Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (5): 50603-050603.doi: 10.11889/j.0253-3219.2019.hjs.42.050603

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Studies on the onset of nucleate boiling in vertical rectangular flow channels

Ning CHENG1,Yun GUO1,Changhong PENG1(),Yong ZHANG2   

  1. 1. School of Physics, University of Science and Technology of China, Hefei 230026, China
    2. Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu 610213, China
  • Received:2019-01-21 Revised:2019-02-21 Online:2019-05-10 Published:2019-05-16
  • Contact: Changhong PENG E-mail:pengch@ustc.edu.cn
  • About author:CHENG Ning, male, born in 1991, graduated from University of Science and Technology of China in 2014, focusing on reactor thermal hydraulics|CHENG Ning, male, born in 1991, graduated from University of Science and Technology of China in 2014, focusing on reactor thermal hydraulics|PENG Changhong, E-mail: pengch@ustc.edu.cn
  • Supported by:
    Supported by National Key Research and Development Plan (No.2017YFE0300604), National Natural Science Foundation of China(No.11305169)

Abstract: Background

Vertical rectangular narrow flow channel has been widely used in engineering field due to its good heat transfer effect and compact structure. While the study on onset of nucleate boiling (ONB) site in vertical rectangular flow channels is very limited.

Purpose

This study aims to figure out the effects of inlet fluid temperature, mass flux and channel height by experiment in the vertical rectangular flow channels with 1.8 mm and 2.8 mm gaps respectively.

Methods

Visualization method was employed to observe the bubble growth and wall superheat at the ONB point under subcooled boiling condition. Deionized water was used as the working medium, a high-speed camera was used to photograph the growth process of bubbles and the temperature of the backing plate was recorded by thermocouples.

Results

It was found that the inlet temperature, mass flux and channel height had the same effects on the bubble growth and the wall superheat at the ONB point in the two flow channels. The bubble size of ONB point in two flow channels increases with the increase of the inlet temperature, and decreases with the increase of mass flow rate.

Conclusions

Under the condition of constant mass flow rate, the flow channel height has no significant effect on the bubble size at ONB point. The superheat degree of the ONB point in two flow channels decreases with the increase of inlet temperature and increases with the increase of the mass flow rate. The relationship between the wall superheat of ONB point and the heat flux is not affected by the flow path height and it can be predicted by the empirical formula in literature.Key words Vertical rectangular flow channel, Visual experiment, Onset of nucleate boiling point, Bubble growth, Wall superheat

CLC Number: 

  • TL331