kayls Autocascade

[kayl]

i went down to boc gas and got a D size c02 bottle.
after reading berkuts post i just couldn’t wait for my copper pipe.
i just grabbed the 1Hp system and gave it a upgrade.

i gave it some bbr290, hc22/502 and some c02.
pressure is 20psig/330psig and -46c, so i must be autocascadeing.
i switched off and are now adding some insulation.


It took me 4.5 hrs to upgrade and to a test run.
I have a long way to go though.

[JSU]

Ghetto style god luck with it. Do you have ethane btw?

[kayl]

no. well there is some in the bbq gas and some in the hc22/502 about 1% maybe and 6%

yeah ya always have to do it that way for fun, cause you know you are gonna change it later to another idea.
i will be getting a 35cm tall 5" pipe with a 12 foot coil 1/4 inside as a replacement.
then a 30cm seperator. i am also getting end caps made.
along with some new evaps stuff should be ready 2 weeks i hope, guy just got back from holiday turesday.

[kayl]

when i was making everything i pressure tested everything under water for a few seconds no leaks then gave it a bash.
then the map gas hx at the base (not where i brazed) at the base of the can leaked. i patched it and no leaks.
then i just noticed its leaking in a differnt place.
i think that eventually the bottom of the mapgas can is going to pop unless i braze it all up. but im all out of solder damit.
and i just went to the parts store today.

i got 30m of 0.028" first time i have been able to find it.
i should of got 0.031" though, owell, i just wanted to try it.
it doesnt come in small packs 0.028".


dd evap is about 8-9' of 0.031"
and r290 1st is 7.5' of 0.028", i think i might shorten that and patch this thing.
but really i need that copper pipe as these things are too big.

[gkiing]

I remember berkut using around 2m of 0.031 for both the 1st and 2nd stage gases.

[JSU]

btw kayl I used one of those condensors for my auto-cascade and it wasnt large enough . You have a desuperheter so it might be ok though.

[gkiing]

Did you static charge it? How are you charging the CO2?

[f00t]

where is your hx. i cant tell from the pictures, could you take a few more (maybe from all sides). thanks

[kayl]

gkiing i will be shortening the r290 capillary line next time to about 6'.
and leave the dd evap along as that length seems to match my cpu heat load well.

the way i charged depended of me regulator used. i got an industrial c02 one for mig and tig welding, so max out is 50psig, so i charged to 50psig and rest r290 to 110psig and turned it on. it started to pull a vacuum straight away, so i added heaps of r290 until low side reached 0psig. then let it cool. i then added some c02 until high side pressure was getting to a limit i could handle 330psig for now.
i hope once i get this thing Wright pressure will go down to about 250-280psig.

Jsu just one of those chilly condensers isn’t enough. I like them though cause they are so small, and I only have 120m,m fans so they match well. I may add another desupaheater for the r290 yet, will see when I get the new copper pipe for the hx.

Foot the map gas bottle on the right is the HX. I used a 1/4OD copper coil inside the map gas bottle as the condenser to condense the c02, and the actual map gas bottle is the evap. I did it this way as I couldn’t bend 3/8”OD pipe with out kinking it as the evap. The second reason as I though it would increase the chance of splitting this mapgas bottle trying to condense c02 in it cause of the cut in the middle of the bottle.

Here is how I did it, forget the temps on the pipe and stuff, I edited one of chillys drawings and put what temps I thing everything should roughly be at if working perfect to explain it to a friend.

[berkut]

Lower temps please

I should finish my rev. 2 autocascade in a couple of days, the one based on a more powerfull compressor and with a PEV controlled HX

[kayl]

yeah colder temps to come i promise.
this was made quick and well not very well, but i just wanted to use some c02 and the cascade wasn’t ready for it.

sounds good berkut a pev and a bigger compressor should make a great difference, are you going to feed it with 1/8OD tubing.

unfortunately i will be only using capillary line as pev's and txvs are so expensive.
i did get a 30m coil of 0.028" capillary line to play with though.


with the rules is there anything to stop me getting a friend to use a lath to machine a few rings in a copper rod say about 30cm long, rings about 5mm wide and about 1cm deep into the rod, the rest well ill show if i can do it, other wise i may use it in a cascade one day.
as i have a really sweet hx in mind the key to my autocascade.
but dont want to break any rules , ie DIY.
i remember i can’t buy commercial hx for the competition, does this fit same category.
i still have to design it and make it myself.

