7 deg C Temp Drop in watercooling!, My Secret weapon!

[Dunno]

Project log up!

Any suggestions welcome.

[LPorc]

Originally Posted by Dunno

Project log up!

Any suggestions welcome.

Nice. The fine mist (definately agitated and non-flat surface) and the airflow maximize evaporation, cooling the air.

Air's capacity to hold water vapor is unaffected by temperature, it is the temperature of the water vapor and its condensation/evaporation equilibrium that matter. Of course the sensible temperature of the comingled gases (air and water vapor) is the same. If the air is exhausted below ambient condensation will be highly unlikely.

About the only suggestion I'd make for piece of mind is a droplet barrier of some sort. This would act as a filter to catch any non-evaporated water. It would be much better to have mineral deposits and the like accumulate there rather than in the air path of your radiator.

[Dunno]

Originally Posted by LPorc

Nice. The fine mist (definately agitated and non-flat surface) and the airflow maximize evaporation, cooling the air.

Air's capacity to hold water vapor is unaffected by temperature, it is the temperature of the water vapor and its condensation/evaporation equilibrium that matter. Of course the sensible temperature of the comingled gases (air and water vapor) is the same. If the air is exhausted below ambient condensation will be highly unlikely.

About the only suggestion I'd make for piece of mind is a droplet barrier of some sort. This would act as a filter to catch any non-evaporated water. It would be much better to have mineral deposits and the like accumulate there rather than in the air path of your radiator.

THX Lpork!

I am thinking of putting an impeller from a card cooler/extractor directly above the mist maker:
This will prevent any larger droplets from hitting the radiator by flinging them out horizontally.
This will:
Hopefuly decrease the droplet size and give them a chance to evaporate more.
Agitate ther mist and help it to evaporate fully.
Perhaps a fan, blowing downward, without a circumferental frame/casing?? would be better? Like a vid card fan.

As I see it there is no way to get the temps down to the point where condensation becomes a problem:
This will only cool until the air becomes saturated. Condensation only occures when the air is over-saturated.

[LPorc]

Originally Posted by Dunno

THX Lpork!

I am thinking of putting an impeller from a card cooler/extractor directly above the mist maker:
This will prevent any larger droplets from hitting the radiator by flinging them out horizontally.
This will:
Hopefuly decrease the droplet size and give them a chance to evaporate more.
Agitate ther mist and help it to evaporate fully.
Perhaps a fan, blowing downward, without a circumferental frame/casing?? would be better? Like a vid card fan.

As I see it there is no way to get the temps down to the point where condensation becomes a problem:
This will only cool until the air becomes saturated. Condensation only occures when the air is over-saturated.

Not sure about impeller idea, seems overly complicated to a droplet barrier. All you need is a simple barrier where the air doesn't travel a straight line. The droplets don't make the corner. Several folks have suggested for Evaps that opposed angle vents work:

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I'd imagine something like a thin scrubby pad would work.

Maybe even a couple of screens with a gap between would do the trick, slowing the droplets a bit.

Anything else with fans starts messing with your airflow, and the results would have to be experimentally determined.

As for condensation, the worry is not with how cool you get, we know you can't get below dew point. The worry is how much water vapor is in the exhaust and its temperature. Saturation is a nisnomer, there is no magic capacity of air to hold water vapor that varies with temperature of the air. Water vapor act like any other gas.

It all has to do with the temperature of the water vapor and its equlibrium of evaporation and condensation. Think of your exhaust water vapor and the ambient water vapor. If your exhaust water vapor were warmer than ambient, it would be quickly cooled. Since it is cooler than ambient it is quickly warmed. Under which condition, rapid heating or rapid cooling, is the equilibrium of condensation and evaporation likely to swing towards condensation?

Note that you can exceed 100% relative humidity with your setup. Relative humidity has to do with still air flat surface boundary conditions, not the actual amount of water vapor that the air can "hold". Water vapor is a gas and behaves like any other gas, having its own independent pressure.

[Dunno]

Originally Posted by LPorc

Not sure about impeller idea, seems overly complicated to a droplet barrier. All you need is a simple barrier where the air doesn't travel a straight line. The droplets don't make the corner. Several folks have suggested for Evaps that opposed angle vents work:

//////
\\\\\\

I'd imagine something like a thin scrubby pad would work.

Maybe even a couple of screens with a gap between would do the trick, slowing the droplets a bit.

Anything else with fans starts messing with your airflow, and the results would have to be experimentally determined.

See what you mean. I'm a bit worried about the mist passing through the rad before its had a chance to evaporate/cool.
In my test setup the mist had a long way to travel/time to evaporate. (through a 120mm 230V fan!)

Originally Posted by LPorc

As for condensation, the worry is not with how cool you get, we know you can't get below dew point. The worry is how much water vapor is in the exhaust and its temperature. Saturation is a nisnomer, there is no magic capacity of air to hold water vapor that varies with temperature of the air. Water vapor act like any other gas..

I thought that the hotter air was the more vapour it could hold: Cool it (the air)down and the vapour condenses out??

Originally Posted by LPorc

It all has to do with the temperature of the water vapor and its equlibrium of evaporation and condensation. Think of your exhaust water vapor and the ambient water vapor. If your exhaust water vapor were warmer than ambient, it would be quickly cooled. Since it is cooler than ambient it is quickly warmed. Under which condition, rapid heating or rapid cooling, is the equilibrium of condensation and evaporation likely to swing towards condensation?

Note that you can exceed 100% relative humidity with your setup. Relative humidity has to do with still air flat surface boundary conditions, not the actual amount of water vapor that the air can "hold". Water vapor is a gas and behaves like any other gas, having its own independent pressure.

Do you have any literature/links on this? (interesting)

[LPorc]

Originally Posted by Dunno

I thought that the hotter air was the more vapour it could hold: Cool it (the air)down and the vapour condenses out??

Do you have any literature/links on this? (interesting)

http://www.shorstmeyer.com/wxfaqs/hu.../humidity.html

http://www.atmos.umd.edu/~stevenb/vapor/

http://www.ems.psu.edu/~fraser/Bad/B...CloudsFAQ.html

http://www.absoluteastronomy.com/enc...ohn_dalton.htm

"Experimental Essays on the Constitution of Mixed Gases; on the Force of Steam or Vapour from water and other liquids in different temperatures, both in a Torricellian vacuum and in air; on Evaporation; and on the Expansion of Gasses by Heat" John Dalton 1802.

He explained that when two elastic fluids, A and B, are mixed together, there is no mutual repulsion between their particles; that is, A particles do not repel B particles, but a B particle will repel another B. Consequently, the pressure or whole weight of the gas arises solely from its particles. One of his experiments involved the addition of water vapor to dry air. The increase in pressure was the same as the pressure of the added water. He also established a relationship between vapor pressure and temperature.

[Dunno]

THX Lpork!

Going to take some reading!

"...THINK ENERGY..."

"...ON A WARM DAY MORE WATER CAN EVAPORATE BECAUSE
THERE IS MORE THERMAL ENERGY AVAILABLE TO DO THE WORK OF EVAPORATION..."

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So... my thinking that "the hotter air was the more vapour it could hold" while wrong, gives the correct.... You know what I mean.

Am still reading though.

THX again.