Calculating Evaporation: Pressure, Vapor Pressure & Temperature

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    Evaporation Formula
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SUMMARY

The evaporation rate of a liquid can be quantified using the formula m-dot=(A)(42.6+37.6V)(Pw-Pa)/Hv. In this equation, m-dot represents the evaporation rate in kg/hr, A is the surface area in square meters, V is the air velocity over the water surface in m/s, Pw is the saturation vapor pressure at the water temperature in mm Hg, Pa is the saturation vapor pressure at the dew point in mm Hg, and Hv is the latent heat of vaporization of water at surface temperature, ranging from 2257-2270 kJ/kg. This formula is crucial for analyzing potential oil contaminants in RGA analysis.

PREREQUISITES
  • Understanding of evaporation principles
  • Familiarity with vapor pressure concepts
  • Knowledge of latent heat of vaporization
  • Basic skills in fluid dynamics
NEXT STEPS
  • Research the calculation of saturation vapor pressure at different temperatures
  • Explore the effects of air velocity on evaporation rates
  • Study the latent heat of vaporization for various liquids
  • Investigate RGA analysis techniques for detecting contaminants
USEFUL FOR

Environmental scientists, chemical engineers, and researchers involved in fluid dynamics and contamination analysis will benefit from this discussion.

marlene0311
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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
 
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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.

I'm not sure if this addresses the issue you are asking about--the contaminant in the mixture.
 

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