Are you sure your not having a problem getting r290? Sounds almost like your adding air to the system.
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Are you sure your not having a problem getting r290? Sounds almost like your adding air to the system.
Adam give me a break :D
No I verified that I was getting liquid propane spurting out of the cylinder when held upside down. And I charged it into my evacuated 3x9 addition tank using an electronic scale, being sure to purge the lines with propane to get rid of any air. Also had a brand new supco filter dryer inline to absorb any water that might have been in the propane. Stuff was getting cold past the first phase separator, and I'm sure that if I had added more that I could have seen the temperatures drop in the first stage, but unlike the R123/R22 combo, the R600/R290 combo tends to reflect the pressure of the R290, which can get quite high when a saturated liquid is present (the R123 actually reduces the pressure of the R22 or R410a when mixed). This wouldn't leave me much room to add the other gases.
I will leave it up to others to puzzle the HC mystery.
Heh thats odd indeed, I'll have to get back to testing my autoc once I get more time.
So you have been making progress on this project. I was beginning to wonder. Pretty stealthy I'd say... NOLTECH = AREA 51 :scope:Quote:
Heh thats odd indeed, I'll have to get back to testing my autoc once I get more time.
Any more details you can divulge?
Not going to use a rotary ;)
My god, the flood of detail is going to drown me. :rolleyes:Quote:
Originally Posted by n00b 0f l337
:rofl:Quote:
Originally Posted by yngndrw
Any reason not to? From my recent experiences, it seems like a rotary makes for an excellent pump. Twice as efficient as a reciprocating, able stand much higher static pressures, great start-up torque, and compact size. What else could you ask for?Quote:
Originally Posted by n00b 0f l337
Perhaps you're going to use a Scroll instead? :idea:
Hey wait a minute... AREA 51... recovered alien technology... Hmmm.... :alien:
A reciproc can fit into a normal SS case. Maybe he wants to build an autocascading system in a SS case.
Well, simply put, height, though not so much in this case, but also noise. Rotary's are lovely and all, however though this version will be much too big for a single stage case, I do want to get it down to that sort of height.Quote:
Any reason not to? From my recent experiences, it seems like a rotary makes for an excellent pump. Twice as efficient as a reciprocating, able stand much higher static pressures, great start-up torque, and compact size. What else could you ask for?
Perhaps you're going to use a Scroll instead?
Damn lost the auction on that Danfoss SC12CLX... Maybe rotary will occur in this build after all.
what was your highest bid and how long left?
Um bid at $45, someone took at $52.50, both with 4 seconds or so left?
Bumping thread due to sheer awsomnes of it!
Thanks MG :)
This also served to remind me that I still need to post an update on this project.
What's been happening:
I did quite a few tests with R410a, until I finally decided that it just isn't anywhere as good a refrigerant as R22 (of course I kinda suspected this all along, but now I'm completely convinced). Although I did get some interesting results by eliminating the argon, and boosting everything else (almost got it to do -90C at 225 watts).
Anyway I shelved it for quite a while, having other projects needing my attention. But as of last week, the AC-2 unit now has a Sub-Cooler, and is undergoing tests to see how cold it'll run (as of today; -139C under a non-loaded condition, and about -115C with 50 watts applied --- probably close to the maximum load). It wont suit a PC cooler application, but it'll do just fine for use as a water vapor cryo-pump on our shop's helium mass spectrometer (5-10 watt load).
I'll be putting the finishing touches on the case, adding a front panel, and basically wrapping up this project over the next 2 weeks. It was great fun building this little pup, and I hope you guys enjoyed it as well. I'll be posting pics and specs in a few days, and will also show you the final form in a couple of weeks.
That we did, that we did.
I think I am done with the refrigerant charge tweaking.
Here is the Cool-No-Load results:
So Michael why is it you still use R22 instead of R290, is it because oil return isn't an issue or the flammability of propane?
Flammability is not an issue (already using ethane in the charge). It is more the fact that I haven't had good success with using R290 alone, or in combination with R600. Or for that matter, R600 alone.
I figure if I've got to use R123 anyway, at least in order to obtain the best overall results, then I may as well use it in combination with R22. Yes there probably is an HC substitute for the R123, but I don't have anything on hand. And we just have a ton of R22 that was recovered from an ice skating rink for free, so I really can't beat the price.
