Critical Heat Flux and Pressure Drop Tests with Parallel Upflow of High Pressure Water in Bundles of Twenty ¾-in. Rods

Critical heat flux and pressure drop tests were run with vertical upflow of water parallel to 20-rod bundles of rods at 1200 to 2000 psia and mass velocities from 0.15 × 10⁶ to 3.0 × 10⁶ lb/(h ft²). The heated rods were 0.75-in. o.d. × 94-in. heated length, spaced by warts in a 5 × 4 array on a 0.765-in. equilateral-triangular pitch in a rhombic shroud box. Tests were run both with all rods uniformly heated and with a linear-transverse heat-flux distribution, with and without protrusions to minimize the effect of large peripheral channels.