Understanding radiators

[R B Customs]

hey guys ive been doing alot of reading around lately.
and ive come to radiators / heatercores.

i just need to know if im right ( by using the folowing statments

dual row are like one long tube bent over and over again with one input and one output, and the water only ever passes through the same tube.

crossflow ( or single pass?) rads are like a series of open ended tube with some kind of sump at either end with the barbs at opposite corners. and the water runs through all the tubes at the same time

cross flow are better for higher flow applications
dual row are better for lower flow rates
ive been on all morning tryign to work this out. pictures of rads without the fins would solve it in an instant for me but cant find any.
i have tried to find the answers for my sefl befor eposting by the way
Rick

[TreeNode]

cross flow are better for higher flow applications
dual row are better for lower flow rates
malum in se

[R B Customs]

right!
i knew it would depend on what else was in the system but i was just checking if i had the mechanics of the rads right... just for reference if nothing else.

on the otherhand... i am on hte verge of buying a 120.2 rad to go with a silverprop cyclone SL, a DTEK White Water, and a aqua extreme 50z to throw it round the loop.

the rad unfortunatly ( ? ) will have to be an XSPC one as its all i can afford and the guy who owns part of that company lives a stones throw away from me
they make a xflow and a dual pass.
astheticly speaking the dual pass would win over the xflow honds down tbh.

but thinking about it i have a restrictive CPU block, a decent pump and a GPU block i may be better off with a dual pass anyway.
ive come to that conclusion by thinking about what you have said.

im trying desperatly to understand watercooling rather than just asking for 'the best stuff' im gettign there though :)
Rick

[thorilan]

Its more like XFlow has higher flow rates while 2-pass (dual row) rads allow the water to stay in the rad longer to cool off more. But, if you consider them side by side with the same pump, an XFlow system would work better with a lower powered pump than a 2-pass rad. With a high powerful pump, a 2-pass would be better.


you have to be very carefull here . you are heading the wrong direction and are about to mislead people into popular urban cooling legend

water stays in a rad the same amount of time in a closed loop weather its single or dual pass so flow is always the most important. while technically if you ONLY count a SINGLE revelution in the cycle ONLY keep in mind , THEN AND ONLY THEN is it possible for water to pick up more heat from a dual rad.
( does not include relationship between DT because its only a single cycle)

once you establish that water cooling is a closed loop and will REcycle meaning make more than 1 pass through the loop, you have just established that water will spend the same amount of time in the rad.

how this relates to efficiency is the DELTA T

you want your DT to be as efficient as possible aka as wide as possible.

that means the diference between the hot and cold basically. which will cool a hot frying pan better ? 1 liter per minute of tap water or 1 liter per minute of ice water?

ice water of coarse. so to let water stagnate inside a 2 pass rad is going to be less efficient. your ice water just warmed up and is not making any room for new ice water to come in..

if this is confusing you need to review that this is a closed loop in which the distance the water travels is always the same and the amount of water is the same. .



a race track... say you have a race track and you go 5 miles an hour around the track ( slow flow). you go around a 1 mile track in 12 minutes . its still 1 mile though.

NOW go around a race track at 60 miles per hour . you just went 1 mile in 1 minute. YOU STILL ONLY WENT 1 MILE . you did it 12x as fast ( high flow).

but you picked up more heat ( more than slow flow) because your ice water was FRESHER ( spent less time and kept the Delta T here after called Dt, WIDER). this is where spead aka flow creates efficiency.


Though, this is not even considering the flowrates through the blocks and hose length which will alter things. If you have restrictive blocks, you can't possibly get the water circulating the "right way" through an XFlow anyhow so you would go with a 2-pass to balance it out.... etc.
now this is just ... i dont know.. i cant see what you are trying to demonstrate.
maybe if you re word it i can figure out what you are trying to say.

pumps are rated to work in efficncy with certain head ratings at certian speeds. so some pumps are like a slow moving wide deep river . they have more force behind them but they are not moving as fast BUT they overcome minor restriction better so that it does not slow their flow FURTHER .

high flow low head pumps are the oposite like a shallow stream that runs at much higher speeds ( or velocity if you like big words). the problem is they are reduced in speed very easily by restriction so thier speed could slow down a LOT more .

so if i have a pump that pumps 10 gallons a minute and its low power and the restriction slows its speed down to 2 gallons per minute it will not be as effective as a higher head pump that pumps max speed of 6 gallons a minute but WITH restriction only pumps 3 gallons . basically the higher head overcame the resitance more effectively to have an over all higher flow to restriction rate..( these are demonstration synthetic numbers only , not based on any particular pump)

this is where choosing your pump is important . some people over do the pump they need in either to high a flow or to high a head for thier system . its a HUGE balancing act where you haev to match your block and rad ( with Fan ) to the right pump for you.

ways to manage the balancing act .
reduce restriction through shorter tubing runs
reduce restriction through less bends in the loop ( this includes going from dua l pass to single pass)
use a pump that is suited to the systems OVERALL restriction require ment and keeps the flow near the water blocks most efficient speed( this also balances the speed vs deminished returns)
balance everything vs noise and stable OC (aka how much bleeding ears are you willing to put up with)

some hints that i dont usually give system designers but might as well.

you can eliminate tubing lenght by using VERTICALLY mounted single pass cores .
keep the pump at the BOTTOM of the loop so that the pump outlet is very close to the core bottom inlet ( this should reduce a large portion of tubing)
the cores outlet should sit just below the water block inlet so that water is still traveling in an upward movement( this bleeds the system as air travels up and with flow not against it)
from your water block you should have a VERTICALLY mounted res or air trap/tline that travels straight down to the pump inlet ( the res acts as both res air trap and tubing emoving even more tubing from the loop)
note that a good res will be tall and skinny with the water INLET slight below the fill opening BUT still higher than the OUTPUT of the water block so that air travels out of the block UPWARDS into the res where it travels to where you fill the res

it literally takes me under 1 minute to completely fill and bleed a system 100%.

your bigest problem with the design is the case. thats why i prefur tall lian li cases for this.