Your early charges with R600 in this thread point to good performance though, then you found a blocked captube. Is it possible that too many HC's makes purification hard? Or is R600 too low a BP? Though its only 0C, and r114 is very ideal...
I have attached what I certainly hope is the final piping diagram for this project (assuming I haven't made any errors). It is a vector pdf, since the resolution of a bit mapped image would probably not capture the detail.
It is a modified version of earlier diagrams that I posted, and shows the AC-2 unit in its new application dress. That being a water vapor cryo-pump for a helium mass spectrometer.
Please note that the offset as shown in the Final vs. the Sub-Cooler captube coming out of the bullet strainer is intentional. Having the SC captube slightly lower then the Final captube insures that the Sub-Cooler always gets fed some condensate, no matter how poor the quality or quantity of what is available. This makes sure that the Sub-Cooler is always trying to operate in an active mode, and thereby continues to create an environment where the Argon will dissolve into a sub-cooled R14 stream that runs through it.
Polycold wasn't purchased for 22 million dollars in 2003 for a outdated cfc/hcfc mix that's no longer usable.
The present invention overcomes the need for using CFC refrigerant mixtures in a refrigeration system by utilizing refrigerants R14, R134a, R508a or R508b, R142b, and R740 in a component mixture. To achieve desired properties, these refrigerants may be used in a special mixture.
Nol -- good observation.
Come to think of it, I probably didn't explore this avenue as well as I should have, but I did do a follow up test with R600 after fixing the captube, and was still seeing some strange behaviour. At the time I attributed this to too good of separation within the various phase separators, possibly causing a starvation effect to occur in the later stages. But then again, I was also trying to make a 4 stage autocascade work more like a 3 stage at the time. Now that the unit has a sub-cooler, and I am using a much greater quantity of Argon (I'll post the final charge soon), I am obviously using all 4 stages (-140C). Perhaps R600 and/or R290 combo would work well in this situation.
Perhaps you'll have better luck with your AutoC project.
Good point Walt. But Polycold has access to refrigerants that I simply don't.
Polycold charge as stated in their patent:
R236fa, R125, R23, R14, Argon (EDIT: forgot to list the R23)
Requires POE oil, and extremely good oil separators (Polycold had some gigantic ones custom made to their specs).
EDIT: BTW; I no longer work for Polycold, and this project was not an attempt to make what they have made, it was simply meant to serve as a tutorial on autocascades (which I think it has done quite well).
I realized that, and it was a great build and informative.:up:Quote:
Originally Posted by mytekcontrols
Getting below -120c oil becomes a major issue. Thats why we need a new compressor design.
Maybe a 3 stage axial oilless design......30 to 40 bar pressure differiantal @ 40,000 rpm. :D
Interesting with r236FA, boils at -1.4C. Then a jump to R125 which is rather high pressure, almost like r410a.
I think from a boiling point sense, they've tried to make like a r114 with r236fa, but then are skipping the r23 like refrigerant in favor of r125 saturated with r14 maybe?
EDIT: Looking over and overlaying some charts, it would seem that R236FA is well, hell almost like butane exactly, except three times the mass, and a tendency to really mess with oil. That's odd indeed.
Wish you had another one mytek of the AC2 to work with, could with your three phase seps, probably try r600, r290, veryyyy small amount of r170, then jump to r14, and maybe some argon.
I think this thread should be added to the guides and or stickied, maybe a cleanup of the stickies is in order.
Opps! I forgot to list the R23, which I have now corrected on my original post.
Nol -- Yep the R236fa/R125 combo is aimed at creating an R114 look-alike. And this along with the other components selected, was intended to be a conforming non-CFC/HCFC charge that would also be non-flammable. To this end, they have indeed succeeded.
But as you and Walt have observed, oil can be quite a problem with this charge.
BTW; R125 is one of the primary ingredients in several of the new alternative refrigerants, including R410a.
Thanks Walt :)Quote:
I realized that, and it was a great build and informative.
Oh so still r23, okay that makes a great deal of sense. Must be a very small r125 charge then I'd imagine. Maybe 2 phase seps in that system Michael?
Actually it has 3 phase seps. Pretty much the same as my latest AC-2 system, but done with much larger, multiple inner tube coaxial heat exchangers, and of course very large oil seps following the compressor discharge.
