Critical heat flux (CHF) refers to the value of heat flux at which
the local heat transfer coefficient decreases sharply due to the
replacement of liquid by vapor adjacent to the heat transfer surface.
There exists other terminologies for this condition in the literature
such as burnout, departure from nucleate boiling (DNB),
dryout, and boiling crisis; however, none of these is fully satisfactory.
In most cases, once this limiting condition is detected as a
sharp rise of surface temperature, the heating power must be cut
before the component physically burns out. For designing microprocessor
chip cooling systems and for the cooling of power electronics,
knowledge of the CHF is essential in determining the
upper operating limit of the cooling system for safe operation.