[TreeNode]

water stays in a rad the same amount of time in a closed loop weather its single or dual pass
thorilan, I've read this explanantion from you before, but wouldn't it require that there is the same length in tubing through in the single-pass and dual-pass radiators? Single pass goes from one end to the other, and dual-pass goes from one end to the other and back. Doesn't this basically mean I could fill more water in the dual-pass radiator? This would show that the length that water needs to travel in the dual-pass is more than the single-pass.

Thanks for the extended explanation for the rest, I kinda generalized the word "power" for my description of a pump, which is a no-no.

[learning curve]

thorilan, I've read this explanantion from you before, but wouldn't it require that there is the same length in tubing through in the single-pass and dual-pass radiators? Single pass goes from one end to the other, and dual-pass goes from one end to the other and back. Doesn't this basically mean I could fill more water in the dual-pass radiator? This would show that the length that water needs to travel in the dual-pass is more than the single-pass.

Thanks for the extended explanation for the rest, I kinda generalized the word "power" for my description of a pump, which is a no-no.
In a dual pass you only have half the tubes going each way. Yes the coolant travels the length of the rad twice So the coolant travels twice the speed each way so the dwell time in the rad would be the same. but the resistence is increased which lowers over all flow, as I understand it. Also if both rads have the same number of tubes and the same size endtanks both types would hold the same amount of coolant.

[Joe Camel]

http://img82.imageshack.us/img82/4696/radguts1mu.jpg

[-aDaM^]

Quit your spamming, or you'll get spanked - Rufus

[TreeNode]

Aaahhh... ok Curve and Joe, that makes sense.

[greenmaji]

Yes the coolant travels the length of the rad twice So the coolant travels twice the speed each way so the dwell time in the rad would be the same.

Whaaaa? This isn't making sence to me, if the coolant has to travel across the rad twice then its going to be traveling twice as far, and with the same pump how is it going to be moving twice as fast?

@thorilan.. wishfull thinking on my part, but any chance of a diagram on that layout you discribed?

[learning curve]

Ok bear with me as I try to explain as best I can. assuming 1 gpm flow into and out of a rad with a single pass and 10 tubes. Now with a dual pass with the same 10 tubes = 5 north and 5 south still the same 1 gpm, the speed of the coolant in the rad has to travel 2x as fast to exit the rad at the same 1 gpm. But this doesn't take into account the added resistance of slowing and then speeding the coolant back up in the end tanks, as well as the resistance of pushing all the flow through half as many tubes. Which tends to slow the flow rate of the entire loop.

[Otter]

Whaaaa? This isn't making sence to me, if the coolant has to travel across the rad twice then its going to be traveling twice as far, and with the same pump how is it going to be moving twice as fast?
The actual velocity of the coolant is doubled, though the flow rate stays the same (if you ignore the slightly higher restriction of the double pass rad).

One thing that hasn't been touched on in this thread is that higher coolant velocity in the rad will produce slightly less thermal resistance between coolant and copper because there will be more turbulence to break up laminar flow. In practice, this isn't terribly important because the difference is lost in the higher thermal resistance of the air side. However, engineers I respect say that, in general, a dual row rad should be dual pass as well to avoid letting the velocity of the coolant in the tubes drop to the point where laminar flow becomes a problem.

[Oper8or]

http://img82.imageshack.us/img82/4696/radguts1mu.jpg
Hmm.. you must have known that the easiest way for me to understand this was to put a pic up..Easily understandable now.

[thorilan]

on the race track .. its 10 miles long( the whole loop) we will say and 1 mile is the rad(pit area) .

if your system flow is 20 miles an hour , in 1 hour you will have completed 2 laps of covered the rad twice or 2 miles of cooling surface. that means you spent 3 minutes per lap in the radiator x2 or a total of 6 minutes

now lets double the speed of the flow . the track distance stays the same and the pit area stays the same . only the flow changes.



if your system flow is 40 miles an hour , in 1 hour you will have completed 4 laps of covered the rad 4 times . that means you spent 1.5 minutes per lap in the radiator x4 or a total of 6 minutes

ok so now you see its still the same time in the rad no matter which speed right?

now how this relates to single and dual pass. they are the same amount of area right ? YES they are.

just imagine that a 2 pass rad is the pit area but its only 2 lanes wide and 2 miles long.
and that a single pass rad ( twice as wide) is 4 lanes wide and only 1 mile long .

thier surface area is the same right? yes. the diference is 2 parts.

1. less resistance ( hair pin turn) more of a wide lane helps maximize the DT because the longer the water sits in the rad the less heat it pics up because the DT SHRINKS as heat is picked up ( remember cold water picks up heat better than already warm water right?)

