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Results for “exchanger”

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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Exchange of adsorbed H2O and CO2 between the regolith and atmosphere of Mars caused by changes in surface insolation

Estimates have been made of the capacity of the Martian regolith to exchange adsorbed H2O and CO2 with the atmosphere-plus-cap system (APCS). These estimates are based upon measured isotherms for H2O and CO2 adsorption on pulverized basalt at low temperatures and on theoretical considerations. A unit column (1 sq cm) of regolith with a deep subsurface temperature of -77 C, considered average for the disk, will contain about 0.4 g of adsorbed CO2 and about 1 g of adsorbed H2O per meter of depth. Under favorable circumstances the top 3 cm can exchange much more H2O with the lower atmosphere each day than is necessary to produce the diurnal brightening. The process appears to be seasonally reversible. The total regolith may contain, in the adsorbed phase alone, as much as 1% of the H2O and 5% of the CO2 surface inventories expected for a hypothetical Mars that has experienced degassing as intensive as that of earth.

Fanale, F. P.↗
NASA NTRS1975

Improved polyelectrolyte for ion exchange fibers

Technique increases ion exchange capacity of hollow-fiber-substrate ion exchange resins. Procedure increases number of quaternary sites on polyquaternary copolymer by 15 to 35 percent.

Rembaum, A.↗
NASA NTRS1975

Condensate removal device for heat exchanger

A set of perforated tubes disposed at the gas output side of a heat exchanger, in a position not to affect the rate of flow of the air or other gas is described. The tubes are connected to a common manifold which is connected to a sucking device. Where it is necessary to conserve and recirculate the air sucked through the tubes, the output of the manifold is run through a separator to remove the condensate from the gas. The perforations in the slurper tubes are small, lying in the range of 0.010 inch to 0.100 inch. The tubes are disposed in contact with the surfaces of the heat exchanger on which the condensate is precipitated, whether fins or plates, so that the water may be directed to the tube openings by means of surface effects, together with the assistance of the air flow. Only about 5 percent of the air output need be thus diverted, and it effectively removes virtually all of the condensate.

Trusch, R. B.↗
NASA NTRS1975

Four particle exchange in solid He-3

Calculations which demonstrate a physically important four-atom exchange process in bodycentered cubic He crystal and thus an important four-spin term in the exchange Hamiltonian are discussed. A simple, mean-field analysis of this Hamiltonian appears to account for a number of the perplexing properties of bodycentered cubic He crystal. It is suggested that an understanding of other properties may require treatment of the exact four-spin term.

Mcmahan, A. K.↗
NASA NTRS1974

Automated measurement of respiratory gas exchange by an inert gas dilution technique

A respiratory gas analyzer (RGA) has been developed wherein a mass spectrometer is the sole transducer required for measurement of respiratory gas exchange. The mass spectrometer maintains all signals in absolute phase relationships, precluding the need to synchronize flow and gas composition as required in other systems. The RGA system was evaluated by comparison with the Douglas bag technique. The RGA system established the feasibility of the inert gas dilution method for measuring breath-by-breath respiratory gas exchange. This breath-by-breath analytical capability permits detailed study of transient respiratory responses to exercise.

Sawin, C. F.↗
NASA NTRS1975

Four-particle exchange in solid He-3

Calculations are reported which suggest that there is a physically important four-atom exchange process in bcc He-3 and an important four-spin term in the exchange Hamiltonian. A simple mean-field analysis of this Hamiltonian appears to account for a number of the perplexing properties of bcc He-3. An understanding of other properties may require treatment of the exact four-spin term.

Mcmahan, A. K.↗
NASA NTRS1975

Asymptotic form of the charge-exchange cross section in three-body rearrangement collisions

A three-body general-type rearrangement collision is considered in which the initial and final bound states are described by hydrogen-like wave functions. It is shown that the charge-exchange amplitude in the first Born approximation can be expanded at all incident energies in terms of the inverse powers of the principal quantum number (n). By expanding the exchange amplitude in this way, it is demonstrated conclusively that the cross section for capture into the s, p, and d states as well as for the sum over all the angular-momentum states is proportional to 1/n-cubed plus terms proportional to higher inverse odd powers of n. It is found that the low-lying levels cannot be scaled to the 1/n-cubed law irrespective of the value of the incident energy except in the case of capture into the s states in accordance with the Oppenheimer-Brinkman-Kramers approximation. Zeros and minima in the differential cross sections are given in the limit of high principal quantum number for electron capture by protons from atomic hydrogen and for positronium formation by proton-atomic hydrogen collisions.

Omidvar, K.↗
NASA NTRS1976

Ring current proton decay by charge exchange

Explorer 45 (S3-A) measurements were made during the recovery phase of the moderate magnetic storm of February 24, 1972, in which a symmetric ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, which is a consequence of the dissipation of the asymmetric ring current, the equatorially mirroring protons in the energy range 5-30 keV decayed throughout the L value range of 3.5-5.0 at the charge exchange decay rate calculated by Liemohn (1961). After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange is more than sufficient as a particle loss mechanism for the storm time proton ring current decay.

