My big project. Cascade/autocascade

[sandman]

I'm currently building a dual evap cascade, with an autocascading first stage.

I plan to use R22, R290, and Co2 for the autocascade, and I have some R1150 on the way for the second stage.

I'm using chilly1 evaps, and 1hp copeland compressors. I'm using the condensor from an A/C, and homemade oil-sep and phase-sep.

I skipped the beginning of making the cascade, but since then I've been taking a few pictures.

So, I'll attach the pictures, and you guys can ask me whatever questions you want, and give me any tips you have.

[n00b 0f l337]

Lookin schweet so far.
*subscribed*

[sandman]

I just noticed I don't have a picture with the 2nd HX in there.

Hmm...

Anyway, both of my HX's are 12ft of 1/4" inside 1/2". A little short, I agree, but they should work.

[afireinside]

Autocascade and dual evap, both a pain in the arse to get to work right. And you're throwing both into your first cascade? You sir, are insane!

[f00t]

i dont really think that you'll need an autocascade for the first stage. i *think* that chilly1 said that condensing r1150 at -40 as opposed to -60 doesn't offer any benefits (i think that was somewhere in the autocascade-cascade thread). imho your just making it more complicated than it has to be

[skate2snow]

The autocascade on first stage will most likely wont have enough capacity to cool the second stage.... So it would be better to cascade an autocascade which I dont think it would handle correctly a duel evap....

The Autocascade capacity is divided by how much stages you have in it.... Think about this seriously

[Bourne]

You have beutiful hands.....nice cascade also

[sandman]

AFI: I've built both a dual evap system, and an autocascade before though.

Foot: Do you have a link?

s2s: And what two gases would you suggest I use to do this?

Thanks for your input.

[skate2snow]

For a cascade the best gases are most likely R402a with R1150.... And to have a "perfect" first stage gas you can add some Ethane which has a boiling point of -88c and a relatively high volumique mass...

[saratoga]

I think autocascading the first stage will only hurt your capacity without gain, unless you want to condense some very high pressure gas on the second stage.

Why not try autocascading the 2nd stage if you want a challenge? AFAIK its never been done for a PC system before.

[skate2snow]

But he wants duel evap... Duel evap AC is most likely not very powerful

[sandman]

But he wants duel evap... Duel evap AC is most likely not very powerful

It would work as well as well as any other dual evap system vs single evap system, it's just harder to tune.

As to why not cascade second stage, it requires two high pressure gases which I have limited access to, plus like I said it'd be really hard to tune.

[skate2snow]

1HP compressor wont handle the load... your load is divided by 2 when using an autocascade (2 stages), your max load would be approx 225W for your 2 heads ( not 225w each....)

[sandman]

1HP compressor wont handle the load... your load is divided by 2 when using an autocascade (2 stages), your max load would be approx 225W for your 2 heads ( not 225w each....)

How exactly did you come by these numbers?

The load depends on the charge, the restriction, the HX, there are alot of avriable to say this is what it'll handle, and this is what it won't.

I'm just wondering how you came about 225watts?

[Jort]

The autocascade on first stage will most likely wont have enough capacity to cool the second stage.... So it would be better to cascade an autocascade which I dont think it would handle correctly a duel evap....

The Autocascade capacity is divided by how much stages you have in it.... Think about this seriously

this is how he got it i think

[skate2snow]

1Hp can handle around 750W, you divide it by 2 because of autocascade.... 375w..... VUR, you have the load the air will do and the compressor itself and all..... I am really not an expert in thermodynamic, but it should give you around 275w BIG max.....

I am sure you are able to do a duel evap AC, I am just not sure that it will handle what you want..... I honestly dont see the point of the AC in your cascade...

[saratoga]

Disclaimer: I'm no expect at this, but I've done some reading on the subject.

1Hp can handle around 750W, you divide it by 2 because of autocascade.... 375w..... VUR, you have the load the air will do and the compressor itself and all..... I am really not an expert in thermodynamic, but it should give you around 275w BIG max.....

