A question about the inter-stage HX

[MutantToad]

Well, I have a basic question about the inter-stage HX; its a bit noobish, so sorry :(. Anyway, in a tube-in-tube inter-stage, does the 1st stage refrigerant go in the larger tube, and the 2nd stage in the small? Or is it vice-versa?

~Toad

[stockhatch]

1st stage evap generally goes on the inside tube for more efficient operation.

[sandman]

No, first stage evap goes on the outside to make the second stage as cold as possible.

[stockhatch]

Really...I thought most ppl put the evap on the inside so all of the cold would be used and not be lost through the outside circumference of the pipe.

EDIT. Jep, I had it bass ackwards...sorry about that. That'll teach you too listen to a n00b :D BTW, I assume others have tested with the inner tube as an evap and proven it is less efficient?

[MutantToad]

Lol, then it's a good thing I didn't recheck this before sandman posted :). J/K, all contributions (even incorrect ones) are appreciated.

~Toad

[_HL4E_HalfLife_]

Really...I thought most ppl put the evap on the inside so all of the cold would be used and not be lost through the outside circumference of the pipe.

I agree with u there stock thats why i got my evap as the inner tube on my 2 stage cascade im building.

I really don't think it matters that much anyway if ur HX is large enough like mine is.

[n00b 0f l337]

Seems more logical.

[sandman]

Seems more logical.

Not really, the goal is to get the "condensor" as cold as possible, not the evaporator part of the interstage HX.

[gkiing]

If you put the first stage on the inside, you will get better temperatures since the only heat source is the 2nd stage condensing gas. However, this hx setup will be larger since you will need a larger inside od pipe as an evaporator..

[stockhatch]

Sweet, we were both right :D I feel slightly less ignorant now :)

[MutantToad]

Lol, then it's a good thing I didn't recheck this before sandman posted :). J/K, all contributions (even incorrect ones) are appreciated.

~ToadOr I may be mistaken...or double mistaken...does anyone have results using 1st in 2nd stage and 2nd in 1st stage?

[gclg2000]

I've put mine on the inside. Cuz you don't lose as much capacity from it being on the outside. Plus the 2nd stage gas completely surrounds the 1st stage evap. I say put the 1st stage on the inside.

I've broke -100C doing the 1st stage evap on the inside. The most important thing in my opinion is making sure your 2nd stage gets enough sub cooling b/f it enters the HX. This will help make it easier to condense your 2nd stage gas.

[stockhatch]

How can you subcool the 2nd stage before its even a liquid?

[gkiing]

How can you subcool the 2nd stage before its even a liquid?

You can't. He probably means that you must desuperheat the second stage gas as much as possible before it goes to condense in the hx.

[stockhatch]

Gotcha. I figured as much. Just making sure I didnt miss a huge section of theory or something. It has been known to happen :)

[Waus-mod]

I also think the inside tube wil have the most effect like gclg2000 said, or you will lose cold because it then goes outside the tube instead of delivering the cold.

[Cr@sh_D1n3r]

You could also make an HX with 3 pipes. center is 2nd stage condensor and both outter and inner pipe would be 1st stage evaps. Put 2 evaps on 1st stage with 2 cap lines. You lose capacity on 1st stage but you incrase surface contact so you can have smaller HX or a more efficient one. I never tryed yet but I will this week :)

[n00b 0f l337]

Or stick with a single evap on the inside and make the pipe like a /\/\/\/\ pipe on the outside. Tons of crazy crap you could do for more inner surface area.

[_HL4E_HalfLife_]

You could also make an HX with 3 pipes. center is 2nd stage condensor and both outter and inner pipe would be 1st stage evaps. Put 2 evaps on 1st stage with 2 cap lines. You lose capacity on 1st stage but you incrase surface contact so you can have smaller HX or a more efficient one. I never tryed yet but I will this week :)

Steal my idea will u :slapass: :nono: :slap:

[n00b 0f l337]

When'd he do that?

[Cr@sh_D1n3r]

what? when we talked that was my idea! yours was to use 2 compressors for 1st stage...and anyway this one was both of our idea :P

[_HL4E_HalfLife_]

what? when we talked that was my idea! yours was to use 2 compressors for 1st stage...and anyway this one was both of our idea :P

nm the one with a tube within a tube within a tube is the one i thought u were talkin about this one i came up with. 1st stage evap is outer and inner tubes and 2nd stage condensor is the middle tube .