[voigts]

This is an interesting thread. My question is that in the real world, does using a dual pass vs using a single pass result in any measurable differences? A good pump like a DDC or D5 is going to be capable of blowing right through each with no problem. Isn't there a point where more flow/less restriction results in differences that are so small as to not really make a practical difference?

[learning curve]

The actual velocity of the coolant is doubled, though the flow rate stays the same (if you ignore the slightly higher restriction of the double pass rad).

One thing that hasn't been touched on in this thread is that higher coolant velocity in the rad will produce slightly less thermal resistance between coolant and copper because there will be more turbulence to break up laminar flow. In practice, this isn't terribly important because the difference is lost in the higher thermal resistance of the air side. However, engineers I respect say that, in general, a dual row rad should be dual pass as well to avoid letting the velocity of the coolant in the tubes drop to the point where laminar flow becomes a problem.
I have read that laminar flow sets in after the coolant travels about 6 inches. My idea was to build a 120.3 with 3 120mm sections like this. endtank-120mm of rad-itermedate tank-120mm of rad-itermedate tank-120mm of rad-endtank All single pass to keep the flow up and this would maximize turbulance and stop laminar flow. So what do you all think of my hairbrained concept ?

[thorilan]

attaching my paint skills pics

[thorilan]

now look at the heat gradient of a single pass. KEEP IN MIND THE WIDER THE DIFERENCE THE BETTER

[thorilan]

notice that as the 2 lane ( double pass rad) reaches the end it is closer to ambient? that means the DT is not as wide or less effective . this is in conjunction with more turns creating restriction.

so you say then if single pass has more advantage why so many double pass cores out?

My question is that in the real world, does using a dual pass vs using a single pass result in any measurable differences? A good pump like a DDC or D5 is going to be capable of blowing right through each with no problem. Isn't there a point where more flow/less restriction results in differences that are so small as to not really make a practical difference?
the main reason is that in most systems the mounting of single pass is dificult and requires longer tubing runs due to CASE size and shape. the tubing ends up adding a counter balance amount of resistance to make up for the lack of resistance in the single pass.

to counter act this you have to design your case with my designs in mind and Severly shorten your tubing runs resulting in better cooling

[learning curve]

This is what I was triing to explain. Hope it clears it up.

[thorilan]

oh btw laminar flow is on every surface of your system minus impellor and directly under the jets. so trying to break it up in a rad would be near impossible as the walls are to close together.

[greenmaji]

thanks for the rad. demo thorian, I get it.. is there anyway you might do a diagarm of your equipment layout?
I understood your word description but Im a little clueless on how you would place the single pass rad. were you were desribing it without a double wide case. (if you want to use a shoud, and possibly push pull, it seems it would be really wide for directly across the CPU)

not that a double wide case would be a bad thing, it seems your using tall cases instead... thats were Im getting confused. :shrug:

[R B Customs]

first of all guys
THANKS !!!!
for the indepth explanations.
thor, ive acctually printed that out to read through tomorrow at college !
i think im starting to grasp this concept now.

is it like
2 men on a field
one runs from one corner to the other diagonaly, where as the other runs around 2 edges of the filed
they both reach the same destination at the same time BUT the man running around the edge had to run FASTER as he had to cover more surface.

this is all making for Very interesting reading.
and thor im very interested in 'the stuff u dont normaly tell people' section
thanks again guys.
Regards
Rick


***EDIT***
i left the reply window open for... oh a good few hours ( playing CSS :9 ) so most of that post wont make any sense.
thor im studying the diagrams now :D
thanks alot

[thorilan]

yes many times the cases i use are tall and or modded and or custom built. the new lian li was designed copying one of my modified cases . the reason i dont usually tell people a lot about design specifics is because every time i do , a few months later i see a lot of copies . it wouldnt be so bad but my newer designs require some skills with tools that if done wrong will make the case ugly and possibly worthless and then people will want to ask me how to fix thier screw ups.

[thorilan]

for instance if you changed the panel to a door that opens in reverse just by adding hinges to

http://www.lian-li.com/Product/Chassis/Server_Full_Tower/Classical/S_C_PC-G70.htm

and mount the water cooling on the door then you would have one of my designs from a year ago.

[thorilan]

here is a smaller comp pc62usb lianli ( extra long case) with a properly laid out cooling loop. it completely bleeds in less than a minute.

[thorilan]

sorry its hard to see everything

[thorilan]

you will notice in the first pic that the outlet from the block goes upwards to the upper area of the res. also you can see as the res is designed so that it sits directly above the pump with a roughly 1 inch input to the pump straight down.

you can see the attachment for filling with the valve as well and how i have a cheep funnel that screws into it for very easy filling.
in this system it is not required or even encouraged to fully fill the res . half way so you can see the water pouring out of the input is enough.

as you can guess this one was designed around the L30/ L35 pump but can easily adapt to other pumps intakes

[greenmaji]

@thorian.. is the rad in the bottom front of the case?

