In flash/falling film evaporators, the liquid film falls by gravity in the vertical evaporation surface, while heat is transferred through the wall by condensing the steam. The mixture of liquid/vapor exits the bottom of the tube or plate and enters a vapor/liquid separator, from which concentrated liquid is pumped out and water vapors are directed to a condensing system. Falling film evaporators can be operated with very low temperature differences between the heating media and the boiling liquid, and they also have very short product contact times, typically just a few seconds per pass. These characteristics make the falling film evaporator particularly suitable for heat-sensitive products.