[gclg2000]

You can't. He probably means that you must desuperheat the second stage gas as much as possible before it goes to condense in the hx.

exactly.

Sorry for the cross up.

I think basically, the goal should be to bring your 2nd stage gas down to ambient temperature b/f you lead into the HX. The colder (or cooler) you can get the 2nd stage gas b/f the HX the easier (and less pressure) it will require to condense your 2nd stage gas. Thus giving you a steady liquid flow of 2nd stage gas to your metering device such as a PEV or captube, although i personally HIGHLY recommend using a PEV.

One of these days, i'll undergo a more advanced cascade. When i do, i think i will use only water cooled condensers and water cooled desuperheater's. This is the most effecient way to condense (or desuperheat) the refridgeration cycles in cascades.

I've used (and chilly1 has to many times) a "water cooled condenser" for your Int. HX. Packless industries makes these units. They are small, compact, corregated and have an INSANE amount of surface area on the inside for heat exchanging to happen.

If your interested in getting a pre made professional HX'er chilly1 can send ya one or i can get them too from the supplier i use.

Be sure to give us some pics as you go.

Good luck!
:toast:

[Cr@sh_D1n3r]

how would you cool the water of water-cooled hx? You would use tap water or an radiator ? either way isn't it a waste of energy / ressource ? Or maybe you have another way?

[n00b 0f l337]

Basically just a watercooling setup that cools the radiator setup... Like a tube for the gas, and the outer tube has water.

[Cr@sh_D1n3r]

I understand how it works. But dosen't adding more and more radiators and such decrase effiency?? The more direct, the better no? Because cooling 1st stage with water still require the water to be cooled with air so if you cool the water with air what's the point in adding it?

[MutantToad]

That's basically saying: Why cool with liquid when there is air cooling around? Liquid cooling is usually better than air...

~Toad

[Cr@sh_D1n3r]

Yes of course but water-cooling it would require a big radiator to cool the water no?

[chilly1]

Well, I have a basic question about the inter-stage HX; its a bit noobish, so sorry :(. Anyway, in a tube-in-tube inter-stage, does the 1st stage refrigerant go in the larger tube, and the 2nd stage in the small? Or is it vice-versa?

~Toad
What it boils down to is temperature. Is the gas being cooled a higher temp then the gas doing the cooling? (Obvious huh?) Always think heat gains where will the heat be coming from to warm my cooling gas willit be from where it will help or hinder. Well the warmer gas goes to the outside so the inner gas only absorbs heat from the gas and not the surrounding insulation. This is the most efficient configuration however due to contstraints in tubing sizes of home made HX's a lot of peeps make them inside out.

[n00b 0f l337]

To Crash...

When or if you work on a cascade normally you have plenty of room and if you want the coolest temps, a pump, tubing, and a heatercore aren't too much troubles.

[hatemi]

But they will gain you nothing if you have siezed your condenser and desoperheating properly. Water can only be as cold as the ambient air so there is no poiint in using it. Just get a condesnser big enough and it will do just the same.

Most people use watercooling on a PC because it is possible to use larger fans on the hatexchanger( HSF VS a heatercore) and with more surface area. This will give better preformance and with less noise than using plain air. But it is not the case in phase change since we already use big azz fans with massive airflow and condenser that is bigger than your average watercooling radiator. If everything is indeed siezed properly the gas/liquid exitting the condeser will be at/or very close to ambient temperature.

[Cr@sh_D1n3r]

But they will gain you nothing if you have siezed your condenser and desoperheating properly. Water can only be as cold as the ambient air so there is no poiint in using it. Just get a condesnser big enough and it will do just the same.

Most people use watercooling on a PC because it is possible to use larger fans on the hatexchanger( HSF VS a heatercore) and with more surface area. This will give better preformance and with less noise than using plain air. But it is not the case in phase change since we already use big azz fans with massive airflow and condenser that is bigger than your average watercooling radiator. If everything is indeed siezed properly the gas/liquid exitting the condeser will be at/or very close to ambient temperature.
This is exactly what I was thinking. There's no point in using water on the condensor if the condensor is already at room temp. If you use water from a cold pipe running in the house then it has to be a massive waste of water.

