Critical heat flux & two phase hydraulic investigation of a 16-rod simulation of a BWR fuel assembly

The combined effects of local power distribution and grid spacers on CHF were experimentally evaluated using an electrically heated 16 rod bundle simulation of a typical BWR fuel assembly. The single and two-phase hydraulic behavior of the test assembly was also evaluated. Data were obtained over a range of pressures (1000-1500 psia), mass velocities (0.5 x 10{sup 6} - 2.0 x 10{sup 6} lb/hr ft{sup 2}), and bundle-average exit qualities (0 - .40). CHF consistently occurred upstream of the last grid spacer indicating that the grid spacer improved coolant mixing downstream of it. CHF results compared well with other rod bundle CHF data available in the literature. Rod bundle two-phase pressure losses were accurately predicted via the COBRA code using the Homogeneous two-phase model in conjunction with empirically established single-phase hydraulic correlations for the bundle components

Momentum transfer in solids-gas flow.

Note: Missing page 542.The movement of a fluid stream relative to a solid boundary generates a complex syndrome of momentum transfer phenomena whose mechanisms still present fertile ground for investigation. The addition of solid particles to the fluid flow creates a new and even more complicated situation because of the interplay of momentum between the fluid-solid boundaries on the particles and the boundary containing the flow. In contrast with work in pure fluid flow, little has been done in the case of solids-gas movement, and the design of these systems remains, at times, a very costly art