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Results for “heat of vaporization”

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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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Process Feasibility Study in Support of Silicon Material Task 1

Analysis of process system properties was continued for silicon source materials under consideration for producing silicon. The following property data are reported for dichlorosilane which is involved in processing operations for silicon: critical constants, vapor pressure, heat of vaporization, heat capacity, density, surface tension, thermal conductivity, heat of formation and Gibb's free energy of formation. The properties are reported as a function of temperature to permit rapid engineering usage. The preliminary economic analysis of the process is described. Cost analysis results for the process (case A-two deposition reactors and six electrolysis cells) are presented based on a preliminary process design of a plant to produce 1,000 metric tons/year of silicon. Fixed capital investment estimate for the plant is $12.47 million (1975 dollars) ($17.47 million, 1980 dollars). Product cost without profit is 8.63 $/kg of silicon (1975 dollars)(12.1 $/kg, 1980 dollars).

Li, K. Y.↗
NASA NTRS1947

Analytical Treatment of Normal Condensation Shock

The condensation of water vapor in an air consequences: acquisition of heat (liberated heat vaporization; loss of mass on the part of the flowing gas (water vapor is converted to liquid); change in the specific gas constants and of the ratio k of the specific heats (caused by change of gas composition). A discontinuous change of state is therefore connected with the condensation; schlieren photographs of supersonic flows in two-dimensional Laval nozzles show two intersecting oblique shock fronts that in the case of high humidities may merge near the point of intersection into one normal shock front.

Heybey↗
NASA NTRS1994

The effects of turbulence on droplet drag and secondary droplet breakup

The objective of this research is to obtain an improved understanding of the behavior of droplets in vaporizing sprays, particularly under conditions typical of those in high pressure rocket sprays. Experiments are conducted in a variety of high pressure, high temperature, optically-accessible flow systems, including one which is capable of operation at pressures up to 70 atm, temperatures up to 600 K, gas velocities up to 30 m/sec and turbulence intensities up to 40 percent. Single droplets, 50 to 500 micron in diameter, are produced by an aerodynamic droplet generator and transversely injected into the flow. Measurements are made of the droplet position, size, velocity and temperature and of the droplet's vapor wake from which droplet drag, dispersion, heating, vaporization and breakup are characterized.

Song, Y.-H.↗
NASA NTRS2023

Universal Two-Phase Convection Heat Transfer Correlations for Cryogenic Pipe Chilldown

This paper presents a set of universal two-phase convection heat transfer correlations for modeling boiling heat transfer during pipe chilldown fit over the widest available range of cryogenic fluids and thermodynamic conditions. The correlations improve upon prior correlations that were developed separately for liquid nitrogen (LN2) and liquid hydrogen (LH2) pipe quenching datasets. The new correlations include equations to calculate the single-phase vapor heat transfer, film boiling heat transfer, transition boiling heat transfer, nucleate boiling heat transfer, single-phase liquid heat transfer, bulk vapor temperature during high quality film boiling, Leidenfrost temperature, critical heat flux, critical heat flux temperature, and the onset of nucleate boiling temperature. The correlations were validated against LH2, LN2, liquid methane, liquid oxygen, and liquid argon pipe quenching datasets. The eight datasets cover the following parameter ranges: pipe lengths of 0.1 to 6.5m; outer pipe diameters of 12.7 to 25.4 mm; pipe wall thicknesses from 0.51 to 1.64 mm; flow directions of upward, downward, and horizontal; gravity levels of 1g and 0g±0.01g. A numerical model assumes homogeneous mixing between the vapor and liquid and implicitly integrates the coupled energy equations for the pipe and fluid, as well as continuity for the fluid. The model was used to estimate the equilibrium quality and fluid mass accumulation along the pipes during chilldown from estimates of the fluid-pipe heat transfer extracted from temperature measurements. The correlations can be implemented in lumped parameter codes such as SINDA/FLUINT and the Generalized Fluid System Simulation Program (GFSSP) to improve the accuracy of chilldown time and chilldown boiloff mass predictions. Such predictions are useful for designing ground or in-space cryogenic liquid transfer systems.

