Critical Heat Flux Correlation Research Articles

A Generalized Correlation of Critical Heat Flux for the Forced Convection Boiling in Vertical Uniformly Heated Annuli

A Generalized Correlation of Critical Heat Flux for the Forced Convection Boiling in Vertical Uniformly Heated Annuli

A generalized correlation of critical heat flux for the forced convection boiling in vertical uniformly heated round tubes

The present study deals with the critical heat flux (CHF) in the conditions that the fluid fed to heated tubes is subcooled (including saturated liquid in the extreme situation) with no entrained vapor. To start with, postulating that there is a state where the hydrodynamic condition is responsible for CHF, a theoretical presumption for the generalized correlation equation of CHF is attempted with the aid of vectorial dimensional analysis. Then, the experimental data of CHF obtained from the literature for fluids of seven different kinds are analyzed, revealing the existence of four characteristic regimes of CHF, called L-, H-, N-, and HP-regime in this paper, and leading to the development of the generalized correlation of CHF data as well as that of CHF-regime correlation.

A study of the sensitivity of loca heat transfer analysis for a water-cooled reactor system

Abstract Results are given of computer calculations, using the reactor thermal analysis code THETA1-B, to determine the significance and relative importance of various heat transfer regimes in predicting maximum fuel cladding temperature for the blowdown phase of a postulated loss-of-coolant accident (LOCA) in a pressurized water reactor system. The factors considered include the choice of heat transfer correlation for a particular heat transfer regime, the method of delineating the boundaries between regimes, and core inlet coolant flow conditions. For a hot-leg rupture, the maximum surface temperature is sensitive to a number of factors, including choices of critical heat flux correlation, flow boiling transition heat transfer correlation, and in particular, stable film flow boiling correlation. However, for a LOCA resulting from a double-ended rupture of an inlet feeder, these factors have only marginal effects on maximum cladding temperature. In this case the importance of heat transfer to dry steam coolant at low net flow rate conditions is demonstrated, indicating a need for further information.

Generalized Correlation of Critical Heat Flux in Natural Convection Boiling Within Confined Channels

Generalized Correlation of Critical Heat Flux in Natural Convection Boiling Within Confined Channels

Use of the “Lagrangian and Eulerian Points of View” in the Transient Critical Heat Flux Calculations for BWR Rod Bundles and Experimental Verifications

The (X, LB) correlation, which is currently used to predict the critical heat flux (CHF) onset in simple and complex geometries under a steady-state regime, is capable of a dynamic interpretation. The two-phase flow mean particles, climbing the channel at linear velocities corresponding to their mass velocity and local densities, reach the CHF conditions—i.e., zero thickness of the liquid film on the rod—when they have traveled a certain distance and have achieved a certain quality. According to this model, the CHF would be predicted in transient condition, when the boiling length and the mass velocities change with space and time, by applying the steady-state CHF (X, LB) correlation to the actual paths of the mean fluid particles.The calculations performed in comparison of the “Lagrangian point of view,” outlined above by means of the DOLCE computer code, with the local space-time approach of the “Eulerian point of view” indicate that the two methods give substantially equivalent results and predict satisfactorily the onset of the transient CHF for the Centro Informazioni Studi Esperienze annuli experimental data and General Electric Company 16-rod bundles data under typical boiling water reactor transients, including loss-of-coolant accident simulations.