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Alcohol in WC Loop

C

Chicken Penni Pasta

Limp Gawd
Joined
Mar 31, 2004
Messages
224
Would you be able to run alcohol in a watercooling loop?

...I'm probably not actually going to do it, I'm just curious. It would cool more effeciently than water.
 
It wouldn't cool more efficiently than water. Water has a much higher specific heat, and thus will carry the heat away better.
 
Ethanol also has a lower boiling point, which means that in an equilibriated water loop there will be a higher proportion of vapour phas ethanol then liquid phase. This will increase the pressure, which will decrease flowrate, which will degrade performance. E

Ethanol is also expensive.

Ethanol also has a lower specific heat (2.44 JC^-1g^-1 vs. waters 4.18JC&-1g^-1)

And besides, i'd rather have ethanol inside me then inside my watercooling loop :D :D :D
 
The best alcohol to use in a Water cooling loop is Methanol.
Run it 33% Methanol, 66% Water. Some low temp Windscreen washer fluid uses that ratio.
Its good down to -15C if I remember correctly.
And as Methanol dilutes Water then flow resistance drops so that any loss due to a lower specific heat is countered by a higher flow rate.
Only disadvantage is as its thinner then leaks are worse.

Luck......... :D
u=Tigerbiten.gif
 
HiTech-Hate said:
Ethanol also has a lower boiling point, which means that in an equilibriated water loop there will be a higher proportion of vapour phas ethanol then liquid phase. This will increase the pressure, which will decrease flowrate, which will degrade performance. E
Click to expand...


How do you figure this? Any gaseous pockets (in the res, radiator, etc) will not be impeding liquid flow so I don't see how flow resistance of the loop would change. Liquids are generally considered non-compressible, also, so no volume or density change would be apparent.
 
A gas bubble in the system acts the same way as a solid block - it reduces the crossection available to the liquid and greatly impedes the flow. Also, any low boiling component of the system can create a gas film on a hot spot (like over that cpu die you want to cool) and ruin your heat transfer.
Suggesting to use methanol in a cooling system that is in an occupied room (and most likely not hermetically sealed) is just criminal. Read the warning lables on the bottle (hint, it has a skull and crossbones).
 
whitewale said:
A gas bubble in the system acts the same way as a solid block - it reduces the crossection available to the liquid and greatly impedes the flow. Also, any low boiling component of the system can create a gas film on a hot spot (like over that cpu die you want to cool) and ruin your heat transfer.
Suggesting to use methanol in a cooling system that is in an occupied room (and most likely not hermetically sealed) is just criminal. Read the warning lables on the bottle (hint, it has a skull and crossbones).
Click to expand...


Any bubbles should be confined to high spots, assuming there is no boiling, such as the top of a reservoir or radiator. Those shouldn't be restrictive to fluid flow. But yes, the boiling may be a problem, although I don't know what the boiling point of ethanol is...
 
accually, alchohal would cool better then water, it would just tear away the hosing, causing a leak in no time...

This is what i heard though.
 
How do you figure this? Any gaseous pockets (in the res, radiator, etc) will not be impeding liquid flow so I don't see how flow resistance of the loop would change. Liquids are generally considered non-compressible, also, so no volume or density change would be apparent.
Click to expand...

I'm not speaking of a localized pocket of gas. I'm talking about the overall Temperature AND PRESSURE phase change system. For example, a 'boiling point' is defined as the temperature at which the vapour pressure of the system is equal to the external pressure of the atmosphere. This ONLY works in an open vessel, since a waterloop is closed (not thermodynamically closed, closed in that vapour cannot escape into the environment) the vapour pressure continues to rise as the temperature rises. As a result the vapours density rises as well (by density I dont mean like g/mol, I mean the proportion of the liquid system that is now in the vapourous phase). All liquid systems have a vaporous component to them, its difficult to believe, but this is how the physical changes to phase transitions work. When the systems critical temperature is reached (which depends on pressure) the interface between liquid and gas phases no longer exists, the system is now in a single uniform phase called a Supercritical Fluid, it is the unique properties of supercritical fluids that provide evidence for phase transition equilibria.