[gkiing]

@berkut: Do you know the ratio of CO2:R290 that worked well in your autocascade?

Kayl if your hx is -40 you shouldnt need more than ~200psi to condense the CO2 your pressures seem a little high. Perhaps a larger condenser/condenser fan would be in order, or a desuperheater?

[kayl]

i didnt get to -40c on hx. (not really sure what temp it was, it was frosted at the bottom of the hx and warm at the top) but some c02 was condensing, the poor hx doesn’t really have much of a chance at working at the moment due to lack of insulation (none on hx) and the fact that its too big doesn’t help as well.
berkut was having too much fun with his so i could wait to do mine properly yet.
once pull down is complete and the hx is working properly (with the new hx) i hope pressures to go down alot.

[berkut]

i think you used too much CO2. My pressures go sky high once i push too much CO2 in the system.

as long as you make the hx i think it can be approved. chilly1 has to express his opinion.

[kayl]

Thanx berkut, im gonna give it another bash tonight, will try more r290 and less c02. i shortened the r290 capillary line to 5.5' of 0.028" that should help too.
if temps are good an no leaks after a while of running i will add some insulation to the HX and see what new temps are.
I think I should add my HPCO soon since I have it here.

this is where the map gas bottle was leaking, it also leaked on the other side.
so i brazed the hole thing all the way around. if the other one leaks i will do the same.
im getting a little better brazing these map gas bottles, its definitely an art.

[kayl]

well the autocascade finally held pressure and i gave it another go.
its crap hey. i think i am going to scrap it.
need new hx
0psig i had -50c evap and -6c liquid co2 line coming out of the map gas hx
the suction line for r290 is -2c so supa heat is real bad at 5.5' of 0.028 caplillary line?
i think itsthe hx cause there is too much volume inside the bottle to cool the 1/4 co2 line through it.
i used bbq r290 and co2 the above doesnt make sense pressures and evap temp

[gkiing]

i think you used too much CO2. My pressures go sky high once i push too much CO2 in the system.

as long as you make the hx i think it can be approved. chilly1 has to express his opinion.

How many psig of CO2 do you reccomend static charging?

[JSU]

You dont static charge with co2. You first get the hx going then slowly add co2

[berkut]

Yep JSU is right.

I charge R290 untill i get some cold and i slowly add R744. The moment when R744 kicks in looks like someone had put the temp probe in to liquid nitrogene.

kayl i think you ran in to the same problem as Jan did with his HX. The R290 part is far too large. That wouldnt be any problem but oil puddling will occur. And the both of you guys use too restrictive cap tubes.

go ahead and copy my HX and cap tube lenghts and everything should work :P

[gkiing]

I thought all high pressure refrigerants had to be static charged...?

So 0.028" or 0.026" wont work well in an autocascade?

[JSU]

My 1/2hp compressor was getting me around -50c so you guys with the big compressors should be able to pump out alot more than that. O my hx was -20c

[berkut]

They should but its not that easy with a autocascade and especially with CO2.

[Unknown_road]

go ahead and copy my HX and cap tube lenghts and everything should work :P

that would be a boring and non educative competition

[Tonic]

You're right, that's why I'm trying, trying and trying to create a new HX's construction
or combinations of other's HXs

Did someone with autocascade think about rebuilding autocascade (after comptetition)
to cascade?

[jan]

Nice cascade so far, kayl. I've the same problem with the hx as you have.
I've changed the cap tube to what berkut suggestet but I need to redo the hx also. Just changing cap tube didnt' help.
At the moment I'am trying with a tube in tube hx.

Did someone with autocascade think about rebuilding autocascade (after comptetition)
to cascade?

First I want to get my a-cascade running Now I'am at -53,7°C ...