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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Development of a solar powered residential air conditioner (General optimization)

A commercially available 3-ton residential Lithium Bromide (LiBr) absorption air conditioner was modified for use with lower temperature solar heated water. The modification included removal of components such as the generator, concentration control chamber, liquid trap, and separator; and the addition of a Chrysler designed generator, an off-the-shelf LiBr-solution pump. The design goal of the modified unit was to operate with water as the heat-transfer fluid at a target temperature of 85 C (185 F), 29.4 C (85 F) cooling water inlet, producing 10.5 kW (3 tons) of cooling. Tests were performed on the system before and after modification to provide comparative data. At elevated temperatures (96 C, 205 F), the test results show that Lithium Bromide was carried into the condenser due to the extremely violent boiling and degraded the evaporator performance.

Lowen, D. J.↗
NASA NTRS1977

Development and performance of power processor system for 2-gigahertz, 200-watt amplifier for communications technology satellite

The electrical and environmental requirements for a power processor system (PPS) designed to supply the appropriate voltages and currents to a 200-watt traveling wave tube (TWT) for a communication technology satellite is described. A block diagram of the PPS, the interface requirements between the PPS and spacecraft, the interface requirements between the PPS and 200-watt TWT, and the environmental requirements of the PPS are presented. Also included are discussions of protection circuits, interlocking sequences, and transient requirements. Predictions of the flight performance, based on ground test data, are provided.

Siegert, C. E.↗
NASA NTRS1983

Background sources in optical communications

The characterization and measurement of background radiation relevant to optical communications system performance is addressed. The necessary optical receiver parameters are described, and radiometric concepts required for the calculation of collected background power are developed. The most important components of optical background power are discussed, and their contribution to the total collected background power in various communications scenarios is examined.

Vilnrotter, V. A.↗
NASA NTRS1988

Extended SP-100 reactor power systems capability

The SP-100 space nuclear power system development program and the NASA Civil Space Technology Initiative (CSTI) are discussed. The advanced technologies being developed for the CSTI high capacity nuclear reactor power system are outlined. The relationship between the CSTI and the Pathfinder project is considered.

Bloomfield, H. S.↗
NASA NTRS1992

Power assist EVA glove development

Structural modeling of the EVA glove indicates that flexibility in the metacarpophalangeal (MCP) joint can be improved by selectively lowering the elasticity of the glove fabric. Two strategies are used to accomplish this. One method uses coil springs on the back of the glove to carry the tension in the glove skin due to pressurization. These springs carry the loads normally borne by the glove fabric, but are more easily deformed. An active system was also designed for the same purpose and uses gas filled bladders attached to the back of the EVA glove that change the dimensions of the back of the glove and allow the glove to bend at the MCP joint, thus providing greater flexibility at this joint. A threshold control scheme was devised to control the action of the joint actuators. Input to the controller was provided by thin resistive pressure sensors placed between the hand and the pressurized glove. The pressure sensors consist of a layer of polyester film that has a thin layer of ink screened on the surface. The resistivity of the ink is pressure dependent, so an extremely thin pressure sensor can be fabricated by covering the ink patch with another layer of polyester film and measuring the changing resistance of the ink with a bridge circuit. In order to sense the force between the hand and the glove at the MCP joint, a sensor was placed on the palmar face of the middle finger. The resultant signal was used by the controller to decide whether to fill or exhaust the bladder actuators on the back of the glove. The information from the sensor can also be used to evaluate the effectiveness of a given control scheme or glove design since the magnitude of the measured pressures gives some idea of the torque required to bend a glove finger at the MCP joint. Tests of this actuator, sensor, and control system were conducted in an 57.2 kPa glove box by performing a series of 90 degree finger bends with a glove without an MCP joint assembly, a glove with the coil spring assembly, and with the four fingered actuated glove. The tests of these three glove designs confirm the validity of the model.

Main, John A.↗
NASA NTRS1992

Projected NASA power requirements for space science and exploration missions

NASA's Office of Space Science and Applications has recently completed its long-range strategic plan which describes a number of exciting space science missions into the early 21st century. In parallel, NASA's new Office of Exploration has begun defining in more detail the architectures of the Space Exploration Initiative (SEI) for returning to the Moon and going to Mars. Both the space science missions and the SEI missions are dependent upon power sources and energy storage with strong requirements for reliability, long life, ease of assembly, autonomy, and light weight. This paper reviews the currently planned space science and SEI missions and focuses upon the power requirements with a view toward guiding technology developers and power designers.

