Autocascade refrigerants and questions

Out of curiousity, what combinations of gas would be recommended in an autocascade using a 1HP compressor?

Steering clear of combustibles, what options are available?

I'm not sure how far you can go with a 1Hp compressor, and what tends to work well together...

I've seen that R22 tends to be a favored High gas. It's relatively cheap, and I haven't seen it noted as combustible.

Easiest option for a Low gas is R410a as it's readily available and reasonably priced, and seems like a gas that 1hp could work with. Is that usable in an Autocascade? Compatible with R22? Would a person need to use R290 at all or would an oil separator make it unnecessary? I have a feeling that 508b/r23/1150 are all going to be out with 1HP compressor, and I'd rather not consider CO2 simply because of the 'Issues' with it at low temp freezing. Would any of the above gases be usable?

Only other question is about rough amounts of each gas in an Autocascade...I realise that it's never the same for different systems, but what kind of ratio's are generally considered correct?

Are working pressures for an autocascade vastly different than other systems?

I appreciate the drawing very much, Coyote is the artist, and it's been very helpful :)

Realising that the configuration may not be entirely correct in that drawing, the R507 wouldn't be measureable as it's a liquid?

The R23 access looks like a measure point, as does the High and Low access points, and in a good working system, idle and load, what kind of working pressures would you expect?

Sorry to be asking so many questions, I'm trying to understand the systems before deciding what's going to work well, and be the least expensive to produce.

Cheers

Gray

I would try to avoid any r4** gasses. Theses gasses seperate giving them unpredictable behavoir unless you know very well what your doing. If you need an oil sep depends largely on the low stage gas (how well it carry's oil) If it doens't carry oil like co2 you don't need any form of an oil sep. When it is a good oil carrier put some copper wool in the top of the phase sep and problem solved. r1150 is pretty hard for an autocascade and I won't recommend it untill your more experienced. r23 and r508b are good options.

ratio of the gasses depens fully on the design of your system.

pressures will be higher as a single stage especially at start up.

R508b seems the best choice of the 2, as both are available on the shelf, and R23 has a reputation for high discharge temps...

Does R508b carry oil?

Gray

wait a min... if ur using co2 u don't need an oil separator??? is that true?

O and btw i wouldn't use 410a thats puron. Its discharge pressures can be as high as 400psi and suction can be up over 100psi! and u need special gauges for that. :nono:

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Originally Posted by _HL4E_HalfLife_

wait a min... if ur using co2 u don't need an oil separator??? is that true?

O and btw i wouldn't use 410a thats puron. Its discharge pressures can be as high as 400psi and suction can be up over 100psi! and u need special gauges for that. :nono:

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in an autocascade yes.

he ment 410a as a low stage gas so discharge pressures won't be that much higher then an r22 only system. And why would suction pressure be 100psi, he is not making an airco :nono:

For startup pressure are we talking about 15-20 bar or higher?

I think if I choose autocascade over 2 stage I'll be incorporating an oil sep regardless, as there's no hit to the overall performance anyway. Is there a common captube size and length for the oil return?

Looking at the configuration, do the same rules apply for heatload as conventional phase? ie 4m .028 = roughly 150w heatload (just a rough example) and each stage is tuned as per standard method, or does an autocascade have different rules that apply to captube tuning?

508b is confirmed as being readily available so that's the logical choice from what I've been reading here.

If I can find a reasonable price on a 1.5HP compressor to use, I'll be going to 2 stage, but at the moment an auto seems to fit the budget more readily, even with the twitchy tuning of gases.

R22 and 508b will definitely work together in an Autocascade then?

Thanks for the help and advise :)

Gray

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Originally Posted by Unknown_road

in an autocascade yes.

he ment 410a as a low stage gas so discharge pressures won't be that much higher then an r22 only system. And why would suction pressure be 100psi, he is not making an airco :nono:

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Thats what puron suction pressures are like in heatpumps that use it.

i think i will be going for R22+R23 for my autocascade. R23 is somewhat expensive, but it should be a nice performer, and not a pain in the ass, as R744 might be.

I was thinking that myself, except that i keep hearing it said that R23 discharge temps are quite high...I've got a decent size condensor, but if 508b is a good alternative, it's not much more than R23, at least here...

Gray

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Originally Posted by _HL4E_HalfLife_

Thats what puron suction pressures are like in heatpumps that use it.

