Autocascade guestions.

[s0lid]

Well i've been planning to do an autocascade for pretty long time and i won't be able to do it before summer, no time or resources atm for that. So i've plenty time to plan this and change parts and so on.

Here's couple questions:
How long pipetype Aux condeser and Hx1/2/3 should be? 5 meters/hx or aux condenser is enought?
How to make an phase sep?

Parts i'm planning to use:
Compressor: 1hp Rotary compressor, need to choose model
Condenser: Rivacold 1140270F00 1.21kW
Gasblend: R600/R170/R14(/Argon)
Expansion tank: 4-5L
Expansion devises: Captube
Stages: 3

Just looking for suggestion in every ways. I'll test my brazing skills with making an normal Single stage first, builing shoul start at next week (hopefully).

[Big SturL]

Firstly, have you any experience building simpler systems? I, nor anyone else for that matter, would advice on building a 3-stage auto-C, without having somewhat extensive knowledge on building simpler systems.

Secondly, are you sure about that gas-blend? Using R600 (butane), with it's evaporating temperature of -0,5 to condense R170 (ethane), would require a pressure of 25 bar (if I am not mistaken by the p/T chart)
http://encyclopedia.airliquide.com/images_encyclopedie/VaporPressureGraph/Ethane_Vapor_Pressure.GIF.

[s0lid]

Gom recommended that blend so no idea actually :shrug:
But R290/R170/r14 may work right?

[Big SturL]

That would seem the sensible option. Perhaps the R600 is for cooling the compressor. Due to it's high boiling point, it stays liquid until it returns to the compressor, where it instantly is heated above boiling point, evaporates, and cools it down. Of course, it would have to be run together with R290 for instance.

But, don't take my word for it. I have yet to build an auto cascade, even a single stager. However, I do know that reading a lot, and experimenting with simpler systems is crucial for constructing and understanding more complex ones. You sort of remind me of myself about two years ago, where I also wanted to build an auto cascade, before even touching a brazing torch. What I learned and experienced was that it is more difficult than it seems at first sight, and there are plenty of tiny, but combined major, problems that arises that no one ever told you about.

I'm not trying to make assumptions here, but seeing as you are asking these questions, it makes me believe that you are perhaps not ready for building an auto-c. With the proper learning curve, these questions would be answered through extensive reading.

[s0lid]

That would seem the sensible option. Perhaps the R600 is for cooling the compressor. Due to it's high boiling point, it stays liquid until it returns to the compressor, where it instantly is heated above boiling point, evaporates, and cools it down. Of course, it would have to be run together with R290 for instance.

But, don't take my word for it. I have yet to build an auto cascade, even a single stager. However, I do know that reading a lot, and experimenting with simpler systems is crucial for constructing and understanding more complex ones. You sort of remind me of myself about two years ago, where I also wanted to build an auto cascade, before even touching a brazing torch. What I learned and experienced was that it is more difficult than it seems at first sight, and there are plenty of tiny, but combined major, problems that arises that no one ever told you about.

I'm not trying to make assumptions here, but seeing as you are asking these questions, it makes me believe that you are perhaps not ready for building an auto-c. With the proper learning curve, these questions would be answered through extensive reading.

I agree with you than i'm not ready, still need to do lot of studying and testing with up coming single stage [mentioned in end of the post #1] :)

It took me couple hours to get autocascades idea even little bit. Pretty confusing at the start...

[tiborrr]

This blend would most likely work very well. This blend wouldn't work in a normal cascade though, but in autocascade it's very doable. Big Sturl, may i recommend you reading mytekcontrols (http://www.xtremesystems.org/forums/showthread.php?t=144007) thread, there he writes about pseudo-refrigerants, absorbtion of one refrigerant in another, etc. etc. which is vital to the understanding of this multiple evaporation unit.

