Experimental study of natural circulation flow instability in rectangular channels

T. Zhou; S. Qi; M. Song; Z. Xiao

doi:10.3139/124.110654

Enjoy 40% off

academic books on De Gruyter Brill *

Article

Experimental study of natural circulation flow instability in rectangular channels

T. Zhou , S. Qi , M. Song and Z. Xiao

Published/Copyright: February 28, 2022

Published by

Become an author with De Gruyter Brill

Submit Manuscript Author Information

From the journal Kerntechnik Volume 82 Issue 2

Abstract

Experiments of natural circulation flow instability were conducted in rectangular channels with 5 mm and 10 mm wide gaps. Results for different heating powers were obtained. The results showed that the flow will tend to be instable with the growing of heating power. The oscillation period of pressure D-value and volume flow are the same, but their phase positions are opposite. They both can be described by trigonometric functions. The existence of edge position and secondary flow will strengthen the disturbance of fluid flow in rectangle channels, which contributes to heat transfer. The disturbance of bubble and fluid will be strengthened, especially in the saturated boiling section, which make it possible for the mixing flow. The results also showed that the resistance in 5 mm channel is bigger than that in 10 mm channel, it is less likely to form stable natural circulation in the subcooled region.

Abstract

Experimentelle Untersuchungen der Strömungsinstabilität von Naturumlaufsystemen wurden in rechteckigen Kanälen mit 5 mm und 10 mm Abständen durchgeführt. Es wurden Ergebnisse für verschiedene Wärmeleistungen erhalten. Die Ergebnisse zeigen, dass die Strömung mit wachsender Wärmeleistung zur Instabilität neigt. Die Schwingungsperioden von Druckschwankungen und Volumenstrom sind gleich, aber ihre Phasenpositionen sind entgegengesetzt. Beide können durch trigonometrische Funktionen beschrieben werden. Das Vorhandensein von Randlagen und einer Sekundärströmung verstärkt die Störung der Flüssigkeitsströmung in rechteckigen Kanälen, was zum Wärmetransfer beiträgt. Die Störung von Blasen und Flüssigkeit verstärkt sich, insbesondere beim gesättigten Sieden. Die Ergebnisse zeigen auch, dass der Widerstand in einem 5 mm Kanal größer ist als in einem 10 mm Kanal. Es ist deshalb weniger wahrscheinlich in der unterkühlten Region einen stabilen Naturumlauf zu bilden.

Acknowledgements

(1) CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Foundation (20130901); (2) Natural Science Foundation of China (50976033).

References

1 Krishnan, V. S.: Stability of natural-circulation flow in a CANDU-type fuel channel. Nuclear Engineering and Design 99 (1985) 403–412, DOI:10.1016/0029-5493(87)90136-110.1016/0029-5493(87)90136-1Search in Google Scholar

2 Sun, Z.; Tan, H.; Yan, C.: Flow instability in vertical narrow annuli with both subcooled and saturated boilings. Journal of Harbin Institute of Technology 35 (2003) 1499–1502Search in Google Scholar

3 Furuya, M.; Inasa, F.; van der Hagen, T. H. J. J.: Flashing induced density wave oscillations in a natural circulation BWR – mechanism of instability and stability map. Nuclaer Engineering and Design 235 (2005) 1557–1569, DOI:10.1016/j.nucengdes.2005.01.00610.1016/j.nucengdes.2005.01.006Search in Google Scholar

4 Tan, S.; Pang, F.; Gao, P.: Experimental Research on Subcooled Boiling Flow Instability of Natural Circulation. Nuclear Power Engineering 27 (2006) 18 –21Search in Google Scholar

5 Zhang, W.; Tan, S.; Gao, P. et al.: Non-linear time series analysis on flow instability of natural circulation under rolling motion condition. Annals of Nuclear Energy 65 (2014) 1–9, DOI:10.1016/j.anucene.2013.10.02010.1016/j.anucene.2013.10.020Search in Google Scholar

6 Tan, S. C., Su, G.H., Gao, P. Z.: Experimental study on two-phase flow instability of natural circulation under rolling motion condition. Ann. Nucl. Energy 36 (2009) 103–113, DOI:10.1016/j.anucene.2008.09.01410.1016/j.anucene.2008.09.014Search in Google Scholar

7 Basu, D. N.; Bhattacharyya, S.; Das, P. K.: Influence of geometry and operating parameters on the stability response of single-phase natural circulation loop. International Journal of Heat and Mass Transfer 58 (2013) 322–334, DOI:10.1016/j.ijheatmasstransfer.2012.11.06310.1016/j.ijheatmasstransfer.2012.11.063Search in Google Scholar

8 Zhou, T.; Dexun, H.; Ke, R.; Ziwei, S.: Research on mechanism of flow excursion in narrow rectangle channel under natural circulation. Nuclear Engineering and Design 254 (2013) 1–4, DOI:10.1016/j.nucengdes.2012.08.01610.1016/j.nucengdes.2012.08.016Search in Google Scholar