The only thing I can think of is if you burry the water pipe underground. This way you could have below ambiant temperatures.

[gclg2000]

This is exactly what I was thinking. There's no point in using water on the condensor if the condensor is already at room temp. If you use water from a cold pipe running in the house then it has to be a massive waste of water.

The only thing I can think of is if you burry the water pipe underground. This way you could have below ambiant temperatures.

The water will give more surface area for the condenser. Water removes and holds heat much better than air does. Thus your not having to use such a loud and giant fan. If you properly size your radiator and radiator fans, it could be a much quieter solution and more effecient solution.

This is one of the reasons the real A/C world uses such parts, its much more effecient.

If / when i ever apply this to my next build, i will have a small (large) rad and some quiet large fans.

You will see more benefit from water cooling your condenser on the 2nd stage in my opinion, for it will make your HX more effecient and help make sure you sub cool all the hot gas you can b/f it enters the HX. But while your at it, i'd go ahead and water cool the 1st stage condenser (if you ever attempt to cool it this way).

I got off on this tangent b/c i use a water cooled condenser (intended use) for my HX on my 2-stager. ANd it works great. It's only like 5.3ft long, but is highly corregated and has a maximal amount of surface area on the inside. And i would suggest this type setup to anyone building a cascade. The part is very cost effective.

[hatemi]

'The main reason vatercooled HXs are used in HVAC is that by using htem you can use those 2000kg water rads on the roofs and not have to fill all the tubes with refrigerant. Imagine how much it would cost to fill hundreds of meters of 15mm tube and tens of meters of 50mm tube with refrigerant. Then compare that to the price of Glycol+water+circulating pump and you can get the idea of why watercooled rads are used in HVAC. If you can use geothermic energy(not sure if it is the right description) or actually the lower water temperature if your condenser is bellow the ground then you would indeed gain some with watercooling.

BTW my cascade is would be pretty damn quiet if the fan wouldnt resonate so much that it does. My first cascade(that is waiting for ethylene) was quieter than Vapo LS :D

[gclg2000]

'The main reason vatercooled HXs are used in HVAC is that by using htem you can use those 2000kg water rads on the roofs and not have to fill all the tubes with refrigerant. Imagine how much it would cost to fill hundreds of meters of 15mm tube and tens of meters of 50mm tube with refrigerant. Then compare that to the price of Glycol+water+circulating pump and you can get the idea of why watercooled rads are used in HVAC. If you can use geothermic energy(not sure if it is the right description) or actually the lower water temperature if your condenser is bellow the ground then you would indeed gain some with watercooling.

BTW my cascade is would be pretty damn quiet if the fan wouldnt resonate so much that it does. My first cascade(that is waiting for ethylene) was quieter than Vapo LS :D

Good stuff.

But water will always be more effecient. If you ever want to build the "best" unit you can, then using water to remove heat is the best choice.

And its hard to keep a quiet cascade rig. Well for me anyways, but i'm running 1 horse copeland and 3/4 horse copeland...i need a good sized fan to keep it down.

[wdrzal]

You will just have to make a split cascade nd put the compressors outside,like a central air unit. LOL

Ps: Hope you weather'd the hurricane ok GCLG2000? I was thinking and praying for you guys down there!!!

[Cr@sh_D1n3r]

You will just have to make a split cascade nd put the compressors outside,like a central air unit. LOL


This is exactly what I did on a single stage. I got a -45c cpu cooler and a really silent computer lol!

[gclg2000]

You will just have to make a split cascade nd put the compressors outside,like a central air unit. LOL

Ps: Hope you weather'd the hurricane ok GCLG2000? I was thinking and praying for you guys down there!!!

I was praying for us too. We really lucked out. This was nothing compared to how bad Ivan was.

[runmc]

You will see more benefit from water cooling your condenser on the 2nd stage in my opinion, for it will make your HX more effecient and help make sure you sub cool all the hot gas you can b/f it enters the HX. But while your at it, i'd go ahead and water cool the 1st stage condenser (if you ever attempt to cool it this way).