I am sure you are able to do a duel evap AC, I am just not sure that it will handle what you want..... I honestly dont see the point of the AC in your cascade...

1 HP is ~ 750w of electrical power, but not cooling power. The power delivered to the evap (or rather from it) depends on the Coeffcient of Performance for the system, which depends on all the parameters in the system. Generally for single stage systems it can be well over 1, but as you run into deeper and deeper vacuum you lose COP. Thats why a short cap tube gives you awesome load, but a longer one gives you lower temperatures, even though the compressor is still consuming roughly the same amount of power.

1 HP worth of compressor will give you as much cooling power as you like. Just maybe not at the temperatures you'd like

1HP compressor wont handle the load... your load is divided by 2 when using an autocascade (2 stages), your max load would be approx 225W for your 2 heads ( not 225w each....)

You're oversimplifing. You can put the load to almost anything if you set the cap tube right and choose the refrigerants correctly, at least in theory. Theres no reason your load will be halfed in an autocascade, but again everytime you lower the temp you will lose capacity. The 2nd law promises that much. How much capacity you lose and how low you can go depends on your system.

Edit: Maybe I'm misunderstanding you? I just don't quite see how you can come up with the wattage figures without knowing about the rest of the system.

[Lotec25]

I just got my Mach 2 installed. Now i am going to have to build one of these. Looking good

Lotec

[skate2snow]

Disclaimer: I'm no expect at this, but I've done some reading on the subject.



1 HP is ~ 750w of electrical power, but not cooling power. The power delivered to the evap (or rather from it) depends on the Coeffcient of Performance for the system, which depends on all the parameters in the system. Generally for single stage systems it can be well over 1, but as you run into deeper and deeper vacuum you lose COP. Thats why a short cap tube gives you awesome load, but a longer one gives you lower temperatures, even though the compressor is still consuming roughly the same amount of power.

1 HP worth of compressor will give you as much cooling power as you like. Just maybe not at the temperatures you'd like



You're oversimplifing. You can put the load to almost anything if you set the cap tube right and choose the refrigerants correctly, at least in theory. Theres no reason your load will be halfed in an autocascade, but again everytime you lower the temp you will lose capacity. The 2nd law promises that much. How much capacity you lose and how low you can go depends on your system.

Edit: Maybe I'm misunderstanding you? I just don't quite see how you can come up with the wattage figures without knowing about the rest of the system.

I know that it depends on all your gas, the COP, your deltas and all, but I tried to make a very simple approximation.... But I have to say you are right on all the line.

But I think that tuned till you can get the correct capacity, you wont even get any benefits from doing autocascade maybe even worst.... With a nomral duel evap, my temp may already be cuted down to -75-80c instead of -90c.... So I honestly dont wanna imagine the load problems you will get

[sandman]

Well, I've decided that I might as well go for it all. The triple stage.

I've got a 5/8hp tecumseh compressor that I'll be using for the third stage.

[_HL4E_HalfLife_]

Well, I've decided that I might as well go for it all. The triple stage.

I've got a 5/8hp tecumseh compressor that I'll be using for the third stage.

A 5/8hp compressor?? is that even a real term to use for hp??? Do u mean a 1/8hp? or a 1/5?

[sandman]

5/8, as in 1/8 over 1/2.

Why wouldn't it be a real term?

It's just a fraction.

[_HL4E_HalfLife_]

5/8, as in 1/8 over 1/2.

Why wouldn't it be a real term?

It's just a fraction.

I have never in my life heard of a 5/8hp compressor...or motor...or engine...or rocket...or anything for that matter.

[GuGaCoSa]

Hey,have u brazed the evaps using this mapp torch?If so,how long it takes?
Thank you.
PS:Looking forward to see the progress,looking very good

[MutantToad]

A triple stage, eh? What gases are you using for it, and what temps are you expecting at load? Keep up the good work, I'm looking forward to results.



~Toad