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bheron
01/25/2016, 08:53 AM
I don't think this is really a "chemistry" question but this seemed the right place to ask this question (mods if not please move).

I'd like to add more water volume to my system in the form of several small tanks/containers. The new tanks and containers would theoretically be completely covered.

Would this increase water evaporation at all? Is the evaporation rate dependent on total water volume or only the surface area exposed to air?

iced98lx
01/25/2016, 08:56 AM
Evap is a function of water temp, surface area and the temp/humidity and air movement above the water. Adding several completely sealed contains should not increase your evaporation in a meaningful way.

The amount of evaporated water can be expressed as:

gs = Θ A (xs - x) / 3600 (1)

or

gh = Θ A (xs - x)

where

gs = amount of evaporated water per second (kg/s)

gh = amount of evaporated water per hour (kg/h)

Θ = (25 + 19 v) = evaporation coefficient (kg/m2h)

v = velocity of air above the water surface (m/s)

A = water surface area (m2)

xs = humidity ratio in saturated air at the same temperature as the water surface (kg/kg) (kg H2O in kg Dry Air)

x = humidity ratio in the air (kg/kg) (kg H2O in kg Dry Air)

http://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html

bertoni
01/25/2016, 05:36 PM
I agree that completely covered water volumes will have no effect on evaporation.

bheron
01/25/2016, 10:28 PM
Ok thats great news. Had no idea of some of that detail so thanks so much. Want to increase the stability and biodiversity of my tank but wanted to be sure what I was getting into first. thanks again

bertoni
01/26/2016, 01:22 AM
You're welcome.