The burnout phenomenon in boiling can be expressed like this
Before that please read
In the Nucleate boiling region we saw the critical heat flux
or the maximum heat flux. And we want more heat transfer and thus we have to
heat the liquid further. But due to the some vapor covering the liquid cannot receive
that heat as result the heater surface has to absorb the heat. This increase
energy with increased excess temperature is absorbed by the heater surface. And
further increase in the surface temperature causes the surface to leave that
heat. It cannot take any more heat. But most of the time the heater surface
cannot come to the position to leave it. Before that it melts. This is called
burnout phenomenon. That’s why critical heat flux is called burnout heat flux. Most
of the boiling heat transfer heaters are operated below the burnout heat flux
to avoid that disastrous effect. High melting point metals can solve this
problem. But in case of cryogenic application the burnout is not a problem.
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