I'd imagine, but then again thats probably not a half horse compressor ;)
Hey Michael,
After looking at your new schematic I was interested in your cap tube sizing, adding up the flow factors from all your cap tubes excluding the one that feeds the subcooler comes to 0.556 according to the flow factor chart, which puts you at the mass flow of the compressor you have.
But your captube that feeds the subcooler would supply about 0.04-0.03 approx, since 192" of 0.026 isnt listed on the chart, so im assuming its beneficial to allow slightly more flow then whats being produced by the compressor?
Also when I asked about R290 instead of R22 I was meaning it would go in combination with R123, I asked this cause in talking to adam he has found it results in lower pressures then R22.
Or would the fact R290 is a HC mean that it won't combine quite as well with R123 as R22 does?
oh i also wanted to ask if using 3/16 in 3/8 would be ok for the subcooler HX instead of 1/8 in 1/4?
Raadster -- You are correct on the fact that I have exceeded the compressor's mass flow abilities with my captube selection. It was a compromise I made, because I really didn't want to resize all the captubes at this point, and for the temperature/wattage requirements I knew it wasn't going to be an issue. Also keep in mind that the captube flow rate specs are based on a constant liquid seal at the entrance of the captube, something that it is difficult to achieve in the later stages of an autocascade, especially under load.
On the sizing of the Sub-Cooler HX; remember that as compared to the other HX's, the mass flow is very low. For the system I built; 1/8" inside of 1/4" was quite sufficient. If you are building a bigger system, then the next logical size would be 3/16" inside of 5/16", although in a pinch, 3/8" would probably work.
Yeah you really want something incredibly tight with the subcooler. Plus 1/8 in 1/4 has gotta be the easiest to bend HX ever ;)
This is most likely going to be my final charge for the newly configured AC-2 unit. Although I might need to tweak it when I get the HMS Cold Probe attached, and run it in a vacuum.
6oz R123
3oz R22
62psi R170
75psi R14
42psi Argon
Being air-cooled, it likes a much higher ratio on the R123 vs. the R22. Also a larger amount of R14 vs. R170 seemed to yield better results for low temps when the load is minimal (which is the case for the HMS application). And as you can see, there is a substantial amount of Argon being used, which is why we can go down to -140C, while still having a suction pressure of 27 psi.
Beautifuly informative as always Michael! I was actually looking at some of your patent info the other day.
Might actually try out the "Zero Gravity Separation" ;) ;)
Hey Adam --- when do you anticipate releasing some more info on your AutoC project? :slobber:
Yeah the "Zero Gravity" system was very easy to fabricate, but being partial separation kinda makes it imperative to add an oil separator even with AB oil, and will also require considerably more separation points for temperatures below -100C.
I did participate in some discussions with Cryo-Tek about this in the AutoC Drawings thread. You might want to check it out. :)
The S.S. Destroyer is in tuning and insulating phase, doing a triple evac to very low microns, thus working on the Window AC Cascade.Quote:
Hey Adam --- when do you anticipate releasing some more info on your AutoC project?
Hey don't give it away! :P And yep I am thinking of going with a 3 captube approach within the HX's, then one to Evap. R600/R290/R1150 is the goal. Probably going to use a 5600 btuh roto and some condensers I have vs a window AC this time though, since I'll want to keep it small.Quote:
Yeah the "Zero Gravity" system was very easy to fabricate, but being partial separation kinda makes it imperative to add an oil separator even with AB oil, and will also require considerably more separation points for temperatures below -100C.
I did participate in some discussions with Cryo-Tek about this in the AutoC Drawings thread. You might want to check it out.
Oh and I think I'll replace oil with Zerol 150, don't expect final temps in the -100C range.
I forgot to answer this question by Raadster:
Although I haven't tried combining R290 (as a substitute for R22) with R123, I would imagine that it should work. As for how well an HC will combine with an HCFC, I really couldn't say. Any chemists out there care to venture a guess?Quote:
Also when I asked about R290 instead of R22 I was meaning it would go in combination with R123, I asked this cause in talking to adam he has found it results in lower pressures then R22.
Or would the fact R290 is a HC mean that it won't combine quite as well with R123 as R22 does?
R290 is CH3CH2CH3, or three carbons long, saturated with hydrogen. This results in a mid to low level dispersion force.