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pressure depends on application and system design not every system that uses r410a has the same pressures. far from it.

@ TS: start up discharge pressure would be around 20 bar estimated could be a few bar higher though. As far as I can see r22 and r508 will work fine.

http://www.crossrefrigeration.com/meducf.asp seems to use R508b and r170 based on need... :P

those are normal cascades not autocascades.

R508B does carry oil as long as its polyolester but if you use R22/R508B and mineral oil it will be easier to get the oil out.. R22 carrys teh mineral oil very well adn the R508B does not.. R508B is R23/R116 blend You can use R23/R410 as a blend also and achieve simmilar results. Iceon89/R23 would also be an ption the advantage its that you can blens the R23 down to stabilize and widen the range it will operate at.. You probably willnot need an oil speperator use 2 stage phase seperation the oil will be carried with the first stage gas.

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Originally Posted by Gray Mole

I was thinking that myself, except that i keep hearing it said that R23 discharge temps are quite high...I've got a decent size condensor, but if 508b is a good alternative, it's not much more than R23, at least here...

Gray

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r508b is dupont suva 95?
i have a friend that builds industrial cascades and works with it, that gass here in argentina is really expensive, r23 is cheaper

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Originally Posted by Gray Mole

I was thinking that myself, except that i keep hearing it said that R23 discharge temps are quite high...I've got a decent size condensor, but if 508b is a good alternative, it's not much more than R23, at least here...

Gray

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508B is a blend of R116 and R23

Actually I talked to the supplier about 508b, and it turns out they've switched suppliers.

That means that they use 508a now(not much difference in spec) and the cost has really shot up.

Looks like full retail is around £800 for a 4.5kg bottle (ouch)

R23 is around £400 for the same size retail.

I get that discounted, but it's not that big a discount, so 508 is now out of the picture.

It's getting harder to source a variety, but I'm hoping the new supplier I found will make it easier.

I tried on 116, but no one I deal with can get it here, so I'll check the new supplier when the account comes through.


Gray

what do you think of such an option:
Isceon 89->R116+R23 blend
what are the prices of isceon89 and r116?

both gasses are pretty expensive and not very common.

R 508 A or B is only R23 blended with R116

R1150 and R1270 with thue use of R600A and R290 al of which are available in the UK and relatively cheap... R1270 is silmmilar to R502 and can be blended with R290 and R600a to imitate about any refrigerant. The only problem is Flammibility... all four gasses are flammable. These gasses are used almost exclsevly intheir purest forme in the medical cooling industry.

I would go with R22 / R170

the first is cheap and won't dissociate like the 4**, and ethane will condense with a -30C HX, like R23 would do, but that's cheaper.

just to ask, would it be possible to go with R410 / 1150 if I oversize the condenser and use a R410 compressor ? same with a R404 compressor ? :)

I think using r410a and r1150 in an autocascade would result in very very high start up pressures no matter what size condensor you have.

Can't we arrange that using expansion tanks with cap tubes ?

You have to find a way to get mostly r1150 in the expansion tank and let the ethylene get sucked out slowly at start up.

just keep in mind to look at the atomic mass (molecular weight) of the refrigerants chosen, the greater the difference the better the seperation.

tnks for the info wdrzal. that would help a lot to choose the refregerants )

why do you think molecular mass difference gives better seperation?

If you have a blend of heavy and light molecules the heavier will sink to the bottom of the pase separator. If there is great difference in mass the heavier molecules will drop like a brick even if they havent entirely condensed... Thats what ive always thought anyway...

Tom

density and molecular mass are 2 different things... And density is not important when you have a gas and a liquid. liquid always has a bigger density then a gas.

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Originally Posted by Unknown_road

density and molecular mass are 2 different things... And density is not important when you have a gas and a liquid. liquid always has a bigger density then a gas.

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Yes, but if the second stage refrigerant (I think that's what it's called) has an even lower molecular density than the first stage as a gas, think of the difference between them when the first stage is a liquid. You're pretty much guaranteed no second stage refrigerant will exit with the first.

I don't really know what your trying to say carlzor. We are not using weird physics or chemistry to seperate the refrigerants just gravity. Liquid is always heavier so it will always be on the bottom of the phase-sep and the not yet condensed refrigerant above it.

