Cooling Technologies Explained Discussion

[Joe]

Hope yuy guys like the article, it took a lot of work and reaserch by Brian, pH, Brad, and myself to get it done!

If you havent read it, please do:
Cooling Tech Explained Article

[DigitalChaos]

http://www.procooling.com/articles/h...xplained.shtml

I think this article was GREAT! Definately a must for anyone getting more into cooling of any type.

The only thing i didn't see was the constantly asked shrouding and fan direction in regards to radiators.

What do you guys think?

[Joe]

hmmm shroud'n fans on radiators...

I guess I could add something about that, just dong have the time tonight I dont think.

[Psychotic]

Excellent job! That's one of the most informative articles I've ever read.

[Techguy]

shroud = good!
problem solved!
:->

I used duct tape and cardboard on mine.

[xerka]

I liked the article a lot. I would really like someone on the procooling staff to use a phase change system and write an article. Phase change is the only thing this site lacks.

[Makaijin]

A very nice article i must say, but i think there is one you thing you failed to mention.
In the beginning where it mentions that thermal energy can only be transfered, it also mentions that the thermal energy comes from the CPU.
I think you should make it clear that this thermal energy comes from the CPU, because the electrical energy from the CPU is transfered into thermal energy.

[Haddy]

excelent work guys....especially the phase cooled section and the hybrid section...

[Haddy]

Originally posted by Joe
hmmm shroud'n fans on radiators...

I guess I could add something about that, just dong have the time tonight I dont think.

yea maybe u can give them dimensions for like a standard heater cores shroud...http://racecar12.freehomepage.com/ductpattern_s.jpg thats one ive seen

[DigitalChaos]

well its not like we havent coverd the topic about 3 time every day =)
but it would just be something to add.

also remember the damn push vs pull topic =)

[Joe]

I guess maybe you did mis the focus of the article, it was meant to talk about the technology in general. giving schematics for shrouds and such is just too damn specific for this article.

[Joe]

Originally posted by Makaijin
A very nice article i must say, but i think there is one you thing you failed to mention.
In the beginning where it mentions that thermal energy can only be transfered, it also mentions that the thermal energy comes from the CPU.
I think you should make it clear that this thermal energy comes from the CPU, because the electrical energy from the CPU is transfered into thermal energy.

I did. just not as wordy as that:
"The power that enters the core, generates a lot of thermal energy, that energy is moved via the path of least resistance to a transport medium"

[meck]

enjoyed article very much just had a small prob with useing a capalary tube ? expansion valve ( suction throttling valve) or fixed orfice tube. capalary is part of above valves sensor . or what did i miss

[Joe]

Thats a Q for Brian, hes down sick right now so it may be a few days

[DigitalChaos]

true, i just meant discussing WHY to use a shroud, and fan direction.

i didnt miss the focus =) i was just suggesting since it is one of those topics that never dies in here. then again the silicone vs vinyl is constantly going even though there is an article specifically comparing the two.. oh well =)

[Haddy]

Originally posted by Joe
I guess maybe you did mis the focus of the article, it was meant to talk about the technology in general. giving schematics for shrouds and such is just too damn specific for this article.

very true considering tomorrow they may find something else to use for the best radiator and that would make the article obsolete

[Brad]

maybe a diagram for using a 120mm fan on a dden heater core, chevette core, big momma, maybe some other popular rads

[Cyco-Dude]

i do believe the DDen core is a chevette core (they look exactly the same). the shroud that Dtek sells should also fit on the DDen cube.

[Marco]

Just a few comments as I read along:

The block can also give a margin of safety, since it generally has a large mass of Copper it can act like a heat battery, and soak up heat if the flow is stopped.

Don't neglect the water content of the block in soaking heat!