R123 is CHCl2CF3, or two carbons, one saturated th Flourine, and one with two Chlorine and a Hydrogen. Flourine results in a very tiny dispersion cloud, thus results in mid to low level dispersion force (and weak intermolecular bonds, thus R14 is such a low boiling point). However it's other end has Chlorine, a very high dispersion force item, which is resulting in very strong intermolecular bonds on that one side, only slightly balanced by the hydrogen there. That is why R123 boils so warm. I would say that your mixing will not be as devastatingly amazing as two Hydrocarbons, however saturation will still be very high as R123 has an irregular shape and electron cloud, which propane will (being very small) attempt to fit into. Should work just fine.
The main difference between the HC's and the others, is the higher oil miscibility, and the lower mass. I've found they like about a 10-20% longer captube.
Now Mytek, got another Q for you. What happens if your captube flow is less then that of the compressor, and what if it's more, like in your case. What is the side effect.
Adam -- Wow! Great explanation of chemical properties of the refrigerants and their inter-relationship. I'll have to read it a couple more times to let it all sink in.
Captube sizing in AutoC is not much different then single stage as far as affect. Less flow = higher differential pressures and vice-versa. And higher differential pressures mean lower evaporating temperature on suction side, or in other words lower temperatures overall.
Oh almost forgot; higher differential pressure also equates to less mass flow, and of course lower mass flow means that we can't pull as many watts out of the system.
It's rather simple,
Like attracts like, and such.
The farther up and right you go on the periodic table, the smaller the electron cloud due to what is called Zeff factor, or the pull of the nucleus on the outer electrons. Very small molecules like to be with other small molecules, but more so they want to be with similar. Non-polar's will not mix with polar molecules well or easily, if at all. The problem with R290 and R123 is that R123 by most standards is probably polar, however "at one end", the Chlorine and Carbon bond is polar, and there going to be pulling electrons to the Chlorine and causing a disturbence there, and effecting the dispersion force (sort of like inner vibrational force of electrons, as they sway back and forth in a sense).
So they will mix, but not the best. The R290 will most likely try and stay on the CF' side of the molecule, where dispersion is still low, polar is still happening however more then likely slightly canceling out across the molecule.
Just my guess though ;)
Really when it comes down to it, most of these refrigerants will mix about the same, and it's more a matter of increasing saturation via lower temperature then anything. And of course the higher temperature refrigerants are normally bigger with more intermolecular forces, so are prone to pull in the little ones ;)
Hey Michael, looking over your patent info for Patent # 4,689,964, and though I understand the crimp and plant technique of the captube, I don't see how its a physical possibilty using 3/16 in 3/8. A .031" captube almost perfectly uses up all available space within a 3/16" tube, with no crimp.
The main reason I ask about the potential for R290 to combine with R123 rather then with R22 is that its been shown as ive come to discover that there are substantial gains to be had by using a SLHX with R290.
Conversely, R22 shows to have a decrease in COP and Capacity when a SLHX is used.
The reason is when we use a SLHX 2 essential factors are conflicting with each other:
1. Theres a gain in capacity by the liquid being subcooled, resulting in greater capacity.
2. We add superheat to the saturated vapor resulting in greater volume of the vapour and since compressors work by a standard volume per unit time we inevitably have less mass being circulated each stroke and thus ultimately have less mass flow overall. Obviously resulting in less capacity.
Thus if we can combine refrigerants which have been shown to result in COP and capacity gains from using SLHX, which in an Auto-cascade obviously can't be avoided, then we can have ultimately better loads for the same temps.
On a side note, since we are essentially never working with pure refrigerants at any stage in a Auto-c you may dismiss the following proposition presented above since there will be a "pseudo refrigerant", and thus the effects would be mellowed by the combination of other refrigerants. I personally think that any time your combining 2 things that you will come to a foreground between the 2 in terms of the good and bad properties of each. Thus to me personally I would think that although the negative effects of COP and capacity that R22 suffers from using a SLHX may be minimised, they are ultimately present.
NB: the gains in COP and capacity of using a SLHX with R290 are shown to be in the 5-15% region while R22 suffers by -5%.
I thought you guys might be interested in what the actual Sub-Cooler looked like, and where I had to cram it in (not kidding about that, starting to run out of room). In the image you can also see most of the 16 foot .026 ID captube residing inside the coils of the Sub-Cooler.
