Does using a res give higher temps?

[bledd]

I've always wondered this..

In a 'T' system, the water is ALWAYS being sucked or pushed by the pump, wheras in a system with a res, it 'rests' in there and water beneath it is taken instead (ie, in a res system it's not in a constant loop)

so the pressure in the water has to be greater in a T system than that of water in a system with a res in it

would this affect temperatures

 

[pastymuncher]

It should'nt do as a good res should have different length inlet/outlet pipes to keep the water circulating better. The turbulence in a res from the water returning to it should keep it all mixed up as well. My res (XSPC 250mm Passive) also has an Aluminium body with cooling fins which should aid a little with cooling.

 

[MikeTimbers]

I've always wondered this..

In a 'T' system, the water is ALWAYS being sucked or pushed by the pump, wheras in a system with a res, it 'rests' in there and water beneath it is taken instead (ie, in a res system it's not in a constant loop)

so the pressure in the water has to be greater in a T system than that of water in a system with a res in it

would this affect temperatures

You've drawn a conclusion there which isn't valid. Why does "the pressure in the water" have to be greater? If you mean that the water entering a pump in a system with no res is travelling faster and therefore leaving faster, you may be right but "pressure"? I don't think so.

Now, let's talk about the water velocity. The water is in a closed loop. It spends part of its time in the block collecting heat and part of the time in the radiator shedding heat. The speed of the water in the loop doesn't change the time it spends in the block or the time in the radiator. This is the "race car on a track" analogy devised by Cathar to explain why the whole water-flow thing isn't as important as it was thought to be a few years ago.

So, bottom line, does a res reduce cooling capability? No. As far as I know (and I do a wee bit of reading about this subject) no-one has ever showed any change in water-cooling system performance because of the presence or absence of a reservoir. Reservoirs aid bleeding, they look pretty (to some) and will delay the loop reaching heat equilibrium, that's all. T-lines are cheap, they reduce the space requirements of water-cooling, make bleeding a pita, but don't "cool" better than a reservoir.

 

[Foehammer2003]

lol im probably wrong and i am no way saying this to be fact.

But i presumed that by having a res temps would be inclined to be a minescule bit lower because there is more water in the loop to transfer and dissipate heat, and the same water thats heated up is given a greater amount of time to cool down (albiet naturally while in the res) instead of being immediately called upon again to cool the block down. obviously the real cooling factor is the rad but i have always thought a resevoir to help.

 

[matt100]

I didn't even think the speed of the liquid would change? I was always under the impression the pressure in a closed loop would be equal throughout the loop. If you have a big res then obviously it wouldn't be the "same" water that was being pushed round the loop but the water would be at the same speed and pressure?

I'm no expert on this, in fact I take a fanatical laissez fair attitude to block orders/res vs no res etc but that is maily built on the assumption that once you close a loop the pressure/speed will be the same as the most restrictive block would allow and the water temp will be the heat dump minus what the rad/fans can get rid of regardless of the amount of water so the only thing worth worrying about is the quality of the blocks/rads/fans?

 

[matt100]

lol im probably wrong and i am no way saying this to be fact.

But i presumed that by having a res temps would be inclined to be a minescule bit lower because there is more water in the loop to transfer and dissipate heat, and the same water thats heated up is given a greater amount of time to cool down (albiet naturally while in the res) instead of being immediately called upon again to cool the block down. obviously the real cooling factor is the rad but i have always thought a resevoir to help.

I would think the res would help to a minute level in the sense that a huge rad would have huge surface areas that would convect heat and act as a sort of radiator but the effect would be so tiny over the sizes of res we use so as to make it basically 0?

make it a swimming pool in an air conditioned room and I guess the ambient/water difference would make a difference but otherwise not so much?

 

[Foehammer2003]

I would think the res would help to a minute level in the sense that a huge rad would have huge surface areas that would convect heat and act as a sort of radiator but the effect would be so tiny over the sizes of res we use so as to make it basically 0?

make it a swimming pool in an air conditioned room and I guess the ambient/water difference would make a difference but otherwise not so much?

Yep thats what i was thinking.... definately on the minute scale, but still in the right direction if you know what I mean

and will delay the loop reaching heat equilibrium

Also that was what i was also thinking/meaning... although after a short time it matters not

 

[bledd]

cheers mike

if cathar said, i'll take it as a law tbh!

still have my LRWW knocking around somewhere here

 

[***F1ZZY***]

I didn't even think the speed of the liquid would change? I was always under the impression the pressure in a closed loop would be equal throughout the loop. If you have a big res then obviously it wouldn't be the "same" water that was being pushed round the loop but the water would be at the same speed and pressure?

Flow rate is constant in a loop (lpm or gpm)

Velocity however varies throughout the loop and is determined by the cross sectional area (csa) at that point and the lpm as above - ie. in a block velocity is high, in a tube the csa is a bit more so velocity is less and in a res, the csa is huge so the velocity here is very low (but the flow rate is constant throughout the loop)

Pressure varies MASSIVELY througout the loop. With no pressure gradient, there would be no flow. Even if the loop was at 1,000,000 psi but constant throughout = no flow. This is what the pump does - it imparts pressure onto the liquid so that it flows. The term "pressure drop" is commonly used and is a measure of the flow resistance (accross blocks typically.) High pressure will be at the pump outlet and reduce throughout the loop due to flow resistance of blocks and tubes and be at its lowest (actually can be negative) at suction side of pump.

Back to the res vs T line - a T line has the potential to have higher flow than a res in an otherwise identical loop purely from the inertia of the slow liquid in the res to get moving again. [OP very close to getting it correct] This increase in flow in a T-line is negligible, not necessarily in terms of lpm but rather , in terms of temp reduction due to "race track analogy" as above and the rather "flat curves" [flow vs dT] of modern blocks and rads.

Basically, unless your res is a passive type it will not have any real impact on maximum temps. Just choose res or T for the pros/cons as detailed above by Mike.

 

[matt100]

snip

well shut my whore mouth!