evaporation rate for water droplets

[lalit4bearings]

I want to know if the small water droplets evaporate much faster than the water in open vessel on heating.What is the theory and formulas behind it.
We are facing a problem.When the water,air spray applied to coke and sinter,it is vaporized.The high temperature of these materials were unknown.Average temp. is nearly 110 degree centigrades.This is about dust containment.

 

[zdas04]

Evaporation theory has developed further in the irrigation industry than anywhere else. They are trying to find delivery configurations that minimize evaporation. So to maximize evaporation look to what they say NOT to do.

One of their key learnings is that for droplets larger than about 50 micron diameter, evaporation is a surface function. Below that it is a body function and evaporates based on droplet volume instead of area and evaporation takes significantly less time with small drops.

In your dust containment example it sounds like you want to reduce the rate of evaporation so you should use big droplets.

David

 

[IRstuff]

Volume scales by R/3 relative to area for a sphere. So, larger drops will survive longer given the same surface mass transfer rate.

There are lots of different atomization techniques. There will be a balance between evaporation loss and over watering.

TTFN

FAQ731-376

 

[davefitz]

Further theories on evaporation of small droplets is contained in tech papers published in "the int'l journal of multiphase flow" circa 1982-1992 by Kiefer, Kohler and Hein from KWU siemens . The primary subject was critical heat flux inside high pressure boiler tubes, but the theory is applicable to any evap from droplets whenever a non-equilibrium state exists.