Universal Correlations↗
DOE OSTI2022

Economic viability of using thermal energy storage for flexible carbon capture on natural gas power plants

Fossil fuel-based power plants generate 80% of the electricity in the United States and provide a reliable generation source for both base and peak power demands. These plants are expected to adapt to changes in environmental policies that will require carbon management with carbon capture and storage (CCS) representing a possible solution. Current solvent-based CCS has a detrimental impact on a power plant's performance due to large heat loads required for carbon capture solvent regeneration. This parasitic load restricts the power plant's output and operation flexibility. Therefore, this study evaluates the feasibility of using thermal storage technologies for natural gas combined cycle (NGCC) power plants coupled with CCS to minimize the impact of solvent regeneration and enable the plant to operate at peak power output. Thermal storage can minimize the impact of CCS on the power plant by providing the heat load required for solvent regeneration during times of peak demand which will allow the plant to operate unrestricted and at full power. In total, fifteen unique thermal storage configurations were evaluated from three thermal storage categories: Brayton cycle heat pump, vapor compression heat pump, and heat recovery steam generator steam extraction for storage. The viability of these systems was determined by evaluating each configuration on thousands of real-world Locational Marginal Pricing (LMP) profiles from the New York Independent System Operator and California Independent System Operator electricity markets using a techno-economic analysis. Afterwards, results were compared to the performance of a base power plant (NGCC with CCS and no thermal storage) to determine the impact of thermal storage on power plant economics. Overall, six of the thermal storage configurations performed better than base CCS enabled power plant on between 11.5% and 38.7% of the LMP signals evaluated. The best performing configuration was a vapor compression heat pump that used flue gas as the working fluid and had both hot and cold thermal storage units. This configuration performed better than the base CCS power plant on 38.7% of the LMP profiles. The results of this study show thermal storage can mitigate the economic impact of carbon capture solvent regeneration on NGCC power plants. Discussion focuses on the impact of electricity pricing on the optimal thermal storage system, the advantages and disadvantages of the systems evaluated, and identifies limitations with the study.

25 ENERGY STORAGE↗
NASA NTRS1978

Process feasibility study in support of silicon material task 1

Process system properties are analyzed for materials involved in the alternate processes under consideration for solar cell grade silicon. The following property data are reported for trichlorosilane: critical constants, vapor pressure, heat of vaporization, gas heat capacity, liquid heat capacity, density, surface tension, viscosity, thermal conductivity, heat of formation, and Gibb's free energy of formation. Work continued on the measurement of gas viscosity values of silicon source materials. Gas phase viscosity values for silicon tetrafluoride between 40 C and 200 C were experimentally determined. Major efforts were expended on completion of the preliminary economic analysis of the silane process. Cost, sensitivity and profitability analysis results are presented based on a preliminary process design of a plant to produce 1,000 metric tons/year of silicon by the revised process.

Li, K. Y.↗
NASA NTRS1979

Process feasibility study in support of silicon material, task 1

Analyses of process system properties were continued for materials involved in the alternate processes under consideration for semiconductor silicon. Primary efforts centered on physical and thermodynamic property data for dichlorosilane. The following property data are reported for dichlorosilane which is involved in processing operations for solar cell grade silicon: critical temperature, critical pressure, critical volume, critical density, acentric factor, vapor pressure, heat of vaporization, gas heat capacity, liquid heat capacity and density. Work was initiated on the assembly of a system to prepare binary gas mixtures of known proportions and to measure the thermal conductivity of these mixtures between 30 and 350 C. The binary gas mixtures include silicon source material such as silanes and halogenated silanes which are used in the production of semiconductor silicon.

Li, K. Y.↗
DOE OSTI2021

Understanding Melting and Freezing/Solidification and the Associated Effects on Heat Transfer

Phase change (solid/liquid or liquid/vapor) is a process that enables a large heat transfer capacity for a broad range of engineering applications, such as steam generators, condensers, thermal energy storage, thermosyphons, and heat pipes. Water has been the most usable phase-change cooling medium. Advanced applications are proposing alkali metals (e.g., sodium, potassium, lithium) to increase the total heat transfer rate for moderate and high-temperature applications. Sodium and potassium have the advantage of relatively low melting temperatures (98 and 64°C, respectively) make them suitable for high-temperature applications (700–1100 K). At too high of temperatures (above 1200 K), lithium is an excellent choice as a working fluid because of its high latent heat vaporization and high-surface tension. The low vapor pressure of alkali metals makes them candidates for closed spaces applications, such as thermosyphons and heat pipes. Lithium has the lowest vapor pressure than potassium and sodium, which can work at a much higher temperature without over-pressurizing the container.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1985

