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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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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Electrodynamic Dust Shield Technology for Thermal Radiators Used in Lunar Exploration

Two general types of thermal radiators are being considered for lunar missions: coated metallic surfaces and Second Surface Mirrors. Metallic surfaces are coated with a specially formulated white paint that withstands the space environment and adheres well to aluminium, the most common metal used in space hardware. AZ-93 White Thermal Control Paint, developed for the space program, is an electrically conductive inorganic coating that offers thermal control for spacecraft. It is currently in use on satellite surfaces (Fig 1). This paint withstands exposure to atomic oxygen, charged particle radiation, and vacuum ultraviolet radiation form 118 nm to 170 nm while reflecting 84 to 85% of the incident solar radiation and emitting 89-93% of the internal heat generated inside the spacecraft.

Calle, Carlos I.↗
NASA NTRS1972

Thermal radiative properties: Coatings.

This volume consists, for the most part, of a presentation of numerical data compiled over the years in a most comprehensive manner on coatings for all applications, in particular, thermal control. After a moderately detailed discussion of the theoretical nature of the thermal radiative properties of coatings, together with an overview of predictive procedures and recognized experimental techniques, extensive numerical data on the thermal radiative properties of pigmented, contact, and conversion coatings are presented. These data cover metallic and nonmetallic pigmented coatings, enamels, metallic and nonmetallic contact coatings, antireflection coatings, resin coatings, metallic black coatings, and anodized and oxidized conversion coatings.

Touloukian, Y. S.↗
NASA NTRS1969

Thermal radiation shields for piping in vacuum environments

System of thermal radiation shielding reduces radiant heat transfer in vacuum installations containing piping which carries working fluids. Method employs successive layers of spacers and rolled metal shields which are easily installed or removed, expedites efficient removal of entrapped gases, and adapts easily to small pipings.

Spagnuolo, A. C.↗
NASA NTRS1969

Spacecraft Thermal Radiation Environment Computer Program

Computer program computes the total thermal radiation flux on each of a set of exposed surface elements of a spacecraft in the vicinity of a celestial body. The incident flux consists of solar, both direct and planetary-reflected, and planetary-emitted infrared radiation as functions of time.

Paoletti, C. J.↗
NASA NTRS1997

Thermal Radiation Effects Analyzed in Translucent Composite and Thermal Barrier Coating

Ceramic parts and coatings are needed to withstand high temperatures in advanced aircraft engines. In hot environments, such as in the combustion chambers of these engines, infrared and visible radiation can penetrate into some ceramics and heat them internally. The internal temperatures depend on radiative effects combined with heat conduction, and on convection and radiation at the material boundaries. Since engine temperatures are high, radiant emission can be large from within translucent parts and coatings, and this must be included in the analysis. Transient and steady-state behavior are both important. During a transient, radiant penetration provides more rapid internal heating than conduction alone, and the temperature distributions are usually considerably different than for steady-state conditions; this can produce transient thermal stresses. Analytical and numerical methods are being used at the NASA Lewis Research Center to predict transient temperatures and heat flows in translucent materials. A transient analysis was done for a composite of two translucent layers. The layer refractive indices were larger than 1, producing internal reflections at the boundaries and at the internal interface. In addition, steady-state results were computed for a two-layer composite with one layer opaque. The results were used to assess the importance of internal radiation in a zirconia thermal barrier coating on a cooled metal wall. Since the radiative transfer equations are rather complex, especially when internal scattering is included, approximate methods are being investigated that might be convenient for computer design programs. An approximate two-flux method was used and verified by comparisons with solutions that used exact radiative transfer relations. The two-flux equations include scattering without increasing solution difficulty.

Siegel, Robert↗
NASA NTRS1997

Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

Weckmann, Stephanie↗
NASA NTRSDate not supplied

Advanced Single Phase Thermal Radiator for Moon-to-Mars Exploration

Pumped loop radiators are commonly used to reject large amounts of heat associated with crewed systems. The State-of-the-Art (SOA) for crewed systems is represented by the International Space Station (ISS) External Heat Rejection System (HRS) Thermal Radiators. The ISS HRS utilizes a manifold design with many parallel flow paths coupled to thin face-sheets and low viscosity ammonia as the working fluid, which may not be preferred due to toxicity concerns. Although contemporary coolant choices provide lower freezing points, the current SOA design may not be well positioned to provide both sufficient heat transfer and manageable pressure drop due to very different fluid thermo-physical properties, including higher viscosities. The planned development of an advanced single phase, pumped loop thermal radiator utilizing a serpentine flow path with high thermally conductive face-sheets is presented herein.

