# Evaporation formula

1. Sep 27, 2010

### marlene0311

Hi,

I would like to know how to quantify the evaporation of a liquid.

I assume it would depend on pressure, liquid vapor pressure & temperature but I can't find a formula.

Can somebody help?

I need to find out if some possible oil contaminant would show up in an RGA analysis

Thanks a lot

Marlene

2. Dec 5, 2010

Try this:
m-dot=(A)(42.6+37.6V)(Pw-Pa)/Hv
Where:
m-dot=evaporation rate kg/hr
A=surface area, square meters
V=air velocity over water surface, m/s
Pw=saturation vapor pressure at water temperature, mm Hg
Pa=saturation vapor pressure at dew point, mm Hg
Hv=latent heat of vaporization of water at surface temperature, from 2257-2270 Kj/Kg

This same formula is contained in other parts of the evaporation rate thread.