Contrast their specific heat capacities (in J kg^-1 K^-1):
Copper: ~390
Water: ~4200

Next look at their densities (in kg m^-3):
Copper: ~8920
Water: ~1000

Since we are dealing with volumes, let's re-express the heat capacity in terms of energy per unit volume per unit temperature (in kJ m^-3 K^-1):
Copper: ~3479
Water: ~4200

As you can see water requires more energy per unit volume to bring about the same change in temperature. Since most modern blocks probably have by volume a similar amount of copper and water space, the water present is also significant in absorbing heat. I know this is nitpicking, but it's just for the record.

This will only work till the copper reaches its heat soak point when overall temps will start to increase very rapidly. ( the entire time frame for most blocks is no more than 5 - 60 seconds between a cut flow and a fried chip on high power CPU's.

Heat soak point? What is that?
Rapid rise in temperatures? The chip produces heat at a relatively steady rate. In fact, the rate of temperature increase should actually slow down as temperature increases as the difference in temperature between the block and the ambient increases, meaning heat is lost at a greater rate to the ambient. Since the heat capacity of the block does not change, the temperature of the block is only affected by absolute heat gain, which is the sum of heat inputs (only from chip in this case) minus sum of heat outputs (loss to environment). Heatsinks, having more surface area, reach a balance between the two at a lower temperature difference with the environment.
Furthermore I don't know if my chip counts as high-end any more, it's a TBird 1ghz. When run at 1.45@1.75v it could run half an hour before locking up at nearing 80 to 90c, but with no immediate damage. In fact it is running now at 1.54@2.10v. This is on a homemade cross-drilled block, with flow completely stopped (don't ask how this happened )

The Liquid that enters the block/evaporator is very compressed, and has a very low boiling point.

If anything the higher the pressure the higher the boiling point. the issue here is the pressure change. That's why what is a gas at standard temperature and pressure is liquefied under high pressure. It's the drop in pressure that causes it to boil off, taking with it its latent heat of fusion.

The Coolant in all cases has picked up ~90% of the heat from the heat source.

How do you arrive at the figure for this and parasitic heat loss? Are they guesstimates or calculation-backed?

heat in either liquid or gas form

Fine, nitpicking again, but I think this is stretching einstein's energy-mass relation a bit far...

In water cooling I would venture a guess that a good deal of heat is lost in the hoses, reservoir, and any places its in contact with a case side or something.

Sorry, nitpicking again, but didn't you previously estabish this as being 10% of heat from source?

Given that silicone and vinyl are not good heat conductors, they do carry some of the heat to the surface where it is dissipated in the air.

Ok, being even more anal now, picking on grammar. Wouldn't "although" make alot more sense than "given"?

So with that said the Radiator on a H2O rig moves a lot of the heat but has a much easier job of it since there is a much higher mass between it and the core to loose heat at different stages.

If so much heat is lost along the way, why do you need a radiator in the first place? If 10% is lost along the way, there is still 90% for the radiator to dissipate. It may be somewhat easier, but I think much is stretching it a bit far.

The water coming back from a radiator on a H2O rig really may not be much cooler than the incoming coolant into the radiator. This is a factor of how effective the radiator is for the volume/speed/type of coolant you are moving through it. Of course the closer to ambient the better.

I think it's important to note at this point that the difference in temperature across the radiator itself is going to be actually rather small. Water in the entire loop should ideally be at as similar a temperature at possible, as that is the temperature at which heat loss in the radiator(and along the way) exactly matches heat gain in the waterblock.

The condensers main operation is to cool the hot gas that was boiled up from the evaporator. Once the gas is cooled down it re-condenses into liquid, so the flow back to the evaporator is a cooler, and liquid form.

I think you are missing one component in discussing your phase-change system, the compressor. I understand that the article is about making the process as simple as possible to understand, but still this description presents a rather inaccurate picture.

You could try using an analogy where you compare the coolant to a sponge. In the compressor you "squeeze" the heat out of the spone, the condenser "dries up" this heat, allowing the coolant to "soak in" the heat from the heat source.

Haha. Reading on I see that Brian uses exactly this analogy

Side note- pH, love how you integrated environmental chem into the bong discussion

Pump: Pumps dont mind warm coolant, and introduce a few watts of heat themselves to the coolant, so its good to have it BEFORE the heat exchanger.