[thorilan]

ok here is a visual i posted a long while back redone . not pretty but you get the idea

[thorilan]

@thorian.. is the rad in the bottom front of the case?
yes its a jr120 on its side so that the bottom is the input and the top is the output

[greenmaji]

Sorry about that thorilan.. I should have waited a few for you to finish posting, I would have got it by your layout pic.
For some reason I was thinking they were wider then that (Ie. would need to be mounted on the side, bottom or top of the case)
Is that rad the same or similar to the one Joe Camel posted a few days ago?
Edit for linkiage.. http://www.ocforums.com/showpost.php?p=4442518&postcount=12

[thorilan]

yes that is the basic example.

the xflow pro2 is the rad i like because of thin ness and use a smaller shroud and couple that with 120x25mm fans pulling through the rad that is mounted ON THE DOOR and blowing air directly onto the mobo , and you have ram cooling video card extra cooling and proc water cooling all in 1

[greenmaji]

I figured on the door would be a better placement, but it was just a guess by me ;)

That and you give alot of hints :D

[Otter]

I have read that laminar flow sets in after the coolant travels about 6 inches.
Under what conditions?

[Otter]

oh btw laminar flow is on every surface of your system minus impellor and directly under the jets. so trying to break it up in a rad would be near impossible as the walls are to close together.
Of course there will still be laminar flow, but turbulence will help get a higher delta T between the coolant and copper as the warmer molecules from the center of the tube get kicked into the sides.

[learning curve]

Under what conditions?This was supposed to be in a Rad, after about 6 inches of travel in the tubes laminar flow would increase. I will seee if I can find where I read that. If I can ?

[thorilan]

the closer your walls are together the more dificult it is to remove boundry layer and since rads are constructed with thin tubes that only travel in 1 dirrection stripping the boundry would require more flow than the rad could deal with ( pressure needed to generate the flow)

[Perseus]

The actual velocity of the coolant is doubled, though the flow rate stays the same (if you ignore the slightly higher restriction of the double pass rad).

One thing that hasn't been touched on in this thread is that higher coolant velocity in the rad will produce slightly less thermal resistance between coolant and copper because there will be more turbulence to break up laminar flow. In practice, this isn't terribly important because the difference is lost in the higher thermal resistance of the air side. However, engineers I respect say that, in general, a dual row rad should be dual pass as well to avoid letting the velocity of the coolant in the tubes drop to the point where laminar flow becomes a problem.

Yeah, but how can there be a laminar effect of any significance in the flat-tube design of your average radiator?

[thorilan]

laminar is on every surface. .its the clinging of molecules . so its always a factor and the closer 2 boundry layers are brought together the harder it is to overcome ( think of blood capalaries that are restricted)

[Perseus]

I don't doubt that laminar is always present or that it's a factor. I do, however, wonder how significant of a factor it is in a flat-tube. From what I've seen the C/W rating of a rad, subjected to nominal flow, can be reduced to as little as .020, depending on the fan used. That doesn't seem like much to me.

[thorilan]

oh its not a huge factor like some would have you believe. just people get obsessed around here and as every little bit adds up , they start getting out of hand with the adjectives in thier descriptions and it fools some guys that dont understand how we talk in minutea

[Perseus]

This is true. :)

[learning curve]

oh its not a huge factor like some would have you believe. just people get obsessed around here and as every little bit adds up , they start getting out of hand with the adjectives in thier descriptions and it fools some guys that dont understand how we talk in minuteaGUILTY :shrug: I tend to get caried away lol

[Otter]

Yeah, but how can there be a laminar effect of any significance in the flat-tube design of your average radiator?
As Thorilan said, it depends on how you define "significant". I think laminar flow in the tubes is something for people designing radiators to consider, but it's unlikely to be the deciding factor when choosing among the designs in production. With the weak fans we use, the air side is far more important. However, the name of the thread is "Understanding Radiators", and the realationship between coolant velocity and laminarity of flow is worth mentioning when talking about single pass vs. double pass. Some racing radiators are set up for triple pass, and I doubt they'd do that unless higher coolant velocity gave better performance. I also doubt Cathar would advocate double pass for double row rads unless there was something to it. He usually knows what he's talking about. ;)

[Perseus]

As Thorilan said, it depends on how you define "significant". I think laminar flow in the tubes is something for people designing radiators to consider, but it's unlikely to be the deciding factor when choosing among the designs in production. With the weak fans we use, the air side is far more important. However, the name of the thread is "Understanding Radiators", and the realationship between coolant velocity and laminarity of flow is worth mentioning when talking about single pass vs. double pass.

Yup, it does indeed depend on the definition of significant. If a .020 variance gets one all moist and salty it's a big deal. OTOH, if you're satifisfied with your temps and the general performance of your loop\rig it means nothing. I did, BTW, read the thread title before deciding to participate. I didn't imply or infer that the laminar effect wasn't worth discussion.

[R B Customs]

so... as far as i can tell by what you guiys are saying is
laminar flow ( excuse the bad terms) is when water 'clings' or stays ... or even moves slower aorund the edges of the channle of water than in the middle / centre

a bit like a river flowing - the current is stronger in the middle of the river than at the sides due to laminar flow ( obviously on a bigger scale) ... is that the sort of thing were talking about here?

please take into account ive put that as simple as i can lol.

so im thinkng laminar flow is a bad thing because it prevents heat dissipating as well as it should / could because of this kind of layer of water. which i presume to be the same 'thickness' no matter what the sixe tube is, therefroe the bigger the tube the hte bigger the free flowing channel in the centre is>the better the cooling.
the smaller the tube the opposite

im literaly reading what you guys are saying and wording it in ways that make sense ot me :)

thanks
Rick
btw shal i start a new thread for 'which out of these rads' so this interesting post doesnt go off topic ?

