The standard evaporation model proposed by Envmodels can be used to estimate VOC emissions to atmosphere due to liquid surfaces evaporation (open vessel containing liquid solvents, spill) exposed to natural wind effects.
In order to use this model, it is necessary to determine the compounds mass transfer coefficients. They are based on products diffusion coefficients (given by Envmodels products database). By default, products molecular masses can be considered (in this case calculation is a little overestimated).
A picture of a polluted spill is shown below:
Evaporation model is based on following assumptions:
A Methyl Ethyl Ketone leak produces a 10 m2 outdoor spill. Liquid temperature is 25°C (298.15°K).
Elapsed time until the spill is confined (recovered with absorption products) is de 20 minutes. Wind speed measured over spill (at 10 meters high) is 6 m/s.
Calculated MEC emissions to atmosphere are 19.8 kg.