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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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Solar wind effects on thermal control coatings reflectance and absorptance, noting simulation and thermophysical measurement requirements
Polyimidazopyrrolone films relative thermophysical properties, noting polymers thermal stability dependence on carbonyl groups percentage
In situ determination of effects of ultraviolet radiation, solar wind protons, and temperature on thermophysical properties of solar cell filters and other spacecraft materials
Mercury microwave and IR observations interpreted for thermophysical models for planetary subsurface, discussing rotation and heating
Thermophysical property measurements were made under transient heating conditions on several materials being considered for use in SCOUT rocket motors. The materials included were ATJ graphite, MX 2600 silica phenolic, FM 5272 cellulose phenolic, and two carbon-carbon composites: CARBITEX 700 and RPP-4. The ATJ was included as a reference or base line material to check performance of the transient tests as it was not expected to be sensitive to heating rate. Measurements included in the program were thermal conductivity, strength, compressive stress-strain (carbon-carbon only), thermal expansion and the effective thermal expansion under partially restrained conditions. Development of this latter measurement was a major part of the program. It consisted of partially restraining the expansion of a specimen as it was heated, measuring the load and strain which occurred (together with a simultaneous modulus determination by superimposing a small cyclic load) and using these quantities to calculate what the effective thermal expansion would have to be to produce the observed stress and deformation. For materials which are sensitive to heating rate, such as reinforced phenolics, it was believed that this would provide a more realistic determination of the thermal expansion as it more nearly simulates the conditions experienced in end use.
Model can be tested directly, which eliminates costly, time-consuming, and inaccurate method of making test models solely for purpose of determining thermophysical properties. Method is adaptable to numerous modifications and variations.
The thermophysical properties of lunar fines for a density of 1600 kg/cu m are reviewed. A list is included of publications resulting from the studies. During this period lunar samples from Apollo 11,12,14,15, and 16 were received and studied.
Thermophysical properties of plasma sprayed materials were determined for the following plasma sprayed materials: CaO - stabilized ZrO2, Y2O3 - stabilized ZerO2, Al2O3, HfO2 Mo, nichrome, NiAl, Mo-ZrO2, and MoAl2O3 mixtures. In all cases the thermal conductivity of the as-sprayed materials was found to be considerably lower than that of the bulk material. The flash-laser thermal diffusivity technique was used both for diffusivity determination of single-layer materials and to determine the thermal contact resistance at the interface of two-layer specimens.
Thermophysical properties data for oxygen at pressures below 5000 psia have been extrapolated to higher pressures (5,000-10,000 psia) in the temperature range 100-600 R. The tables include density, entropy, enthalpy, internal energy, speed of sound, specific heat, thermal conductivity, viscosity, thermal diffusivity, Prandtl number, and dielectric constant.
Heat transfer within the lunar surface layer depends on several thermophysical properties of the lunar regolith, including the thermal conductivity, the specific heat, the thermal diffusivity, and the thermal parameter. Results of property measurements on simulated lunar materials are presented where appropriate as well as measurements made on the actual samples themselves. The variation of temperature on the moon with depth is considered, taking into account various times of the lunar day. The daily variation in temperature drops to about 1 deg at a depth of only 0.172 meters. The steady temperature on the moon below this depth is 225 K.
An electronic system is described which measures the surface temperature of a small portion of the surface of the model or sample at high speeds using an infrared radiometer. This data is processed along with heating rate data from the reference heat gauge in a small computer and prints out the desired thermophysical properties, time, surface temperature, and reference heat rate. This system allows fast and accurate property measurements over thirty temperature increments. The technique, the details of the apparatus, the procedure for making these measurements, and the results of some preliminary tests are presented.
The relationships are described among prepolymer purity, processing parameters, and additives to the thermophysical and chemical properties of polybenzimidazole foams in the density range from 24 to 80 kg/cu m. Foam properties are shown to be affected by differences in prepolymer purity, curing schedule, and the presence of additives in the foam. High-temperature compressive properties were improved by postcuring at 527 C. Surfactant additives were found to improve uniformity of cell size. Foams were characterized according to high-temperature mechanical properties, density, porosity, thermal diffusivity, thermal conductivity, and specific heat.