I got off on this tangent b/c i use a water cooled condenser (intended use) for my HX on my 2-stager. ANd it works great. It's only like 5.3ft long, but is highly corregated and has a maximal amount of surface area on the inside. And i would suggest this type setup to anyone building a cascade. The part is very cost effective.

How do you plan on watercooling your "condenser" on the 2nd stage? :confused: I don't get it.

You suggest using the factory made water cooled condenser for a interstage heatexchanger. Have you had better results with the factory made HX than you've had with the homemade coil type (tube in tube)?

[MutantToad]

I think gclg2000 might mean to water cool the desuperheater...there's an idea...
And tell me, how big should the radiator be for the water?

~Toad

[gclg2000]

How do you plan on watercooling your "condenser" on the 2nd stage? :confused: I don't get it.

You suggest using the factory made water cooled condenser for a interstage heatexchanger. Have you had better results with the factory made HX than you've had with the homemade coil type (tube in tube)?

I'm sorry, i mean desuperheater. ANd yes i've used a tube in tube design, it will work also. Just using the pre-made "water cooled condensers" for a HX is much easier. It's only 5.3ft long or so and works wonders. Very smal and compact coil.

[n00b 0f l337]

A double heatercore may or may not be enough.... Good question.... How big?

[saratoga]

Maybe I'm misunderstanding, but I don't see how water is useful unless you're doing it to save on refrigerant. The reason we use watercooling for CPUs is to address the thermal density of the CPU core. With a condensor, this issue is already delt with at the evap, so the benefit is lost. Likewise for a desuperheater, you could make the unit arbitarily large until you get the thermal density down to the sweet spot for air, again eliminateing the advantage of water (although you will need more refrigerant).

[n00b 0f l337]

I dont see how it saves refrigerant or anything..... Its simply instead of having a condensor with a fan, its a tube inside tube and water cools the gas to condense it. It works better than air to condense the gas and would allow for quiter operation

[saratoga]

I dont see how it saves refrigerant or anything..... Its simply instead of having a condensor with a fan, its a tube inside tube and water cools the gas to condense it. It works better than air to condense the gas and would allow for quiter operation

A huge condenser would probably occupy a lot more gas then a tiny HX and a huge heatercore. I doubt its an issue for most people though since we don't use condensors that are that large anyway.

[runmc]

I dont see how it saves refrigerant or anything..... Its simply instead of having a condensor with a fan, its a tube inside tube and water cools the gas to condense it. It works better than air to condense the gas and would allow for quiter operation

:stick: Your going to cool the discharge gas with a water cooled heat exchanger -right? - How are you going to cool the water that cools the discharge gas? A radiator with a fan. :spam:

:idea:

[n00b 0f l337]

Yeah..... But....... The fan could be quiter..... :) Your the one wiht the HX for that purpose.....

You explain it!

[Cr@sh_D1n3r]

IMO there's no point to use a water-cooled condensor if it ain't sub ambiant. You still have to dissipate the same amount of heat than on the condensor itself. If you use quieter fan (lets says it do less cfm) you will need a bigger radiator. If you make a condensor with output at room temp, using water will have no effect at all.

[gclg2000]

The big advantage i'm getting at, is it could be more compact and mainly MUCH quieter. I have a small 3 row condenser from chilly i am thinking about using on my rebuilt cascade...but the 2nd stage is a 3/4 HP compressor....that's not going to bring the high side down to ambient b/f it goes to the HX....thus putting alot more load on the HX and making the system less effecient...So i'm prob gonna just use some smaller condenser's (1/2 ton or so) for the desuperheater so the gas is at least ambient b/f it goes to the HX.

THe 1st person (or me if it is me) that undergo's a water cooled cascade would be really cool. Cuz you could cut down on the noise level, have one reservoir that fed the 1st stage condenser and 2nd stage desuperheater and just use one (or two) good sized heatercore's...

I bet 2 77' bonneville core's in series w/ each other w/ 2 120mm's on each core would be enough to manage it all.

[Cr@sh_D1n3r]

Ok then, project for tomorrow, install my commercial grade water-cooled condensor, install my 3 pipe hx and test it out :) Kidding, I bet I won't even have time to finish my new hx lol.

