# Bong evaporation rates.

#### cjtune

##### Member
I've just finished cobbling together a bong & reservoir for my WC and has measured the rate of water loss (thru drift and evaporation) at 0.1 litres every hour w/o any CPU heat. But I expect the evap rate to double to 0.2L/hr when my waterblock's ready. That's 0.016% of the 350gph (1327L/hr) flow rate. The pump itself is rated at 500gph @ 0 head. I'm using a 30cfm, 80mm fan to blow out the moist air. Can anybody give me some input on their bong's evaporation rate?

Colin, i think it is time you considered a car radiator or three to cool the water with.

Yes indeed. That is quite a big amount of water you're evaporating, Colin.

Yipes! That's 1.26 litres/hr. Your setup literally guzzles 1 soft drink bottle's worth of water per hour. Did you take any measures to minimise lost by drift? Some of the water lost isn't due to evaporation but is actually due to minute droplets being blown away by your super strong 120mm fans. The latent heat of evaporation of water at 35'C is 2263kJ/kg @ 1 atm. If ALL of your 1.26L/hr is due to evaporation, then you should have removed (1.26L/hr)*(1kg/L)*(1hr/3600sec)*(2263kJ/kg)=792 watts!

Cut back on the fans and the temps rise. One of my best friends, a mechanic and PC nut has a large selection of older autos in semi scrap mode. We have been discussing the possibility of a radiator. I suspect the ten 120 mm Panaflows I purchased may all go into use.

BTW, the 1 liter per hour figure is only with the pelts. In a none pelt set up, I feel the two gallons per day is acceptable. Bare in mind, not only is the tower evaporating water, but there is a piece of foam rubber on the surface of the reservoir with a fan blowing on it to increase evaporation.

Colin, thanks for your input but I think you ought to try to reduce water lost from drift first. In real cooling towers/bongs, this is a significant factor that determines the amount of make-up water needed. Old cooling towers (early last century) lose a lot of water this way. Modern bongs will have a system of baffles to help recapture water lost by drift.

Water droplets have mass and will have trouble going 'round corners or sharp bends. You can try to fix several scotchbrite pads in your tower as to form a baffles to try to capture the stray water droplets. Don't worry, as the scotchbrites won't condense the already evaporated water 'cause it's not thermally conductive and will not help the water vapor release the latent heat it carries when it comes into contact with a pad.

Colin (Jun 17, 2001 06:35 p.m.):
Cut back on the fans and the temps rise. One of my best friends, a mechanic and PC nut has a large selection of older autos in semi scrap mode. We have been discussing the possibility of a radiator. I suspect the ten 120 mm Panaflows I purchased may all go into use.

Using a car radiator is very possible, I have done it. We got a cheap small car radiator that was in ok shape and rigged it up for fun. This is before I knew too much so I don't have numbers or anything. The beauty was for a non pelt system and all, we could actually have a radiator without a fan and run essentially at ambient with a DD amazing block.