This is a point I always like to contend. Its not that water will suddenly jump a few degrees between before and after the pump. It's that the pump adds another heat source to the water, raising the temperature the water has to be at to dissipate the heat. I lay before you a challenge, measure the water temperature before and after your pump. Is it even perceivably different? I'll venture as far as saying no.
What does this mean? It doesn't really matter where the pump is, the deltaT across it is negligible. It's not a sudden rise in temperature across it, it's the added heat that it contributes that raises the equilibrium temperature. This implies that the pump can pretty much go anywhere.

The rule of thumb is to keep the line delivering the cooled coolant to the WaterBlock as short, direct, and away from hot objects as much as possible.

Back to the point above about relatively stable temperatures in the entire cooling system given normal flow rates (read eheim/danner/etc. as opposed to senfu). If you can experimentally prove otherwise I will withdraw my statements and do your laundry for a week.



Well that's it. Sorry if some of my points above sound a bit nitpicky, just trying to throw up some ideas for constructive discussion. Please don't take this personally, it isn't meant to be personal!

Overall it just seems to me that the overview is a bit confused, the specific articles are solid and well-written. Will serve as an outstanding primer for newbies.

Thumbs up on an excellent job!

[Mr Evil]

I agree that it wa a very good article - far superior to most of the rubbish I see on the internet. On the other hand, everything Marco said is correct, so there is still some work to do to get it perfect.

[DigitalChaos]

diagrams n stuff would be for a "Cooling tech article: in-depth look" for each of the sections.

[Haddy]

Originally posted by Marco
Just a few comments as I read along:

lol riiiight....

[DigitalChaos]

holy shit... marco go be a college english teacher or something
hehe

i love the article. alot of good stuff laid down, and should be a mandatory read for anyone wanting to better cool their box.
like i said in the other post, the only thing i think was missing (for the water cooling) was a comment on shrouding, and fan direction.

[Brians256]

OK, I'm still sick, but getting better.

Phase change questions:

From meck:

enjoyed article very much just had a small prob with useing a capalary tube ? expansion valve ( suction throttling valve) or fixed orfice tube. capalary is part of above valves sensor . or what did i miss

To be honest, I'm having difficulty understanding the question. So, I'll just go over the purpose of the capillary tube and TEV.

The capillary tube performs the same function as a thermal expansion valve: restriction/metering. By restricting flow, it allows a pressure differential (the compressor is pushing on one side of the restriction to create high pressure, and is sucking on the other side, creating low pressure). By metering, I mean that only the right amount of refrigerant should be allowed into the evaporator. Too much, and you run the risk of sending liquid refrigerant back to the compressor. Too little and you are not cooling as well as possible.

The advantage of a thermal expansion valve is that it optimally adjusts according to the current situation. As the evaporator temp rises, it allows more refrigerant to flow into the evaporator, and vice versa. It does this by monitoring the superheat temperature (the temperature of the gaseous refrigerant coming from the evaporator). The advantage of a capillary tube is cost.

I hope that answers your question.

From Marco:

I think you are missing one component in discussing your phase-change system, the compressor. I understand that the article is about making the process as simple as possible to understand, but still this description presents a rather inaccurate picture.

You could try using an analogy where you compare the coolant to a sponge. In the compressor you "squeeze" the heat out of the spone, the condenser "dries up" this heat, allowing the coolant to "soak in" the heat from the heat source.

Haha. Reading on I see that Brian uses exactly this analogy

Do you mean that I did cover compressors enough or not? It looks as though you started to comment before reading the article all the way through. I hope that I did cover it well enough; let me know if you do have some questions. As for the sponge metaphor, it just seems natural, doesn't it? Glad you liked it!

Also, your proofreading needs some work. You missed at least two grammar errors in my portion, and (I think) two spelling errors in Joe's portion.

[Joe]

I am merge'n t he threads so this and the other cooling tech article thread are the same.