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Originally Posted by Unknown_road

I think using r410a and r1150 in an autocascade would result in very very high start up pressures no matter what size condensor you have.

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Mine uses both those gasses....along with ~10 others :p:

heheh

I think your's is about the only one that you're probably better off NOT knowing exactly how it works inside, cos you'd know less than you started off with :p:

Funny though, it would be really cool to see it. Personally I think you should take Reg up on his offer and let him open that baby up and see what makes it tick. After reading the little about it that he's posted though, I think I'd probably be lost after about 2-3 stages trying to figure out where everything goes.

What gas? More like what gas HASN'T it got! :D


Gray

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Originally Posted by s7e9h3n

Mine uses both those gasses....along with ~10 others :p:

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that isn't a 2 stage...

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Originally Posted by Unknown_road

I don't really know what your trying to say carlzor. We are not using weird physics or chemistry to seperate the refrigerants just gravity. Liquid is always heavier so it will always be on the bottom of the phase-sep and the not yet condensed refrigerant above it.

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That's what I mean though. You could have two refrigerants, one a liquid and one a gas, yet if they both had the same density/weight for that amount of volume, they would not seperate very well at all. On the other hand, when you have two refrigerants that have a large difference in density/mass between them as gases, when one turns into a liquid it becomes denser, and will seperate much easier.

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Originally Posted by Gray Mole

heheh

I think your's is about the only one that you're probably better off NOT knowing exactly how it works inside, cos you'd know less than you started off with :p:

Funny though, it would be really cool to see it. Personally I think you should take Reg up on his offer and let him open that baby up and see what makes it tick. After reading the little about it that he's posted though, I think I'd probably be lost after about 2-3 stages trying to figure out where everything goes.

What gas? More like what gas HASN'T it got! :D


Gray

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Hehehe..he still thinks there's some sort of "hidden compressor" in that HX area :D

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Originally Posted by Carlz0r

That's what I mean though. You could have two refrigerants, one a liquid and one a gas, yet if they both had the same density/weight for that amount of volume, they would not seperate very well at all. On the other hand, when you have two refrigerants that have a large difference in density/mass between them as gases, when one turns into a liquid it becomes denser, and will seperate much easier.

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I don't think such gasses exist...

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Originally Posted by Carlz0r

That's what I mean though. You could have two refrigerants, one a liquid and one a gas, yet if they both had the same density/weight for that amount of volume, they would not seperate very well at all. On the other hand, when you have two refrigerants that have a large difference in density/mass between them as gases, when one turns into a liquid it becomes denser, and will seperate much easier.

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not quite. Giving example of 2 gases, one will condense while the other wouldn't. Condensed one will flat out be heavier. Go to bottom while not condensed one will stay in middle to top. Just gotta be careful not to get too much of first stage gas or not too little of it into the separation to get good load capacity. The real problem is the load capacity of most autocascade so far since we are not dealing with as much gas as we used to on single stage or cascade per volume passing through compressor that gets in evaporator eventually.

i wanted ro ask you guys if i could use not a very powerful compressor with isceon89 and r508a blend (i can get r508 from my local supplier and Reggie has isceon89 if i'm not mistaken)
the thing is that i'll have my condenser cooled by relly cold air compared to the one in our rooms ;) 15C or even lower
pressures depend on condensering temps, right?

what condenser do i need for an auto? aprox 1kw, correct? or a higher rated one?

ps the compressor i'm planning to use is Danfoss NL11F or i can get a more powerful SC21CL

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Originally Posted by .Cyber1an>>

i wanted ro ask you guys if i could use not a very powerful compressor with isceon89 and r508a blend (i can get r508 from my local supplier and Reggie has isceon89 if i'm not mistaken)
the thing is that i'll have my condenser cooled by relly cold air compared to the one in our rooms ;) 15C or even lower
pressures depend on condensering temps, right?

what condenser do i need for an auto? aprox 1kw, correct? or a higher rated one?

ps the compressor i'm planning to use is Danfoss NL11F or i can get a more powerful SC21CL

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have you ever build a single stage or cascade before? Autocascades aren't easy as you can see around the forums. using isceon89 as a first stage gas isn't a good plan either. an autocasade already has high discharge pressures when you use also use a high pressure gas it will be very very high.

the question "pressure depens on condensing temps" say to me your not ready for building an autocascade (or even a single stage in my opninion).