Minimum overall nutritional deterioration of foodstuffs is generally attained by maximizing the rate of heat input and minimizing the duration of heating. Measurement of thermophysical data for foodstuffs is discussed in terms of specific heat, latent energy, enthalpy, thermal conductivity, thermal diffusivity, and density. Since phase change in foodstuffs occurs over a temperature range rather than at a discrete temperature, enthalpy is preferred over sensible and latent energy measurements as it can be used to fix the state of a sample very accurately; also, in the fusion process there is no precise way of separating sensible and latent energies. The first step in determining property data for foodstuffs is to describe the material in conventionally accepted terms. Future work should be concentrated in the area of thermal diffusivity and enthalpy measurements.
The thermophysical properties of salts having potential for thermal energy storage to provide peaking energy in conventional electric utility power plants were investigated. The power plants studied were the pressurized water reactor, boiling water reactor, supercritical steam reactor, and high temperature gas reactor. The salts considered were LiNO3, 63LiOH/37 LiCl eutectic, LiOH, and Na2B4O7. The thermal conductivity, specific heat (including latent heat of fusion), and density of each salt were measured for a temperature range of at least + or - 100 K of the measured melting point. Measurements were made with both reagent and commercial grades of each salt.
An infrared radiometer is described which was developed to measure temperature rises of wind tunnel models undergoing transient heating over a temperature range of -17.8 C to 260 C. This radiometer interfaces directly with a system which measures the effective thermophysical property square root of rho ck. It has an output temperature fluctuation of 0.26 C at low temperatures and 0.07 C at high temperatures, and the output frequency response of the radiometer is from dc to 400 hertz.
An on-going program to characterize advanced composites for up to 50,000 hours of exposure to simulated supersonic cruise environments is summarized. Results are presented for up to 25,000 hours of thermal exposure and 10,000 hours of flight simulation at temperatures up to 560K (550 F) with emphasis on HTS/710 graphite/polyimide composite material. Results to date indicate that the maximum use temperature for HTS/710 may be reduced to 505K (450 F) for long-time (1000 hours) application such as the supersonic transport. Preliminary thermophysical properties data for HTS/PMR15 graphite/polyimide were generated. These data include thermal conductivity, thermal expansion, and specific heat from 115K (-252 F) to 590K (600 F) and emittance at room temperature and 590K (600 F). The purpose in generating these data was to validate use of state-of-the-art property measurement methods for advanced graphite fiber reinforced resin matrix composites. Based on results to this point, thermal expansion measurements for composites are most difficult to perform. A high degree of caution in conducting thermal expansion tests and analyzing results is required to produce reliable data.
Some of the thermophysical and flammability properties of a phosphorylated epoxy adhesive, which has potential applications in aircraft interior panels, are described. The adhesive consists of stoichiometric ratios of bis(3-glycidyloxphenyl)methylphosphine oxide and bis(3-aminophenyl)methylphosphine oxide containing approximately 7.5% phosphorus. Preliminary data are presented from adhesive bonding studies conducted utilizing this adhesive with polyvinyl fluoride (PVF) film and phenolic-glass laminates. Limiting oxygen index and smoke density data are presented and compared with those of the tetraglycidyl methylene dianiline epoxy resin-adhesive system currently used in aircraft interiors. Initial results indicate that the phosphorylated epoxy compound has excellent adhesive properties when used with PVF film and that desirable fire-resistant properties are maintained.
Technique development and the application of electromagnetic levitation to thermophysical property measurement, including determining heats of fusion, heat capacities, and enthalpy increment functions for extremely refractory materials are discussed. Tungsten properties and the development of an apparatus employing electromagnetic levitation and electron beam heating capable of melting levitating tungsten high temperature heat content measurements by drop calorimetry are emphasized. The development of a prototype microcomputer data acquisition system suitable for controlling the ground based system, with consequent improvement in system handling, which can serve as a model for the system needed for flight experiments is described, which include the development of techniques for imaging pyrometry at temperatures above 3500 K, a semiautomatic calorimeter system capable of handling liquid tungsten, and development of a two color imaging pyrometer system.