[Perseus]

You got it exactly right, RB. :p

[sumka]

Run a singlepass setup here. Just thought I'd post an image for those interested...

http://img103.imageshack.us/img103/1183/lianli287small2hr.jpg
click here for full res image (http://img103.imageshack.us/img103/4843/lianli287full8hc.jpg)

The reason I chose singlepass (crossflow, xflow, ...) here was because it allowed me to layout the tubing/pump in a good way. I tend to believe double-pass rads probably have the edge when it comes to cooling ability although I'd be surprised if it amounted to much in reality. I've never used a 3x120 doublepass here so really couldn't say what difference it might make.

The rad there (XSPC) has 24 flattened pipes running from one end to the other. I understand the doublepass version also has 24 pipes, though 12 would feed the water across the rad, and the other 12 feed it back (resulting in about twice the velocity). My system probably has quite a low flowrate I guess as along with this singlepass I also run the D4 pump @ 7 volts. But still the temperatures I get are very reasonable for my liking (even with the rad fans @ 5 volts). :)

[Perseus]

My understanding was that single-pass rads were less restrictive. This stands to reason when you consider an intake serviced by 24 tubes as opposed to 12. I also seem to remember some heavy-hitter types (Cathar maybe?) saying that dual-pass was better for PC water-cooling, though I don't remember the reasons why. Anyway, very nice rig, sumka. :thup:

[sumka]

Thanks for the kind words, Perseus. :)

Indeed I think think it's probably a very low restriction setup overall (especially with the Polarflo blocks).

[thorilan]

what you are remembering is actually i think something bill said . but you have to remember i cathar bill pheastus and a few others all usually talk in context. so it usually relates to what the question was. overall i would personally state from my experiance and i have literally made over a hundred systems is that single flow rads if configured right will gain you a better benifit. and since i said configured right that puts context into it .

the problem is some people take things out of context and relay it to someone else that understands the context but a third person who is new to cooling comes along and reads it and misses the context completely then parrots the info as "law" without understanding the "whys" and "Hows".
tbh that is what has kinda kept me in the not so likable group as when this happens i challenge it so that people dont spread it farther. some younger and newer members think of it as either old timer attitude or leetist .
unfortunately you cant always convey tone in posts and as such people will just come across some way other than what they intended

for instance if i say i have more experiance building water coold computers than cathar or bill put together ( which in the correct context is true ) i might sound like im full of my self but if you look at purely statistically i have built more computers and made more money doing so . but you guys know from other peoples contexts and hopefully from mine now that numbers only play a part and knowledge and brain power play very important roles and that it is not intended in the way this text could make it appear

[Perseus]

Thanks for the kind words, Perseus. :)

Indeed I think think it's probably a very low restriction setup overall (especially with the Polarflo blocks).

I'm a sap for clean wiring. What can I say? :p

What are your temps and what blocks do you use? I almost popped for a Polarflo TT last time because of its flow characteristics, but I just HAD to try a Storm. :cool:

[voigts]

I'm glad you obviously have more time on your hands Thor given the increased activity I have noticed by you here on the forum. Thanks for taking the time to set the record straight on this. I for one am learning a lot.

[R B Customs]

yes tone is very hard to convey over text. if it matters im just listening to what everyoen has to say in a mutual way. nothing else has crossed my mind.
i am happy learnign the theory even if i never build another PC :D... seriously im loving this thread !

anyway...
would anybody aggree that mounting a single pass rad horizontaly will be any different to mounting it verticaly... i HAVE considerend the what goes up must come down theory and th theres no gravity in a closed rig whenre water is being pushed as much as it is pulled. but to be i just still have a thought in the back of my mind that its going to be more effective lying flat thena verticle
in my cas rhe rad MUST be standing verticle. so would it make a difference if say for instance i had a single pass being fed from the bottom or at the top ? as i said.. theres still a part of me thats grasping onto gravity.
again excuse mye crude terminology :) ( i widh there was a WC glossary )
Rick

[Perseus]

thorilan, it was during the time when X-flow rads had first appeared. You know, when most people are fascinated by the idea of something new.

As for the rest: In my experience, online and off, it's not what you say so much as how you say it.

[learning curve]

I am sure glad to have you around these forums thorilan. I've learned alot form you, and I look forward to learning alot more...

[thorilan]

for R B C . feeding from the bottom and having the liquid move upwards helps in the bleeding process as air has to go with the flow of water . as far as the gravity goes its not only you. its just natural since the age of 2 weeks old to understand gravity and sometimes its hard to think that it doesnt apply. will post more in a bit . have to check flight schedule stuff for room mate

[Vrykyl]

sumka isnt that d4 pump pulling water out of the cpu block and into the rad? should it not flow the other way?

[R B Customs]

sumka isnt that d4 pump pulling water out of the cpu block and into the rad? should it not flow the other way?

i though the idea was to get the water cool by putting it through te rad first then through your blocks or in other words cooling it before it hits the blocks ratehr than after... id imagine the GPU has a fair bit less watts than the CPU so as far as i can see ( from using what ive learned so far) that loop is correct.

so thor... im right in thinking gravity does not exist in WC. so it will not matter what orrientation ( sp?) the rad goes ?
thanks
Rick

[citronym]

RB, needing to cool the water before it enters your blocks is an old myth. The water temp likely changes less than 0.5º anywhere throughout the loop, so order of components does not matter.

