Reasons for running a SLHX?

Hello all, I have been looking around lately for ways to improve single stage performance. I have seen a few people using SLHX's in single stages....but I started wondering....If you are running a Gas that is already condensing decently with a condenser and perhaps a desup, wouldn't the refrigerant still boil off at the same temps? I can see why you would use it to help a gas condense but if thats already taking place what do you gain?

Also what is the benefit of running a SLHX over just subcooling the cap tube by wrapping it around the suction line or through it?

When SLHX is using, gas that is going to cap tube is cooling by gas that is going back to the compressor. Then gas that is going to cap tube or ev is cooled to suction line temp. Example:

Compressor --> condenser --> slhx --> cap tube --> evap --> slhx --> compressor.

After condenser gas have room temp, so for example ~22*C. After Evap gas will have for example ~-40*C, so SLHX will have similar temperature. When you are cooling gas by slhx, before cap tube, it will have ~ -40*C, so then you are really decreasing heat losses. Decreasing heat losses = lower loaded evap temps.

Maybe I`m wrong, so correct me please :)

Advantage of SLHX would be for REALLY high heatload where wrapping cap tubing around might not be able to make the refrigerant fully condense before it hits evap. Well... I don't see how that will happen anytime soon with properly tuned system though :P
Real advantage I see for myself is...
#1 being able to work with lower condensing temp gas possibly.
#2 controlling liquid slugging back to compressor quite easily
#3 just added efficiency in general. For most r402a installation though... I can't see how SLHX can help much if you use 0.031 cap tubing and wrap it real nice. I only gained about 1-2c measurable temperature benefit using SLHX on my test... and I had to put more gas than usual... -_-;
Now, SLHX is pretty much required components once you start using TXV though.... something to ponder over.

An idea I've been toying with, but couldn't you in theory have an SLHX and use it instead of a radiator in a watercooling setup? It would allow you to boil away any remaining liquid in the suction line and give you a half decent chilled water loop for your graphics card. Sort of a halfway between dual evap and seperate phase change + water cooler.

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Originally Posted by Carlz0r

An idea I've been toying with, but couldn't you in theory have an SLHX and use it instead of a radiator in a watercooling setup? It would allow you to boil away any remaining liquid in the suction line and give you a half decent chilled water loop for your graphics card. Sort of a halfway between dual evap and seperate phase change + water cooler.

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it does work... somewhat... need at least 2 ft to start giving meaningful temp for gpu cooling :) For SLI... might need bit more length...

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Originally Posted by jinu117

it does work... somewhat... need at least 2 ft to start giving meaningful temp for gpu cooling :) For SLI... might need bit more length...

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I was thinking something along the lines of a small enclosed condensor basically. That way you have fins in there too to aid in heat transfer.

Ok, so if I run a SLHX where is the best place for the discharge line to come from...I.E. before the condenser, after the condenser or does it not really matter?

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Originally Posted by Fhqwhgads6680

Ok, so if I run a SLHX where is the best place for the discharge line to come from...I.E. before the condenser, after the condenser or does it not really matter?

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After the condensor, otherwise the condensor will heat the cold gas to ambient temp.

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Originally Posted by jinu117

#3 just added efficiency in general. For most r402a installation though... I can't see how SLHX can help much if you use 0.031 cap tubing and wrap it real nice. I only gained about 1-2c measurable temperature benefit using SLHX on my test... and I had to put more gas than usual... -_-;Now, SLHX is pretty much required components once you start using TXV though.... something to ponder over.

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Have You gained 1-2*c better evap temps or where ?? :confused:

Can You write about these tests here ?

Regards
Peter

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Originally Posted by piotres

Have You gained 1-2*c better evap temps or where ?? :confused:

Can You write about these tests here ?

Regards
Peter

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Hmm maybe gain is not a good word... I got 1-2c better loaded temp for 150w real heat load (amd dual core dual priming 1.78v dmm) readingusing same setup (same cap tubing same evap, same all). It is one of many experiments I've been doing to improve my units. I noticed it does take tad longer to pull down with SLHX probably due to added amount of refrigerant I had to keep in, highside once load is applied and stablized is lower psi than without slhx, lowside isn't much different obviously. My gut feel of refrigerant used is about 30-40% more than previously (standing pressure is tad higher by 10 psi than without slhx after all tuning running than letting it sit out there for over night so it gets all static)
Considering I do get good subcooling with good wrapping of cap tubing probably is reason why i see not much difference. Once heatload gets higher though, it might help... but I haven't tested that... someone else can lol... got few other things I need to test first before I get back to it.

Why not just wrap capillary around the suction.

Well I think the major point of the SLHX is not only to cool the liquid, but reduce overall discharge pressure so it is possible to run a higher pressure gas at lower pressures aswell as increasing capacity...From what I understand...Wrapping of the cap tube I believe just ensures the liquid is good and condensed when it hits the evap to get best performance...correct me if im wrong....

The main question I had was....if the refrigerant is already condensing well, and at reasonable pressures...then...there isn't much of a point....other than lowering pressures...I.E. not much of a Temp gain on evap..It would lessen the strain on the compressor I'd imagine tho....

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Originally Posted by Fhqwhgads6680

Well I think the major point of the SLHX is not only to cool the liquid, but reduce overall discharge pressure so it is possible to run a higher pressure gas at lower pressures aswell as increasing capacity...From what I understand...Wrapping of the cap tube I believe just ensures the liquid is good and condensed when it hits the evap to get best performance...correct me if im wrong....

The main question I had was....if the refrigerant is already condensing well, and at reasonable pressures...then...there isn't much of a point....other than lowering pressures...I.E. not much of a Temp gain on evap..It would lessen the strain on the compressor I'd imagine tho....

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Im not sure you will lessen the strain on the compressor, you the heat removed by the slhx is dumped straight back in.

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Originally Posted by johann

Im not sure you will lessen the strain on the compressor, you the heat removed by the slhx is dumped straight back in.

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yes, but i think the heat is used in the succion line, preventing liquid returning to compressor.

Mmm correct me if i'm wrong, but using a slhx is like using a bigger condenser, I had some issues with little condensers and too much air flow over it, it makes the pressures goes too low and then the gas flow is also low and I needed to cover the condenser to get better temps and less air flow, so, where is the gaining there?
If you need to stop liquid return to compressor, just charge the system better or put a liquid trap.

Carlz0r, I had the same idea, and I will do it in my next unit, I don't want "super low temps" just ambient, so I think it will work great cooling my vga water and stoping any liquid return.

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Originally Posted by Ssilencer

Carlz0r, I had the same idea, and I will do it in my next unit, I don't want "super low temps" just ambient, so I think it will work great cooling my vga water and stoping any liquid return.

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Cool. Let me know how it works as I may do that sometime later this year.