Heat-transfer characteristics of cryogenic hydrogen from 1000 to 2500 psia flowing upward in uniformly heated straight tubes

SUMMARY Some heat-transfer characteristics of cryogenic hydrogen flowing vertically upward in uniformly joule-heated straight tubes were assessed over the pressure range of 1000 to 2500 psia. The fluid appeared to exhibit gas-like behavior in this regime. Heat-transfer data for the most part were predictable to -+20 per- cent by the Nusselt-film correlation Nuf = CRefPrf p 0.4 where C = 0.021 and p = 0.8. A closer examination, however, of the data for each test section indicated that the Reynolds number exponent p can vary be- tween 0.83 and 0.9 with the constant C changed correspondingly from 0.011 to 0.006. These correlations hold for heat fluxes up to 10 Btu per square inch per second, wall-to-bulk temperature ratios to 11, mass-flow rates to 0.4 pound mass per second, film Reynolds number from lo5 to 4X1O6, and inside tube diame- ters from 0.21 to 0.438 inch; the effects of length-to-diameter ratio and Mach number were not established under all conditions. Corresponding friction factor data for these test sections are not presented.