Heat transfer near spacer grids in rod bundles

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5326683

Yoder, G L

Heat transfer data from several sources have been assembled which show the effect of spacer grids on local heat transfer within a rod bundle. Both single phase (air and steam) data and two phase (steam/water) data show heat transfer augmentation in the grid region. Heat transfer improvement immediately beyond the grid ranges from a few percent to over fifty percent in these experiments, depending on flow conditions. The data are examined using several nondimensional parameters which relate the above effects to known quantities. The relative effect of the grid on local heat transfer is altered by both the Reynolds number and blockage ratio. Twenty to thirty hydraulic diameters are required before the local effect of the grid dissipates. Locally, both the single phase and two phase data show the same trends. Comparison of the single and two phase data also shown some differences. Some film boiling data indicate that an altered heat transfer regime may exist near the grid. High rod heat transfer coefficients at the grid locations indicate either a rewet of the rods or at least a change from film boiling to transition boiling near the spacer. The comparison also indicates that the film boiling data is affected on a global as well as local basis. This is due to the effect of the grid on the liquid distribution.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5326683
• Report Number(s): CONF-850810-25; ON: DE85016312
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220300* -- Nuclear Reactor Technology-- Fuel Elements
42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
BOILING
ENERGY TRANSFER
FILM BOILING
HEAT TRANSFER
PHASE TRANSFORMATIONS
ROD BUNDLES
SPACERS