Critical heat flux phenomenon, mechanism

Mechanisms of CHF in Fool Boiling. The mechanism of the critical heat flux phenomenon in pool boiling has been the subject of widespread interest and controversy. Recent reviews relating to mechanisms are presented by Katto [157], Dhir [87], and Bergles [158]. The postulated mechanisms can be approximately classified into four types as follows ... 

Eventually, the velocity of vapor in the jets becomes so large that the jets themselves become unstable near the interface as a result of Helmholtz instability (of wavelength XH) as shown in Fig. 15.63). The breakup of the jets destroys the efficient vapor-removal mechanism, increases vapor accumulation at the interface, and leads to liquid starvation at the surface and to the critical heat flux phenomenon. If jet breakup occurs at a vapor velocity UH within the jets, the critical heat flux q"m is given by... 

Boundary layer separation models. In this class of model, the critical heat flux phenomenon is considered to be analogous to the phenomenon of boundary layer separation from a permeable plate through which gas is flowed in a direction normal to the flow over the plate. This mechanism was initially suggested by Kutateladze and Leontiev [312] and was further developed by Tong [313] and others and more recently by Celata et al. [314], This method of prediction leads to an equation of the form... 

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