Multiphase Science and Technology A Quarterly

ISSN for PRINT: 0276-1459

For Online Access

Best Paper Award Selection - Editorial Board Site

1993, Volume7

Issue 1-4

440 pages

Issue price - $560.00

Kemal Tuzla
Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015, USA

C. Unal
Lehigh University, P C Rossin College of Engineering and Applied Science, 19 Memorial Drive West, Bethlehem, PA, USA

John C. Chen
Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015, USA

This contribution describes post-CHF heat transfer experiments in a 3×3 rod bundle. The objective of these experiments was to obtain measurements of thermodynamic non-equilibrium in the post-CHF regime and to characterize its effects on two-phase heat transfer.
The nine rod test bundle incorporated a heated shroud to simulate the operating characteristics of a large rod bundle. A special 'hot patch' technique was developed and used successfully to achieve steady-state post-CHF conditions in rod bundle. Special steam temperature probes, developed earlier for tests in single tubes, were modified for use in the rod bundle. Each test provided measurements of system pressure, coolant flow rate, wall heat flux, wall temperatures, two-phase equilibrium qualities, and vapour superheat temperatures.
Experiments were conducted in three different modes: a) steady-state experiments with fixed-CHF location, b) reflood experiments with slowly advancing-CHF locations, c) boil-off experiments with retreating-CHF locations. A total of 468 data points were generated from 144 experimental runs in the following range of conditions.

Coolant mass flux        0.1 to 26 kg/m2s

Inlet quality            40°C subcooled to 0.40

Pressure                 105 to 120 kPa

Heat flux                5 to 43 kW/m2

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