Haha sorta as I pictured it. Looks nice, I love watching you dig in the foam :P
With 3/16" tubing, and .031 ID captube, no crimping required. As you said, it practically takes up all the space inside. Instead; drill into the 3/16" at an extreme angle, so that when the captube is inserted, it will tend to lay flat against the tubing. Basically what you are trying to achieve is to create a highly restrictive area where the captube enters the discharge tubing. This will create a turbulent area around the entrance of the captube, and thereby cause some liquid to feed it. Crimping the tubing would only be required for a higher mass flow system that uses larger discharge side tubing.Quote:
Hey Michael, looking over your patent info for Patent # 4,689,964, and though I understand the crimp and plant technique of the captube, I don't see how its a physical possibilty using 3/16 in 3/8. A .031" captube almost perfectly uses up all available space within a 3/16" tube, with no crimp.
I was thinking on that all day actually Mike, and yep came to that conclusion. It would result in almost a capillary effect around the capillary, restriction indeed. That will let the gas slip by as it would fit through easier, probably due to "surface" tension on the liquid at least in some part, and the liquid would be forced into the evap.
Hopefully If I have time before school in Sept, I will get to that.
50ft of 3/8" on the way though, have 3/16 ;)
Yes its kinda like being a sculptor :)Quote:
Haha sorta as I pictured it. Looks nice, I love watching you dig in the foam
I also had to specially grind a drill bit that would cut-out a plug (sort of like a mini hole saw) in order to make a spot for the return of the subcooler to enter the top of Cascade #3. Also kept a nitrogen bottle attached with the regulator set to about 30 psi to blow out any chips.
Yep good idea. I would suggest a concrete drill bit, its more flat then anything, and if your good and have internal pressure, no need to worry about chips, you wont puncture till the last of last miliseconds and then you'll be through.
Never thought about that, but I can see how a concrete bit would be very similar to what I custom made.
Sorry to not reply sooner to your other question (too much thinking will short out your brain).
I should have some more pics tomorrow with the cold probe attached, and the case partially assembled.
LoL your good man, its just fine, why not checkout the cascade thread of mine ;)
Tons of pics for you there.
Hey again,
Was pondering as I normally do about this stuff ( yep I'm a freak, laugh all you want, I love it ). And was thinking about condenser sizing, you had said it seems like you don't need as big a condenser since it's all done in the first third. So got me thinking, with well, why.
Odd theory, but let me know what you think.
In a given situation with a hot discharge temperature X entering a condenser, the refrigerant will condense when at that pressure it achieves the temperature needed to condense. In some situation A, this may require the full rated and normal condenser to achieve said temperature. Now in situation B, our autocascade, for a given temperature X of input, let's say the same temperature is achieved at the end, however, with refrigerant like R123, the temperature required to condense the refrigerant, is much warmer then temperature X, and thus it condenses much earlier in the coil. Thus when R123 or similar begins to condense, it transfers to a liquid obviously. Now as something changes phases there's an energy transfer as well, with condensing it gives off heat, thus making the area around it "hotter", and thus we perceive the hot condenser. This also now "enters" the coil as load much earlier, versus towards the end.
Now the rest of the coil you are still reducing temperature, however condensing is done much earlier of the refrigerants that will condense, and the rest are simply being cooled on there way to ambient.
Sound possible? Logical?
EDIT: Also! When in this top area of the coil, or earlier shall I say, the refrigerant becomes liquid, heat transfer also increases! :)
Adam -- I think this makes very good sense of the what is perceived to be happening. And yes heat transfer is increased, hence the reduced requirement for condenser area as compared to a conventional single stage unit for a given compressor mass flow.
This theory has been proven over the years that Polycold has been building AutoC's (you should see how small the condenser is on their air-cooled 1.5hp gas chillers).
I think it would be safe to say that at least a 50% reduction in surface area can be implemented (and maybe as much as 65% is possible).
Of course, but then again why not go with a big one like a window AC anyway ;)
But the reason I bring it up, is if your looking at a 200W heatload, how much condenser do you need. Your window AC has like a 1.7kw condenser!
Michael what did you think about the COP gains and the capacity gains of using a SLHX with R290 as opposed to R22?
And in terms of condensor sizing, if you buy a Window AC may as well as you said Adam go with the condensor it comes with.