[n00b 0f l337]

Just get a monstercore from weapon... But yeah for watercooling desuperheaters in second and third stages would be the only really good use.

[saratoga]

Yeah..... But....... The fan could be quiter..... :) Your the one wiht the HX for that purpose.....

You explain it!

Or the fan on the condenser could be quieter. Neither is more effcient then the other, so which ever is bigger will tolerate the quieter fan.

The way I look at it, if you can use a large condensor, or an equally large radiator + pump + hx, then you might as well just use the condenser since it does the same thing as the radaitor, except doesn't require a pump (plus you don't have to worry about cooling the heat generated by the pump).

The only reason I could see to use water would be if you need to have the radiator far away from the rest of the system for some reason, and don't want to run refrigerant that far.

[gclg2000]

.....it's quieter.....the heat from the pump would be picked up in the water and blown off by the radiators.

And once again, its overkill but this is xtreme and we are used to overkill. It would make the best differance on desuperheater's...like i said in my case a 3/4hp compressor puts out a good amount of heat and my current (smaller) air condenser (applied as desuperheater) IMO is not enough, so i'm upgrading it.

The whole reason i brought up the water cooled condenser's is for the general knowledge idea's of them and the fact they work as the best HX's you can get for cascades.

http://www.namike.com/albums/Cascade-Build/MVC_029F.jpg

http://www.namike.com/albums/Cascade-Build/MVC_030F.jpg

http://www.packless.com/desuper/supertube2.jpg

[gclg2000]

also...funny we are talking about this...the guy below has 3 for sale in this boards FS section....

http://www.xtremesystems.org/forums/showthread.php?p=964420&posted=1#post964420

[runmc]

Well, I have a basic question about the inter-stage HX; its a bit noobish, so sorry . Anyway, in a tube-in-tube inter-stage, does the 1st stage refrigerant go in the larger tube, and the 2nd stage in the small? Or is it vice-versa?

As you can see from my pic below - the first stage evaporates into the bottom outer shell of this HX. The discharge from the second stage condenses in the inner tube, entering the HX from the top. Sorry your thread got so far off topic. :(



I agree with you on the Water cooled HX. I also like them. I have been using one on two different cascades for well over a year now.
http://www.teampuss.com/runmc/new%20cascade/runtek%20cascade%201.jpg

http://teampuss.com/forums/viewtopic.php?t=25

However there are other alternatives that work as well or better.

http://teampuss.com/forums/files/slihx_755_108.jpg

[wdrzal]

hey runmc who makes that tubing cutter in the pic? I like the triangle tightening knob on it. All the small ones I have like a ridgid 101 have a small round knob that hard to turn,the knob on yours looks like you cn get good leverage!!!

[runmc]

hey runmc who makes that tubing cutter in the pic? I like the triangle tightening knob on it. All the small ones I have like a ridgid 101 have a small round knob that hard to turn,the knob on yours looks like you cn get good leverage!!!

Hey walt :D That is a picture of |Ricky|'s latest HX. That tube cutter is Portugese :eek:

[wdrzal]

Hey walt :D That is a picture of |Ricky|'s latest HX. That tube cutter is Portugese :eek:


No wonder why I never seen one like that :confused:

[Jort]

i've got the same here, its from ITE afaik:)

[LardArse]

How many you guys use desuperheaters on the low stage?
I have rather big oil seps in comparision to the systems, and they act as desuperheaters well enough such that when the low stage refriegrant reaches the HX its pretty ambient.

[jan]

No wonder why I never seen one like that :confused:


I'Ve got a cutter with triangle nob. Its from Refco

[runmc]

How many you guys use desuperheaters on the low stage?
I have rather big oil seps in comparision to the systems, and they act as desuperheaters well enough such that when the low stage refriegrant reaches the HX its pretty ambient.

I have used desuperheaters B4 :woot: :clap:

[sandman]

How many you guys use desuperheaters on the low stage?
I have rather big oil seps in comparision to the systems, and they act as desuperheaters well enough such that when the low stage refriegrant reaches the HX its pretty ambient.

I just use a long coiled up copper pipe. Like 8' of 1/4" placed somewhat close to the main condensors fan. It dropps the line temps about 5degrees from 34C to 29C.

This was in an autocascade though, so not sure if that matters or not.