[thorilan]

RB, needing to cool the water before it enters your blocks is an old myth it is not a myth as i have proven hundreds of times. even though a system reaches equilibrium if you put a thermo right before your rad and right after you will see a diference and that should situate 1 thermo between your rad and cpu. if you put a third thermo after the cp you will see that its hotter than its input by more than 1C especially in games.

1c is 1c ,,2c is 2c . while it may not make a diference to the average person it does prove that it is not a myth and for those crazy people that like to squeeeeeeze every last bit out of thier system weather it be by fans that make your ears bleed or spending 300+ dollars on a water block its still valid.

[citronym]

I def will not argue that there is a difference, but we end up back in the whats worth what argument...
So I won't tread :)

[sumka]

I'm a sap for clean wiring. What can I say? :p

What are your temps and what blocks do you use? I almost popped for a Polarflo TT last time because of its flow characteristics, but I just HAD to try a Storm. :cool:

It's difficult to explain temps (though I monitor them closely) as they depend a lot on the ambient air temp in the room, rad fan speed, pump speed, whether I'm crunching at the time (usually am, all CPU), benching (CPU & OC'ed GPU) and 'thickness of dust on the rad' setting, LOL. :confused: :shrug: :D
I'd have to run tests to give some sort of reliable idea of ambient versus core/water temps (delta-t is it called ?). I think they're in the region of about about 6-12C at load depending on the variables mentioned above.

The blocks are somewhat mediocre (I guess) Polarflo TT's. Actually I don't think the CPU block is even designed for being run on a bare-die Athlon like I'm doing. It's probably a bit of a weak link really which could be changed for something better/more suitable like an Apogee/Storm or something to bring improvements. Also I'm only using 2 of the 3 barbs for cooling so it's a pretty daft choice I made in purchasing it with hindsight (1st build with water, aka n00b :p).

sumka isnt that d4 pump pulling water out of the cpu block and into the rad? should it not flow the other way?

Yeah, it pulls coolant from the top barb on the block and pumps upwards into the rad (bottom barb is a drain). I think it might have been better to have the pump pushing coolant directly into the middle barb of the block though if memory serves me right it wasn't easily doable due to the way the pump is mounted (suspended by the rad tube). Anyway, as it's a closed loop I didn't imagine pumping up to the radiator would be of any concern as the pump is also pulling coolant down from the rad through the blocks at the same time, just depending on which way you look at things. Regarding correct order of componentry, I'm not sure whether ordering makes any real difference overall (pump before/after blocks/rad, etc.) as I've read allsorts of conflicting opinions over time. I just thought about it, built it, watched how things went temp-wise and all seems well enough for me (I'm not an hardcore overclocker or anything, just wanted a nice quiet & efficient system really).

http://img99.imageshack.us/img99/5870/lianli308small0ee.jpg

full res here (http://img137.imageshack.us/img137/2319/lianli3080jg.jpg)

[Otter]

I did, BTW, read the thread title before deciding to participate. I didn't imply or infer that the laminar effect wasn't worth discussion.
Oh! I didn't mean to imply that you hadn't read the title or that you were implying or infering anything about what was worthy of discussion. I was just trying to be clear about why I brought it up lest someone get the idea that they absolutey had to have a double pass rad to keep their cpu from melting a hole in the floor. :)

[Otter]

it is not a myth as i have proven hundreds of times. even though a system reaches equilibrium if you put a thermo right before your rad and right after you will see a diference and that should situate 1 thermo between your rad and cpu. if you put a third thermo after the cp you will see that its hotter than its input by more than 1C especially in games.
I don't doubt you performed this experiment, but if your data is accurate, I don't understand the physics.

Consider a 200W CPU in a system with a flow rate of 1GPM.

200W dumps 3.33 watt hours, or 11.4 BTU or into the water each minute.

Water weighs 8.3 pounds per gallon, hence 1 GPM = 8.3 lb/min.

One BTU is the energy required to raise the temperature of one pound of water one degree fahrenheit. Hence, the temperature differential across our 200W CPU is
(11.3 BTU/min) / (8.3 lb/min) = 1.36 F = 0.76 C

A more likely 125W CPU would heat 1GPM only .48C, and would produce a temperature differential of more than 1C only if the flow dropped below .5GPM.

Unless your Vcore is insanely high or your flow rate unusually low, I suspect one of your thermometers might be miscalibrated. But you say you've done this hundreds of times? :confused:

Most people are more concerned about cooling their CPU, as the GPU is relatively easy to cool. If you put a 50W GPU and a 20W pump between the rad and CPU, and all the pump's energy turns to heat before it reaches the CPU (which it wouldn't), the CPU temp will be only one quarter C higher than if you put the rad right before the CPU block.

Of course, the water temp will rise as it goes through each block and drop as it goes through the rad. The "myth" is that this temperature differential is enough to matter, and I think for most people, .5C at the GPU or .25C at the CPU wouldn't be very important. It might even be less than the bump for taking the long winding road around the case to hit all the components in the ideal order.

