Joe's Thermosyphon at overclockers.com

[HammerSandwich]

Originally Posted by jaydee

I would have thought it would have to be quiet to be considered... :shrug:

That's correct, of course. However, the silent folk are extraordinarily picky about components, particularly fans. Quiet 120s massively outnumber quiet 92s, so they have become the standard for silent PCers. How much buzz do you hear for cases with 92mm exhausts?

[jaydee]

Originally Posted by HammerSandwich

That's correct, of course. However, the silent folk are extraordinarily picky about components, particularly fans. Quiet 120s massively outnumber quiet 92s, so they have become the standard for silent PCers. How much buzz do you hear for cases with 92mm exhausts?

I don't see it relevant really. If they want to be particular it is their loss. It should be judged on how quiet it is not on what parts it uses.

I don't see any reason why 120's couldn't be used anyway.

[bigben2k]

Originally Posted by Long Haired Git

because....


If I were Joe, I'd drop to just one shrouded fan @ 4v and see how that goes. Is the competing HSF going to compete on the noise level?

...

I don't think it would make much difference.

This unit would respond very much like a heatpipe; it'll maintain a relatively stable C/W, until it reaches its capacity, at which point the C/W curve would look like a bad water cooling block.


The reason I'd like to test it, is because this type of cooling, along with heatpipes, generates radically different response curves. Obviously this unit can be overwhelmed, as any heatpipe can, but we just don't know when. Assessing the response curve for a unit like this is an excellent testing challenge.


Otherwise, as for the functionality, yes it is a disadvantage that one can't add extra cooling points, but if this unit comes out with a low price point, one can simply add another unit. Joe already hinted at a $50 price, and it might not be far off, in the end; it's just a block, a radiator, and special tubing.

As for the orientation issue, I'd have to state that ideally, it should probably be mounted on a diagonal, in case the user flips the case to the side. The problem of course is that it could only be flipped to one side. CPU thermal protection should kick in, in case the user flips it wrongly.

My only issue with this product, to repeat myself, is that it's really, really hard to maintain a vacuum; personally, I wouldn't trust it to not fail.

That aside, it's actually a very compact cooling solution. If Joe can meet that price point and address the reliability issue, this might turn out to be the magical solution that would replace the HSF.

[Ls7corvete]

why is vacuum harder to hold than pressure?

[Althornin]

Originally Posted by Ls7corvete

I wasnt the first to to call things shit. Guess that was more Alth's opinion than yours.

Um, NO.
Learn to read...
You don't know what a logical fallacy is, and you don't know how to read. Why am I not suprised.
I never said anything here was shit. I used something called an analogy (look it up) to show you the flaw in your "If you can't make a better one , then shut up" logical fallacy (look that up as well, ok?).

So, got anymore incorrect statements to fling around, or are you done?

(BTW: I always say what I mean, and mean what I say. Your inability to comprehend does not change that).

[bigben2k]

Originally Posted by Ls7corvete

why is vacuum harder to hold than pressure?

There isn't much difference really. An o-ring (for example) seperates two areas with different pressures, regardless of the actual pressures. It's the difference in pressure that determines how good a seal has to be.

There are no specifications listed in the article, but a complete vacuum is 14.7 psi. A water cooled loop has to deal with, worst case, 5 psi.

The big difference is that one can afford to loose a bit of pressure in water cooling (i.e. a negative pressure leak that injects air in the loop, or coolant evaporation through the tubing), but here one cannot afford to loose any of the vacuum: if the vacuum fails, what you have left is a really bad cooling solution. The cooling unit is then (essentially) unserviceable, aka junk.

AC systems use solid tubing, because they have to hold upwards of 300 psi, but they still break down and leak, on occasion. They're generally considered "high-maintenance" solutions, requiring yearly pressure checks.

All in all, it's the connection failures that's preventing water cooling from going mainstream (that, and cost). In the electronic cooling industry, Stainless Steel tubing is often perceived as being needed. :shrug:

Heat pipes are a bit better, as Cathar already pointed out; their construction is simple, and they remain as a fixed part of a larger assembly (i.e. no mechanical stress to bend and break it).

IBM recently annouces a rackmount cooling solution, but all it is, is a large radiator running chilled water, to cool the exhaust from the rack (to keep the data center temperature cool). IBM's ultimate plan is to incorporate the same setup within each unit placed within a rack, but it'll still be a "radiator after the exhaust" kind of solution; there are no plans to run water within a computer. (it sounds suspiciously like a plumbing exercise to me!)

BTW, did ya'll know that water cooling has been around since the sixties? (yes, 60's!).

[Long Haired Git]

1. Whilst I like innovation and experimentation, the thing that kills this idea for me is the fans. I run a PC, and I have it set to beep when it gets too hot, and shutdown when the temperature "runs away". So, given that, whats the diference between having a pump and having fans? Its not a passive setup, its not a silent setup, its just pumpless. If it was pumpless AND fanless, now that would be something. But its not.

