In solar desalination still, the water is heated by the absorbed solar energy. At some point, the temperature in the still reaches the boiling temperature. I would like to understand the mechanisms within this process and find out how to calculate the mass transfer.

For non-boiling temperature, I normally use the analogy between heat and mass transfer to calculate the mass transfer. With Sherwood number, we can approximate the convective mass transfer from the diffusive mass transfer, with a Sherwood number obtained from the Schmidt number and Grashof/Reynolds number from heater transfer. But if the water is boiling, the turbulence within the water kind of breaking the laminar boundary assumption used in diffusion theory. In this case, what is the dominant mechanism in the mass transfer? How to calculate the mass transfer?

Any discussion is welcome!

Thanks

Wenlong Chen