Theoretical Study on the Characteristics of Critical Heat Flux in Rectangular Channel of Natural Circulation under Motion Conditions

Mengmeng Xi,Wenxi Tian,Rong Cai,Xu Ran,Zhifang Qiu,Fan Yang,Jian Deng,Xiao Chu

doi:10.1155/2020/9390645

Abstract

With the wide application of sea-based reactors, the impact of ocean conditions on the safety performance of reactors has gradually attracted attention. In this paper, by establishing the thermal hydraulic transient analysis model and the critical heat flux (CHF) model of natural circulation system, the CHF characteristics in the rectangular channel of natural self-feedback conditions under ocean conditions are studied. The results show that the additional acceleration field generated by ocean conditions will affect the thermal hydraulic parameters of the natural circulation system, that is, the external macroscopic thermal hydraulic field. On the other hand, the boiling crisis mechanism will be affected, that is, the force on the bubble and the thickness of the liquid film. Within the parameters of the study, ocean conditions have a great impact on CHF of natural circulation, and the maximum degradation of CHF is about 45%. The obtained analysis results are significant to the improvement of design and safety operation of the reactor system.

Highlights

Critical heat flux (CHF) is one of the important safety guidelines for reactor thermal hydraulic design. e CHF is the heat flux when the heat transfer on the surface of the nuclear fuel element deteriorates. It is the result of the transition of the coolant flow boiling mechanism
According to the parameters such as the enthalpy and vapor content of the fluid, the DNB type and the Dryout type of boiling crisis phenomena may appear in the tube
If the boiling crisis occurs on the surface of the fuel element of the reactor, the surface temperature of the fuel element will be too high, causing the heated wall to burn out, and the radioactive material leaks, causing serious operational accidents, directly affecting the safety of the reactor

Summary

Introduction

Critical heat flux (CHF) is one of the important safety guidelines for reactor thermal hydraulic design. e CHF is the heat flux when the heat transfer on the surface of the nuclear fuel element deteriorates. E CHF is the heat flux when the heat transfer on the surface of the nuclear fuel element deteriorates. Critical heat flux (CHF) is one of the important safety guidelines for reactor thermal hydraulic design. It is the result of the transition of the coolant flow boiling mechanism. If the boiling crisis occurs on the surface of the fuel element of the reactor, the surface temperature of the fuel element will be too high, causing the heated wall to burn out, and the radioactive material leaks, causing serious operational accidents, directly affecting the safety of the reactor. In order to meet maneuverability, ship reactors need to change power frequently, and if necessary, natural circulation is a reliable way to remove heat without any driving components such as pumps

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Results

Conclusion