Originally Posted by nub
the only way evaporative cooling can get sub ambient is by venting the heat to atmosphere.
Closed evaporative cooling without a compressor does exist, it is called a heat pipe
ignition of alcohol fumes should not be an issue then as ethanol would not build up / become concentrated. I doubt that alcohol added in small quantities would make much of a difference in evaporation rate / loop temperatures.
Think you've misunderstood, although the vapor chamber would be sealed the vapor would be cooled to ambient by a dual rad closed loop quite separate from the pc/cooler circulation. one radiator inside the vapor chamber and one outside connected by an isolated water loop....so the vapor in the chamber would be re-condensed internally as the vapor temp would be kept close to ambient.....so sub ambient temps would be possible in just the same way as with a norm bong/volenti cooler.......probably lower temps because of lower boiling point of the ethanol.
I wouldn't be so sure that the alcohol would not reach flammable limits within the chamber if ventilated as normal.... 3% is the lower flammability limit for ethanol vapor....the other problem with having this open as you suggest is that you would have to be constantly topping up with expensive ethanol to replace that lost to evaporation.
I was not considering adding alcohol in small quantities, you could use pure alcohol inside the chamber....although you would have to be aware that if you pumped this directly though your component cooling loop that it has lower heat capacity than water.... you could overcome this by having your cooling system on a separate loop with a rad submerged in the bong/volenti reservoir....but you may actually be able to find a balance point at a certain % of alcohol/water that would negate the need for a separate component cooling loop to save on complexity/expense as you may well find you'd have to use antifreeze/alcohol in the component loop anyway to prevent freezing.Edited by technogiant - 4/28/13 at 4:34am