9 Zhou, T.; Duan, J.; Hong, D.: Characteristics of Single Bubble in Subcooled Boiling Region in Narrow Rectangular Channel under Natural Circulation. Annals of Nuclear Energy 57 (2013) 22–31, DOI:10.1016/j.anucene.2013.01.05210.1016/j.anucene.2013.01.052Search in Google Scholar

10 Li, J.; Zhou, T.; Ju, Z.; Huo, Q.; Xiao, Z.: Sensitivity analysis of CHF parameters under flow instability by using a neural network method. Annals of Nuclear Energy 71 (2014) 211–216, DOI:10.1016/j.anucene.2014.03.04010.1016/j.anucene.2014.03.040Search in Google Scholar

11 Watanabe, T.; Anoda, Y.; Takano, M.: System-CFD coupled simulations of flow instability in steam generator U tubes. Annals of Nuclear Energy 70 (2014) 141–146, DOI:10.1016/j.anucene.2014.02.02910.1016/j.anucene.2014.02.029Search in Google Scholar

12 Duan, J.: Study of Flow Instability in Narrow Rectangular Channel under Natural Circulation. North China Electric Power University, 2014Search in Google Scholar

Books · Bücher

Cyclotron Produced Radionuclides: Emerging Positron Emitters for Medical Applications: ⁶⁴Cu and ¹²⁴I. IAEA Radioisotopes and Radiopharmaceuticals Reports No. 1, Published by the International Atomic Energy Agency 2016, ISBN 978-920-109615-9, 63 pp., 38.00 EUR.

The application of radionuclides in medicine has undergone significant growth in the last two decades, with the availability of a large number of cyclotrons exclusively dedicated to their production contributing to this growth. The widespread use of positron emission tomography (PET) in oncology and the rapid dissemination of PET-computed tomography (PET-CT) cameras throughout the world have revolutionized nuclear medicine.

New radiopharmaceuticals which can be routinely used for diagnosis or for evaluation of cancer therapy would be valuable additions to the arsenal available. There is great potential for production and development of new radiopharmaceuticals using PET radionuclides other than ¹⁸F and ¹¹C at most of the present day medical cyclotron facilities with cyclotrons in the energy range of 10 – 20 MeV. Cyclotron time is usually available for research, but there are several other factors to be addressed in the development and use of new radiopharmaceuticals. More than 30 potentially useful cyclotron produced positron emitting radionuclides have been reported, and ⁶⁴Cu and ¹²⁴I in particular have received considerable attention. Because of low positron energy, low abundance of gamma radiation, suitable half-life and favourable coordination chemistry, these radionuclides are attracting widespread interest. There are two major challenges in wider production of these PET tracers:

The targets for the production of these radionuclides are not widely available or are considered too difficult to use.
The separation of the radionuclide from the target material requires ion exchange chromatography or thermal diffusion and the labelling efficiency of the resultant nuclide needs to be further developed.

This IAEA publication was initiated following a coordinated research project (CRP) on “Production and Utilisation of Emerging Positron Emitters for Medical Applications with an Emphasis on ⁶⁴Cu and ¹²⁴I” with participation of 15 institutions worldwide and with the aim to enhance the capability of Member States in production of emerging positron emitters for medical applications in order to meet the demand for new PET based diagnostic agents for specific diseases and provide improved dosimetry of therapeutic radionuclides. This publication is intended to provide broad information (with ample references for those who wish to go deeper) on better production routes and better separation and purification of these PET radionuclides so as to achieve high specific activity and chemical purity suitable for labelling molecules of medical interest and also enable fruitful use of the spare capacity available in medical cyclotron centres.

Guidance provided here, describing good practices, represents expert opinion but does not constitute recommendations made on the basis of a consensus of Member States.

This publication provides methods and guidelines on development of targets (making use of standardized nuclear data) capable of producing sufficient quantities of ⁶⁴Cu and ¹²⁴I for clinical investigations, chemistry for the separation of radionuclides from target materials to improve extraction and purity of the radionuclides and to minimize metal contaminants which might reduce the labelling efficiency, and development of new radiopharmaceuticals labelled with these non-standard PET radionuclides.

This publication contains sections on production of ⁶⁴Cu and ¹²⁴I; techniques for preparation of targets, irradiation of targets under high beam currents, target processing and target recovery; and conclusions. The accompanying CD-ROM, which supports the book, contains accounts of the participants’ work during the CRP demonstrating the successful application of the principles described in the publication. These are the unedited reports of the CRP participants as presented at the final research coordination meeting.

Received: 2016-06-26

Published Online: 2022-02-28

You are currently not able to access this content.

Articles in the same Issue

https://doi.org/10.3139/124.110654