The importance of the critical heat flux phenomenon has led to the development of a very large number of CHF correlations. It is beyond the scope of this section to present a comprehensive description of these many correlations. In fact, the most accurate correlations are not publicly available but rather proprietary. Thus, Table 7.1 is provided to give examples of the various types of correlations adopted for CHF in tubes, annuli and rod bundles when the applied heat flux is spatially uniform. One should first note that the thermodynamic quality is the prime independent variable in most of these correlations. This parameter inherently contains through the energy balance the effect of mass velocity, *G*, pressure, *P*, inlet subcooling, , and geometry, and *L*. In addition some of these correlations have included second order effects for these same variables and as well as others. Finally, one should be cautious not to apply these correlations outside of their range of applicability based on the test data gathered. The reason for this final point is that since these CHF correlations are quite empirical, it is prudent not to extrapolate the empirical correlation fit. The sample correlations provided give a good range of data to apply toward a correlation.

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