging, and in exchange for some consulting, he sent me about 10lbs of the stuff in a cylinder that I provided.Quote:
Where'd you get the butane from this time around Michael?
I think I've gone through about half of it, if not slightly more. Perhaps we can make arrangements to get some out to you. How much do you need?
Also check with UltraLow, because he might be closer to you, thus saving on the shipping, assuming he still has some available. It is high purity refrigeration grade stuff.
Not more than a pound I don't think.
I'll have to ask where he got it from, I don't mind paying, just not $45 a pound.
Nol...Yeah pretty pricey stuff, and almost impossible to get in small quantities. Let me know what happens (send me an email if you like), and if UltraLow can't do it, then I'm sure we can work something out. I'll just need shipping covered, the 1lb of butane you can have for free. But you gotta promise me that you'll post the results of whatever it gets used in.Quote:
I'll have to ask where he got it from, I don't mind paying, just not $45 a pound.
Ha of course, I'll let you know, and thanks as always.Quote:
But you gotta promise me that you'll post the results of whatever it gets used in.
hi guy,
I didn't know, about your AC-2,or AC-3, what's refrigeration in the lastest evaporator to work,
Ar or R14 ?
please answer to me
refrigerant pressure/temperature chart I had looked
The Ar critical temp is -122.4℃,
In the lastest evaporator to used Ar lique, so R14 evaporation temperature
is about -128℃,
:ROTF:
what do you think?
He is not attempting to condense argon.
kang-China...Unfortunately I think we are having a language translation problem :confused:Quote:
In the lastest evaporator to used Ar lique, so R14 evaporation temperature is about -128℃
As Nol just stated: the Argon is not condensed.
But in order to have the evaporator get colder then -128C, especially when the evaporator pressure is above 0 psi, Argon is required. However due to the critical point of Argon, no amount of pressure would be able to condense it.
So what does the Argon do if it can not be condensed?
The exact mechanism is unknown, but as I stated in an earlier posted answer to your question, it is felt that two possibilities exist. The first one having to do with "Partial Pressure", where the presence of Argon in the evaporator, creates an effect on the evaporating R14, of being evaporated into a lower pressure than reality.
The use of Argon to create a "Partial Pressure" on the R14 is the same principle as used in Absorption Refrigeration Systems, and is best described by this excerpt from this WorldLingo article (for our scenario, substitute R14 for the Ammonia, and Argon for the Hydrogen)...
The 2nd possibility of what happens with the Argon and R14 mixture, is that the Argon gas will dissolve to a small degree into the condensed R14, thereby causing the R14 to evaporate at a temperature below it's norm when later expanded. The degree of Argon that goes into solution with the R14, is wholly dependent on the temperature of the condensed R14. So as it gets colder, and goes into a subcooled state, more Argon will tend to dissolve into it, thus the R14/Argon solution will evaporate even colder. This effect will continue until such time that an equilibrium is obtained, where the physical constraints of heat load versus evaporating pressure exert themselves (determined by limits of pressure drop through heat exchangers, and pumping ability of the compressor).Quote:
The cooling cycle starts at the evaporator, where liquefied anhydrous ammonia enters. (Anhydrous means there is no water in the ammonia, which is critical for exploiting its sub-zero boiling point.) The "evaporator" contains another gas (in this case, hydrogen), whose presence lowers the partial pressure of the ammonia in that part of the system. The total pressure in the system is still the same, but now not all of the pressure is being exerted by ammonia, as much of it is due to the pressure of the hydrogen. Ammonia doesn't react with hydrogen - the hydrogen is there solely to take up space - creating a void that still has the same pressure as the rest of the system, but not in the form of ammonia. Per Dalton's law, the ammonia behaves only in response to the proportion of the pressure represented by the ammonia, as if there was a vacuum and the hydrogen wasn't there. Because a substance's boiling point changes with pressure, the lowered partial pressure of ammonia changes the ammonia's boiling point, bringing it low enough that it can now boil below room temperature, as though it wasn't under the pressure of the system in the first place. When it boils, it takes some heat away with it from the evaporator - which produces the "cold" desired in the refrigerator.
It is my belief that both of these theories are in effect with the R14/Argon mixture within an AutoC.
hi guy,metek
in your AC-2,AC-3
I don't know the area
each cascade condenser
common temp about -20or-30 ,figure out the area is very easy.
But your AC-2,OR AC-3, condenser area is very very difficulty!
so you are a marvelous guy
could you tell about this '
:up:
:clap:
:yepp::yepp:
I believe it's in the thread here.