Also the pump provides pressure to the system, when this pressure is applied to the condensed component of the systemits vapour pressure rises (aka a lower temperature is needed to increase the proportion of vapour phase. This is quite often used in organic chemistry in distillation of compounds with high boiling points, by creating a high pressure system the compounds will boil at much lower temperatures). Gas solvation also pulls liquid phase molecules out of the liquid phase and into the gas phase, consequently the equation representing the change in vapour pressure as a function of pressure is ...

p = p*(1 + Vm* deltaP/RT)

At any rate, an increased proportion of vapour phase in a system leads to a signifigant increase in pressure. The increase in pressure in turn leads to restrictive flowrate from the pump.

All in all what you need to remember is that a glass of water is NOT purely a liquid, it is an equilibria between vapour phase and liquid phase water molecules. If you left a bowl of water out for 3 weeks you'd see that it had all 'evaporated' yet the temperautre of your house isnt 100C, its because of the vapour phase slowly leaving the system (which is in turn replaced by liquid phase water molecules in the ever ensuing battle to reach equilibrium conditions).
 
HiTech-Hate said:
I'm not speaking of a localized pocket of gas. I'm talking about the overall Temperature AND PRESSURE phase change system. For example, a 'boiling point' is defined as the temperature at which the vapour pressure of the system is equal to the external pressure of the atmosphere. This ONLY works in an open vessel, since a waterloop is closed (not thermodynamically closed, closed in that vapour cannot escape into the environment) the vapour pressure continues to rise as the temperature rises. As a result the vapours density rises as well (by density I dont mean like g/mol, I mean the proportion of the liquid system that is now in the vapourous phase). All liquid systems have a vaporous component to them, its difficult to believe, but this is how the physical changes to phase transitions work. When the systems critical temperature is reached (which depends on pressure) the interface between liquid and gas phases no longer exists, the system is now in a single uniform phase called a Supercritical Fluid, it is the unique properties of supercritical fluids that provide evidence for phase transition equilibria.

Also the pump provides pressure to the system, when this pressure is applied to the condensed component of the systemits vapour pressure rises (aka a lower temperature is needed to increase the proportion of vapour phase. This is quite often used in organic chemistry in distillation of compounds with high boiling points, by creating a high pressure system the compounds will boil at much lower temperatures). Gas solvation also pulls liquid phase molecules out of the liquid phase and into the gas phase, consequently the equation representing the change in vapour pressure as a function of pressure is ...

p = p*(1 + Vm* deltaP/RT)

At any rate, an increased proportion of vapour phase in a system leads to a signifigant increase in pressure. The increase in pressure in turn leads to restrictive flowrate from the pump.

All in all what you need to remember is that a glass of water is NOT purely a liquid, it is an equilibria between vapour phase and liquid phase water molecules. If you left a bowl of water out for 3 weeks you'd see that it had all 'evaporated' yet the temperautre of your house isnt 100C, its because of the vapour phase slowly leaving the system (which is in turn replaced by liquid phase water molecules in the ever ensuing battle to reach equilibrium conditions).
Click to expand...


I understand vapor pressure and phase equilibria, but still fail to realize how an increase in vapor pressure translates to a pressure drop (differential) in the fluid loop. Pressure in the loop deals with a differential between opposing sides of the pump. Vapor pressure deals with a differential between what, the liquid and gas components of the system? If the vapor is not physically blocking the path of the fluid and restricting its flow, how is it increasing resistance of the physical components of the loop?
 
understand vapor pressure and phase equilibria, but still fail to realize how an increase in vapor pressure translates to a pressure drop (differential) in the fluid loop. Pressure in the loop deals with a differential between opposing sides of the pump. Vapor pressure deals with a differential between what, the liquid and gas components of the system? If the vapor is not physically blocking the path of the fluid and restricting its flow, how is it increasing resistance of the physical components of the loop?
Click to expand...

