Effect of oscillations during reflooding of a tubular test section

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6350946

Oh, S J

Flow oscillations were observed during large-scale reflooding experiments such as FLECHT-SET and SEASET. To investigate the effect of such oscillations on quench velocities and heat transfer, a series of reflooding experiments were conducted with a vertical test section, 14.25 mm in inside diameter and 3.6 m long. The test section was electrically directly heated to initial wall temperatures in the range of 315 to 760C. Oscillations were imposed on the inlet flow corresponding to peak-to-peak variations of 0.30 to 1.52 m of water level in the test section. The period was varied between 2.0 and 6.0 seconds. A constant injection rate of 76 mm/s was superimposed to the oscillatory flow. The injection temperature was held at 24C and the exit pressure was atmospheric for all the experiments. At the beginning of the tests, the oscillations increase heat transfer downstream of the quench front, particularly in the dispersed-flow film-boiling heat transfer regime; the quench velocity is also increased. However, as reflooding progresses, the oscillations reduce the quench velocities to values well below those obtained with constant-injection reflooding. The quench times of 760C initial-wall-temperature runs were delayed by more than 100 seconds at the 8-ft elevation. The increase and decrease in quench velocity were accentuated as the oscillation amplitude and frequency increased.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 6350946
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
ACCIDENTS
BOILING
ENERGY TRANSFER
FILM BOILING
FLUID FLOW
HEAT TRANSFER
LOSS OF COOLANT
OSCILLATIONS
PHASE TRANSFORMATIONS
QUENCHING
REACTOR ACCIDENTS
REACTOR SAFETY
SAFETY
TEST FACILITIES