Exactly! That is why if you really want to shrink the package down you can achieve this quite easily by reducing the fan and condenser size. But if the original AC unit size suits your needs, why bother?Quote:
if your looking at a 200W heatload, how much condenser do you need. Your window AC has like a 1.7kw condenser!
What can I say, other then "Most Impressive", and I think it speaks for itself as to the performance increases that can be achieved with HC refrigerants.Quote:
Michael what did you think about the COP gains and the capacity gains of using a SLHX with R290 as opposed to R22?
Exactly my thoughts ;)
Well I got the actual cold probe, or what can also be called the final evaporator configuration for the AC-2 unit attached a few days ago, and have been testing the performance. Presently it is not in a vacuum (although the final application will be), and it is instead sitting in a box of fiberglass insulation.
On the initial warm start-up; the probe temp pulled down fairly good during the 1st hour, hitting -117C. But it was soon apparent that the rate of decent was beginning to level out, so I tweaked the charge just a tad bit with some more R170 and about another ounce of the R123. This got things moving again, and within the next 1 1/2 to 2 hours it got down to about -130C (this was with an 82 F or 27.8C ambient).
I've kept it running for about 4 days now, and it's gotten down to -138.5C on the probe when the ambient conditions drop to 68 F (20C) in the late evening.
Presently as I write this post I am seeing the following:
Comp Discharge: 77.0C
Comp Suction: 9.0C
Ambient Air: 26.4C
Middle of Probe: -134.2C
Comp + Fan Amps: 3.4
Low-Side Press: 30 psi
High-Side Press: 175 psi
I expect to see even better temps when the probe is in a vacuum.
Here's some pics (sorry for the lack of a temperature meter):
Really incredibly impressive, every shot, every picture.
Did you make a different top?
That's a fantastic piece of work and amazing temps. :up:
Probably saved your shop quite a bit of money there too.
Nope, stock AC sheet metal. Just added the 1/2" aluminum angle to create a place for the front panel to mount to (Having Front Panel Express make me a nice custom one).Quote:
Did you make a different top?
Thanks loonym :) Although to be clear, I didn't fabricate the actual cold probe and vacuum flange. These were stolen off of a faulty Polycold P-75 unit (see image below).Quote:
That's a fantastic piece of work and amazing temps.
Yes I did save them quite a bit, considering that my little bitty AC-2 unit does everything and more then a properly working Polycold P-75, which carries a price tag of $10,000 new. However I will be getting reimbursed for the materials (approximately $850), and about a weeks contracting fees to convert the AC-2 into its new HMS configuration.Quote:
...Probably saved your shop quite a bit of money there too.
I know this doesn't sound like much in comparison, but it was never my intention to make money on this project, so anything is appreciated.
Polycold P-75 Unit:
The front panel as I said earlier is being custom made by Front Panel Express. I have attached a captured image from the program (free version has no export filters), and the actual construction file (you'll need to download the free program from Front Panel Express to view it).
Don't let the quality of the image fool you, the finished product from these guys is top notch.
The Mytek Logo is actually going to be a stick-on PC style case badge I had made by a company called Scotgold. Their pricing is pretty reasonable, and they'll do quantities as few as 10 pieces.
At this point in time, I'm just waiting for the front panel to arrive (ships 8/22/08), and then the unit can be buttoned up.
Sweet, Real nice!!
Very nice indeed! :) Not going to show off the discharge pressure though? Too bad, I like watching it with a buffer valve ;)
Again great project, with the Polycold costing that much, have you considered making a few more and selling near half that?
No room for 2 gauges, so I had to compromise on the one. I picked suction, because it allows for a better resolution, and I think shows the unit's overall pumping condition better than the high side alone. Yes it would have been cool to see the discharge gauge dip each time the system buffers, something it will do at least 10 times on a warm start-up.Quote:
Very nice indeed! Not going to show off the discharge pressure though?
No I've had my fun, and hopefully helped others learn more about autocascades, that's all I really wanted. Of course the info on how to do it is now available if someone else wants to step up to the plate ;).Quote:
...with the Polycold costing that much, have you considered making a few more and selling near half that?
Polycold no longer makes or sells the P-75 model, and instead concentrated on it's 1hp brother (same basic design, and dimensions, just a bit more mass flow --- 1hp vs. 3/4hp). So I'm sure there is ample opportunity for someone else to enter the market, especially considering the AC-2's physical size reduction, and about half the power consumption of the P-75. I'll be sure to post a picture later on of the AC-2 sitting next to a P-75 for comparison.
