As far as I've seen, its an equal amount of gas, 1:1:1:1.
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As far as I've seen, its an equal amount of gas, 1:1:1:1.
Quote:
Originally Posted by 404Power
In the UK I think the problem we have is finding 'small quantities' of certain gases / liquified gases. Most companies only want to sell you large amounts! It may be different where you live though.
I have a feeling I know the answer to this and it goes something like....."The charge is going to vary from system to system. It will all be dependant on the exact specifications of your particular unit. :p: "Quote:
Originally Posted by 404Power
I've watched Cryo-tek charge my Polycold a couple of times and he doesn't seem to use a "set formula" for charging it. Basically, we put the autocascade onto a scale and he charges/releases various gases until the charge "feels" right to him. I can almost definately say though, the ratio of gases was not 1:1:1:1 ;)
not to be an *ss but from this answer I have to conclude that either your blind or you know nothing about autocascades/refrigeration or you just say something to get a higher post count :lol:Quote:
Originally Posted by n00b 0f l337
edit: I almost forgot, stephen is right, there is no way to determine the charge on just a scematic. However I think 404power just wanted a rough figure. I can't help you on that though since I never worked with r14
That is absolutely correct Steven :D. Anyone who knows what they are doing will most likely give that answer :p:.Quote:
Originally Posted by s7e9h3n
404Power... most often single stages and cascades have been said to use around 50-100g as an estimate, but I don't know about R14.
I gave a ratio because I know theres different charges for all, but by searching patent information on these forms of coolers, and its easy to find, they are often listing like 20oz for first gas, 19 for 2nd, 18 for 3rd, 17 for 14th.
Just saying what I've seen.
FOUND IT; http://www.xtremesystems.org/forums/...d.php?t=114671
Thanks @ all for your answers! :)
As Unknown_road already said, I just want(ed) some "rough numbers" and no exact numbers! ;)
Yeah .. I know what you mean! :D But I don't have problems with this because cold-ice is really a nice guy and is willed to sell my really small amounts of R23, R14 and Ethane maybe! R600(a), R290 and Argon are already here @ my place! :)Quote:
Originally Posted by Brettbeck
@ n00b: Thanks for this link! :)
the ratio is offcourse also completly dependent on the system.Quote:
Originally Posted by n00b 0f l337
especially on the volume ratio of high and low side of the stages.Quote:
Originally Posted by Unknown_road
Right but take this into consideration that with whatever design they had, which if you read the long long sentences is the same, you need only start to work around with that 1:1:1:1
Hmmm... very good question, and not an easy answer. I'll base my estimate on the unit that s7e9h3n has, which is a P-100. Now please keep in mind that I'll be using American units of measure.Quote:
404Power asked... What about the amounts of the gasses?
How much kg's of R14 for example do you think will I need for this unit?
The method that I use on charging this unit is based on both weight (for liquids), and pressure (for gases). Basically any of the refrigerants that are able to be a liquid under room temperature conditions when contained within a presure vessel, will be charged into the system based on their weight. Everything else is charged based on additive pressure as a gas.
Normally I would charge everything into a recovery tank (which is easy to weigh with an electronic scale), but if your unit is small enough, and presuming your scale can read high enough, you could weigh the unit directly as you add the refrigerants. If you use the external tank method of charging, everything can be charged into the tank and then later transfered into the evacuated unit, using the unit's own compressor to suck out the contents of the tank (front seat suction valve). This later method is nice, since you can create premixes for your unit, and in the event of a leak and subsequent repair, a field recharge could be easily done.
Anyway... after the liquids are charged into the evacuated system (or tank) based on weight, you will end up with some amount of positive pressure in the system (or tank) which I'll call the "balance pressure" for the sake of giving it a name. This balance pressure (B.P.) will be the combined partial pressure of the liquids as charged. With the refrigerants I would use (R123 & R22) this ends up being approximately 15 psi in a P-100 (approximately 14 ounces of liquid by weight). Using the 15 psi as your starting point, you would add the following gases in the ratios shown below.
As charged into unit: (Unit Volume = 0.55 cubic feet)
Total desired unit B.P. = 115 psi - 15 psi = 100 psi = total pressure of gases to be added.
R23 30% (add 30 psi to 15 psi liquid partial pressure = 45 psi B.P.)
R14 50% (add 50 psi to 45 psi previous B.P. = 95 psi B.P.)
Argon 20% (add 20 psi to 95 psi previous B.P. = 115 psi B.P.)
Note: Due to soak-in, when adding a given refrigerant gas, allow 5 minutes to pass between gas additions, and top up before preceeding to the next one.
As charged into Recovery Tank: (Tank volume = 0.78 cubic feet)
Total desired tank B.P. = 80 psi - 15 psi = 65 psi = total pressure of gases to be added.
R23 30% (add 19.5 psi to 15 psi liquid partial pressure = 34.5 psi B.P.)