Actually I said it would lead to a pressure INCREASE, not drop (The equation I used shows that the two are proportional). I think we're confusing each others definitions too, when I say pressure im not necessarily talking about the differental at different sides of the pump (I dont necessarily agree with this either, because I consider the pressure differential from the pump outlet, and the CPU block outle more important then from the pump outlet to pump inlet, because some ppl put things in between the cpu outlet and pump inlet, such as res's, and in my mind the pressure differential is only important with respect to the CPU/GPU blocks ... but thats basically just semantics, I dont think it matters for this discussion heh).

At any rate, this increase in pressures leads to a transfer of force from the pump to the force against the tubing walls (which is the definition of pressure, the outward force of the liquid/gas system per unit area on the container aka tubing). So if x units of force are being produced by the pump (related to head), an increase in pressure leads to a 'diversion' of more of these x units of force onto the tubing (to lead consequently to x - dp/dA ... integrate over the area of tubing). I hope this makes more sense heh.
 
The only way you are going to get localized boiling in a closed loop cooling system is if the temp of the system is close to the boiling point of your working fluid.
Plus it will boil at the point of lowest pressure first.
Which is in the impeller.
So the first sign of your system running hot is that the pump cavitates.

All in all what you need to remember is that a glass of water is NOT purely a liquid, it is an equilibria between vapour phase and liquid phase water molecules. If you left a bowl of water out for 3 weeks you'd see that it had all 'evaporated' yet the temperautre of your house isnt 100C, its because of the vapour phase slowly leaving the system (which is in turn replaced by liquid phase water molecules in the ever ensuing battle to reach equilibrium conditions).
Click to expand...
That discribes a bong cooling system well.
Large surface area open to external air.
Now close the system by putting a sheet of cling film over the bowl.
How much water will evaporate?

I ran my cooling system for around 18 month without stripping it down to clean.
In that time I added about 500 ml of water.
Most in the first month as I got the rad fully topped up.
Total capacity was 5,000 ml and a lot of the time air temps where +25C.

Luck.......... :D
u=Tigerbiten.gif
 
Chicken Penni Pasta said:
I figured it would cool better due to the fact it's less dense. Apparently not.
Click to expand...

Density doesn't really have anything to do with a liquid's cooling ability. It's all about heat capacity. Water has incredible heat capacity and very few liquids compare.
 
The only way you are going to get localized boiling in a closed loop cooling system is if the temp of the system is close to the boiling point of your working fluid.
Plus it will boil at the point of lowest pressure first.
Which is in the impeller.
So the first sign of your system running hot is that the pump cavitates.
Quote:
All in all what you need to remember is that a glass of water is NOT purely a liquid, it is an equilibria between vapour phase and liquid phase water molecules. If you left a bowl of water out for 3 weeks you'd see that it had all 'evaporated' yet the temperautre of your house isnt 100C, its because of the vapour phase slowly leaving the system (which is in turn replaced by liquid phase water molecules in the ever ensuing battle to reach equilibrium conditions).
That discribes a bong cooling system well.
Large surface area open to external air.
Now close the system by putting a sheet of cling film over the bowl.
How much water will evaporate?

I ran my cooling system for around 18 month without stripping it down to clean.
In that time I added about 500 ml of water.
Most in the first month as I got the rad fully topped up.
Total capacity was 5,000 ml and a lot of the time air temps where +25C.
Click to expand...

Let me repeat myself, you will NEVER get localized boiling in a loop, that was the entire point of my posts lol (I was trying to clarify with zerosignal that thats NOT what I meant at all in my original post, apparently I didnt do a good job, I am talking about the properties of an equilibriated liquid/vapour phase system).

No water will evaporate, I never suggested that any would.

I agree it explains a bong cooler well, I was only using it as an example of the liquid/vapour phase transition properties of fluids because I was unaware that zerosignal knew of this property, apaprently he did ... my bad

Density doesn't really have anything to do with a liquid's cooling ability. It's all about heat capacity. Water has incredible heat capacity and very few liquids compare.
Click to expand...