[Dice]

Using That logic, the watercooling loop would only remove .48c from the 125 watt CPU. There is the flaw. The water will hold more heat than its actual temperature would suggest and it is that heat, the unmeasured heat, that the radiator is removing before the water gets to the CPU block.

[greenmaji]

Useing that logic thats all the heat the CPU generates for the rad to remove.

[Otter]

Using That logic, the watercooling loop would only remove .48c from the 125 watt CPU.
No. 0.48C is how much the coolant temperature rises as it flows through the CPU block. It will be less confusing if you think about the water removing BTU's or watts from the CPU block instead of degrees.

There is the flaw. The water will hold more heat than its actual temperature would suggest and it is that heat, the unmeasured heat, that the radiator is removing before the water gets to the CPU block.
Huh? If you add heat to liquid water, the water temperature goes up. The only exception to this occurs at the boiling point, and if your loop is running that hot, you've got far worse problems than the order of your components. ;)

[Perseus]

Oh! I didn't mean to imply that you hadn't read the title or that you were implying or infering anything about what was worthy of discussion.


It sure seemed like it, but okay. ;)


I was just trying to be clear about why I brought it up lest someone get the idea that they absolutey had to have a double pass rad to keep their cpu from melting a hole in the floor. :)


I doubt there was any real danger of that happening. It isn't too hard to understand that there are tradeoffs associated with differing design methodologies.

[Dice]

No. 0.48C is how much the coolant temperature rises as it flows through the CPU block. It will be less confusing if you think about the water removing BTU's or watts from the CPU block instead of degrees.


You are probably correct. It would be less confusing. While I concede that you are far smarter than I, I don't see your math accounting for these constants and variables:

~Specific gravity of distilled water (90% by volume) + Liquid Ethyl Glycol additive (10% by volume) as is accepted practice.
~Specific heat of both of the above.
~Thermal capacity of both of the above.
~Temperatures of coolant samples. (Which, as I am sure you know, affect the thermal capacity of the coolant.)


I only say this because you are using your math and physics against Thorilan's thermometers, and suggesting his equipment may be faulty.

Since the Pump-rad-block-x-pump loop order 'myth' is easily debateable by both sides of the fence, and since the final results of a through examination would be very helpful to all newcomers, and some of those with more experience, I'd venture to guess that a "Definitive loop component order" thread may get stuck.

Huh? If you add heat to liquid water, the water temperature goes up. The only exception to this occurs at the boiling point, and if your loop is running that hot, you've got far worse problems than the order of your components.

With a 1:1 ratio of heat units to water units? That still doesn't account for the thermal capacity, does it?


Edited for gender-bending reference.

[TreeNode]

... and suggesting her equipment may be faulty.

HAH, is this considered a flame at Dan?

[greenmaji]

HAH, is this considered a flame at Dan?

Or refering to Dan's rig as a woman, much like alot of guys do their cars ;)

[Dice]

Or refering to Dan's rig as a woman, much like alot of guys do their cars ;)


Nice try at saving me, but I ate foot on that one. :p

[greenmaji]

Nice try at saving me, but I ate foot on that one. :p

Nobody can say I didn't look at the bright side.. (sorry you didn't take the lousy excuse I so convently provided for you ;) )
Now.. How about them rads ;)

[Otter]

You are probably correct. It would be less confusing. While I concede that you are far smarter than I, I don't see your math accounting for these constants and variables:

~Specific gravity of distilled water (90% by volume) + Liquid Ethyl Glycol additive (10% by volume) as is accepted practice.
That's a good point. I didn't include the antifreeze, but I know Thorilan uses 5% or less in most of his rigs, hence my numbers will be close. They might be 3% low, but the measured value shouldn't be twice what I calculated.

~Specific heat of both of the above.
~Thermal capacity of both of the above.

The specific heat and thermal capacity of water are included in the definition of a BTU. Again, Thorilan is savvy enough to know that antifreeze can't compete with water as a coolant, and his experience gives him the confidence to use as little as possible. Do a search of his posts with antifreeze as a keyword and you'll see he often points out that people use too much antifreeze in their systems.


~Temperatures of coolant samples. (Which, as I am sure you know, affect the thermal capacity of the coolant.)

Not enough to matter. Pure water is only .43% less dense at 30C than it is at 4C. Hence we can neglect the effect of temperature on the thermal capacity of water for estimates like this.


I only say this because you are using your math and physics against Thorilan's thermometers, and suggesting his equipment may be faulty.
I also suggested my understanding might be faulty. As the two don't agree, at least one of them has to be off. But there is no fight here.


Huh? If you add heat to liquid water, the water temperature goes up. The only exception to this occurs at the boiling point, and if your loop is running that hot, you've got far worse problems than the order of your components.
With a 1:1 ratio of heat units to water units? That still doesn't account for the thermal capacity, does it?
That's why I said it would be less confusing if you considered BTU's (heat) or watts (heat/time) instead of degrees. Celsius degrees are units of temperature, not heat. What's a water unit?

