A simple analytical model to predict the onset of Ledinegg instability in vertical channels under downflow conditions has been developed and evaluated. The model divides the flow field into three regions based upon the fluid temperature. The pressure drop is then found by solving an appropriate set of equations for each region. The theoretical results are compared to an extensive set of experimental data covering a range of channel diameters and operating conditions. Agreement is excellent, and the prediction of the velocity at which the minimum point in the demand curve occurs is within 12 percent over the range of experimental results. A parameter, the ratio between the surface heat flux and the heat flux required to achieve saturation at the channel exit for a given flow rate, is found to be a very accurate indicator of the minimum point velocity.

Issue Section:
Phase-Change and Multiphase Heat Transfer
Keywords:
Boiling, Flow Instability, Multiphase Flows
Topics:
Flow (Dynamics), Flow instability, Heat flux, Boiling, Fluids, Multiphase flow, Pressure drop, Temperature
1.
Block, J. A., Crowley, C. J., Dolan, F. X., Sam, R. G., and Stoedefalke, B. H., 1990, “Nucleate Boiling Pressure Drop in an Annulus,” CREARE TN 499, Oct.
2.
Collier, J. G., 1972, Convective Boiling and Condensation, McGraw-Hill, New York.
3.
Davis
E. J.
, and
Anderson
G. H.
,
1966
, “
The Incipience of Nucleate Boiling in Forced Convection Flow
,”
AIChE J.
, Vol.
12
, pp.
774
–
780
.
4.
Dittus, F. W., and Boelter, L. M. K., 1930, “Heat Transfer in Automobile Radiators of Tubular Type,” Publ. in Engineering, University of California, Berkeley, p. 443.
5.
Dormer, J., and Bergles, A. E., 1964, “Pressure Drop With Surface Boiling in Small Diameter Tubes,” Report No. 8767-3l, Department of Mechanical Engineering, MIT, Cambridge, MA
6.
Dougherty, T., Fighetti, C., McAssey, E., Reddy, G., Yang, B., Chen, K., and Qureshi, Z. C, 1989, “Flow Instability in Vertical Down-Flow at High Heat Fluxes,” ASME HTD-Vol. 199, pp. 17–23.
7.
Dougherty, T., Fighetti, C., Reddy, G., Yang, B, Jafri, T., McAssey, E., and Qureshi, Z., 1990, “Flow Boiling in Vertical Downflow,” Proc. Ninth International Heat Transfer Conference, Vol. 2, Jerusalem, Israel.
8.
Duffey, R. B., and Hughes, E. D., 1990, “Static Flow Instability in Tubes, Channels, Annuli, and Rod Bundles,” ASME HTD-Vol. 150, pp. 145–159.
9.
Johnston, B. S., 1989, “Subcooled Boiling of Downward Flow in a Vertical Annulus,” ASME HTD-Vol. 109, pp. 149–156.
10.
Lahey, R. T., and Moody, E. J., 1977, The Thermal Hydraulics of a Boiling Water Nuclear Reactor, American Nuclear Society.
11.
Lee, S. C., Dorra, H., and Bankoff, S. G., 1992, “A Critical Review of Predictive Models for the Onset of Significant Void in Forced-Convection Subcooled Boiling, Fundamentals of Subcooled Flow Boiling,” ASME HTD-Vol. 217, pp. 33–39.
12.
Levy
S.
,
1967
, “
Forced Convection Subcooled Boiling Prediction of Vapor Volumetric Fraction
,”
Journal of Heat and Mass Transfer
, Vol.
10
, pp.
951
–
965
.
13.
Marshek, S., 1958, “Transient Flow of Boiling Water in Heated Tubes,” Savannah River Laboratory Report DP-301TL
14.
Maulbetsch, J. S., and Griffith, P., 1966, “A Study of System Induced Instabilities in Forced-Convective Flows With Sub-cooled Boiling,” Report No. 5382-35, Department of Mechanical Engineering, MIT, Cambridge, MA
15.
Saha, P., and Zuber, N., 1974, “Point of Net Vapor Generation and Vapor Void Fraction Subcooled Boiling,” Proc. Fifth International Heat Transfer Conference, B4.7, Tokyo, Japan.
16.
Thom, J. R. S., Walker, W. M., Fallon, T. A., and Reising, G. F. S., 1965, “Boiling in Subcooled Water During Flow Up Heated Tube Annuli,” presented at the Symposium on Boiling Heat Transfer in Steam Generating Units and Heat Exchangers, Inst. Mech. Engrs., Manchester, United Kingdom, Paper No. 6.
17.
Whittle
R. H.
, and
Forgan
R.
,
1967
, “
A Correlation for the Minimum in Pressure Drop Versus Flow-Rate Curves for Sub-cooled Water Flowing in Narrow Heated Channels
,”
Nuclear Engineering and Design
, Vol.
6
, pp.
88
–
89
.
18.
Zigrang
D. J.
, and
Sylvester
N. D.
,
1982
, “
Explicit Approximations to the Solution of Colebrook’s Friction Factor Equation
,”
AIChE Journal
, Vol.
28
, No.
3
., pp.
514
–
515
.
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