Gary L Bennett↗
NASA NTRS1992

Power assist EVA glove development

The design of the EVA glove is examined, emphasizing the development of a more flexible metacarpophalangeal (MCP) joint for the EVA glove. The analysis of the EVA glove MCP joint is reviewed and the glove design process is recapitulated. Experimental tests of the glove are summarized.

Main, John A.↗
NASA NTRS1994

Performance evaluation of the Russian SPT-100 thruster at NASA LeRC

Performance measurements of a Russian flight-model SPT-100 thruster were obtained as part of a comprehensive program to evaluate engineering issues pertinent to integration with Western spacecraft. Power processing was provided by a US Government developed laboratory power conditioner. When received the thruster had been subjected to only a few hours of acceptance testing by the manufacturer. Accumulated operating time during this study totalled 148 h and included operation of both cathodes. Cathode flow fraction was controlled both manually and using the flow splitter contained within the supplied xenon flow controller. Data were obtained at current levels ranging from 3 A to 5 A and thruster voltages ranging from 200 V to 300 V. Testing centered on the design power of 1.35 kW with a discharge current of 4.5 A. The effects of facility pressure on thruster operation were examined by varying the pressure via injection of xenon into the vacuum chamber. The facility pressure had a significant effect on thruster performance and stability at the conditions tested. Periods of current instabilities were noted throughout the testing period and became more frequent as testing progressed. Performance during periods of stability agreed with previous data obtained in Russian laboratories.

Sankovic, John M.↗
NASA NTRS1997

Chemical Inventory Management at NASA Lewis Research Center

The Chemical Management System (CMS) is a client/server application developed with Power Builder and Sybase for the Lewis Research Center (LeRC). Power Builder is a client-server application development tool, Sybase is a Relational Database Management System. The entire LeRC community can access the CMS from any desktop environment. The multiple functions and benefits of the CMS are addressed.

Kraft, Shirley S.↗
NASA NTRS2000

Development Status of a Power Processing Unit for Low Power Ion Thrusters

An advanced breadboard Power Processing Unit (PPU) for a low power ion propulsion system incorporating mass reduction techniques was designed and fabricated. As a result of similar output current requirements, the discharge supply was also used to provide the neutralizer heater and discharge heater functions by using three relays to switch the output connections. This multi-function supply reduces to four the number of power converters needed to produce the required six electrical outputs. Switching frequencies of 20 and 50 kHz were chosen as a compromise between the size of the magnetic components and switching losses. The advanced breadboard PPU is capable of a maximum total output power of 0.47 kW. Its component mass is 0.65 kg and its total mass 1.9 kg. The total efficiency at full power is 0.89.

Pinero, Luis R.↗
NASA NTRS2005

Development of the NEXT Power Processing Unit

Boeing Electron Dynamic Devices, Inc. (EDD) has designed and fabricated a breadboard version of a 6 kW power processing unit (PPU) for gridded ion thrusters. This breadboard PPU will be integrated with an engineering model 40 cm ion engine designed and tested at NASA Glenn. The results of our tests using resistive loads are reported in this paper. The PPU demonstrated efficiencies to date are higher than 95 percent for the beam supply and higher than 92 percent for the discharge supply at full power. Overall PPU efficiency is greater than 94 percent at full throttle settings.

Phelps, Thomas K.↗
NASA NTRS2009

Development of Jet Noise Power Spectral Laws Using SHJAR Data

High quality jet noise spectral data measured at the Aeroacoustic Propulsion Laboratory at the NASA Glenn Research Center is used to examine a number of jet noise scaling laws. Configurations considered in the present study consist of convergent and convergent-divergent axisymmetric nozzles. Following the work of Viswanathan, velocity power factors are estimated using a least squares fit on spectral power density as a function of jet temperature and observer angle. The regression parameters are scrutinized for their uncertainty within the desired confidence margins. As an immediate application of the velocity power laws, spectral density in supersonic jets are decomposed into their respective components attributed to the jet mixing noise and broadband shock associated noise. Subsequent application of the least squares method on the shock power intensity shows that the latter also scales with some power of the shock parameter. A modified shock parameter is defined in order to reduce the dependency of the regression factors on the nozzle design point within the uncertainty margins of the least squares method.

Khavaran, Abbas↗