The critical heat flux (CHF) mechanisum is considered tightly connected to the flow pattern. According to the most often-encountered sbcooled boiling flow pattern (the first kind of flow pattern), a new mechanistic CHF model is developed for vertical subcooled flow boiling. The model is based on the liquid sublayer dryout mechanism. The model is simple with explicit physics meaning, and is characterized by the absence of empirical constant. The model is tested over a very large data bank, showing a general good accuracy. The model is compared to the Celata model in the predivtion ability for the CHF and important parameters (UB, LB, DB, δ). Although the prediction approaches of the two models differ greatly, it is interesting to see that the important parameters are predicted with no big difference existing. The parametric trends of the CHF are summarized and interpreted in the paper from the model theory viewpoint. The CHF is an increasing function of the coolant subcooling and mass flux. The influence of the pressure on the CHF turns out to be negligible. ･･･Thesis (Ph. D. in Engineering)--University of Tsukuba, (A), no. 2357, 2000.3.24Includes bibliographical references (p. 98-105)CONTENTS,Abstract -- Nomenclature -- Chapter 1-Introduction -- Chapter 2-Review of the CHF Predictions for the Subcooled flow Boiling -- Chapter 3-Proposed Model for the Subcooled Flow Boiling CHF -- Chapter 4-Verification of the Model -- Chapter 5-Other Adaptations of the Model -- Chapter 6-Disussions on the Proposed Model -- Chapter 7-Conclusions -- Appendix1-Table:Data Used for the Model Verification -- Appendix2-Mathematics Demonstration for the Equal Wavelengths at the interfaces I and II -- Appendix3-CHF Calculation Procedure -- Reference -- Acknowledgement