This thread has been amazing to say the least. The work you have done here will be immensely useful for years to come. If it hasn't already been added to the stickies, I'd like to see it added as it's the first 100% successful autocascade I've seen on these forums built by a professional.
Thanks Gom :)
And to just let you know (and everyone else as well), I am hoping to create a nicely formatted pdf that covers this entire build, so as to make it easier for someone to duplicate my results. It'll take a while, but I am hopeful that it'll happen by the end of this year.
Edit: (10/10/2009): Sorry, but it looks like I'll never find the time to do the pdf.
Ya know what,
I'm going to put mine together, got an evap to spare on the way from Teyber I think,
Have an HX stack all brazed up and pressure tested, have spare condensers, just none exactly what I'd like, and total dimensions aren't as beautiful as I'd like. But why not.
Mytek expect a thread soon after I finish and ship the Mini Window AC Cascade and one other build, hopefully will have this then done before I ship away on the Sept 1st.
Expect:
Dual condenser (incase one isn't enough), of 8.5 x 10.
SC18CLX.2
HX Stack
Teyber stepper
24-30" flex line (have to order some Flex from Ron, will do that now).
Buffer valve and such as well.
*Yep ordered Braid from Ron, two gauges, some more captube, some more its and bits, an expansion tank of decent size empty volume bout 9" tall 4" diameter rated very highly on pressure. So on it's way, we'll see how this cooks out ;), I'm thinking a "tower" as before*
I'll be looking forward to it :DQuote:
I'm going to put mine together... Mytek expect a thread soon after I finish and ship the Mini Window AC Cascade and one other build
Ya know whats odd, Frosty Freeze, an ebay seller, has cans of R114, for like $60 a can, its like an 8-16ounce can. Though you couldn't even sell that anymore!
http://www.xtremesystems.org/forums/...1&d=1199338468
U have not created an a machine! That is a true monster dude!
Btw when u add cpu evap to this autocascade monster :D?
Yes it is quite a little monster. No CPU Evaporator for this one; it's destined for other things. Besides with the wattage requirements of the present generation CPUs, this little guy was just a bit too small, and would have required a bigger compressor, and most likely higher flow captubes. Something that I'll leave up to others to pursue.Quote:
Btw when u add cpu evap to this autocascade monster ?
Well I've been running this thing non-stop since Tuesday morning, and I am happy to report that all seems well.
Below I have attached a cut-n-paste from the chart that is running on a remote PC at work connected to 5 temperature points on the AC-2 unit (I am presently at home right now --- gotta love remote view software). Unfortunately our current version of test software doesn't support pressure read-outs, so the running pressures are: ???
The other problem is that the software crashes after a few days, and then I have to restart it (hence the 38:XX hour:min point listing at the bottom of the chart).
An explanation of the various temperature points being monitored:
Comp Dschrg = Compressor Discharge Line (within 2" of compressor body exit point)
Comp Suction = Well I guess this one is pretty obvious
Ambient = Air temperature of the AC-2's surroundings
Probe Middle = This is a taped on TC at the middle of the Evaporator Cold Probe (aluminum metal tape and several turns of black electrical tape)
Average In/Out = Feed and Return TC's on Cold Probe connection tied together to yield an "average" temperature across the probe (this will eventually be connected to a permanent panel mounted TC meter)
As can be seen; there is a little bit of oscillation in temperatures, but it is extremely small (worse case = +/- 1/2 degree C, even less on the cold end). If we were going to have an issue with oil freezing out, I'm sure it would have shown itself by now, with the cold end warming up considerably.
Keep in mind that I never changed the oil in the compressor, so it is most likely a standard temperature variety of AB as supplied by the factory. This would have a typical freezing point of -40 to -50C. Also there is no oil separator in use. This really shows how good the phase separation is working to return the oil, as well as the excellent miscibility of the oil with several of the refrigerants selected.
Mikey likes it :up:
Does that average really work? I'd imagine it might read very false results if TC's act like resistors, as resistors in parallel result in less then the two combined... might give you a warmer or colder temp then you might otherwise see, but they might read completely different so might be totally off.
I love your reading and control system though, it really is very elegant.
