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Results for “RESISTANCE HEATING”

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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

The effect of heat treatment on the resistivity of polycrystalline silicon films

The resistivity of doped polycrystalline silicon films has been studied as a function of post deposition heat treatments in an oxidizing atmosphere. It was found that a short oxidation cycle may produce a resistivity increase as large as three orders of magnitude in the polycrystalline films. The extent of change was dependent on the initial resistivity and the films' doping level and was independent of the total oxidation time.

Fripp, A. L., Jr.↗
NASA NTRS1973

Thermal contact resistance in a non-ideal joint

Analysis has been conducted to determine thermal contact resistance at interface of two heat conductors and effect of roughness of mating surfaces on pressure distribution. Investigation reveals how heat transfer resistance may be decreased or increased by changing surface properties of particular interface being considered.

Roca, R. T.↗
NASA NTRS1981

Temperature minimum heating in solar flares by resistive dissipation of Alfven waves

The possibility that the strong heating produced at temperature-minimum levels during solar flares is due to resistive dissipation of Alfven waves generated by the primary energy release process in the corona is studied. It is shown how, for suitable parameters, these waves can carry their energy essentially undamped into the temperature-minimum layers and can then produce a degree of heating consistent with observations.

Emslie, A. G.↗
NASA NTRS1978

Power Coupling Alternatives for the NEP Thermionic Power System

Three output power coupling methods which can eliminate the high temperature insulator from the Nuclear Electric Propulsion (NEP) power system are described and estimates of their effects on the NEP system masses and cooling requirements are presented. Nominal 400 kWe power systems using push-pull and flux reset inductive output coupling are shown to have specific masses of 22.2 kg/kWe and 18.8 kg/kWe, respectively. Series connected heat pipe systems, which use the heat pipe-to-heat pipe resistance to isolate converters on adjacent heat pipes, are shown to have specific masses 0.5 to 1.4 kg/kWe lower than the NEP baseline system. Increasing the number and temperature of the heat pipes in the system without changing the electric output reduces the calculated system specific mass only slightly, whereas increasing the output power significantly reduces the specific mass. Estimates of cooling requirements indicate that 11-45 sq m of power conditioning radiator are needed. A possible location for the power conditioning radiator may be in the present location of the kapton sputter shield.

Manda, M. L.↗
NASA NTRS2000

Realistic Development and Testing of Fission System at a Non-Nuclear Testing Facility

The use of resistance heaters to simulate heat from fission allows extensive development of fission systems to be performed in non-nuclear test facilities, saving time and money. Resistance heated tests on a module has been performed at the Marshall Space Flight Center in the Propellant Energy Source Testbed (PEST). This paper discusses the experimental facilities and equipment used for performing resistance heated tests. Recommendations are made for improving non-nuclear test facilities and equipment for simulated testing of nuclear systems.

Godfroy, Tom↗
NASA NTRS1981

The effect of mechanical surface and heat treatments on the erosion resistance of 6061 aluminum alloy

The effects of both mechanical surface treatments and heat treatments on the erosion resistance of 6061 aluminum alloy were studied in order to gain a better understanding of material properties which affect erosion behavior. It was found that mechanical surface treatments have little or no effect on the erosion resistance. This is due to the formation by particle impact of a work-hardened surface layer, independent of the initial surface condition. The erosion resistance of aluminum single crystals was found to be independent of orientation, which is due to destruction of the surface microstructure and formation of a polycrystalline surface layer by the particle impact as observed by X-ray diffraction. Although on solution treatment of annealed aluminum 6061 the increase in hardness is accompanied by an increase in erosion resistance, precipitation treatment (which causes a further increase in hardness) results in a slightly lower erosion resistance.

Salik, J.↗
NASA NTRS1981

Fast plasma heating by anomalous and inertial resistivity effects in the solar atmosphere

A simple model is presented to describe fast plasma heating by anomalous and inertial resistivity effects. It is noted that a small fraction of the plasma contains strong currents that run parallel to the magnetic field and are driven by an exponentiating electric field. The anomalous character of the current dissipation derives from the excitation of electrostatic ion-cyclotron and/or ion-acoustic waves. The possible role of resistivity deriving from geometrical effects ('inertial resistivity') is also considered. Using a marginal stability analysis, equations for the average electron and ion temperatures are derived and numerically solved. No loss mechanisms are taken into account. The evolution of the plasma is described as a path in the drift velocity diagram, where the drift velocity is plotted as a function of the electron to ion temperature ratio.

Duijveman, A.↗
NASA NTRS1972

Safe atmosphere entry of an isotope heat source with a single stable trim attitude at hypersonic speeds

A theoretical investigation has been made to design an isotope heat source capable of satisfying the conflicting thermal requirements of steady-state operation and atmosphere entry. The isotope heat source must transfer heat efficiently to a heat exchange during normal operation with a power system in space, and in the event of a mission abort, it must survive the thermal environment of atmosphere entry and ground impact without releasing radioactive material. A successful design requires a compatible integration of the internal components of the heat source with the external aerodynamic shape. To this end, configurational, aerodynamic, motion, and thermal analyses were coupled and iterated during atmosphere entries at suborbital through superorbital velocities at very shallow and very steep entry angles. Results indicate that both thermal requirements can be satisfied by a heat source which has a single stable aerodynamic orientation at hypersonic speeds. For such a design, the insulation material required to adequately protect the isotope fuel from entry heating need extend only half way around the fuel capsule on the aerodynamically stable (wind-ward) side of the heat source. Thus, a low-thermal-resistance, conducting heat path is provided on the opposite side of the heat source through which heat can be transferred to an adjacent heat exchanger during normal operation without exceeding specified temperature limits.