Liquid fueled external heating system for STM4-120 Stirling engine

The STM4-120 Stirling engine, currently under development at Stirling Thermal Motors, Inc., is a 40 kW variable stroke engine with indirect heating using a sodium heat pipe. The engine is functionally separated into an application independent Energy Conversion Unit (ECU) consisting of the Stirling cycle and drive heated by condensing sodium and the application dependent External Heating System (EHS), designed to supply the ECU with sodium vapor heated by the particular energy source, connected by tubes with mechanical couplings. This paper describes an External Heating System for the STM4-120 ECU designed for the combustion of liquid fuel, comprised of a recuperative preheater, a combustion chamber, and a heat exchanger/evaporator where heat is transferred from the flue gas to the sodium causing it to evaporate. The design concept and projected performance are described and discussed.

Meijer, R. J.↗
NASA NTRS1994

Thermocapillary flow with evaporation and condensation and its effect on liquid retention in low-G fluid acquisition devices

The steady motion, thermal and free surface behavior of a volatile, wetting liquid in microgravity are studied using scaling and numerical techniques. The objective is to determine whether the thermocapillary and two-phase convection arising from thermodynamic nonequilibrium along the porous surfaces of spacecraft liquid acquisition devices could cause the retention failures observed with liquid hydrogen and heated vapor pressurant. Why these devices seem immune to retention loss when pressurized with heated helium or heated directly through the porous structure was also examined. Results show that highly wetting fluids exhibit large negative and positive dynamic pressure gradients towards the meniscus interline when superheated and subcooled, respectively. With superheating, the pressure variation and recoil force arising from liquid/vapor phase change exert the same influence on surface morphology and promote retention. With subcooling, however, the pressure distribution produces a suction that degrades mechanical equilibrium of the surface. This result indicates that thermocapillary-induced deformation arising from subcooling and condensation is the likely cause for retention loss. In addition, increasing the level of nonequilibrium by reducing accommodation coefficient suppresses deformation and explains why this failure mode does not occur in instances of direct screen heating or pressurization with a heated inert gas.

Schmidt, George R.↗
NASA NTRS1972

Vaporization characteristics of carbon heat shields under radiative heating.

Study of the vaporization characteristics of samples of ATJ graphite, a material that has been considered for use on a Jovian probe. These samples were subjected to radiative heating loads of approximately 2 kW/sq cm in argon atmospheres of pressures from 0.00046 to 1 atm. Surface temperatures, mass loss rates, and spatially resolved emission spectral data were recorded. These data are analyzed to determine carbon vapor pressure as a function of temperature and are compared with current models for the vapor pressure of carbon. The effects of finite vaporization (i.e., nonequilibrium) rates are considered and compared with experiment. Estimates of the heat of vaporization from an energy balance are also presented.

Davy, W. C.↗
NASA NTRS1975

Flat device for heat concentration or dispersion

Device provides low-cost unit for efficiently transferring heat between, either to or from, flat surface and central point or region. It is based upon vapor heat transfer principle and therefore, extends applicability of heat pipe.

Jenkins, R. V.↗
NASA NTRS1933

Ice Prevention on Aircraft by Means of Engine Exhaust Heat and a Technical Study of Heat Transmission from a Clark Y Airfoil

This investigation was conducted to study the practicability of employing heat as a means of preventing the formation of ice on airplane wings. The report relates essentially to technical problems regarding the extraction of heat from the exhaust gases and its proper distribution over the exposed surfaces. In this connection a separate study has been made to determine the variation of the coefficient of heat transmission along the chord of a Clark Y airfoil. Experiments on ice prevention both in the laboratory and in flight show conclusively that it is necessary to heat only the front portion of the wing surface to effect complete prevention. Experiments in flight show that a vapor-heating system which extracts heat from the exhaust and distributes it to the wings is an entirely practical and efficient method for preventing ice formation.

Theodorsen, Theodore↗