R14 50% (add 32.5 psi to 34.5 psi previous B.P. = 67 psi B.P.)
Argon 20% (add 13 psi to 67 psi previous B.P. = 80 psi B.P.)
Note: Due to soak-in, when adding a given refrigerant gas, shake tank between gas additions, and top up before preceeding to the next one.
!!! IMPORTANT !!! remember to always charge liquids into the discharge (high pressure circuit) only. So if you are using the premix tank method of charging, invert the tank (or use the dip-tube valve if it has one), and charge everything intially into the discharge side of the unit. When the pressure on both the high and low sides of the system have balanced, close off the hi-side valve on your charging manifold, open the low-side valve, front seat the compressor suction valve, and activate the compressor to draw in the remaining gases from the premix tank. CAUTION... Do not run the compressor in a vacuum for more than 4-5 minutes, since heat build up in the motor windings will not have a way to escape in the rarified atmosphere.
:fact:
The information given above, is only an approximation of the actual refrigerant charge amounts, is based on a particular blend of refrigerants, and a particular type of unit. You will of course have to make adjustments dependant on the refrigerants chosen, and the target temperature/capacity desired.
EDIT: Leaving out the Argon and substituting with proportional amounts of R23 and R14 will increase system heat load capacity considerably, although at the expense of coldest temperature achievable. Also keep in mind that including Argon in the charge blend, will very quickly raise the high-side running pressure of the system. So caution would be in order when doing so.
I hope this helps :D But please don't ask me for anything more specific beyond what I have already given on charge amounts in this post, since I am already treading on a thin line to disclose what I have.
maybe you should mention the size of the recovery tank mytekcontrols, pressure alone says nothing about the amount of gas unless you know the volume.
the autocascade 404power wants to build is that much different from a p100 that these figures could be 500% off, keep that in mind 404power. The only way to charge an autocascade imo is to look at the temperatures of heat exchangers, liquid lines and pressures. We use such small evaporators that the amount off r14 is lower then the amount you would expect in a "tube" evaporator. You can't build a car by only knowing that it has four tires. :D
for a real rough estimate of how much r14 you need, calculate how much liquid r14 would fit in the evaporator and buy that times 10 or something. :D
Thanks @ mytekcontrols & Unknown_road! :)
Anyway, as Unknown already said, my unit is totally different, I think your "rough" numbers help a lot! :D :) But unfortunaely I think that I will have to go fo r the way as Unknown explained:
I hope that I can do it that way good enough! :)Quote:
The only way to charge an autocascade imo is to look at the temperatures of heat exchangers, liquid lines and pressures.
@ mytekcontrols: Looking at my newest drawing (still aux + 2 stages + SLHX) ... which temps can you think of without Ethane (since it's still a 2-stager :))?
Because I don't know if that's good for me to try to build a 3 stager with so many gasses .... atm I'm already thinking of builing a smaller 2-stage auto-C with pipe-in-pipe HXs and a 1HP rotary first! :)
As you read about most of the builds here, you'll find that a majority of people tend to run their low-side pressures in vacuum. Cryo-tek was amazed by how many builds he saw which utilized this technique to achieve lower temps...although it seems to be common practice on the units phase units built for computers, it definately isn't ideal for the compressors :p:Quote:
Originally Posted by mytekcontrols
we really push everything to it's maximum I geuss. :D
404power, I'll think about the cap tube sizing some more but some questions you can only really answer by building it and analyse the results.
Here...let me help you guys out with the info regarding my modified P100 ;) :Quote:
Originally Posted by Unknown_road
Charge: r123, r22, r23, r14.
#1 = 81" x .055
#2 = 90" x .042
#3 = 90" x .042
sub = 30" x .026
evap = 72" x .031 x 2
(one captube per head)
Exp. tank= 30" x .026
Load, Inlet, head, out, suc/dis
0 w, -123c, -123c, -123c, 13/145
50 w, -121c, -121c, -121c, 15/175
100 w, -121c, -120c, -120c, 18/185
150 w, -119c, -117c, -116c, 20/200
200 w, 116c, -100c, - 112c, 23/225
Of course it's been tweaked from then, but at the time, the numbers were correct.....
Edit: By the way, this particular charge was done with NO ARGON ;)
@ s7e9h3n:
Thanks a lot! :) I think I will build 3/4 - 1HP rotary auto-c first and try to use these captube lengths! ;) I will go for one gigantic HX I think! :D ;)
EDIT: Drawing of my HX's (SRY but this is REALLY difficult to "paint" :D :():
http://img383.imageshack.us/img383/337/hxsbc1.th.png
(If really NOBODY is able to understand this strnage drawing, just ask! :))
I edited my original post, and have added both the Unit and Recovery Tank volumes. I also added a note about the judicious use of Argon.Quote:
As Unknown_road suggested... maybe you should mention the size of the recovery tank mytekcontrols, pressure alone says nothing about the amount of gas unless you know the volume.
s7e9h3n nice info on the cap tube sizes (better you then me on posting this information, since you never worked for Polycold ;) ) I forget what the CFM rating is on the P-100 compressor, but if I find it I'll be sure to post it, since I think this would be very beneficial in sizing 3 cascade system captubes based on the information you have already given.
