# Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2013, Vol. 24 ›› Issue (6): 060601

• NUCLEAR ENERGY SCIENCE AND ENGINEERING •

### Mechanism of ONB based on nonequilibrium thermodynamics of natural circulation in narrow channels

ZHOU Tao1 LI Jingjing 1,* LIU Ping 1 SHENG Cheng 1#br# HUANG Yanping 2 XIAO Zejun 2

1. 1Institute of Nuclear Thermal-Hydraulic Safety and Standardization, North China Electric Power University, Beijing 102206, China
2National Key Laboratory of Bubble Physics and Natural Circulation, Chengdu 610041, China
• Contact: LI Jingjing E-mail:lijingjing604@126.com
• Supported by:

Supported by National Natural Science Foundation of China (No.50976033), National Key Laboratory of Bubble Physics and Natural Circulation (No.9140C7 101030905) and North China Electric Power University’s 211 Project

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ZHOU Tao, LI Jingjing, LIU Ping, SHENG Cheng. Mechanism of ONB based on nonequilibrium thermodynamics of natural circulation in narrow channels.Nuclear Science and Techniques, 2013, 24(6): 060601

Abstract:

Based on the experiment of onset of nucleate boiling (ONB) in natural circulation and the nonequilibrium thermodynamics dissipative theory, the mechanism of ONB in narrow rectangle channels of natural circulation is proposed. It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels. Under the conditions of both density difference in natural circulation and narrow rectangle channels, the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established. The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels. Features of ONB in natural circulation narrow rectangle channels are as follows: heating power is the incentive of the happen of ONB; the higher the heating power is, the higher the degree of superheat is, and the earlier the ONB will appear. With the pressurizing, the appearance of ONB will be delayed. The higher the degree of supercooling is, the later the ONB appears. The ONB will happen easier when there are noncondensable gases and roughness in the channels.