I sincerely recommend you to first build a simple single-stage phase change cooler, we have all started like this. This is asking for trouble, especially with highly flammable R600 & R170 in the mix. You will most likely fail with this build. Sorry if this sounds harsh but that's the reality. Even the most skilled builders on this forums haven't really build one with much success. Besides, have you seen the price for a couple of kilos of R-14?

Be smart and don't rush to kill yourself :up:

[Big SturL]

Thank you for the link :)

[s0lid]

I sincerely recommend you to first build a simple single-stage phase change cooler, we have all started like this. This is asking for trouble, especially with highly flammable R600 & R170 in the mix. You will most likely fail with this build. Sorry if this sounds harsh but that's the reality. Even the most skilled builders on this forums haven't really build one with much success. Besides, have you seen the price for a couple of kilos of R-14?

Be smart and don't rush to kill yourself :up:

Well like i already said i'm not goin to build autoC until summer, maybe not even then.
R14, nope but i know it's sky high...

[[XC] gomeler]

This blend would most likely work very well. This blend wouldn't work in a normal cascade though, but in autocascade it's very doable. Big Sturl, may i recommend you reading mytekcontrols (http://www.xtremesystems.org/forums/showthread.php?t=144007) thread, there he writes about pseudo-refrigerants, absorbtion of one refrigerant in another, etc. etc. which is vital to the understanding of this multiple evaporation unit.

I sincerely recommend you to first build a simple single-stage phase change cooler, we have all started like this. This is asking for trouble, especially with highly flammable R600 & R170 in the mix. You will most likely fail with this build. Sorry if this sounds harsh but that's the reality. Even the most skilled builders on this forums haven't really build one with much success. Besides, have you seen the price for a couple of kilos of R-14?

Be smart and don't rush to kill yourself :up:


Michael's thread really should be stuck to the top of this sub-forum. It is an amazing primer for autocascade development and theory.

[s0lid]

gomeler;3649528']Michael's thread really should be stuck to the top of this sub-forum. It is an amazing primer for autocascade development and theory.

I agree with you 100%. Those autoCs are really godlike :slobber:

[aenigma]

Yeah, I've seen quite a few people attempt it and just end up frustrated. But they weren't even trying 3 or 4 stage autocascades, mind you. I've wanted to try that with mine, but the price of R14...yeesh no thanks! I'd be lucky to get Ethylene!

As for the blend, using butane for the 1st stage refrigerant should work since it will mix with the higher pressure refrigerant and lower the boiling point. I tried it with mine and it worked, but using propane worked better for me, and I didn't really have enough butane to really test it, so mileage will no doubt vary from mine since I am not using the 2nd stage refrigerant you would be using and I didn't have enough butane to test. I may have had better luck with Ethylene. Also, adding in a high boiling point refrigerant such as butane can help compressor cooling as said, and it can lower condensing pressure.

If you haven't made a cascade at least, I wouldn't recommend trying this.

[s0lid]

Is that R14 really that expensive?
what is it then? 200e/kilo?

[[XC] gomeler]

Is that R14 really that expensive?
what is it then? 200e/kilo?

It depends on the volume you purchase it in. If you can purchase several hundred kilos it's actually comparable with R1150 in price. However in 1 to 10 pound quantities you are looking at $50/pound to $100/pound. I think I was quoted around $250 for 3 pounds last time I tried in the summer of 2007. However since last summer it's been impossible to get a quote as I keep getting the "R14 is currently in great demand globally and restricted to re-existing contracts" hence my interest in natural occurring gases like R1150/R50.

[aenigma]

Yeah, I haven't actually been quoted a price for R14, just going off of what I have heard and a price quote for R23 for 80 dollars a pound with a minimum purchase of 20 pounds! Why do cascade refrigerants have to be so expensive? :p:

[mytekcontrols]

Yep R14 is very expensive. I am lucky in that I have a source for small quantities any time I want due to my affiliation with a Polycold service company. Otherwise I'd never be able to afford it either.

