Engineering Papers⌕ Search

SEARCH · Engineering Papers

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Use of long-lived radon daughters as indicators of exchange between the free troposphere and the marine boundary layer

Fluxes and exchange coefficients are derived for the transport of Sr-90, Pb-210, Bi-210, and Po-210 between the free troposphere and the marine boundary layer and between the boundary layer and the sea surface. Radionuclide concentrations previously measured near Hawaii are used in the derivations. Values obtained for the free troposphere/boundary layer exchange coefficient (expressed as a piston velocity) were 185, 228 and 203 m/d for Pb-210, Bi-210, and Sr-90, respectively. The magnitude of the local sea-surface source of Po-210 is also determined.

Kritz, M. A.↗
NASA NTRS1983

Use of cooling air heat exchangers as replacements for hot section strategic materials

Because of financial and political constraints, strategic aerospace materials required for the hot section of future engines might be in short supply. As an alternative to these strategic materials, this study examines the use of a cooling air heat exchanger in combination with less advanced hot section materials. Cycle calculations are presented for future turbofan systems with overall pressure ratios to 65, bypass ratios near 13, and combustor exit temperatures to 3260 R. These calculations quantify the effect on TSFC of using a decreased materials technology in a turbofan system. The calculations show that the cooling air heat exchanger enables the feasibility of these engines. Previously announced in STAR as N83-34946

Gauntner, J. W.↗
NASA NTRS1982

Flight crew performance when pilot-flying and pilot-not-flying duties are exchanged

This study compares reports from the ASRS database depicting operational anomalies related to flight crew performance when pilot-flying and pilot-not-flying duties were exchanged. A greater number of near midair collisions, takeoff anomalies, and crossing altitude deviations were reported when the Captain was flying. More altitude deviations, near midair collisions during approach, and landing incidents occurred when the First Officer was flying. There were differences in monitoring effectiveness and in the type and distribution of information transfer problems associated with the anomalies. In addition, a number of crew performance factors were noted that were not affected by the exchange of duties. Several of these were deemed important enough to be included as matter of general interest.

Orlady, H. W.↗
NASA NTRS1985

Contact Heat Exchanger

Fluid pressure controls contact between heat pipe and heat exchanger. Heat exchanger system in cross section provides contact interface between fluid system and heat pipe with easy assembly/disassembly of heat-pipe/ pumped-liquid system. Originally developed for use in space, new device applicable on Earth where fluid system is linked with heat pipe, where rapid assembly/disassembly required, or where high pressures or corrosive fluids used.

Fleming, M. L.↗
NASA NTRS1984

Shuffle-exchanges on augmented meshes

A mesh connected array of size N = two to the Kth power, K an integer, can be augmented by adding at most one edge per node such that it can perform a shuffle-exchange of size N/2 in constant time. A shuffle-exchange of size N is performed on this augmented array in constant time. This is done by combining the available perfect shuffle of size N/2 with the existing nearest neighbor connections of the mesh. By carefully scheduling the different permutations that are composed in order to achieve the shuffle, the time required is reduced to 5 steps, which is optimal for this network.

Bokhari, S. H.↗
NASA NTRS1984

Air-sea heat exchange, an element of the water cycle

The distribution and variation of water vapor, clouds and precipitation are examined. Principal driving forces for these distributions are energy exchange and evaporation at the air-sea interface, which are also important elements of air-sea interaction studies. The overall aim of air-sea interaction studies is to quantitatively determine mass, momentum and energy fluxes, with the goal of understanding the mechanisms controlling them. The results of general circulation simulations indicate that the atmosphere in mid-latitudes responds to changes in the oceanic surface conditions in the tropics. This correlation reflects the strong interaction between tropical and mid-latitude conditions caused by the transport of heat and momentum from the tropics. Studies of air-sea exchanges involve a large number of physica, chemical and dynamical processes including heat flux, radiation, sea-surface temperature, precipitation, winds and ocean currents. The fluxes of latent heat are studied and the potential use of satellite data in determining them evaluated. Alternative ways of inferring heat fluxes will be considered.