Levy, L. L., Jr.↗
NASA NTRS1980

Solar energy system performance evaluation report for Solaron-Duffield, Duffield, Virginia

The Solaron Duffield Solar Energy System was designed to provide 51 percent of the space heating, and 49 percent of the domestic hot water (DHW) to a two story 1940 square foot area residence using air as the transport medium. The system consists of a 429 square foot collector array, a 265 cubic foot rock thermal storage bin, heat exchangers, an 80 gallon DHW preheat tank, pumps, blowers, controls, air ducting and associated plumbing. A air-to-liquid heat pump coupled with a 1,000gallon water storage tank provides for auxiliary space heating and can also be used for space cooling. A 52 gallon electric DHW tank using the solar preheated water provides domestic hot water to the residence. The solar system, which became operational July 1979, has the following modes of operation: First Stage: (1) collector to storage and DHW; (2)collector to space heating; (3) storage to load. Second Stage: (4) heat pump auxiliary direct; (5) auxiliary heat from heat pump storage. Third Stage: (6) electrical resistance (strip) heat.

Source record↗
NASA NTRS2004

Heat, Moisture and Chemical Resistant Polyimide Compositions and Methods for Making and Using Them

Polyimides having a desired combination of high thermo-oxidative stability, low moisture absorption and excellent chemical and corrosion resistance are prepared by reacting a mixture of compounds including (a) 3,3',4,4'- benzophenonetetracarboxylic dianhydride (BTDA), (b) 3,4'- oxydianiline (3,4'-ODA), and (c) 5-norbornene-2,3- dicarboxylic anhydride (NA) in a high boiling, aprotic solvent to give 5 to 35% by weight of polyamic acid solution. The ratio of (a), (b), and (c) is selected to afford a family of polyimides having different molecular weights and properties. The mixture first forms a polyamic acid precursor. Upon heating at or above 300 C, the polyamic acids form polyimides, which are particularly suitable for use as a high temperature coating, adhesive, thin film, or composite matrix resin.

Ruth H Pater↗
NASA NTRS1986

Heat- and Radiation-Resistant Lubricants for Metals

Protective and lubricating coatings formed in situ. Orthophthalonitrile reacts with metal-surface asperities at high frictional temperatures to form lubricating films of metal phthalocyanine. Compounds also formed with hot metal fragments torn from asperities. Bearing surfaces better protected from scoring, and fragments rendered less harmful to base fluids. Lubricants useful as additives to oils and greases in gears, transmissions, motors, and other machines where rubbing loads between metal parts may be severe. Because of their low volatility and lack of requirement for air or moisture, lubricants also useful in vacuums.

Lawton, E. A.↗
NASA NTRS1990

Heat- And Oxidation-Resistant Electrodes

Alloys coated with electrically conductive ceramics used to make strong, oxidation-resistant electrodes for electrochemical cells operating at temperatures of 1,000 to 1,300 degrees C. Fe3Al or Ni3Al coated with strontium-doped lanthanum manganite more resistant to chemical attack than all-metal electrode, less brittle than all-ceramic electrode, and less costly than either alternative.

Schroeder, James E.↗
NASA NTRS1952

Oxidation-resistance Mechanism and Other Properties of Molybdenum Disilicide

The outstanding oxidation resistance of molybdenum disilicide at 2400 F and above was found to depend on the formation of a protective siliceous coating which a-cristobalie has been identified. Molybdenum disilicide is not inherently resistant to oxidation and in powdered form burns at low temperatures.Melting and casting experiments have demonstrated the decomposition of the material at the melting point. The room-temperature modulus of elasticity has been determined and electric-resistivity data are given to 2000 F.

MATERIALS, PROPERTIES-CORROSION RESISTANCE↗
NASA NTRS1987

Electron heating by ion acoustic turbulence in simulated low Mach number shocks

Explicit and fully electromagnetic particle-in-cell simulations of perpendicular, collisionless, and nominally subcritical shocks are performed in one and two spatial dimensions using the code wave. Shock parameters are chosen to maximixe the growth rates of the current-driven ion acoustic instability in the shock. Electron heating by ion acoustic turbulence is observed at the shocks, at rates in agreement with second-order Vlasov theory predictions. However, the amount of resistive electron heating is small and ion reflection provides the major source of dissipation. Strictly resistive shocks do not exist for the parameters suitable for explicit particle codes running on today's supercomputers, because the plasma convects through these shocks so quickly that current-driven instabilities have little time to be amplified and to heat the electrons resistively. This effect is primarily a result of the relatively small values of omega(pe)/omega(ce) that can be analyzed.

Tokar, Robert L.↗