Symphy`s 3 stager

[LukeXE]

Yo Luke I was afraid of this, you need to get a higher pressure going on the high side. Something like autocascading it and having propane condense or the like will definitly bring your pressure up.

Yes, I see that now.

that sucks about the very low pressure in the third stage.
How big is that look, maybe ya need a bigger compressor for that stage also. Sometimes low pressure means compressor cant pump enough, also what low side pressure you have?

low side pressure of third stage, -0,9bar or less while HX temps is around -100. When, for example, I will open oil return valve on stage 2, then Hx temps is going up to about -70, discharge pressure on stage 3 is raising to around 11-12bar (still going up, but at 11-12 gas become condensed I think) and evap temps is going down very, very, very fast to -130. Then I`m closing 2 stage oil return valve, HX temp is going to -95-100C and evap temps is usually -13xC. If I won`t do that, HX will have -100C and at third stage discharge will be around 3-4bar...all the time, evap temp around ambient.

I was afraid about first stage when I was building that unit, that it won`t hold load etc. I think around -55*C with 3 stages ON is pretty good ! autocascading power

[symphy]

Good to hear that you guys are already on your way to solve this problem

I'll take a shower now and drive to wirehead, he will borrow us his nice looking SC12 cascade with R23. Should be enough for the Celeron to reach 7 GHz.

Just like said... Hall 20 / C42 @ Enermax

Thanks again Luke I'm looking forward to play with your beast

[LukeXE]

No problem, remember to take a lot of photos for me from CeBIT.

R14 is borring, I would try methane (-161) in that cascade and probably I will do it

[symphy]

Now you have time to play . But, remember the Conroe coldbug. XD

I will not only take photos, i've a little "special" surprise in my mind - you will see.

And of course, i will translate the roadtrip and CeBIT video in english for you (english subtitles)

[LukeXE]

thanks

Conroe should start worry (1k posts !! lol)

[kayl]

Yes, I see that now.


low side pressure of third stage, -0,9bar or less while HX temps is around -100. When, for example, I will open oil return valve on stage 2, then Hx temps is going up to about -70, discharge pressure on stage 3 is raising to around 11-12bar (still going up, but at 11-12 gas become condensed I think) and evap temps is going down very, very, very fast to -130. Then I`m closing 2 stage oil return valve, HX temp is going to -95-100C and evap temps is usually -13xC. If I won`t do that, HX will have -100C and at third stage discharge will be around 3-4bar...all the time, evap temp around ambient.

I was afraid about first stage when I was building that unit, that it won`t hold load etc. I think around -55*C with 3 stages ON is pretty good ! autocascading power

hmm that is strange. lets hope that doesnt happen when you get argon in there.

No problem, remember to take a lot of photos for me from CeBIT.

R14 is borring, I would try methane (-161) in that cascade and probably I will do it

if i was to ever tackle a 3 stage methane would be my only choice, r50 is in your gas mains in your country hey luke?
even a blend of the two gases worth a try.

[LukeXE]

Yes, methane is for about 0,5euro for 1m^3 pretty cheap

[Pete]

Gutted it didn't come togther intime how ever the feat of work, enginering and skill on this is amazing and i'm really imprssed Luke. I just hope she don;t go down on you and blow up in your face! fINGERS CROSSED AND ALL THE BEST

[n00b 0f l337]

Sorry I missed your MSN message Luke, hop me a PM.

[Brettbeck]

Sorry to hear it didn't work in time Luke... at least now you have a bit more time to help you finish it. Considering it's been a fast build, you could keep up that incredible pace until its completely finished !

[symphy]

Whoa, i never thought that cascades are really so complex...

I spent some hours today at wireheads house and was able to see how he tuned his "little" sc12/nl11 cascade which he borrows us for CeBIT. So much work for such a "easy" construction...

Now i read this explanations... and that's so much more complex than a simple dual stage...

My full respect to all of you guys

... and still waiting for the "beast"

[LukeXE]

Thanks Tom for that answer

Today I will try to check some things.

About gravity, just after HX, on HX R14 liquid line is 15cm pipe placed horizontaly, to it there is brazed captube going to evap. So I don`t see any chance for liquid refrigerant, that it`s "staying" somewhere in pipe or something :|

Only subcooling on stage III is captube wrapped around suction line. Static pressure @ 3 stage is 10bar.

I thinked about adding some more captube to 3 stage.

