Turbulent Heat Transfer in a Rod Bundle With Liquid Metal Coolant.

Abstract

D B V~L~M T I P P O R T JULY-; # . ' JBREEDER REACTOR DEYELOPMEHT OPERAT1@1 G E N E R A L @ ELECTRIC LEGAL NOTICE C-2 Code Description 22 ABSTRACTThe coupled heat-transfer equations in the fuel, gap, cladding, and coolant have been solved for a triangular-spaced, close-packed fuel rod bundle with liquid metal coolant. The model includes temperature-dependent material properties, turbulent velocity distribution in the coolant, and contributions to coolant heat transfer by turbulent mixing.

Actual Problems of Thermal-Hydraulic Modelling in Fast Neutron Reactors

“…But if a digital computer is available, one can just as well treat both momentum transports simultaneously and use a two-dimensional orthogonal grid. This has been done by Bender et al [ 2 ] in the first of two reports on turbulent flow of liquid metals in rod bundles.…”

“…All the methods for prediction of detailed velocity and temperature fields for turbulent flow in rod bundles, reviewed in paragraph i 2.3.1, except those of Bender et al [2] and Ramm and Johannsen [74], rely on some kind of universal velocity distribution for calculation of the radial variation of the axial velocity.…”

“…The instantaneous value of the absolute velocity V may be written V = V (u + u' ) 2 + (v + v ) 2 + (w + w' ) 2 (1-41)…”

“…It seems reasonable to recommend that the :iet i-x^han^r due to turbulence and miscellaneous secondary flows is estimated as between25 To and 100 % oi the value predicted with eqs (2-4) -(2)(3)(4)(5)(6)(7)(8). On the average a reduction to 50 To of the predicted value, can be used winch gives an uncertainty of a factor of 2.0 in both directions.…”

“…It will be assumed that the momentum transport between subchannels, due to net cross-flows caused by the pressure differences which develop as a result of non-uniform heating, a non-uniform distribution of the spacer grid resistance and similar known disturbances, are accounted for in a proper manner. This matter is discussed in an earlier paper by the author It is therefore recommended that the turbulent exchange is estimated as 25 % of that calculated from eqs (2-4) - (2)(3)(4)(5)(6)(7)(8).…”