I would also agree that an AutoC is not a good project for most people to attempt without some prior experience in working with either standard cascades, or if you were lucky, prior experience in AutoC's. However with that said; the AC2 project that I did earlier, if built and charged as described in the thread, will work.

[s0lid]

gomeler;3650391']It depends on the volume you purchase it in. If you can purchase several hundred kilos it's actually comparable with R1150 in price. However in 1 to 10 pound quantities you are looking at $50/pound to $100/pound. I think I was quoted around $250 for 3 pounds last time I tried in the summer of 2007. However since last summer it's been impossible to get a quote as I keep getting the "R14 is currently in great demand globally and restricted to re-existing contracts" hence my interest in natural occurring gases like R1150/R50.

Hmm 3 pounds = 1.5kg, 250$ = 193e, so it's 128e/kg well not that bad price since i've to pay 70e/kilo for R404s and other real refrigrerant gasses :(

This R50, what's its name and boiling point?

[aenigma]

R-50 would be methane (http://encyclopedia.airliquide.com/Encyclopedia.asp?LanguageID=11&CountryID=19&Formula=&GasID=41&UNNumber=&btnMolecule.x=9&btnMolecule.y=12&EquivGasID=29&VolLiquideBox=&MasseLiquideBox=&VolGasBox=&MasseGasBox=&btnMSDS=0&MSDSLanguageBox=11&RD20=29&RD9=8&RD6=64&RD4=2&RD3=22&RD8=27&RD2=20&RD18=41&RD7=18&RD13=71&RD16=35&RD12=31&RD19=34&RD24=62&RD25=77&RD26=78&RD28=81&RD29=82) which has a very low boiling point, so you would want to use it as a 4th stage refrigerant.

As for the R-14 "only" being $250 for 3 pounds, you will usually find you have to purchase a minimum of 20 pounds or so, but you never know unless you search around! :)

[s0lid]

R-50 would be methane (http://encyclopedia.airliquide.com/Encyclopedia.asp?LanguageID=11&CountryID=19&Formula=&GasID=41&UNNumber=&btnMolecule.x=9&btnMolecule.y=12&EquivGasID=29&VolLiquideBox=&MasseLiquideBox=&VolGasBox=&MasseGasBox=&btnMSDS=0&MSDSLanguageBox=11&RD20=29&RD9=8&RD6=64&RD4=2&RD3=22&RD8=27&RD2=20&RD18=41&RD7=18&RD13=71&RD16=35&RD12=31&RD19=34&RD24=62&RD25=77&RD26=78&RD28=81&RD29=82) which has a very low boiling point, so you would want to use it as a 4th stage refrigerant.



Yupp, methane should't cost much since it's pretty common gas.


As for the R-14 "only" being $250 for 3 pounds, you will usually find you have to purchase a minimum of 20 pounds or so, but you never know unless you search around! :)

Well, here's atleast 5 different gas sellers nearby oulu :)

But gasses aren't an problem so far as this autoc is being planned or it isn't ready and pressure tested :)

I'm still holding from my plan :D
Singlestage first and autoC much later.

[s0lid]

Hey,

Is there any good quide for TXV modding?
Or is it even neccesary with R402a singlestage?

[tiborrr]

Why would you wan't to use TXV on an single-stage? The smallest orifices are too large for conventional SS load in my opinion. Besides, cooling head system becomes bulky, just take a look at bazx's three-stager.

I have a feeling you're skipping all the basic steps. Modding TXV valves is something only most highly skilled builders are capable of pulling off successfully.

[s0lid]

Why would you wan't to use TXV on an single-stage? The smallest orifices are too large for conventional SS load in my opinion. Besides, cooling head system becomes bulky, just take a look at bazx's three-stager.

I have a feeling you're skipping all the basic steps. Modding TXV valves is something only most highly skilled builders are capable of pulling off successfully.

Yea i kinda trashed that idea after little visit at some phasechange part webshop... Too pricy for that build.