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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Initial guidelines and estimates for a power system with inertial (flywheel) energy storage

The starting point for the assessment of a spacecraft power system utilizing inertial (flywheel) energy storage. Both general and specific guidelines are defined for the assessment of a modular flywheel system, operationally similar to but with significantly greater capability than the multimission modular spacecraft (MMS) power system. Goals for the flywheel system are defined in terms of efficiently train estimates and mass estimates for the system components. The inertial storage power system uses a 5 kw-hr flywheel storage component at 50 percent depth of discharge (DOD). It is capable of supporting an average load of 3 kw, including a peak load of 7.5 kw for 10 percent of the duty cycle, in low earth orbit operation. The specific power goal for the system is 10 w/kg, consisting of a 56w/kg (end of life) solar array, a 21.7 w-hr/kg (at 50 percent DOD) flywheel, and 43 w/kg power processing (conditioning, control and distribution).

Slifer, L. W., Jr.↗
NASA NTRS1981

NASA Redox system development project status

NASA-Redox energy storage systems developed for solar power applications and utility load leveling applications are discussed. The major objective of the project is to establish the technology readiness of Redox energy storage for transfer to industry for product development and commercialization by industry. The approach is to competitively contract to design, build, and test Redox systems progressively from preprototype to prototype multi-kW and megawatt systems and conduct supporting technology advancement tasks. The Redox electrode and membrane are fully adequate for multi-kW solar related applications and the viability of the Redox system technology as demonstrated for multi-kW solar related applications. The status of the NASA Redox Storage System Project is described along with the goals and objectives of the project elements.

Nice, A. W.↗
NASA NTRS1981

High power solar array switching regulation

It is pointed out that spacecraft utilization projections for the 1980s and beyond show a trend toward extended lifetimes and larger electric power systems. The need for improved power management and energy transfer arising in connection with this trend has resulted in the conduction of a Solar Array Switching Power Management study. A description is presented of initial development work performed in the study, taking into account the characteristics for three mission classes. Attention is given to the manned LEO platform (250-kW average load), the unmanned GEO platform (50-kW average load), and an ion propulsion orbit transfer vehicle (50- to 250 kW load).

Decker, D. K.↗
NASA NTRS1982

A lightweight electronically commutated dc motor for electric passenger vehicles

A functional model breadboard converter and a rare-earth-cobalt, permanent magnet motor; as well as an engineering model converter and PM motor suitable for vehicle installations were developed and tested. The converter and motor achieved an 88% peak efficiency, a maximum output of 26 kW at 26,000 rpm, and a continuous rating of 15 kW. The system also generated power to the source during braking, with a demonstrated peak power available at the converter terminals of approximately 26 kW at 88% efficiency. Major conclusions include: (1) the SAE J227a(D) driving cycle efficiency for the converter/motor is 86% to 88% when energy available for recovery at the converter terminals is included; (2) the converter initial cost is approximately five times that of the permanent magnet motor, but can be reduced by means of LSI logic and integrated liquid cooled semiconductor packages; and (3) an electronically commutated motor with a liquid cooled converter will operate reliably without service or maintenance for the life of a passenger vehicle.

Echolds, E. F.↗
NASA NTRS1982

Develop and test fuel cell powered on-site integrated total energy system

Satisfactory performance is reported for the first 12-cell sub-stack of the 5 kW rebuild using improved ABA reactant distribution plates. Construction and test results are described for the first full-sized single-cell test (0.33 m x 0.56 m). Test duration was 450 hours. Plans are outlined for construction and testing of two methanol reformer units based on commercially-available shell-and-tube heat exchangers. A 5 kW-equivalent precursor and a 50 kW-equivalent prototype will be built. Supporting design and single-tube experimental data are presented. Stack support efforts are summarized on corrosion currents of graphite materials and acid-management of single-cell test facilities. Comparative properties are summarized for the two methanol/steam reforming catalysts evauated under Task V (now completed); T2107RS and C70-2RS.

Kaufman, A.↗
NASA NTRS1983

Construction of low-cost, Mod-OA wood composite wind turbine blades

Two sixty-foot, low-cost, wood composite blades for service on 200 kW Mod-OA wind turbines were constructed. The blades were constructed of epoxy resin-bonded Douglas fir veneers for the leading edge sections, and paper honeycombcored, birch plywood faced panels for the afterbody sections. The blades were joined to the wind turbine hub by epoxy resin-bonded steel load take-off studs embedded into the root end of the blades. The blades were installed on the 200 kW Mod-OA wind turbine facility at Kahuku, Hawaii, The blades completed nearly 8,000 hours of operation over an 18 month period at an average power of 150 kW prior to replacement with another set of wood composite blades. The blades were replaced because of a corrosion failure of the steel shank on one stud. Inspections showed that the wood composite structure remained in excellent condition.

