Cooling Technologies Explained Discussion
 

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

Cooling Tech Article
 

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?

hmmm shroud'n fans on radiators...

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

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

shroud = good!
problem solved!
:->

I used duct tape and cardboard on mine.

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.

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.

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

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

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 =)

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.

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"

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

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

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 =)

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

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

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.

Just a few comments as I read along:

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.

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 :D )

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.

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

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

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

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

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.

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.

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 :D

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

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.

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. :D



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!

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.

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

lol riiiight....:p

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

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

Phase change questions:

From meck:
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:
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. :p

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

With an article of that size and depth there are bound to be some slip ups :)

"quote:
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The Coolant in all cases has picked up ~90% of the heat from the heat source.
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How do you arrive at the figure for this and parasitic heat loss? Are they guesstimates or calculation-backed? "

Half guestimation and half educated guess :) I discussed this topic at length with a few geeks from different places. One is a thermals geek who works at GM working on Engine block design, mainly coolant paths. He had some interesting numbers about car engines and how much heat they loose to the surrounding air compared to what goes through the radiator. For a car engine its around 15% by their calculations at a certain temp Delta from the ambient ( don’t know what that delta number was). After we talked and discussed the thermal densities and the environment that the cooling system runs in we came to a round about number of 5 - 10%. The fact is the parasitic loss is there, the EXACT number is almost impossible to figure out with testing gear most geeks have access to. Also it will change by how cool or hot the ambient air is, and air flow, and a billion other factors.

"quote:
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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.
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Sorry, nitpicking again, but didn't you previously establish this as being 10% of heat from source? "

Yep! the extra 2 lines of text didn’t take to long to download I hope.....

"quote:
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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.
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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. "

Well compared to how many places a HSF has to loose heat... You need to look at the bigger picture in the writing not one sentence at a time.

"quote:
--------------------------------------------------------------------------------
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.
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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."

Isn’t that what I said... Just not as over worded?

"quote:
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Pump: Pumps don’t 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. "

Maybe you missed a line that I wrote:
"Just as with any other cooling, the movement of the coolant is vital to how well the entire system works. This is a topic that many people differ on, and some claim it makes no difference in reality for our cooling systems. That may be true, but if you are designing a cooling system, why not do it right?"

the difference may be VERY SMALL... But why would you spend that much money and time on a cooling system just to design it half assed?

Yes there are some nice grammar issues in this one ;) I got some fixes to do tonight on it hehehe

It wasnt meant to teach old dogs many new tricks, it was meant to act as a base level for people to see what technology does what and where they may be able to use it. glad overall you liked it!

Joe your comments on designing loops and Marco's disputes about the importance of positioning the components I think might only come in conflict in people dealing with small cases. As the trend moves to water cooling in smaller and smaller cases, there are a lot of tradeoffs to be made to fit everything in. No it isn't perfect to put a pump right before a block instead of right before a radiator, but it might allow you to get the overall loop a lot cleaner than putting it together a more technically sound way.

I was also glad to see your distaste at radiators on the top of cases; I don't even consider "top of the loop" when putting water cooling in a case. I just have never had luck keeping them airfree that way.

heheheh my distaste :)

Its just logic, personally I think teh top of a case makes a great location for a radaitor if you can some how keep the reservoir and air trap over it.

One logical reason not to put a radiator in the top of a case is, Heat goes up. Why you want the hot air in your case to go up and through your radiator?

and Yes I agree on tradeoffs like that have to be made some times... I just cant ever seing myself settle for that though in one of my systems... I am just weird that way.

oops brian256 i thought a capliary tube is to be inserted into the evaporator core to allow a expansion valve to throttle .in fridges i thought they used fixed orfice tubes. tev could you break that down for me please thank you :)

I got a question about the phase change topic. In the article it was stated numerouse times that before building your own setup, it would be prudent to get HVAC certified. I have a question about that. Where would one go to get this certification? Are there age restrictions? How much is it? and this may be really dumb, but how is it pronounced?....
(H-V-A-C) or H-vac (as in vacume cleaner)

I have read a couple articles about phase change setups, and all of them say that getting HVAC is a good idea, but no one gives any details about the course/certification itself. I would really apreceate any people that are already HVAC certs to shed some light on this.

Thanks