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The analysis of two-phase flow instability in a vertical U-tube evaporator

Die Berechnung von Instabilitäten von Zwei-Phasenströmungen in einem senkrechten U-Rohrverdampfer

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Abstract

This paper describes both the experimental and theoretical analysis of two-phase flow instability in a vertical U-tube evaporator. In the experiment investigation the effects of various parameters on flow instability are studied by using Freon-12 as working medium and the influence of flow oscillations on heat transfer deterioration is obtained. The mathematical model to describe flow oscillations occurring in the vertical U-tube with flow stagnation and upward movement of bubbles due to buoyancy in the heated downcomer is developed. The finite differential equations are solved by using a modified two-step iteration technique. The calculated results are in good agreement with the experimental data.

Zusammenfassung

Dieser Aufsatz beschreibt sowohl die experimentelle als auch die theoretische Analyse von instabiler Zwei-Phasenströmung in einem senkrechten U-Rohrverdampfer. In der experimentellen Untersuchung wurden die Effekte von verschiedenen Parametern auf die Instabilität der Strömung untersucht, wobei Freon-12 als Arbeitsmedium benutzt wird und der Einfluß der Oszillation der Strömung auf die Verschlechterung der Wärmeübertragung herausgefunden wird. Es wird ein mathematisches Modell entwickelt, welches die Oszillation der Strömung beschreibt, die in dem senkrechten U-Rohr mit Strömungsstagnation und Aufwärtsbewegung von Blasen, infolge von Auftrieb in dem geheizten Rücklaufrohr, auftritt. Die Finite-Differenzen-Gleichungen werden mittels einer modifizierten Zwei-Schritt-Iterationstechnik gelöst. Die errechneten Ergebnisse stimmen gut mit den experimentellen Daten überein.

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Abbreviations

A :

cross sectional area

C f :

coefficient

C p :

specific heat

D :

diameter of tube

f fo :

friction factor based on total flow assumed liquid

Fr :

Froude number

G :

mass velocity

g :

acceleration due to gravity

h :

enthalpy of fluid

¯ h :

heat transfer coefficient

hfg :

latent heat of vaporization

P :

pressure

Pc :

critical pressure

Q :

heat flux

Re :

Reynolds number

S :

slip ratio

T :

temperature

t :

time

v :

velocity

x :

mass vapour quality

z :

space coordinate

α :

void fraction

β :

volumetric quality

θ :

time weighting constant

¯θ :

angle to horizontal plane

λ :

thermal conductivity

μ :

viscosity

θ :

density

σ :

surface tension

Φ :

time weighting constant

φ 2f0 :

two-phase frictional multiplier based on pressure gradient for total flow assumed liquid

b :

bulk

f :

liquid

g :

vapour

gj :

drift

i,i+1,i−1:

spatial noding index

n,n+1,n−1:

time level index

w :

wall

References

  1. Zhong-qi, Lu; Rui-chang, Yang; De-qiang, Shi: An experimental study of CHF in a U-tube by fluid modeling. China-U.S. Seminar on Two-Phase Flows and Heat Transfer, Xian 1984

  2. Tsuchiya, T. et al.: Hydrodynamic stability tests for LMFBR sodium heated steam generators. In: Two-phase flow dynamics (eds.: Bergles, A. E.; Ishigai, S.). New York: Hemisphere 1981

    Google Scholar 

  3. Bouré, J. A.; Bergles, A. E.; Tong, L. S.: Review of two-phase flow instability. Nucl. Eng. Des. 25 (1973) 165–192

    Google Scholar 

  4. Bergles, A. E.: Review of instability in two-phase system In: Two-phase flows and heat transfer (eds.: Kakac, S.; Mayinger, F.). New York: Hemisphere 1977

    Google Scholar 

  5. Kakac, S.; Veziroglu, T. N.: A review of two-phase flow instabilities. In: Advances in two-phase flows and heat transfers (eds.: Kakac, S.; Ishii, M.). Sijhoff & Noordhoff 1983

  6. Klaziakova, L. V.; Gloskel, B. N.: On flow stability in U-type element of once through boilers. Teploenergetika 11, USSR 1963

  7. Aritomi, M.; Aoki, D.; Narabayashi, T.: Instabilities in parallel channel of forced-convection boiling upflow system (IV). J. Nuc. Sci. Technol. 18 (1981) 324–340

    Google Scholar 

  8. Solberg, K. O.; Bakstad, P.: A model for the dynamics of nuclear reactors with boiling coolant with a new approach to the vapour generation process. Euratom Report, Proc. Symp. Two-Phase Flow Dynamics, Eindhoven 1967

  9. Crump, M. W.; Lee, J. C.: Nonlinear transient analysis of nuclear steam generator. Nucl. Sci. Eng. 77 (1981) 192–210

    Google Scholar 

  10. Kornfilt, J.; Lee, J. C.: Stability analysis of boiling water system and steam generators. Proc. 2nd Int. Topical Meeting on Nuclear Reactor Thermal-Hydraulics, California 1983

  11. Chatoorgoon, V.; Thibeault, P. R.: Sports — on advanced thermal-hydraulic stability code. ANS Proc. 1985 National Heat Transfer Conference, Colorado 1985

  12. Ishii, M.: Thermo-fluid dynamic theory of two-phase flow. Paris: Eyrolles 1975

    Google Scholar 

  13. Collier, J. G.: Convective boiling and condensation. Second Edition. New York: McGraw-Hill 1981

    Google Scholar 

  14. Wallis, G. B.: One-dimensional two-phase flow. New York: McGraw-Hill 1969

    Google Scholar 

  15. Zuber, N. et al.: Steady state and transient void fraction in two-phase flow systems. GEAP 5417 (1967)

  16. Rui-chang, Yang: The study of two-phase flow instability in a vertical U-tube evaporator. Ph.D. Thesis, Tsinghua University 1987

  17. Miropolskiy, Z. L. et al.: Vapour void fractions for forced steam-water mixture flow in heated and adiabatic channels. Teploenergetika 5, USSR 1971

  18. Dittus, F. W.; Boelter, L. M. K.: Heat transfer in automobile radiators of the tubular type. Univ. of Calicornia-Publ. (in English) 2 (1930)

  19. Chen, J. C.: A correlation for boiling heat transfer to saturated fluids in convective flow. ASME psper 63-HT-34 (1963)

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Authors and Affiliations

  1. Department of Thermal Engineering, Tsinghua University, Beijing, The People's Republic of China

    R. C. Yang, J. K. Feng & Z. Q. Lu

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  1. R. C. Yang
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  2. J. K. Feng
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  3. Z. Q. Lu
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Yang, R.C., Feng, J.K. & Lu, Z.Q. The analysis of two-phase flow instability in a vertical U-tube evaporator. Warme- und Stoffubertragung 23, 127–136 (1988). https://doi.org/10.1007/BF01376544

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  • DOI: https://doi.org/10.1007/BF01376544

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