[kayl]

10bar that’s around 145PSI static, that’s quiet low, I have around 180psi on my current cascade second stage, there is bugger all gas in there hey luke.
maybe have a read over runmc 3 stage, i love the pic where 3rd stage compressor is frozen

http://teampuss.com/forums/viewtopic...=asc&start=135


he had same issue at 220PSI static, chilly mentioned something about float getting stuck, i havnt read it all but if you have another read might get some good info there. it seems that you are having oil troubles and have a block somewhere?


http://teampuss.com/forums/viewtopic...=asc&start=180


Longer capillary line should enable you to condenser more refrigerant, what length are you currently using, and whats your low side pressure??

[LukeXE]

If I remember correcly, about 2,2m for I stage, about 2,4m for II stage and about 2,55 or 2,6m for III stage.

I`m thinking about adding extra ~30-40cm of captube, to have about 3m on III stage.

Suction pressure when at evap is -130*c is at about -0,2bar.

[n00b 0f l337]

Have you tried brazing or soft soldering the capillary as well for a bit more heat transfer? Might want to consider the autocascade with r290/r14 so you don't need a oil separator as well.

[kayl]

i think maybe a cold trap and 2 oil seps might help.
From reading runmc post and your results it seems around -100c your oil is freezing and there comes a point where you condense all the r14 as Redwolf said hence 0psi. pitty Redwolf wasnt around to help. maybe pm chilly1 and see what he thinks.
Then when you let the 2nd stage warm up it oil melts and things run again. also runmcs static pressure was 220psi like chilly1 said yours is alot lower. When chilly was doing his cascade was having same issues as well with r14.

As noob said i guess autocascades dont have this issue because the first stage returns the oil alot better. you would also maybe change the oil in the 3rd stage compressor to a better oil that doesnt freeze.

[LukeXE]

Have you tried brazing or soft soldering the capillary as well for a bit more heat transfer? Might want to consider the autocascade with r290/r14 so you don't need a oil separator as well.

i think maybe a cold trap and 2 oil seps might help.
From reading runmc post and your results it seems around -100c your oil is freezing and there comes a point where you condense all the r14 as Redwolf said hence 0psi. pitty Redwolf wasnt around to help. maybe pm chilly1 and see what he thinks.
Then when you let the 2nd stage warm up it oil melts and things run again. also runmcs static pressure was 220psi like chilly1 said yours is alot lower. When chilly was doing his cascade was having same issues as well with r14.

As noob said i guess autocascades dont have this issue because the first stage returns the oil alot better. you would also maybe change the oil in the 3rd stage compressor to a better oil that doesnt freeze.

I would try that option with autocascading third stage or just buy methane and try with it. I don`t have R14 anymore, only some in thrid stage with some ethylene

Must talk with Symphy about getting methane, it costs 80euro netto for 1,73kg, not bad price I think. Then I could do R290/Methane autocascade on last stage.

For more modifications I must talk with owner of cascade. This unit have really big potential, but need still some more work on it !

[Pete]

This is getting really XS but it shows how we all pull togther and help and look at other promblem during builds and work them out. I like seeing this. I can't help bt i wish you all the best in getting it to work Luke

Edit:



Guess you don;t have to worry about having an air flow over it..hehe

[n00b 0f l337]

That can't be good for the compressor though. I beleive that was overcharged as well. I suggest making sure you have a good accumulator to avoid problems like that.
Also if you build, you might want to try what Blaster did and install a hot gas bypass. This will help with wawrming up the evap, but it also might be possible to use it to avoid coldbugs. Possibly put a hot gas bypass on a cpev?

[Blaster]

my opinion is different from many ppl here heheheh but i think its undercharged

r14 is a very high pressure gas

[LukeXE]

It could be possible Blaster, I charged unit with all my R14, I thinked that I`ve got in bottle at last 400g of it, but from what I see, there wasn`t that amount of gas.

[s7e9h3n]

Also if you build, you might want to try what Blaster did and install a hot gas bypass. This will help with wawrming up the evap, but it also might be possible to use it to avoid coldbugs. Possibly put a hot gas bypass on a cpev?

I may be wrong, but I don't think a hot gas bypass will work as it should while the unit is running.....

[Pete]

Was Blaster that did the hot gas

[Blaster]

yes, but i have to say its Cryoteks idea... im using it on all bench units i might build.... no more need of hair dryer LOL

[n00b 0f l337]

Right, its uncondensed warm refrigerant going back to the evap. If you could find a way to get a slow trickle, possibly on a cpev, you could heat up the evap I'd imagine while its cooling to a temp above a cold bug. Thats if you dont want to just put a CPEV with r14.