Downward flow of water with entrained air in a nonuniformaly heated subdivided annulus

Conference · Thu Oct 01 04:00:00 EDT 1992

OSTI ID:10183300

Johnston, B S; May, C P

This paper describes an experimental study in which water was fed to a vertical annulus, entraining air in downward flow. The annulus was subdivided by longitudinal fins into four subchannels and was heated with an azimuthally varying heat flux. A bypass was provided to simulate flow in parallel channels. For steady liquid flow, inlet temperature, and pressure boundary conditions, the power was increased until critical heat flux was reached. Overheating characteristics were grouped according to the prevailing flow pattern. In annular flows (j{sub L} < 0.3 m/s) overheating of the whole test section occurs when steam production causes countercurrent flooding. In intermittent flows (0.3 < j{sub L} < 0.9 m/s) the overheating is confined to a portion of the hot subchannel. The mechanism is postulated to be stagnation of a large bubble. In bubble flows (0.9 m/s < j{sub L}) overheating occurs by diverting inlet flow to the bypass and again involves the whole test section. Except at the very lowest flow rates, critical heat flux occurs when the effluent liquid temperature is below saturation.

• Research Organization: Westinghouse Savannah River Co., Aiken, SC (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC09-89SR18035
• OSTI ID: 10183300
• Report Number(s): WSRC-MS--91-416; CONF-920804--25; ON: DE93000593
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400
AIR
ANNULAR SPACE
BOILING
BUBBLES
FLOW MODELS
HEAT TRANSFER
HEAT TRANSFER AND FLUID FLOW
HEATING
HYDRAULICS
LOSS OF COOLANT
REACTOR COOLING SYSTEMS
TWO-PHASE FLOW
WATER