Ok so I will be using either a 1/2hp rotary or a 3/4hp rotary 507/CO2 captube both side well thats the spec so far but the 1/2hp could be a scroll
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Ok so I will be using either a 1/2hp rotary or a 3/4hp rotary 507/CO2 captube both side well thats the spec so far but the 1/2hp could be a scroll
LukeXE,
Yes, we know, and keep on mind about ice bath, but we have no thermometers which will be installed on our systems.
As soon as they arrive - we'll make some shots.
Hehe, okey, I can wait :toast:Quote:
Originally Posted by xooler
Henery 450 psi releif valve on ebay , this seller has 5 for sale. This is 3/8" which is a little larger than needed ,but they are all the same price. he has 1/4" and 1/8" also the same seller has multiply valves and pressures.
http://cgi.ebay.com/HENRY-RELIEF-VAL...QQcmdZViewItem
Remove me from the list, I won't be able to afford to compete :(
Some of you know I was building a r290/r170 cascade, it was finished this weekend but the tests didn't work out as I hoped. It worked much better as my previous autocascade but the r290 and r170 blended too much. The condensed r290 didn't contain (much) r170 but the r170 stage did contain much r290. Too bad. I don't have a pure replacement refrigerant for the r290 but maybe I'll try r507 for testing. If that doesn't work my autocascade charging methode is still faulty.
In gasdynamic physics terms it should have 100% seperation (I always understand theory better then practise) .
well I'll tell you guys more info if I get it working.
edit: I just realised that fluor bases refrigerants are slightly negative charged on the sides of the molecule while r290 and r170 are slightly positivly charged. So fluorcarbon bases refrigerants will probably blend even better with r170 as r290. :( I think when your using mostly fluor based refrigerants the negative fluor charge helps in the seperation. maybe the higher molecular mass of the fluor based refrigerants helps something. I think I'm going to do a minor chemistry. :lol:
Chemist present?
Unknown road How about r134a and 170. Another option to help separation is to have SLHX before the phase separator and HX after. That is how I will be doing my auto when I catch up on current work load. Have you updated TP with pics dieing to see the auto hey.
well I still don't trust SLHX's to be part of the operation proces. For efficiency ok but such a setup would mean that when you apply to much load to the system the whole seperation would fail. But I might have an idea that will have the same effect but is more reliable. I'll post pic's etc soon ;) Want to experiment some more before that
oh btw, I don't have r134a here either :( need to import some gasses I geuss because I can't get them here.
Hmmm,so who already have built working autocascade for this competition ? :)
I`ve built one, it`s not working as I wanted, but I think I will do something with it ;)
I havent found the time just yet for my autocascade, but I need to work out some more kinks in my design.
Hehe, I will found some free time for auto-c when I will end school (the end of this year semester in poland is on 23 June) :D :D
Can someone help me with capillary lenght ? From what lenght I should start, now auto has 2,35m of 0,031" on I stage (r290) and 2,5m for 2 stage (r744)and I`m stil playing with gasses ratio (without positive effect :/ )
can you give some more info? what is exactly the problem? why do you think you need different cap tube length?
I`m stupid, I forget that I didn`t write any info on this forum about auto-c.(on TP yes).
So...
I`m using R290 and CO2. Charging autocascade is looking that:
1. Static charge with R290 to 3-4 bar (40-60PSI).
2. Turning on auto-c and charging with R290 until HX will frezze.
3. OK, so I stage is working...now I must start charge with CO2...
4. I`m charging with co2 until evap temp will go down.
5. I`m playing with ratio of gasses, try to keep I stage holding II stage etc.
6. Lowest temp I saw -- -55*C
Pressures 0,6bar // 16bar, HX temp ~30*C.
So, I`m wondering, what I should do, play one more time (vacuum and charge once again) or cut/add cap tube.
Now if your initial charge is pure r290, there is still some r290 then moving thru ur low side, that area isnt just in vacuum. Maybe try charging to 20-25PSI with co2 first, then add r290 till the hx freezes along with evap, then begin to play.
does the evap only starts to freeze when you add co2? that would be weird.
imo the way in which you charge doesn't affect anything since the gas is continues pumped round
when you HX and evap are still fed enough refrigerant to cool it there is no need to shorten the cap tube. adding cap tube is only usefull when you have lots of floodback.
Evap starts freeze only when I will add co2, not earlier.
co2 in autoC is not very good cause to prevent dice you need some other gas to "wash down" (or something lol) the dice
i got same -56 on Cryos design, with R23 you should have good temps :)
R23 is fine, but very exepnsive
cascade works good with co2+r290 r290 is also a heavy gas if the mixture is right there s no problem @ all
best things to think about is a good evap design and a nice suction line (bigger tubes)
it can hel to use bigger captubes .31 instead of .28 and tweak it for load (short captube)
you can easy get -80 to -90C unloaded without freezing co2, its all about right mixture.
can you show us this -90 Co2 autoc ? :)Quote:
Originally Posted by andL64
i also thought about to go up with the low pressure site because i thought then it wouldnt evaporate that cold and it wouldnt get frozen, thats wrong.Quote:
Originally Posted by LukeXE
you should cut captube, yes
i think youve got too much R290 in the system you dont need that much.
just start with bout 1,5-2bar R290 static and add some R744 about in the ration 2:3, so i used about 2bar R290 and 3bar CO2 and it was fine, but sure such things are very variable depending onb the system you built.
i just got the -85C with oridnary R290+Co2 cascade and it works great (finally) i used 1st stageR290 and 2nd R290+R744, i only used about 1,5-1,6m of .28 0,7mm captube, i think if i had teaked it for temps (longer captube) i may reached -100 but the load temps are worse then.Quote:
Originally Posted by Blaster
it was hell of tweaking i had problems with about -70C evap temp or little less and i couldnt find a solution so i tried everything and finally i came to -85C unloaded without freezing the evap anymore.
i just thought it would be possible 4 sure to do this in autocascade too, but s sure even harder
i can only show you pics of the -85C co2+r290 cascade which isnt freezing and can hold load temps well.
yes on normal cascade is easy to "trip" the dice problem by adding another gas to 2nd stage
on the other hand, on autoCs its much harder cause you need something to "carry" the dice, and if you have full separation that will not happen
sure thats true, full seperation will not work, but s not hard to seperate a part of the "lower" gas.
even with CO2 I doubt you can get anywhere near full seperation.Quote:
Originally Posted by Blaster
I thinked about adding second gas that will have low condensing temp, maybe similar to co2. It will go with co2 to evap and "push" dice from it....but which gas ? :| It`s easy to say/write, but much harder to do :|
Now I really see, that do working autocascade with co2 is very hard job, we will have real competition in co2 division, good luck to everyone !
Unknown_road @ could I add you to members list ?