Chahine, M. T.↗
NASA NTRS1984

O(+) charge exchange in the polar wind

O(+) density and flux profiles are calculated for a steady state polar wind flow of O(+) ions and electrons along geomagnetic field lines in the polar cap. Profiles are computed both with and without allowance for accidentally resonant charge exchange (ARCE) between O(+) and H. It is found that ARCE acts to reduce the limiting O(+) escape flux by less than 30 percent for typical atmospheric conditions and by only a factor of about 3.5 for atmospheres with low exospheric temperatures. Allowing for ARCE, the limiting O(+) escape flux is of the order of 5 x 10 to the 8th to 9th/cu cm/s, depending on the atmospheric conditions. This indicates that, contrary to previous predictions, there is no O(+) charge exchange barrier and it is therefore not necessary to have an acceleration mechanism at low altitudes in order to have an appreciable O(+) escape flux.

Barakat, A. R.↗
NASA NTRS1985

Calculation of the exchange ratio for the Adaptive Maneuvering Logic program

Improvements were made to the Adaptive Maneuvering Logic (AML) computer program, a computer-generated, air-to-air combat opponent. The primary improvement was incorporating a measure of performance, the exchange ratio, defined as the statistical measure of number of enemy kills divided by number of friendly losses. This measure was used to test a new modification of the AML's combat tactics. When the new version of the AML competed against the old version, the new version won with an exchange ratio of 1.4.

Neuman, F.↗
NASA NTRS1986

Measuring Heat-Exchanger Water Leakage

Water leakage in heat exchanger measured directly with help of electroytic hygrometer. In new technique, flow of nitrogen gas set up in one loop of heat exchanger. Other loop filled with water under pressure. Water concentration produced by leakage of water into nitrogen flow measured by hygrometer. New measurement method determines water concentrations up to 2,000 parts per million with accuracy of +/- 5 percent.

Zampiceni, J.↗
NASA NTRS1986

Repairing Hard-to-Reach Cracks in Heat-Exchanger Tubes

Inaccessible leaks repaired from accessible side of tube. Fish-Mouth insert placed in cut in leaky heat-exchanger tube. Insert welded or brazed to tube, and remaining open area of cut patched. Method developed for repairing leaks in nozzle coolant tubes of Space Shuttle main engine. Method also used on other types of tubular heat exchangers.

Mills, R. C., Sr.↗
NASA NTRS1986

Carbon exchange between the mantle and the crust and its effect upon the atmosphere: Today compared to Archean time

Paleobiologists now recognize that the Earth's biosphere has been profoundly affected by geologic processes. One very important process is the dissipation of heat which has been generated by radioactivity and/or stored within the earth. Heat flow is responsible for crustal movements and therefore it is the principal architect for constructing the environments (e.g. shallow marine, continental, etc.) wherein life developed and flourished. Heat flow has also influenced the movements of volatile elements (e.g. C, N, H, S, rare gases, etc.) both within the Earth's crust and between the crust and mantle. The inventory of these elements in the Earth's crust is important, not just because some of them constitute the building blocks of organic matter, but also because they influence the biosphere's climate. The purpose of this work is to evaluate how the decline of heat flow over the course of the Earth's history has influenced the carbon inventory in the Earth's crust. Such an evaluation must first consider whether the rate at which carbon is presently being exchanged between the mantle and crust is sufficient to play an important role in controlling the crustal inventory. Secondly, this exchange of carbon must be reevaluated in the context of the Precambrian Earth's environment. One very important consideration is that the upper mantle was perhaps 300 C hotter 3 b.y. ago than it is today.