Aside from the lack of compressor cooling this creates, it can also have a detrimental affect on system safety if even the smallest leak exists on the suction side circuit, especially considering the flammable nature of the refrigerants involved. Compression + Heat + Air (as in oxygen) is not a good mix with R290 or R600 :explode2:Quote:
s7e9h3n stated... As you read about most of the builds here, you'll find that a majority of people tend to run their low-side pressures in vacuum. Cryo-tek was amazed by how many builds he saw which utilized this technique to achieve lower temps...although it seems to be common practice on the units phase units built for computers, it definately isn't ideal for the compressors
Even if these conditions don't add up to an explosion, the combination of Compression + Heat + Air + Refrigerants = Acid = Compressor Burn-out = A Big Mess to clean up. This is also the reason that a good system design utilizes a low pressure electrical cut-out switch, in the event a leak is created down-the-road.
Although I understand that running in a vacuum may be necessary in traditional multi-compressor cascades, it is completely unnecessary when dealing with properly designed auto cascade systems that are sized appropriately for the load vs. temperature requirements.
I think it is important to note that this statement refers to using the compressor as a transfer pump, with the compressor suction valve front-seated, so as to cut it off from the normal flow coming back from the heat exchanger circuit. In this condition, and assuming that most of the gases have been pumped out of the attached Recovery Tank, we run the risk of having absolutely no mass flow through the compressor, and no gases surrounding the compressor's internal motor. Under these conditions (neither convection or conduction exist within this vacuum), the heat will build-up in the motor windings with no place to go , and eventually melt-down.Quote:
As I originally posted... CAUTION... Do not run the compressor in a vacuum for more than 4-5 minutes, since heat build up in the motor windings will not have a way to escape in the rarified atmosphere.
A 2 stager (auxiliary condenser + 2 cascades) should comfortably do -90C with only R23 and R14 as the low boiling components, and probably -100C with a Sub-Cooler (SLHX) attached. Of course heat load vs. system size will greatly influence your results. And one more thing that I haven't mentioned, but is oh so important, your performance will suffer if inadequate insulation is used (armaflex around the heat exchanger package will have tremendous losses as compared to polyurethane foam). Understandably you will want to prototype with an easily removed insulation, but in the final package you will need to commit to a closed cell hard foam insulation.Quote:
404Power asked... Looking at my newest drawing (still aux + 2 stages + SLHX) ... which temps can you think of without Ethane (since it's still a 2-stager )?
officially polyurethane is only rated down to -40 (celcius or farenheit doesn't matter in this case ). never had problems with that?
The polyurethane foam I speak of has been used for years to insulate Polycold auto cascades which commonly operate down to -150C. I don't recall the company name or product number, but I'll see if I can dig up some info on it and post it later. I know at one time Polycold sold it in 1 gallon metal cans (Part A & B), which could be mixed together by hand, and then poured into the enclosure or cavity. Perhaps they still sell this re-foaming kit. If they do, this may be more economical then buying it direct from the source, which probably comes in much larger quantities only.Quote:
Unknown_road asked... officially polyurethane is only rated down to -40 (celcius or farenheit doesn't matter in this case ). never had problems with that?
The self-expanding foam that they sell in the hardware and home improvement stores now-a-days doesn't work very well, and I've noticed that it wont cure properly in a sealed enclosure.
Mytek, do you think r1150 can be used if cold enough to let argon saturate?
R1150 (Ethylene) with an atmospheric boiling point of -104C, places it 1/2 way between R23 (-82C) and R14 (-128C). It would seem logical that this might yield some improvement in heat load capacity for a system using these three low temperature components (R23, R1150, R14) at -120 to -125C.Quote:
n00b 0f l337 asked... Mytek, do you think r1150 can be used if cold enough to let argon saturate?
As for your actual question, I really don't think I understand exactly what it is you are trying to say. As I stated, it would seem like there would be some benefit of using R1150, but this is not limited by having, or not having Argon in the system. Can you re-state your question in a different way that perhaps will make what you are after more clear?
Here is a thread discussing both Zeon and R1150 use: http://www.xtremesystems.org/forums/...ad.php?t=66141
Argon is normally said to begin saturating liquids at around -115C as far as I've read. R1150 boils at -104C, do you know if argon will still saturate even a little bit into a liquid in the -90C range. Ethylene is a much better gas for some to use because its much cheaper and easier to find then r14 which is incredibly expensive.
I'm also still trying to find a decent gas for around -70 to -80C that isnt incredibly pricey if anyone has any ideas.
-70C = Co2 = R744Quote:
Originally Posted by n00b 0f l337
-80C = R23
Here in Germany 8,0kg R23 costs only 250 . Whats your price in the USA?