What is the "evaporation surface" formula?

gh = Θ A (xs - x)

where

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)

Lol yay engineering - hope this helps