Hi,mytek in you AC-2
To buffer valve in the phase separator#1 is not very well
I think in the lastest phase separator is best,
and you say that in your AC-2(buffered 4 times within the first 15 minutes)
if to To buffer valve in the lastest phase separator i think is better
:p:
:rolleyes:
Based on what? That seems rather unfounded. Have you considered the temperature that the solenoid valve would then have to deal with?
kang-China...Theoretically you are correct, but in actual practice nothing is really gained in moving the Buffer gas source to the last Phase Separator (I've run tests both ways). Remember that in an ideal set-up, where the Buffer/Expansion Tank is sized so that the static balance pressure is <=175 psig, the need to buffer will only occur once soon after start-up. In my unit I was limited to using a rather small tank, hence the need to buffer several times.Quote:
To buffer valve in the phase separator#1 is not very well
I think in the lastest phase separator is best
Another factor that needs to be considered, is the added pressure drop when moving the Buffer gas source near the end of the system. This pressure drop can be detrimental to the response time in lowering the discharge pressure, which kinda defeats your buffering to some degree.
And Nol brings up a good point about the operation of the valve using a potentially much colder gas stream, although I think this would only be an issue if the buffer valve were to open much later in the run time, such as when encountering a high heat load late in the game.
hi mytek
in your AC-2,AC-3
I don't know the area
each cascade condenser
common temp about -20or-30 ,figure out the area is very easy.
But your AC-2,OR AC-3, condenser area is very very difficulty!
so you are a marvelous guy
could you tell about this '
Yes calculating the areas for the discharge and/or suction circuit of each Cascade Condenser (as well as the Auxiliary Condenser) does get a little tricky, especially with the dual 3/16" tubes inside of the 1/2". But it is doable by using the area of the circles, subtracting the wall thicknesses, and then factoring in the overall length. But I'll leave this for someone else to do, since it wasn't a great concern for me when I built the AC-2 (I made an educated guess when designing the heat exchangers). Although my design might not be optimized, it did work pretty well.
hi ,mytek
what about the captube in your AC-2 OR NEW machine AC-C
why ,the 2#,3#,4# in the same length,
and i think, it use the different Refrigeration ,so the captube is different
length.
:confused:
:confused:
Again he's working out of experience, more tweaking the charge than the capillary tubing. Part of this process is simply making the most of expansion, and if a refrigerant isn't boiled at one HX it will be boiled off at the next and pass back through the first.
Michael, If I may have a moment of your time.. I'm not sure what kind of run time the Polycold units were subjected to (IE. 24 hours, seven days a week), but how did the Polycold cope with oil migration and clogging of the evaporator over extended run time at these temperatures? Defrost cycles?
I can answer that I believe,
Defrost cycles and often times, parallel high end oil separators. Some of them went as far as being upgraded to serial 905 Temprites, but more then a few I've seen with parallel 902's that boast 99.95% oil removal.
Thank you, Adam. I'm modifying my 'standard' cascade design in which it will be able to cope with 24/7 operation. This is due to a customer request.Quote:
Originally Posted by n00b 0f l337
This should get me headed in the right direction. :)
http://cgi.ebay.com/TEMPRITE-902-ODS...ht_2162wt_1139
or
http://cgi.ebay.com/TEMPRITE-905-1-3...ht_2429wt_1139
both are half price ;)
Thanks, Adam. I have a 902 in my run of the mill cascade and I'm not sure if it's enough at -103c loaded for 24x7 operation.Quote:
Originally Posted by n00b 0f l337
I would say it is most likely enough. I used one in a 3 stager.
I guess there is one way to find out. =].Quote:
Originally Posted by n00b 0f l337
Thanks again, Adam.
Glad to help, you can always install a sight glass to live view it.
Actually some of the Polycold units did exhibit problems with oil, especially after switching from CFC's to HCFC's and then to HFC's. On the early larger 1100 units, dual 902's (in series) were used for the hot gas (defrost) supply only. At the place I contract to, I encouraged them to replace these with dual 905's also in series as Nol pointed out, but now being used in the full flow coming from the compressor discharge and into the water cooled condenser, and then on to the HXC stack.
On the latest Polycold 1102 units that use an HFC only charge, they have begun experiencing problems with oil migration once again in certain applications, and especially when run for extended periods of time. these units use 2 custom made oil separators (one large and one small) in series with the full system flow. We are now starting to replace the large oil sep with 2 Temprite 905's (in series), so this in essence gives us 3 oil separators in series when you count the small custom one that we leave in. So far this appears to be fixing the oil migration problem on these units.
kang-China...Well most of my reasons were pretty well explained on cap tube selection in early threads to this post, so instead of being redundant, I would suggest that you go back and review the information that was already presented.Quote:
what about the captube in your AC-2 OR NEW machine AC-C
why ,the 2#,3#,4# in the same length, and i think, it use the different Refrigeration ,so the captube is different length.