2. I also don't like the radiator/condensor. To me, as per that pumpless-peltier rig, the radiator should be single pass, and have the "hot end" raised slightly to the "cold end".

3. Similarly, the waterblock is curious in its design. The inlet and outlet barbs are on the corners. I would have thought the optimum design would be for a vertical-motherboard orientation, with the outlet barb exiting parallel to the motherboard, or at least at 45° ala Swiftech MC6000's. The inlet would then be below the "contact" area.

I'd then have the "air chamber", where the vacuum is created, in a short tube above the height of the radiator inlet, so that the radiator is totally flooded.
But then the bubbles aren't going through the radiator to be cooled.

Hmmm....

[cotdt]

Long Haired Girl: do you think it's possible to use a large passive radiator instead? I think it's possible the way I understand it. The ones that are marketed claims to be able to dissipate up to 125W, though i'm not sure at all what that really means. My question is, does the boiling water make any noise?

[UNDERBYTE]

I do not think vacuums are such a big deal, the technology has been refined over the last hundred years - light bulbs, thermos bottles to name a couple. They have high reliability, Just need the right process

Metal hose, metal condenser poly carbonate cap does not look to be to tough of a challenge. Add a few ml of fluid and you are only talking a couple of pounds vac at rest and a couple pounds pressure at load, considering the small system volume.

A condenser is not a radiator and the boiler is not a block. This is a completely different animal. I would not be to quick to apply a water cooling template, I believe design considerations are much removed from water cooling. Plenty of thermosyphone literature out there

[Long Haired Git]

Re radiators, "You can't make butter with a toothpick". Ie, size matters.
However, the graph is awfully steep getting near zero air flow - every little bit of CFM helps, especially the first few. A truely passive rig would be an acheivement, and probably not portable.

I've not done any research on this, and so I agree that my design ideas above are probably newbie and illconsidered - hence my "Hmmmm".

[AngryAlpaca]

So, given that, whats the diference between having a pump and having fans? Its not a passive setup, its not a silent setup, its just pumpless. If it was pumpless AND fanless, now that would be something. But its not.

Joe didn't just chose to remove the pump for noise, but also the high cost and failure rate of pumps.

2. I also don't like the radiator/condensor. To me, as per that pumpless-peltier rig, the radiator should be single pass, and have the "hot end" raised slightly to the "cold end".

Single/double pass doesn't strike me as too important for this. In fact, single pass sounds like it'd be worse because of the tubing required to get to the other end. I don't think the idea is that the water will go in one end and exit the other, but rather some water will enter and some will exit from barb A, and some water will enter and some will exit from barb B.

3. Similarly, the waterblock is curious in its design. The inlet and outlet barbs are on the corners. I would have thought the optimum design would be for a vertical-motherboard orientation, with the outlet barb exiting parallel to the motherboard, or at least at 45° ala Swiftech MC6000's. The inlet would then be below the "contact" area.

I'd think that both the inlet and the exit should be facing up at 45 degrees from the MB, in the same direction (up).


What I want to know is if having two hoses is necessary. It seems to me that having one, larger hose would do the job better, take up less space, cost less, and reduce the failure rate.

[Razor6]

Originally Posted by AngryAlpaca

Joe didn't just chose to remove the pump for noise, but also the high cost and failure rate of pumps.

Single/double pass doesn't strike me as too important for this. In fact, single pass sounds like it'd be worse because of the tubing required to get to the other end. I don't think the idea is that the water will go in one end and exit the other, but rather some water will enter and some will exit from barb A, and some water will enter and some will exit from barb B.

I'd think that both the inlet and the exit should be facing up at 45 degrees from the MB, in the same direction (up).

What I want to know is if having two hoses is necessary. It seems to me that having one, larger hose would do the job better, take up less space, cost less, and reduce the failure rate.

Sounds like a Vapochill Micro.

http://www.burnoutpc.com/modules/wfs...?articleid=213

I couldn't find any detailed reviews where it is put up against other high-end air coolers.

[bobkoure]

So... how is this setup not a heatpipe?
There's state change at the hot end and state change at the cold end (vacuum simply being a way to lower coolant state change temp - one could just as easily use something like butane and a slight positive pressure to, again, get coolant state change temp into a useful range).
Anyway, I'd always thought that this was the way heatpipes worked - many of them now have a wick to move liquid coolant against gravity, but the original ones I'd run into (late '60s) did not and were indeed position sensitive.
Is it that there is an "outbound" and "return" line? AFAICT the only thing that makes the return side a return is that is exits from the lower side of the radiator (which maybe we should be calling a condenser?). And, again, I have this foggy memory that early heatpippes, at least, also had outbound and return lines.

