Annual Review of Heat Transfer: Critical Heat Flux

This volume is organized into separate chapters, each dealing with many different aspects of a separate issue. Chapter 1 provides an overview of the flow boiling phenomena in totality. The distinct phenomenology of the Departure from Nucleate Boiling (DNB) and Dryout are described. Chapter 2 deals with the experimental methods and results on the determination of CHF. It also provides a glimpse of the available correlations as well as their shortcomings. The message from this chapter is that the correlation-based approach for CHF predictions should be replaced by the mechanistic approaches to predict DNB and dryout to facilitate universal predictions of CHF. Chapters 3 and 4 are dedicated to the phenomenological modeling of dryout and DNB, respectively. The calculation methodology and results for both tubes as well as rod bundles are presented in these chapters. Chapter 4 also presents predictions of CHF using Computational Fluid Dynamics (CFD) modeling. Chapter 5 describes relatively new situations for which CHF has not been widely studied. They include, for example, CHF in downward boiling under the bottom of the calandria vessel of a Pressurized Heavy Water Reactor (IPHWR). This phenomenon is critically important during the retention of core melt in severe accident scenario. Another phenomenon of interest is the flow oscillations which might occur in certain scenarios when the coolant flows under natural circulation. The essence of all Chapters 1-5 is presented in Chapter 6 followed by the future approach emphasizing the important key areas that need to be addressed for better modeling of Dryout and DNB.