Critical heat flux, transient

Figure 2.32 Dependence of the dimensionless critical heat flux on the contact angle during steady-state heating and transient cooling. (From Liaw and Dhir, 1986. Copyright 1986 by Hemisphere Publishing Corp., Washington, DC. Reprinted with permission.)...

Celata, G. P., M. Cumo, F. D Annibale, G. E. Farello, and T. Setaro, 1985, Critical Heat Flux in Flow Transients, in Advances in Heat Transfer, Vol. IV, ENEA Publicatione, Rome. (5)... 

Tachibana, F., M. Akiyama, and H. Kawamura, 1968, Heat Transfer and Critical Heat Flux in Transient Boiling, 1. An Experimental Study in Saturated Pool Boiling, J. Nuclear Sci. Technol. of Japan 5(3) 117. (5)... 

Annular flow modeling has been used extensively in predicting critical heat flux phenomena in annular flow. It has been used for prediction of critical heat flux in annuli and rod bundles (see Hewitt [291] for a review) and has also been successfully applied to the prediction of transient critical heat flux and to limiting cases of rewetting of a hot surface (see Hewitt and Govan [298]). 

Transient and accident analyses for RBMK reactors should reflect the peculiarities of the design, such as the use of adequate correlations for critical heat flux, and consideration should be given to hydrodynamic instabilities. 

Prediction of the thermal margins of fuel elements to a harmful phenomenon like critical heat flux (CHF) during normal operation and transients is considered to be of the utmost importance. Mass flow rate in the core of the CAREM reactor is rather low compared to typical light water reactors and therefore available correlations or experimental data are not completely reliable in the range of interest. Thus, analytical data should be verified by ad-hoc experiments. 

Meade et al. [24] reported the responses of heat and oxygen flux to varying levels of environmental oxygen for the Australian crayfish Che rax quadricarinatus. When crayfish were exposed to p y2 values less than approximately 5 kPa, both heat dissipation and oxygen uptake were depressed. However, the depression of heat dissipation was only transient, and it recovered to normoxic values within 4 h, which suggested some form of metabolic compensation. CR ratios at or below the critical Pq2 were not determined, so the quantitative contribution of anaerobic pathways to any compensation could not be estimated. These juvenile crayfish were incapable of surviving a 1-2 h anoxic treatment at 28"C. 

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