Feel free to point out what I've missed, the error of my ways, etc. - so long as you've got a decent reason why this thing is not kind of a heatpipe.

Thanks!

[AngryAlpaca]

It works like a heatpipe but the means is different - way more surface area at both ends, and no solder joint between the heatpipe and the heatsink, or between the pipe and the metal chunk on the CPu.

[Long Haired Git]

Maybe we'll get a clarification.

I don't see any difference between a heatpipe and how AngryAlpaca thinks this works. The amount of SA at the condensor, and number of thermal interfaces at the condensor, are merely implementation compromises of commercial heatpipe waterblocks. The "home made" heatpipe (already linked within this thread) did away with the latter. Anyway, if the sole means of heat transfer is the evap/condense (bubbles), then its a heat pipe. Given two parallel paths, and returning of liquid via the same path, I can't see how any real coolant "flow" would be created, and the cooling of any flow would be immaterial compared to the cooling by the bubbles. So its a heat pipe.
Given this, then one large tube would be probably better, and yes AngryAlpaca's comments on the waterblock apply.

But I don't think its a heat pipe.

I think its a "syphon" as described. I think , as per a posting above, the bubbles contribute to fluid flow in that they go up one tube only, and hence there is a real "flow" eventually established. Not exactly a high flow rate, but flow none-the-less. This flow allows "normal watercooling" to contribute significantly to the overall efficiency of the rig.

However, UNDERBYTE's comments on condensor/evaporator design still apply, so I'll shut up now.

[Althornin]

Originally Posted by Long Haired Git

Maybe we'll get a clarification.

I don't see any difference between a heatpipe and how AngryAlpaca thinks this works. The amount of SA at the condensor, and number of thermal interfaces at the condensor, are merely implementation compromises of commercial heatpipe waterblocks. The "home made" heatpipe (already linked within this thread) did away with the latter. Anyway, if the sole means of heat transfer is the evap/condense (bubbles), then its a heat pipe. Given two parallel paths, and returning of liquid via the same path, I can't see how any real coolant "flow" would be created, and the cooling of any flow would be immaterial compared to the cooling by the bubbles. So its a heat pipe.
Given this, then one large tube would be probably better, and yes AngryAlpaca's comments on the waterblock apply.

But I don't think its a heat pipe.

I think its a "syphon" as described. I think , as per a posting above, the bubbles contribute to fluid flow in that they go up one tube only, and hence there is a real "flow" eventually established. Not exactly a high flow rate, but flow none-the-less. This flow allows "normal watercooling" to contribute significantly to the overall efficiency of the rig.

However, UNDERBYTE's comments on condensor/evaporator design still apply, so I'll shut up now.

Well, in the article, there is a link to an article on thermosyphons, where the following is said:

The thermosyphon involves four
components in a loop: an evaporator with a boiling enhancement structure, a rising tube, a condenser
and a falling tube.

It also says this:

A thermosyphon is such a device, which successfully implements two-phase liquid cooling by
indirect contact with electronics. A two-phase thermosyphon basically consists of an evaporator
and a condenser, which are connected through a passage, or a loop. Heat is transferred from the
source through an interface to the evaporator, where the fluid vaporizes taking the latent heat of
vaporization. The vapor then moves to the condenser, where it condenses. The released heat is dissipated
to the ambie nt from the condenser and the condensed liquid is returned to the evaporator,
thus completing a closed loop

So, what it is describing is a heatpipe - there is no "liquid flow", but a cycle.

[redleader]

Home Depot sells those same gas line tubes with flared and (IIRC) brazed endings, so theres no reason you couldn't make this thing tight enough for decades of operation. People use them in ghetto refrigeration systems already, and those often have 200+ PSI in them. Ditch the plastic for copper and you're good to go.

Edit: And put a $0.75 shrader valve on there. That way you can pump the pressure as high or low as you like.

[UNDERBYTE]

shrader valve - interesting

hard plastics may be OK, Bic lighters do pretty well with butane.

is that a shrader fill valve on the bottom of a bic?

[jaydee]

Originally Posted by UNDERBYTE

shrader valve - interesting

hard plastics may be OK, Bic lighters do pretty well with butane.

is that a shrader fill valve on the bottom of a bic?

I think the correct spelling is "schrader valve". I believe they are used on car tires and inner-tubes and what not to fill air (and other stuff such as AC units). The part at the tip of the valve stem.

[bobkoure]

I don't think a schrader will hold vacuum - at least not to any greater (negative) pressure than the spring holding the valve closed - when holding positive pressure the internal pressure also holds the valve closed, so seal clamping force goes up with the pressure it's holding.
If you were thinking of something that required positive pressure to move state-change temp (like butane, maybe) then they should work fine.
Also - at least some schrader valves stand up to butane and propane just fine - they're used as part of the gas regulation systems in a number of outdoor gas grills (usually with a diaphragm pushing the schrader open - but I digress).
Presta valves might work for vacuum as they screw shut rather than being pushed shut - but I don't think presta valves with threaded ends are very common (I've never seen one).

