During an operation of desalination, a process is to perform a flash of salt water, which has the effect of vaporizing a fraction of the total flow-rate and to increase the concentration of the solute.

A flash chamber acts as a divider receiving as input the product to concentrate, and from which exit two fluids: water vapor and the concentrated solution. The room being adiabatic, the enthalpy of vaporization is taken from the aqueous solution, whose temperature drops.