Method for Generating a Complete Saturated Pool Boiling Curve for Cryogenic Fluids under Terrestrial Gravity

Constructing a complete and continuous boiling curve is a very challenging endeavor because correlations have historically been developed in individual studies only for specific boiling regimes or transition points, often using different fluids and operating conditions. The present study tackles systematically the complexities of this endeavor by relying on predictive correlations recently developed by the present authors for all individual pool boiling curve regimes and transition points for cryogenic fluids. It is shown how, by integrating the previous correlations and correcting for any discontinuities between correlations, a continuous saturated pool boiling curve can be constructed across the entire range of wall superheats and heat fluxes for all cryogens. The predicted boiling curves are validated against experimental data for key cryogens such as liquid helium, liquid hydrogen, and liquid nitrogen across varying pressure ranges. The critical heat flux is shown to decrease with increasing surface orientation angle, measured from horizontal upward facing, and this effect becomes more pronounced with increasing pressure. The heat transfer coefficient in both the nucleate boiling and film boiling regions increases with increasing pressure, but this trend, especially for nucleate boiling, is less evident at very high pressures. Reinforcing published trends, the decrease in the nucleate boiling heat transfer coefficient near the critical heat flux point is clearly captured, especially for cryogens with relatively high saturation temperatures, such as liquid oxygen and liquid methane. Additionally, the presented methodology shows the wall superheats for the critical heat flux and minimum heat flux points decrease with increasing pressure, excepting very high pressures. Overall, the methodology for generating the complete boiling curve for cryogens is validated over broad pressure ranges, up to 75 % of critical pressure (p = 0.75pc).