In-Space Active Thermal Control↗
NASA NTRS1972

Thermal radiation heat transfer.

A comprehensive discussion of heat transfer by thermal radiation is presented, including the radiative behavior of materials, radiation between surfaces, and gas radiation. Among the topics considered are property prediction by electromagnetic theory, the observed properties of solid materials, radiation in the presence of other modes of energy transfer, the equations of transfer for an absorbing-emitting gas, and radiative transfer in scattering and absorbing media. Also considered are radiation exchange between black isothermal surfaces, radiation exchange in enclosures composed of diffuse gray surfaces and in enclosures having some specularly reflecting surfaces, and radiation exchange between nondiffuse nongray surfaces. The use of the Monte Carlo technique in solving radiant-exchange problems and problems of radiative transfer through absorbing-emitting media is explained.

Siegel, R.↗
NASA NTRS1964

Applications of the method of Monte Carlo to problems in thermal radiation

A summary of the work involving the Monte Carlo method in the solution of problems in thermal radiation transfer is presented, which indicates general methods previously used for solving problems in which radiation is coupled with other modes of energy transfer. Previous work involving radiation in absorbing-emitting media is included. An example is outlined to indicate the use of the Monte Carlo method in the design of a space radiator. Suggestions are given for solution of a complex case incorporating the effects of coupled conduction, convection and radiation, wavelength dependent and selective surfaces, nonisothermal conditions, and strongly directional or nondiffuse emitting and reflecting surfaces. A discussion is given of the factors that may affect convergence, running time, and accuracy of the Monte Carlo solutions and of the advantages and disadvantages of this approach for practical problems. Also discussed are the case of programming for complex problems and the probable machine time requirements of the method.

THERMAL RADIATION↗
DOE OSTI2024

A Survey of Multimaterial Treatments for Thermal Radiative Transfer

Arbitrary Lagrangian-Eulerian methods are a popular choice for hydrodynamic modeling in radiation (rad-hydro) simulations. Because these methods involve a relaxation step that moves the mesh relative to material boundaries, multimaterial spatial zones are generally present. Accurate treatments of these zones are needed to resolve various physical phenomena of interest for inertial confinement fusion applications. However, these codes are often paired with single-material, deterministic thermal radiative transfer (TRT) codes that are oblivious to the material compositions of each zone. These single-material TRT codes can only accept homogenized material properties (opacities, specific heats, etc.) from the hydrodynamic code and output homogenized solutions. After each TRT time step, the multimaterial hydrodynamic code must dehomogenize the quantities computed by the TRT package in order to update subzonal material temperatures. The process by which hydrodynamic codes perform this dehomogenization has not been well documented in previous literature, and the methods can vary significantly from code to code. The purpose of this paper is to document, study, and compare existing techniques used for rad-hydro simulations as well as present a new method with potentially promising results. We summarize several methods and give comparisons on infinite-medium problems as well a finite-medium problem for two of the methods.

42 ENGINEERING↗
NASA NTRS2024

Electrodynamic Dust Shield for Active Dust Mitigation of Thermal Radiators

This project sought to investigate whether the Electrodynamic Dust Shield (EDS) would work with various thermal control coatings (TCC) to remove dust off the TCC. Keeping surfaces dust free is essential for thermal radiators as the dust acts as both a blackbody and a thermal insulator so it will absorb more sunlight and prevent the radiator from radiating heat. The lack of heat rejection on dusty surfaces causes the radiator to be oversized and potentially cause catastrophic system failure due to overheating. With an EDS integrated into the radiator system, dust impacts can be mitigated by removing the dust off the surface using electric fields. This project tested dust removal, solar absorptance, emittance, and limited thermal vacuum with a TCC on an EDS which is bonded to an aluminum plate acting like a radiator. The results of various coatings suggests that the EDS can work with insulative TCC in high vacuum for removing dust, and that after removing dust, the solar absorptance can be restored to within 5-10% of its original value when the EDS works properly. More work is necessary to determine how the EDS impacts the emittance of the whole radiator system and bonding between the different layers needs to be investigated to withstand temperature cycling of the moon without delamination occurring.

Krystal Acosta↗