Desmarais, D.↗
NASA NTRS1985

Application of AVHRR vegetation index to study atmosphere-biosphere exchange of CO2

The Advanced Very High Resolution Radiometer (AVHRR) satellite-borne sensor is presently used, together with field data, to determine the geographic distributions of the seasonal exchange of CO2 between the earth's atmosphere and the terrestrial biota. The exchange functions thus obtained are validated in virtue of the ability to reproduce the observed annual cycle of atmospheric CO2 in a three-dimensional tracer transport model. The AVHRR is carried by the TIROS-N series of polar-orbiting satellites.

Fung, I. Y.↗
NASA NTRS1987

Heat-Exchanger/Heat-Pipe Interface

Monolithic assembly reliable and light in weight. Heat exchanger and evaporator ends of heat pipes integrated in monolithic halves welded together. Interface assembly connects heat exchanger of furnace, reactor, or other power source with heat pipes carrying heat to radiator or power-consuming system. One of several concepts proposed for nuclear power supplies aboard spacecraft, interface useful on Earth in solar thermal power systems, heat engines, and lightweight cooling systems.

Snyder, H. J.↗
NASA NTRS1986

Evaluation of geophysical parameters measured by the Nimbus-7 microwave radiometer for the TOGA Heat Exchange Project

The data distributed by the National Space Science Data Center on the Geophysical parameters of precipitable water, sea surface temperature, and surface-level wind speed, measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, are evaluated with in situ measurements between Jan. 1980 and Oct. 1983 over the tropical oceans. In tracking annual cycles and the 1982-83 E1 Nino/Southern Oscillation episode, the radiometer measurements are coherent with sea surface temperatures and surface-level wind speeds measured at equatorial buoys and with precipitable water derived from radiosonde soundings at tropical island stations. However, there are differences between SMMR and in situ measurements. Corrections based on radiosonde and ship data were derived supplementing correction formulae suggested in the databook. This study is the initial evaluation of the data for quantitative description of the 1982-83 E1 Nino/Southern Oscillation episode. It paves the way for determination of the ocean-atmosphere moisture and latent heat exchanges, a priority of the Tropical Ocean and Global Atmosphere (TOGA) Heat Exchange Program.

Liu, W. Timothy↗
NASA NTRS1986

Charge exchange of solar wind ions in the Comet Halley coma

The He(2+) and He(+) radial profiles measured by the Giotto mass spectrometer on the inbound trajectory to comet Halley are compared to a simple 1-dimensional charge exchange model. Results indicate that charge exchange alone cannot account for the observed radial profiles of He(2+) and He(+).

Shelley, E. G.↗
NASA NTRS1987

Structural and preliminary thermal performance testing of a pressure activated contact heat exchanger

A contact heat exchanger concept is being developed for use onboard Space Station as an interface device between external thermal bus and pressurized modules. The concept relies on mechanical contact activated by the fluid pressure inside thin-walled tubes. Structural testings were carried out to confirm the technology feasibility of using such thin-walled tubes. The test results also verified the linear elastic stress analysis which was used to predict the tube mechanical behaviors. A preliminary thermal testing was also performed with liquid Freon-11 flowing inside tubes and heat being supplied by electrical heating from the bottom of the contact heat exchanger baseplate. The test results showed excellent agreement of test data with analytical prediction for all thermal resistances except for the two-phase flow characteristics. Testing with two-phase flow inside tubes will, however, be performed on the NASA-JSC test bed.

Lee, C. Y.↗
NASA NTRS1988

Heat Exchanger For Rotating Modular Structures

Heat exchanger transfers heat from one structure to another while accommodating rotary motion of structures. Flat-panel heat exchanger passes heat from fluid in middle panel to fluid in outer panels. Diaphragm-like outer panels swell to conform to surfaces of middle panel, ensuring thermal contact. Rotary fluid coupling provides connection for both supply fluid and return fluid. Flexible hoses carrying fluid to and from coupling accommodate tilt of one structure with respect to other. Adapted to transfer of fluids and heat across joints of machine tools and robot arms and to flow of coolant through portable electronic equipment.

Clark, William E.↗