Smith, P. H.↗
NASA NTRS1976

Heat exchanger

An improved lightweight heat exchanger particularly suited for use in systems having low volume flow, high longitudinal gradient and high effectiveness requirements is described. The heat exchanger is characterized by a shell of an annular configuration, an endless plate of minimal thickness and of a substantially uniformly convoluted configuration disposed within the annular shell for defining a plurality of endless, juxtaposed passages, each having a low Reynold's number and being of an annular configuration. A pair of manifolds disposed 180 deg apart is mounted on the shell in communication with the passages through which counterflowing fluids are simultaneously introduced and extracted from the passageways for achieving a continuous transfer of heat through the convoluted plate.

Holmes, R. F.↗
NASA NTRS1976

Interaction of a solar array with an ion thruster due to the charge-exchange plasma

The generation of a charge exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma is described accurately from thruster geometry and operating conditions. The transport of the charge exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

Kaufman, H. R.↗
NASA NTRS1976

Joule-Thomson expander and heat exchanger

The Joule-Thomson Expander and Heat Exchanger Program was initiated to develop an assembly (JTX) which consists of an inlet filter, counterflow heat exchanger, Joule-Thomson expansion device, and a low pressure jacket. The program objective was to develop a JTX which, when coupled to an open cycle supercritical helium refrigerating system (storage vessel), would supply superfluid helium (He II) at 2 K or less for cooling infrared detectors.

Norman, R. H.↗
NASA NTRS1977

Improved ceramic heat exchange material

Improved corrosion resistant ceramic materials that are suitable for use as regenerative heat exchangers for vehicular gas turbines is reported. Two glass-ceramic materials, C-144 and C-145, have superior durability towards sulfuric acid and sodium sulfate compared to lithium aluminosilicate (LAS) Corning heat exchange material 9455. Material C-144 is a leached LAS material whose major crystalline phase is silica keatite plus mullite, and C-145 is a LAS keatite solid solution (S.S.) material. In comparison to material 9455, material C-144 is two orders of magnitude better in dimensional stability to sulfuric acid at 300 C, and one order of magnitude better in stability to sodium sulfate at 1000 C. Material C-145 is initially two times better in stability to sulfuric acid, and about one order of magnitude better in stability to sodium sulfate. Both C-144 and C-145 have less than 300 ppm delta L/L thermal expansion from ambient to 1000 C, and good dimensional stability of less than approximately 100 ppm delta L/L after exposure to 1000 C for 100 hours. The glass-ceramic fabrication process produced a hexagonal honeycomb matrix having an 85% open frontal area, 50 micrometer wall thickness, and less than 5% porosity.

Mccollister, H. L.↗
NASA NTRS1977

Charge-exchange plasma generated by an ion thruster

The charge exchange plasma generated by an ion thruster was investigated experimentally using both 5 cm and 15 cm thrusters. Results are shown for wide ranges of radial distance from the thruster and angle from the beam direction. Considerations of test environment, as well as distance from the thruster, indicate that a valid simulation of a thruster on a spacecraft was obtained. A calculation procedure and a sample calculation of charge exchange plasma density and saturation electron current density are included.

Kaufman, H. R.↗
NASA NTRS1978

Exchange and relaxation effects in low-energy radiationless transitions

The effect on low-energy atomic inner-shell Coster-Kronig and super Coster-Kronig transitions that is produced by relaxation and by exchange between the continuum electron and bound electrons was examined and illustrated by specific calculations for transitions that deexcite the 3p vacancy state of Zn. Taking exchange and relaxation into account is found to reduce, but not to eliminate, the discrepancies between theoretical rates and measurements.

Chen, M. H.↗
NASA NTRS1977

Charge exchange of metastable 2D oxygen ions with N2 in the thermosphere

The charge exchange of metastable 2D oxygen ions with N2 in the thermosphere is investigated through analysis of N2 (+) measurements and related data obtained by the Atmosphere Explorer-C satellite. The rate coefficient for the charge exchange process is found to be 5 + or - 1.7 times 10 to the negative 10th power cu cm per sec. A rate coefficient is also developed for atomic oxygen quenching of the metastable 2D oxygen ions.

Torr, D. G.↗
NASA NTRS1980

Liquid/liquid heat exchanger

Conceptual design for heat exchanger, utilizing two immiscible liquids with dissimilar specific gravities in direct contact, is more efficient mechanism of heat transfer than conventional heat exchangers with walls or membranes. Concept could be adapted for collection of heat from solar or geothermal sources.

Miller, C. G.↗
NASA NTRS1978

A transportable system for management and exchange of programs and other text

A system is presented for exchanging information on tape, that allows information about the data to be included with the data. The system is designed for portability, but requires a few simple machine dependent modules. These modules are available for a variety of machines, and a bootstrapping procedure is provided. The system allows content selected reading of the tape, and a simple text editing facility is provided. Although the system recognizes 30 commands, information may be extracted from the tape by using as few as three commands. In addition to its use for information exchange, the system is expected to find use in maintaining large libraries of text.

Snyder, W. V.↗
NASA NTRS1978

Heat exchanger and method of making

A heat exchanger of increased effectiveness is disclosed. A porous metal matrix is disposed in a metal chamber or between walls through which a heat-transfer fluid is directed. The porous metal matrix has internal bonds and is bonded to the chamber in order to remove all thermal contact resistance within the composite structure. Utilization of the invention in a rocket chamber is disclosed as a specific use. Also disclosed is a method of constructing the heat exchanger.

Fortini, A.↗