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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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High-performance once-through boiling of potassium in single tubes at saturation temperatures of 1500 deg to 1750 deg F - application to design of large power boiler
Effect of number of active nuclei on heat transfer rate in large-volume nucleate boiling
Density wave type flow oscillations in boiling Freon 11 examined, noting effects of partial evaporation superheat and liquid inlet temperature on stability
Rapid depressurization transients effect on saturated pool boiling system from stainless steel surface
Pool film boiling based on cellular model, postulating time-averaged cell configuration to adjust itself to maximize rate of heat transfer
Theoretical dimensionless correlation for vaporization times of drops in film boiling on flat plate in Leidenfrost state
Electric analog simulation of periodic nonuniform heat transfer mechanism in film boiling from coated plate
Zero gravity effects on boiling from flat horizontal surface for various subcoolings, fluid properties and heat transfer rates
Rohsenow nucleate pool-boiling data correlation, stressing coefficients dependence on surface preparation and liquid-surface combination
Sinusoidal surface vibration effect on nucleate pool boiling reveals lowered surface temperature for low heat flux, LF and high acceleration
Surface vibration effect on nucleate pool boiling, measuring heat-transfer coefficient and proposing mechanism
Laminar film boiling on thin wire, determining heat-transfer coefficient and vapor dome spacing and diameter
Vertical magnetic induction effect on nucleate boiling of mercury on horizontal heating surface
Relative velocity effect on vaporization times and heat-transfer coefficients of water drops in Leidenfrost film boiling on heated rotating wheel
The Cryogenic Boil-Off Reduction System was tested with LH2 and LOX in a vacuum chamber to simulate space vacuum and the temperatures of low Earth orbit. Testing was successful and results validated the scaling study model that predicts active cooling reduces upper stage cryogenic propulsion mass for loiter periods greater than 2 weeks.
In many convective liquid-vapor phase change heat transfer engineering applications, cryogenic fluids are widely used in industrial processes, spacecraft and cryosurgery systems, and so on. For example, cryogens are usually used as liquid fuels such as liquid hydrogen and oxygen in the rocket industry, liquid nitrogen (LN2) and helium are frequently used to cool superconducting magnetic device for medical applications. In these systems, proper transport, handling, and storage of cryogenic fluids are of extreme importance. Among all the cryogenic transport processes performed in room temperatures, quenching, also termed chilldown, is a unavoidable initial, transient phase-change heat transfer process that brings the system down to the cryogenic condition. The Leidenfrost temperature or rewet temperature that signals the end of film boiling is practically considered the completion point of a quenching process. Therefore, rewet temperature has been considered the most important parameter for the engineering design of cryogenic thermal management systems. As most of the previous correlations for predicting the Leidenfrost temperature and the rewet temperature have been basically developed for water, they are shown to disagree with recent liquid nitrogen pipe chilldown experiments in upward and downward flow directions over a wide range of flow rates, pressures, and degrees of inlet subcooling. In addition to a complete review of the literature, two new correlations are presented in this work, one based on bubble growth and another based on the theoretical maximum limit of superheat. Each correlation performs well over the entire data set.
A high-level description of the Flow Boiling and Condensation Experiment (FBCE) system capabilities, design and interface characteristics is presented. Each of the eight FBCE modules are discussed as well as the mechanical, electrical, and software interfaces with the Fluid Combustion Facility’s (FCF) Fluid Integration Rack (FIR), where the experiment will be installed for International Space Station (ISS) operations.
This study explores use of Computational Fluid Dynamics (CFD) to predict near-saturated flow boiling of FC-72 in microgravity. The computational method employs transient analysis to predict detailed interfacial behavior and heat transfer characteristics along a rectangular channel heated along two opposite walls. Predicted results are validated against experimental temperature measurements and high-speed video images captured during a series of parabolic aircraft maneuvers for three sets of operating conditions which include variations of both mass velocity and wall heat flux. The computational method is based on the multi-phase volume of fluid (VOF) model, which is combined with appropriate phase change and turbulence models, and accounts for both shear-lift force on bubbles and conjugate heat transfer along the heating walls. A key advantage of the CFD method is ability to capture details that are very difficult to measure experimentally, including detailed spatial variations of bubble shape, void fraction, mixture fluid temperature, liquid velocity, and vapor velocity, results for which are presented for each of the three test cases. Different flow regimes predicted along the heated length exhibit a number of dominant mechanisms including bubble nucleation, bubble growth, coalescence, vapor blankets, interfacial waviness, and residual liquid sub-layer, all of which agree well with experiment. Vapor velocity is shown to increase appreciably along the heated length because of increased void fraction, while liquid velocity experiences large fluctuations. Non-equilibrium effects are accentuated with increasing mass velocity, contributing minor deviations of fluid temperature from simulations compared to those predicted by the analytical method. Predicted wall temperature is fairly uniform in the middle of the heated length but increases in the entrance region, due to sensible heat transfer in the subcooled liquid, and decreases toward the exit, mostly because of flow acceleration resulting from increased void fraction.