Research Article | OPEN ACCESS
Nonlinear Analysis of Onset of Nucleate Boiling in Natural Circulation under Different Pressure Conditions
Cheng Sheng, Tao Zhou, Lei Zhang and Zhongyun Ju
Institute of Nuclear Thermal-Hydraulic Safety and Standardization, North China Electric Power University, Beijing 102206, China
Research Journal of Applied Sciences, Engineering and Technology 2013 16:4123-4128
Received: July 27, 2012 | Accepted: September 17, 2012 | Published: April 30, 2013
Abstract
In this study, we obtain the flow signals before and after the ONB through natural circulation experiments under pressure conditions of 0.15MPa and 0.3MPa. Researches were conducted by applying nonlinear analysis techniques. Results revealed that the power spectrum of volume flow data declined exponentially over time in semi logarithmic coordinates, the autocorrelation coefficient declined gradually and the phase diagram exerted the subtle structures of chaotic movement, which might prove the existence of chaos in natural circulation system. The natural convection of single phase appeared before the occurrence of ONB belonged to a non equilibrium process which showed remarkable random features. The occurrence of ONB was a process containing the beginning of chaotic motion and the continuing occurrence of bubbles at ONB and the tendency of phase change to become nucleation boiling would achieve certain states, which embodied the characteristics of chaos. In addition, the intense density difference environment of natural circulation could accelerate the occurrences of both chaotic motion and ONB. While the density difference of heated liquid decreased with the increase of pressure, which could delay the occurrence of ONB.
Keywords:
Chaos, natural circulation, nonlinear, onset of nucleate boiling,
Competing interests
The authors have no competing interests.
Open Access Policy
This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Copyright
The authors have no competing interests.
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ISSN (Online): 2040-7467
ISSN (Print): 2040-7459 |
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