And now a few questions for you kang from China... what is it that you are trying to do? Are you attempting to duplicate what I have done? If so, no problem, but I am curious because you are asking so many questions.
That's rather incredible. But do you think that may also be somewhat due to the very high flow in those units as compared to what we work with? Or the use of refrigerants?Quote:
Actually some of the Polycold units did exhibit problems with oil, especially after switching from CFC's to HCFC's and then to HFC's. On the early larger 1100 units, dual 902's (in series) were used for the hot gas (defrost) supply only. At the place I contract to, I encouraged them to replace these with dual 905's also in series as Nol pointed out, but now being used in the full flow coming from the compressor discharge and into the water cooled condenser, and then on to the HXC stack.
I didn't realize the 905's were being used for the hot gas system, from most of the piping I saw it seemed to be post-condenser.
That's rather incredible. But do you think that may also be somewhat due to the very high flow in those units as compared to what we work with? Or the use of refrigerants?Quote:
Actually some of the Polycold units did exhibit problems with oil, especially after switching from CFC's to HCFC's and then to HFC's. On the early larger 1100 units, dual 902's (in series) were used for the hot gas (defrost) supply only. At the place I contract to, I encouraged them to replace these with dual 905's also in series as Nol pointed out, but now being used in the full flow coming from the compressor discharge and into the water cooled condenser, and then on to the HXC stack.
I didn't realize the 905's were being used for the hot gas system, from most of the piping I saw it seemed to be post-condenser.
Actually it was originally two 902's in series, with the source being tee'd into the compressor discharge line (pre-water condenser). The 905's or custom Parkers as used by Polycold were added inline (full-flow) many years later, which filtered out the oil from both the hot gas defrost circuit and the main refrigeration stream.Quote:
I didn't realize the 905's were being used for the hot gas system, from most of the piping I saw it seemed to be post-condenser
#1 I think it comes down to how much oil the particular compressor pumps, and #2 how miscible is the oil with the refrigerants in use.Quote:
That's rather incredible. But do you think that may also be somewhat due to the very high flow in those units as compared to what we work with? Or the use of refrigerants?
A bit of Polycold history related to oil separation...
The 1000-1102 series Polycolds were all based on a Caryle (Carrier) 10 HP 37 CFM R-22 air conditioning compressor. In the first use (Polycold 1000), it was discovered that this compressor was a particularly high oil pumper. Polycold worked with Carrier on installing a 3rd ring on all the cylinders (of which there were six), in order to effect better oil control. This seemed to the trick at first, but many production units later, it was discovered that this was still not the case. The problem was further compounded by the owner/inventor Dale Missimer's refusal to let the engineers use full flow oil separators, insisting on the Phase Separators being enough to do the job (hence only allowing the use of two Temprite 902's on the hot gas defrost stream).
When Polycold moved on to the 1102 series, which required the use of HFC's for European compliance, there was no choice but to use full flow oil separation due to the poorer oil miscibility with said refrigerants (also Dale was out of the picture, having sold Polycold to Intermagnetics). However two series connected oil separators the size of the Temprite 905's were still not quite enough, so Polycold enlisted Parker to build some custom ones that they felt would solve the problem. But as the story goes, bigger is not always better. And even though they had implemented one that was twice the volume of a 905 for the first oil separator, in some applications they are still seeing the oil migration problem occur in these units.
So when I left Polycold, and started doing work for an independent Polycold service company, I was free to implement changes to the original designs. At first we tried a single full flow 905 on the 1100HC series, but this didn't quite do the trick. Next a 2nd one was added in series, and suddenly things began to improve. It seems that series filtration was the key, giving the final oil separator in the chain a non-saturated environment in which to work (see image below). Now we are taking this idea into the 1102HC units, and adding a 3rd series oil separator by replacing the large #1 custom Parker oil separator with two 905's, and retaining what used to be the #2 oil separator, moving it into the 3rd position.
Interesting.
If you consider it, the entire autocascade is one long serial separator, so it's funny that "serial was the answer" when it was already sort of present.
In your blend using HC's then are you having any issue? Or is the increased miscibility playing out nicely.
It seems to me that coalescent could use an improvement, either the oils blowing through the catcher or just the flow is so high that the atomized droplets are flying on out. The design itself really only features a single attempt to remove oil, it surprises me that helical would not perform better in this application.
@Michael and Adam: Thank you gentlemen, you answered my questions. Cheers.
Really? I figured I was just confusing everyone!