In a cooling loop density does have an impact. The less dense the fluid the easier it is to push aroudn the loop, aka increased flowrate (and head).
 
In a closed loop cooling curcuit density has no impact on cooling.
The only factors that effect it with respect to the working fluid are the heat capacity of the fluid and its flow viscosity.
So for a sub-zero cooling loop the alchols you can add from best to worst are.....
Methanol -> Ethanol -> Propanol -> Ethylene Glycol.
For any temps above zero then plain Water is the best.

Luck........ :D
u=Tigerbiten.gif
 
In a closed loop cooling curcuit density has no impact on cooling. The only factors that effect it with respect to the working fluid are the heat capacity of the fluid and its flow viscosity.
So for a sub-zero cooling loop the alchols you can add from best to worst are.....
Methanol -> Ethanol -> Propanol -> Ethylene Glycol.
Click to expand...

Density is directly related to flow viscosity :)

But yest your right, thats the best order for sub-zero cooling. People need to consider that Methanol is HIGHLY toxic too, it is absorbed through the skin, and will lead to blindness. Do not mess with methanol unless you know what you're doing lol
 
In a closed loop cooling curcuit density has no impact on cooling. The only factors that effect it with respect to the working fluid are the heat capacity of the fluid and its flow viscosity.
Click to expand...

hmm, density has a huge influence on the cooling, since heat capacity is defined per mass, not volume. But the capacity of your loop is defined in volume usually. Densities for most commonly used liquids is between 0.8 and 1, so the difference is not huge. But if you do the math for mercury density becomes the determining factor, mercury is lousy per weight, but actually pretty decent per volume.
 
HiTech-Hate said:
Density is directly related to flow viscosity :)
Click to expand...

Not really. There are a lot of liquids that have lower density than water but higher viscosity...and vice versa.

whitewale said:
hmm, density has a huge influence on the cooling, since heat capacity is defined per mass, not volume. But the capacity of your loop is defined in volume usually. Densities for most commonly used liquids is between 0.8 and 1, so the difference is not huge. But if you do the math for mercury density becomes the determining factor, mercury is lousy per weight, but actually pretty decent per volume.
Click to expand...

Big flaw in your argument there. As you said yourself, heat capacities for fluids can be converted to a per volume measurement, completely eliminating density.

So to basically reiterate what Tigerbitten said before...
The only factors that influence a fluid's ability to cool in a closed loop cooling system are volumetric heat capacity and viscosity.
 
Suntar said:
accually, alchohal would cool better then water, it would just tear away the hosing, causing a leak in no time...

This is what i heard though.
Click to expand...

That is untrue. The alcohol as a better coolant myth comes from the cool feeling you get when alcohol evaporates off skin. When a liquid evaporates, (decompression) it absorbs heat energy but when vapor is compressed back into liquid, it releases heat energy. This is why air in a can gets cold when you spray it (decompression) and why the air being compressed heats up. Inside a closed loop, alcohol would not be evaporating.
The best thermally conductive liquid (at least available to most of us) is water. Period.
 
HiTech-Hate said:
In a cooling loop density does have an impact. The less dense the fluid the easier it is to push aroudn the loop, aka increased flowrate (and head).
Click to expand...

Are you referring to density differences between two different fluids or between the same fluid at different temperatures or the same fluid at different pressures? With liquids being essentially noncompressible and experiencing very little density change at the temp differentials we're considering, I don't think there would be a noticeable density change as temp/pressure changes in a WC loop.
 
Parja said:
Big flaw in your argument there. As you said yourself, heat capacities for fluids can be converted to a per volume measurement, completely eliminating density.
Click to expand...

Just following the debate here, but I don't get this one.. If you have a system that has 1 liter of liquid, there would be more of a denser liquid in the system then there would be of a less dense liquid. More mass in loop, more liquid to move heat in system.

