Vat Evaporation Calculations

It is fairly easy to calculate average evaporation rates, providing you have some data specific for the locality (such as the average temperature, the average relative humidity and the mean dew point) using the following formula:

lh = ((Tv + (Ta x As2)) x Ea x (Sh – Hr))/Ec

lh = litres per hour of evaporation
Tv = mean temperature of vat (°C)
Ta = mean temperature of atmosphere (°C)
As = Air speed (metres per second)
Ea = evaporation area (m2)
Sh = saturation humidity ratio (kg of water per kg of air)
Hr = humidity ratio (kg of water per kg of air)
Ec = Evaporation constant

Sh – Hr provides us with the evaporation potential and is calculated this way:

Sh = (( Dp / 100) x RH ) / Tv
Hr = ((sh / 100) x RH )

Dp = Dew Point (°C)
RH = Relative Humidity (%RH)

and Ec is the evaporation constant, in this case it is the evaporation constant of water as a percentage of a saturated brine solution, because the liquid to evaporate in the vat is brine.… Read the rest