Study of Heat Transfer Correlations for Supercritical Hydrogen in Regenerative Cooling Channels

Understanding the cooling efficiency of supercritical hydrogen is crucial to the development of high-pressure thrust chambers for regeneratively cooled liquid-oxygen/liquid-hydrogen rocket engines. Available Nusselt number correlations are compared with an extensive data set of local heat transfer coefficients to determine the domains of validity for each correlation. The data set was compiled from previous heated straight-tube experiments with supercritical hydrogen. Results indicate that particular correlations perform better than others for certain regimes of fluid properties, with the accuracy of heat transfer coefficient predictions ranging from ±23±23 to over ±100%±100%. Correlation uncertainty due to inherent uncertainties in the equation-of-state and transport properties of supercritical hydrogen is also evaluated. The property dependent uncertainty was found to range from 2 to 10%, and therefore is not the main contributor to the larger errors in the correlation predictions. A number of published correlations for nonhydrogen supercritical fluids are shown to achieve comparable performance with hydrogen. [PUBLISHER ABSTRACT]