CO2 mist, aeration and gases

Tom Barr

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This thread is to provide more back ground for ideas surrounding gas-liquid phase dissolution.

This intial post is math heavy:

Chapter 21 Aeration and Oxygenation in Aquaculture

This link provides background on how much gas (in grams) can be transferred per unit water volume/time.

Then it discusses more about bubble sizing.

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Loop Venturi Reactor-A Feasible Alternative to Stirred Tank Reactors?

Discusses loops for venturi recirculation methods and micromixing.

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Venturi calculator for those less math inclined:

Flowrate Calculation for a Venturi

and

Venturi flow meter

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Small bubbles is that they rise more slowly in the liquid than larger bubbles. This is due to an increase in the friction ratio of gas to liquid. The term friction is used because it is easier to visualize the slower rising bubble slowed by friction. For an example picture one large bubble about 1/2 inch in diameter. Imagine how fast that single bubble would rise through a body of water. Now contrast that single large bubble with thousands of bubbles about one half millimeter in diameter released into the same body of water at the same time and depth. These tiny bubbles resemble smoke as they rise. The multitude of smaller bubbles would reach the surface much later than the large single bubble. This increase in friction with the liquid means that the gas bubbles can drag more liquid along as it rises therefore creating greater lift per volume of gas.

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Impacts on microbubbles on fish and bubble size:
"Very small (micro-size) oxygen bubbles should dissolve faster than larger bubbles because of their greater surface to volume ratio, but all gas bubbles (air or oxygen) need some 'solubility space'. Without sufficient 'space' available for the bubbles to dissolve, tiny micro-fine bubbles may remain suspended within the water column, attach to surfaces, or slowly, rise to the surface. Of course, fish do not breathe (gaseous) oxygen or air bubbles, the oxygen must first be dissolved in water for it to diffuse across their lamellar membranes."

Joseph J. Cech, Ph.D.

University of California - Davis Campus
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Regards,
Tom Barr