[thorilan]

ok to help with some insite. many of you are trying to use a formula that can only approximate the heat change and what happens in a loop. there are so many variables that it would take a lot more than our basic calcs to do so i go by real world .

keep in mind thermos that have .02 accuracy in conjunction with tim and mounting of blocks and ambient and every other variable you can think of will effect this. now my data comes from real world builds where i consistantly get a better temp. when i build some systems i will try more than 1 plumbing route just to see since my systems bleed so fast this is easy.
and what i have seen is that the way i do it i see about 2c better temps at load and they drop faster when load is reduced .
so taken on the whole i have tried to design my systems using good solid principles and it pays off. now the price for the pay off is in case size and shape. generally the case is the number 1 influencing factor in the loop as it determines the loops components and layout. hence if you look at the how to ask questions sticky you will see the pattern of how i chose the questions

[Otter]

It sure seemed like it, but okay. ;)
In hindsight, I can see how it might seem that way. But when I wrote the post, that was the furthest thing from my mind. And because I wasn't thinking it or saying it, it didn't occur to me to be diplomatic about it. :rolleyes: No offense intended. :beer:

I was just trying to be clear about why I brought it up lest someone get the idea that they absolutey had to have a double pass rad to keep their cpu from melting a hole in the floor.

I doubt there was any real danger of that happening. It isn't too hard to understand that there are tradeoffs associated with differing design methodologies.
True. But we'd just been talking about how these small differences in performance can take on exaggerated importance for someone still absorbing the basic concepts. See where I was coming from now? Though it was part of a reply to you, the bit about the thread title was intended as a general comment rather than a reference to anything you'd said.

[Otter]

and what i have seen is that the way i do it i see about 2c better temps at load and they drop faster when load is reduced .
Hmmm. 2C better than what? Do you have enough data to separate the effect of other things, like having the pump at the bottom of the loop, from having the GPU between the rad and CPU?

If component order really does make 1-2C difference, do you have any idea about the physics behind it? Do you think there is uninterrupted laminar flow from one block, through the tubing and all the way through the next block, for instance, making the effective flow rate far less than the actual GPM?

[thorilan]

its just over all design in order of components and tubing length and 100% bled system ( you would not believe how many people have incomplete bled systems)

when i make a system with other than my standard it increases the tubing length and i can see a visual diference in flow in the res

[Otter]

its just over all design in order of components and tubing length and 100% bled system ( you would not believe how many people have incomplete bled systems)
Okay, so that 2C is for optimized vs. whatever rather than just for component order.

when i make a system with other than my standard it increases the tubing length and i can see a visual diference in flow in the res
So which do you think is more imporant, component order or tubing length? If you can do anything with the case, of course, you can design for both. But if forced into a tradeoff, which do you perfer?

[thorilan]

tubing lenght as long as res comes before pump

[Otter]

Ah, so you agree with the "accepted wisdom" of favoring short runs over ideal component order. You just prefer to have the best of both and don't mind designing the whole system around that.

Edit: Have you ever installed a res anywhere but before the pump? I always wonder about this when it comes up, as some say it doesn't affect flow rates to put it elsewhere, and none of those who disagree seem to be able to explain why putting the pump somewhere else is a problem. One of these days I may have to build a res just to see.

From the standpoint of bleeding, of course, it doesn't make sense to put the res anywhere else. But have you tried it anyway?

[thorilan]

Ah, so you agree with the "accepted wisdom" of favoring short runs over ideal component order. You just prefer to have the best of both and don't mind designing the whole system around that.
pretty much . since most of my work is custom i take advantage of everything i can including case real-estate wich is something not everyone can do

Edit: Have you ever installed a res anywhere but before the pump? I always wonder about this when it comes up, as some say it doesn't affect flow rates to put it elsewhere, and none of those who disagree seem to be able to explain why putting the pump somewhere else is a problem. One of these days I may have to build a res just to see.

From the standpoint of bleeding, of course, it doesn't make sense to put the res anywhere else. But have you tried it anyway?
actually i have put the res after the pump three times and the effect was not to noticeable with a good pump but on the l20 hydor and the ehiem46 it was enough that you could see a lower horizontal streem into the res ( i dont fill the res all the way so i can actualy see the streem when doing this )

[Perseus]

In hindsight, I can see how it might seem that way. But when I wrote the post, that was the furthest thing from my mind. And because I wasn't thinking it or saying it, it didn't occur to me to be diplomatic about it. :rolleyes: No offense intended. :beer:


No offense taken, Otter. I love reading your posts too much to be honked at you over nothing. :D


True. But we'd just been talking about how these small differences in performance can take on exaggerated importance for someone still absorbing the basic concepts.


I'd agree with this if it wasn't for the fact that even advanced users can get caught up in minutiae, and are more than capable of missing basic concepts as well. I quess it's all dependent upon individual focus, which is fine by me.


See where I was coming from now? Though it was part of a reply to you, the bit about the thread title was intended as a general comment rather than a reference to anything you'd said.


There was never an issue with me understanding your intent, only why it seemed to be focused at me. ;)

[Oper8or]

so... as far as i can tell by what you guiys are saying is
laminar flow ( excuse the bad terms) is when water 'clings' or stays ... or even moves slower aorund the edges of the channle of water than in the middle / centre

a bit like a river flowing - the current is stronger in the middle of the river than at the sides due to laminar flow ( obviously on a bigger scale) ... is that the sort of thing were talking about here?

please take into account ive put that as simple as i can lol. ?

And that is exactly how some of us need it explained. Very simply put. But now I understand what it means. Thankyou. :attn:

Stephen

[Otter]

... even advanced users can get caught up in minutiae, and are more than capable of missing basic concepts as well.
LOL. Very true.