HX Config

[_HL4E_HalfLife_]

Would 4&1/2 feet of 3/16 inside of 3/8 be enough for a small 2 stage cascade?

[n00b 0f l337]

Doubt it, but then again, I constantly hear that our massive HX's (10+ft) are way overboard. Why not give it a shot?

[_HL4E_HalfLife_]

Noone else has an opinion on this???

[LukeXE]

4 and 1/2 feet HX for cascade is quiet small, but maybe try ?

I have never tried that small HX

[Blaster]

depends on 2nd stage gas you'll be using also...

[_HL4E_HalfLife_]

Well 1st stage will be 402A and 2nd stage will be a blend of either 402A or 290 if i don't have enough 402A left over and Co2.

Also im trying to decide on which 2 compressors would work the best with this small cascade, this is what i got:

6000Btu Rotary
575Btu Recip @ -23.3c
725Btu Semi-Hermetic @ -31.6c
2500Btu Recip
2600Btu Recip
4100Btu Recip
4280Btu Recip
10000Btu Recip
11300Btu Recip

[Blaster]

you could try find some R23 :)

[kayl]

i found it hard to keep short HX flooded with heavy loads.
Mybe try a coil of 3/8" as well after the hx to help keep it flooded.

[Gray Mole]

Well the Autocascade I just put together has 3.5m of 1/2" over 3/16" (single pipe) and it's working just fine.

For a cascade I'd say your 4.5' could be a little short, but it's worth trying. As Kayl said, it's only the load you'll have to deal with, but it could very sell work for you.

I've used 1/4" inside 1/2" at about 6' at the shortest, but if you're going small on the cascade I'm sure that 3/16" in 3/8" should work about the same.

Is there any way you could go a little longer? Using 3/8" you should be able to coil up quite tight and keep it pretty small.

Cheers

Gray

[_HL4E_HalfLife_]

Well the Autocascade I just put together has 3.5m of 1/2" over 3/16" (single pipe) and it's working just fine.

For a cascade I'd say your 4.5' could be a little short, but it's worth trying. As Kayl said, it's only the load you'll have to deal with, but it could very sell work for you.

I've used 1/4" inside 1/2" at about 6' at the shortest, but if you're going small on the cascade I'm sure that 3/16" in 3/8" should work about the same.

Is there any way you could go a little longer? Using 3/8" you should be able to coil up quite tight and keep it pretty small.

Cheers

Gray

Yes i can make it longer ill just have to buy another peice of 3/8 and braze them together. How much longer should i make it?

Also im going to be using the 6000Btu Rotary and the 4100Btu recip compressors. The 4100Btu recip is gonna be on 1st stage and the 6000Btu rotary on 2nd stage is that gonna cause a problem seeing as the 1st stage compressor is a bit smaller than 2nd?

[_HL4E_HalfLife_]

Does anyone know if it will matter or not weather the 1st stage compressor is smaller than the 2nd stage??? I need to know before i begin brazing.

[n00b 0f l337]

Sorta, especially if your HX is smaler I think your going to want bigger compressor on the 1st stage.

[[XC] gomeler]

From what I can think about this I think you would want your larger compressor cooling your first stage. Since the first stage has to cool the gas + the heat output by the compressor you'll want more power on the bottom. That is what makes sense to me, however I could be wrong.

[_HL4E_HalfLife_]

From what I can think about this I think you would want your larger compressor cooling your first stage. Since the first stage has to cool the gas + the heat output by the compressor you'll want more power on the bottom. That is what makes sense to me, however I could be wrong.

That is true BUT will the heat from the 2nd compressor + the heat load from the 2nd stage be more than 4100Btu's? This 1st stage compressor is i think either a high temp or med temp its from a dehumidifier.

[bazx]

from my experience the hx is the most important part of your cascade

i would put all of your most power full components there. if you can get a good hx temp in and out under load you will succeed

i could not get a 4m hx to work well it showed good temps in and out (-45 402a)
but would not hold the load from the second stage and temps would collapse pressure would rise fast

so far the best hx i have made is 6m 1/2 with 1/4 coil /tev feed/507/3/4hp

the extra 2 m allow the hx to catch up when i turn on the second stage

as the heat load hit the hx i have found there is about a 5min battle where the hx must regain its temps and crush the heat load to be of any use in controlling and condensing the gas from the second stage

[_HL4E_HalfLife_]

I think the HX is ok now i added a 3 1/2foot peice to it making its total length around 7 feet now.