It works perfect so long as the TC's are of the same length (See excerpt below --- obtained from: Lessons in Electric Circuits).Quote:
Does that average really work? I'd imagine it might read very false results if TC's act like resistors, as resistors in parallel result in less then the two combined... might give you a warmer or colder temp then you might otherwise see, but they might read completely different so might be totally off.
Edit: You can also see this to be true if you compare the last 2 strip charts in my previous post. One of them is an average obtained by taping a TC to the actual middle of the Cold Probe, and the other is obtained by 2 identical length TCs attached at the FEED and RETURN points of the Cold Probe's coil. The readings are less than 1 degree apart, with the "averaged" TC's showing a slightly lower temperature and oscillation (due to the 1/4" tubing's smaller mass being more responsive to temperature change vs. the higher mass of the Cold Probe's 2 1/8" copper tubing).
Thanks :) It's nice to chart temperatures in real time instead of only using a TC meter. Makes for an easier determination of improvement when making refrigerant additions as well.Quote:
I love your reading and control system though, it really is very elegant.
Ah perfect! That really is very useful! :)
The new machined front panel for my AC-2 unit has arrived!
It looks very nice and shiny, and was shipped on a laminated card, and packaged inside of a sturdy box with inflated air-bag packing. As I said in an earlier post; the people at Front Panel Express do a great job :up:
As you can see; I didn't have much room for the TC Meter, hence the necessity for mounting it so close to the top edge. But as you may recall from some of my earlier photos, the expansion tank really fills up most of this area to the left, and the foamed stack takes up all the space to the right. I just hope that I planned this layout properly, and that everything fits :hrhr:
I'll be buttoning up the unit later today, so hopefully I'll have some pics of the completed unit by tomorrow.
Nice!! :D
Now that is a beautiful thing!! Great design there mate!
looking nice
is that lasercut engraved or a sticker?
won't try to say on quality as no compliment will do it justice
Quote:
Originally Posted by mytekcontrols
That is BEAUTIFUL. :up:
First of all; thank you everyone for very kind words :)
It is all engraved, and then filled with paint. not sure if it is laser cut or machined, but judging by the quality of the fine lined print it wouldn't surprise me in the least that it was laser cut.Quote:
is that lasercut engraved or a sticker?
Yep I am very happy with how it turned out. It's always a tricky thing to figure out how to best layout such a thing, and to get everything in just the right place, and to the right dimensions.Quote:
Great design there mate!
Well as it turns out, I did get it right, and everything went together smoothly when I did the final assembly today. I will have pics to show you guys tomorrow, complete with frost on the cold probe.
Is it tomorrow already? No, I just couldn't wait so here are some more pics showing the completely assembled unit, and as promised some frost :D
Note: the unit had been running for approximately 2 hours when the frosty pics were taken --- not bad temps for the cold probe being in free air
Hot damn
Cold damn
I left the unit running when I left the shop. It'll be quite interesting to see how much ice I have tomorrow morning, and how much colder the probe is with the ice acting as insulation.
Hopefully it isn't like one of those horror movies where the thing has grown to 20 times its original size, and starts freezing people :shock2:
Oh man I cannot wait to see this HAHAQuote:
Originally Posted by mytekcontrols
I'll be sure to post a picture. That is... if I don't get caught in its icy stare and freeze to death ;)Quote:
Oh man I cannot wait to see this HAHA
Looks great with the new front. :D
Question, why can you not move the flex line when it's cold ?
Actually the flexline itself doesn't care, but the insulation that surrounds it will become very brittle when cooled down to the temperatures that this unit can produce. So if you move it, the insulation will crack.Quote:
Question, why can you not move the flex line when it's cold ?
Why not that would be awesome, it would probably obey you as you created it, and it would aid in your ultimate quest of world domination!Quote:
Originally Posted by mytekcontrols
Well it didn't turn into a 10 foot tall ice creature (I know you guys are disappointed), but it was very frosty.
Next and last test will be in the actual application. That being in a deep vacuum on a Helium Mass Spectrometer.
Man, I wish I could have snuck in and placed a heavy duty humidifier right next to the evaporator....and then removed it before you arrived in the morning. That might have made for some hilarious results.
OMG, how did i miss this thread :shakes:.... its damn cold!
Better yet, get a big drum of olive oil, proper it under, would have frozen it all up, and when you removed the bucket it would be incredibly wierd looking as the outside started to melt!