But really this is all moot, water is the best available liquid to move heat within the temperature ranges that we work with.

==>Lazn
 
Lazn_Work said:
Just following the debate here, but I don't get this one.. If you have a system that has 1 liter of liquid, there would be more of a denser liquid in the system then there would be of a less dense liquid. More mass in loop, more liquid to move heat in system.

But really this is all moot, water is the best available liquid to move heat within the temperature ranges that we work with.

==>Lazn
Click to expand...

1 liter of a more dense fluid would have greater mass than 1 liter of a less dense fluid. But no, more mass does not equal more liquid to move heat in the system. Furthermore, mass is not important in a closed loop system like this, as any amount of mass is going to be cylced through continuously.
 
Big flaw in your argument there. As you said yourself, heat capacities for fluids can be converted to a per volume measurement, completely eliminating density
Click to expand...

Not eliminating - incorporating
 
Are you referring to density differences between two different fluids or between the same fluid at different temperatures or the same fluid at different pressures? With liquids being essentially noncompressible and experiencing very little density change at the temp differentials we're considering, I don't think there would be a noticeable density change as temp/pressure changes in a WC loop.
Click to expand...

Two different liquids.

I already explained my logic with regards to the pressure/temp. of a one liquid system.
 
zer0signal667 said:
1 liter of a more dense fluid would have greater mass than 1 liter of a less dense fluid. But no, more mass does not equal more liquid to move heat in the system. Furthermore, mass is not important in a closed loop system like this, as any amount of mass is going to be cylced through continuously.
Click to expand...

Ah got it, because the heat capacity is rated by volume, not mass.

==>Lazn
 
Lazn_Work said:
Ah got it, because the heat capacity is rated by volume, not mass.

==>Lazn
Click to expand...


Well, what I said is unrelated to heat capacity... I was just relating volume to density. But heat capacity is usually given in terms of energy per mass, like Joules/kg, or energy per mole (a mole is 6.02x10^23 atoms/molecules for those who don't know)..
 
zer0signal667 said:
Well, what I said is unrelated to heat capacity... I was just relating volume to density. But heat capacity is usually given in terms of energy per mass, like Joules/kg, or energy per mole (a mole is 6.02x10^23 atoms/molecules for those who don't know)..
Click to expand...

Then would not density be a factor? More mass in the system, more stuff to carry heat.

Conciveably something with a lower specifc heat could cool better than something with a higher specific heat for a given volume if the density were vastly different. (almost gas vs almost solid)

==>Lazn
 
Lazn_Work said:
Then would not density be a factor? More mass in the system, more stuff to carry heat.

Conciveably something with a lower specifc heat could cool better than something with a higher specific heat for a given volume if the density were vastly different. (almost gas vs almost solid)

==>Lazn
Click to expand...


Heat transfer properties of fluid systems varies with several material properties. So yes, a fluid with lower specific heat could cool better if it had other favorable properties such as low viscosity. And you're opening a whole new bag of worms describing high/low density as similar to almost solid/almost gaseous states, since those don't necessarily correlate with density.

I was trying to say earlier how you don't need lots of mass to carry the heat away. Think of it this way, if you add a reservoir, it doesn't make your system cool better.
 
SO... your saying that the use of acohol in cooling is safe?
Can I quote you on this?
LMK

Larry
 
Big Lar said:
SO... your saying that the use of acohol in cooling is safe?
Can I quote you on this?
LMK

Larry
Click to expand...
Yes you can quote me on that. Are you implying that alcohol contained in a closed loop without oxygen is dangerous?
 
Im going to have to agree there is no danger to haveing alcohol in a closed loop

1)there has to be O2 for it to ignite
2)there has to be a flame or spark to ignite it (not many of those in a computer case)
3)Its safer because it wont damage components in the event of a leak(its non conductive)
 
Using alcohol with a bong cooler could give you excellent temps! Just don't smoke around the computer :eek:
 
yes it would work but you would have a continuous supply of alcohol (exspensive but way cool)
 
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