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Abstract

This paper presents a comparison of the dynamical behaviours manifested by two singlephase experimental natural circulation loops. Both of the loops are rectangular and symmetric, with a heat source and a heat sink placed respectively at the bottom and at the top of the loop. The main differences between the two loops are their height and width, the inner diameter of their pipes and the length of the heating and cooling sections. In order to emphasize the differences in the dynamical evolution, the comparison was performed considering the same operating conditions. A phase space representation was chosen, so as to guarantee an adequate representation of the complex non-linear process dynamics. The proposed analysis, which is based on the morphological description of the attractors and on the evaluation of their correlation dimension, aims to give a preliminary characterization of the behaviours of the natural circulation loops under comparison. The proposed approach allowed it to be demonstrated that the differences of geometry lead to substantial changes in the dynamics that the two experimental loops may manifest for the same operating condition, defined by the heat power supplied to the fluid. In particular, reported results show that for some values of the heat power one of the experimental loops displays periodic oscillations whereas the other is governed by chaos.

Keywords

natural circulation loop chaos attractor morphology fractal dimension

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References

Vijayan

P. K.

Nayak

A. K.

Pilkhwal

D. S.

Saha

Venkat

Effect of loop diameter on the stability of single-phase natural circulation in rectangular loops. In Proceedings of 5th International Topical Meeting on

Reactor Thermal Hydraulics—NURETH-5, 1992, vol. 1, pp. 261–267.

Cammarata

Fichera

Fortuna

Xibilia

M. G.

Bifurcation in a natural circulation loop. In Proceedings of Nolta ‘98, 1998.

Frogheri

Misale

D'Auria

Instabilities in single-phase natural circulation: Experiments and system code simulation. In Proceedings of 15th UIT National Heat Transfer Conference, 1997.

Wang

Singer

Bau

H. H.

Controlling chaos in a thermal convection loop. J. Fluid Mechanics, 1992, 37, 479–498.

Gorman

Widmann

P. J.

Robins

K. A.

Chaotic flow regimes in a convection loop. Phys. Rev. Lett., 52, 1984, 2241–2244.

Lorenz

E. N.

Deterministic nonperiodic flow. J. Atmos. Sci., 1963, 20, 131–141.

Abarbanel

H. D. I.

Analysis of Observed Chaotic Data, 1995 (Institute for Non-Linear Science Editions, San Diego, California).

Thompson

J. M.T.

Stewart

H. B.

Nonlinear Dynamics and Chaos, 1986 (John Wiley, New York).

Rasband

S. N.

Chaotic Dynamics of Nonlinear Systems, 1990 (John Wiley, New York).

10.

Takens

Lecture Notes in Mathematics, Dynamical System and Turbulence (Eds Rand

D. A.

Young

L. S.

), 1981 (Springer, New York).

11.

Cammarata

Fichera

Pagano

Nonlinear analysis of a rectangular natural circulation loop. Int. Commun. Heat Mass Transfer, 2000, 27, 1077–1089.

12.

Banbrook

McLaughlin

Mann

Speech characterization and synthesis by nonlinear methods. IEEE Trans. Speech Audio Processing, 1999, 7, 1–17.

13.

Merkwirth

Parlitz

Lauterborn

TSTOOL—a software package for nonlinear time series analysis. In Proceedings of the International Workshop on

Advanced Black-Box Techniques for Nonlinear Modeling (Eds Suykens

J. A.

Vandewalle

), 1998, pp. 144–146.

14.

Rodriguez-Bernal

Van Vleck

E. S.

Diffusion induced chaos in a closed loop thermosyphon. SIAM J. Appl. Math., 1998, 58 (4), 1072–1093.

Comparison of the dynamical behaviour of rectangular natural circulation loops

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