IMPROVED METHOD OF PREDICTING SURFACE TEMPERATURES IN HYDROGEN-COOLED NUCLEAR ROCKET REACTOR AT HIGH SURFACE-TO BULK-TEMPERATURE RATIOS

摘要

In extrapolating presently used gaseous-hydrogen heat-transfer correlations to conditions far removed from the experimental points, unexplained behavior in the predicted results of such equations has been noted. Experimentally, under the proper circumstances, a small reduction in the bulk hydrogen temperature can cause an increase rather than a decrease in the surface temperature of a constant-heat-flux test specimen. Mathematically, the correlations used at the present time exhibit the same effect, but usually to a much greater degree, and result in some questionable values at higher sur face temperatures.nTo determine whether a more accurate method of predicting heat transfer at high surface- to bulk-temperature ratios is available, various correlations were examined. The result of this examination indicates that a correlation is available which achieves an appreciable decrease in the data scatter and at the same time reduces (but does not eliminate) the anomaly noted with equations now commonly used. The range of variables considered in this investigation were: (1) the ratio of distance from entrance L to hydraulic diameter D between 10 and 240, (2) the bulk fluid temperature from 200° to 2800° R, and (3) the ratio of wall temperature to bulk fluid temperature between 1. 1 and 8. 0.