I look forward to seeing your project. I found a decent source of butane/isobutane/(little bit of propane) mix as well if you need it.
hi,
review the information,but i don't find that :confused:
i ask you cap tube,and i will know you design principle,
as so i wont to know this cade(AC-2)design principle. :ROTF:
I'll be attempting to duplicate AC-2
must need help form you :p:
and mytek your AC-2 will to work the -150℃ OR -160℃
and the refrigeration is ..R14,Ar can do that :shrug:
The Revco -150 and -140s have gotten away from series seperators and switched to parallel. Their test showed that with the volume and velocity of gas they were pushing, it was overloading the oil sep when they were in series.
The R600 came from National welders.
Youcan try here for small quanities of most any gas.
http://www.scottgas.com/
Thank you! I just sent in a request.
kang-China...Sorry to disappoint you, but I don't have an exact method of choosing cap tube sizes for an AutoC. With that said, here are links to earlier posts that explain my methodology: Post #109 -and- Post #112Quote:
review the information,but i don't find that
i ask you cap tube,and i will know you design principle
kang-China...If all you want to do is create an exact clone of the AC-2 unit, taking the time to completely read through this thread is the best way to accomplish this. Because nearly every single detail has been covered to allow anyone with basic refrigeration skills to do this. It is only when one decides to go beyond this, or take a different approach, that the knowledge provided here might not be sufficient to the task.Quote:
I'll be attempting to duplicate AC-2 must need help form you
So my suggestion to you, would be to build this unit as I have shown, and charge it with something equivalent to what I have used. Then play around with it, by trying different refrigerants and/or quantities of such to gain a better understanding of how the system actually works before attempting to build something entirely different.
So please, enough questions for now and I wish you luck on your AutoC journey :up:
Remember: Take the time to thoroughly review and understand all the posts related to the AC-2 unit
ultralo1..Very interesting, and not what I would have thought. Everything that I have experienced and learned over the years, suggests that series filtering would always be superior to parallel. So were those tests conclusive? Meaning did they try using a single oil separator with the same volume as the two in parallel? If not, then their problem may have just been related to being undersized.Quote:
The Revco -150 and -140s have gotten away from series seperators and switched to parallel. Their test showed that with the volume and velocity of gas they were pushing, it was overloading the oil sep when they were in series.
if the machine is working -150℃ OR -160℃,and what's the refrigeration we can use ,and how much cade in the cooling like your AC-2
And what about R50
and in the Aoutcascade system use this
R14 in 3#
R50 Ar in 4#and sub-cooler
and another like your AC-2
what will happen
:shrug:
:confused:
:clap:
Cade? I'm not sure the term.
But methane could work but as you go further and further downstream you need more flow, so a larger system.
Certain things you will need to try yourself.
kang-China...The possibility of using R50 in an AutoC was discussed in Post #285Quote:
And what about R50
and in the Aoutcascade system use this
R14 in 3#
R50 Ar in 4#and sub-cooler
Something we haven't discussed here, evaporator design.
What kind of evaporator do you normally use in your systems? Is it just a simple loop of tubing?
Nol...Hmm... how best to answer this? Well to put it simply, no different then any other system. Whether that be Single Stage, Cascade, or AutoC, the principles remain the same. But in my case, yes I have used a coil of tubing, or a machined copper bar (see image below).Quote:
Something we haven't discussed here, evaporator design.
What kind of evaporator do you normally use in your systems? Is it just a simple loop of tubing?
Essentially basic evaporator design 101: Allow sufficient room for the refrigerant to fully expand, minimize pressure drop, and minimize the temperature gradient between the refrigerant and the actual heat load.
Image: Vacuum Insulated Cold Head (w/attachment option for heat absorbing array), as used on the AC-3 project.
That's really enough eh? I'm trying to work my way through a bunch of patent papers and books on evaporator design, we need some changes in ours ;)
hi,mytek
i looked the post thank you very much
the defrost valve in polycolde
the valve's brand is SPORLAND .
why don't used the DANFOSS
or maybe SPORLAND IS better than DANFOSS
by your rule of thumb which is better
:confused:
Nol...Well if I remember right, it's enough to handle 50 watts on the attachment end of the Cold Head with a temperature gradient <= 5C. Not really sure how it'd do at 300 watts.Quote:
That's really enough eh? I'm trying to work my way through a bunch of patent papers and books on evaporator design, we need some changes in ours
Note(1): It would seem that the "Stepper" design that I see being used for CPU cooling, has proportionately more surface being cooled on the circumference then on the CPU side. This seems like a waste of material and extra machining. Where as a low profile design would seem to be more efficient.
Note(2): Has anyone measured the surface temperature versus the refrigerant temperature of any of the currently used evaporator designs while under full load? If not, then how can anyone know if a given design is any better (or worse) than another?