[redleader]

Originally Posted by UNDERBYTE

shrader valve - interesting

hard plastics may be OK, Bic lighters do pretty well with butane.

is that a shrader fill valve on the bottom of a bic?

If those are Schrader Valves, they're not the kind I'm thinking of:

http://www.rparts.com/Catalog/Major_...s/schrader.jpg

I got a 5 pack for a project for about $4 locally.

I don't think a schrader will hold vacuum - at least not to any greater (negative) pressure than the spring holding the valve closed - when holding positive pressure the internal pressure also holds the valve closed, so seal clamping force goes up with the pressure it's holding.
If you were thinking of something that required positive pressure to move state-change temp (like butane, maybe) then they should work fine.

Interesting point. I've not tested the negative pressure limit, however I believe its fairly low. At least I've never seen or heard of a problem on systems running at below ambient pressure. Most likely you would not need to go that low for common coolants.

The worst case is probably water, where you'd be around 40 mmHg. Typically refrigeration systems are vacuumed at much lower pressure then this, often for hours and I've not heard of valves leaking. But I suppose its possible they leak slow enough that the vacuum pump overcomes the leak. At any rate, if I were to design something like this I'd probably use a coolant that worked at a slightly positive pressure anyway. R134a might be a good choice because its so cheap, nonflammable and comes in pure form. Pressure would be a bit high though, so you'd have to braze or at least use flare fittings on everything.

[bobkoure]

Originally Posted by redleader

Typically refrigeration systems are vacuumed at much lower pressure then this, often for hours and I've not heard of valves leaking.

What kind of valves are used?

R134a might be a good choice because its so cheap, nonflammable and comes in pure form. Pressure would be a bit high though, so you'd have to braze or at least use flare fittings on everything.

I was just looking at boiling points - too bad pentane's flammable (and a suspected neurotoxicant ) a boiling point of ~36C at 1ATM looks pretty good...

R134a might be a good choice because its so cheap, nonflammable and comes in pure form. Pressure would be a bit high though...

What about SP34E boiling point of -15 vs R134a at -26 - which should mean lower pressures needed. I know they make a big deal about R12 computability (mostly ester oil vs mineral oil, right?) but for a heatpipe-like-thing with a target temp around, say 22 to 26 then a boiling point closer to that target temp is a good thing as there'd be need for less pressure (plus or minus). Or have I missed something important? Other than playing with heat-driven refrigeration in the late '70's (arab oil embargo, energy panic) I have no experience with this stuff.

[redleader]

What kind of valves are used?

They're simply called "Schrader Valves" which in the context of HVAC means the ones I linked above. You can buy them for less then a buck a piece at any supplier or from Rparts.com

What about SP34E boiling point of -15 vs R134a at -26 - which should mean lower pressures needed. I know they make a big deal about R12 computability (mostly ester oil vs mineral oil, right?) but for a heatpipe-like-thing with a target temp around, say 22 to 26 then a boiling point closer to that target temp is a good thing as there'd be need for less pressure (plus or minus). Or have I missed something important? Other than playing with heat-driven refrigeration in the late '70's (arab oil embargo, energy panic) I have no experience with this stuff.

That site is highly confusing and contridicts itself repeatidly. They say its not a blend like R134a and then they say its mostly R134a. Not to mention the boiling point they claim isn't the same as the one in the data sheet

I'm going to assume the data sheet is correct, in which case the boiling point is virtually identical to R134a (within 1 PSI). So you'd be looking at ~100 PSI under operating conditions, and maybe 200 PSI worst case (dead fan). Sounds like a lot, but its actually quite manageable with common materials. Realistically you could use a propane torch to put the thing together (though MAPP or oxyace would be better).

Mainly the reason I looked at R134A is you can get it in cans for about 10 bucks a pop, and its relatively easy to hook these into standard manifold fittings. No need to fit a square peg in a round hole. I'm not sure if its actually a good choice from a performance perspetive, and the pressure is needlessly high. If you find something cheap with a boiling point closer to 20C, then I think its worth considering.

Also, while searching, I found this:

http://www.benchtest.com/heat_pipe1.html

Seems like we're a few years late to the game Though he made the condesner himself which I think really hurts his performance. Should have picked up a real one.

[Long Haired Git]

Twas reading that last night too.
What's interesting is that in the heat_pipe_2 article, the pipe works best when about 1/3rd full of liquid. That suprised me, and opened up a world of thinking.....

[bobkoure]

Originally Posted by Long Haired Git

...opened up a world of thinking.....

As in "what would happen to the thermosyphon device efficiency if about 2/3 of the coolant were removed?" Something less obvious that I missed...?