Lark, R. F.↗
NASA NTRS1983

Improved transistor-controlled and commutated brushless DC motors for electric vehicle propulsion

The development, design, construction, and testing processes of two electronically (transistor) controlled and commutated permanent magnet brushless dc machine systems, for propulsion of electric vehicles are detailed. One machine system was designed and constructed using samarium cobalt for permanent magnets, which supply the rotor (field) excitation. Meanwhile, the other machine system was designed and constructed with strontium ferrite permanent magnets as the source of rotor (field) excitation. These machine systems were designed for continuous rated power output of 15 hp (11.2 kw), and a peak one minute rated power output of 35 hp (26.1 kw). Both power ratings are for a rated voltage of 115 volts dc, assuming a voltage drop in the source (battery) of about 5 volts. That is, an internal source voltage of 120 volts dc. Machine-power conditioner system computer-aided simulations were used extensively in the design process. These simulations relied heavily on the magnetic field analysis in these machines using the method of finite elements, as well as methods of modeling of the machine power conditioner system dynamic interaction. These simulation processes are detailed. Testing revealed that typical machine system efficiencies at 15 hp (11.2 kw) were about 88% and 84% for the samarium cobalt and strontium ferrite based machine systems, respectively. Both systems met the peak one minute rating of 35 hp.

Demerdash, N. A.↗
NASA NTRS1983

Develop and test fuel cell powered on-site integrated total energy system

Test results are given for a 5 kW stack and initial results for an integrated, grid connected system operating from methanol fuel. Site selection criteria are presented for future demonstration of a 50 or 100 kW OS/IES. Preliminary results are also given with approximate internal rates of return to the building owner. Progress in development and construction of a 50 kW modular methanol/steam reformer is reported.

Source record↗
NASA NTRS1983

Downsizing assessment of automotive Stirling engines

A 67 kW (90 hp) Stirling engine design, sized for use in a 1984 1440 kg (3170 lb) automobile was the focal point for developing automotive Stirling engine technology. Since recent trends are towards lighter vehicles, an assessment was made of the applicability of the Stirling technology being developed for smaller, lower power engines. Using both the Philips scaling laws and a Lewis Research Center (Lewis) Stirling engine performance code, dimensional and performance characteristics were determined for a 26 kW (35 hp) and a 37 kW (50 hp) engine for use in a nominal 907 kg (2000 lb) vehicle. Key engine elements were sized and stressed and mechanical layouts were made to ensure mechanical fit and integrity of the engines. Fuel economy estimates indicated that the Stirling engine would maintain a 30 to 45 percent fuel economy advantage comparable spark ignition and diesel powered vehicles in the 1984 period.

Knoll, R. H.↗
NASA NTRS1983

Design considerations for high-power VHF radar transceivers: T/R switch design

The transceiver (TR) switch developed at NOAA's Aeronomy Laboratory for use in their 50 kW peak power, 50 MHz transmitter is described. The switch mounts inside the transmitter chassis and was designed to be compact while retaining the ability to handle well over 50 kW peak power at average power levels up to 2 kW. The TR switch is a conventional TR/ATR design with equivalent /4 transmission line sections constructed of lumped constant coils and transmitting capacitors in ''Tee' sections. Two TR sections are placed in series to achieve adequate receiver protection. The switch is set into the ''transmit' mode by forward biasing the 3 pin diodes to about 1.2 amperes each. The receive mode is achieved by back biasing the diodes to -15 volts. A directional coupler is also incorporated into the TR switch box to provide a convenient monitor point for forward and reflected transmitter power.

Ecklund, W. L.↗
NASA NTRS1984

A Battery Charger and State of Charge Indicator

A battery charger which has a full wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches, which are programmed to actively shape the input dc line current to be a mirror image of the ac line voltage is discussed. The power circuit operates at 2 kW peak and 1 kW average power. The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state of charge software programs. The state of charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery. The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz. The switches selected for the battery charger are the single most important item in determining its efficiency. The combination of voltage and current requirements dictate the use of high power NPN Darlington switching transistors. The power circuit topology is a three switch design which utilizes a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends. An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation.

Latos, T. S.↗
NASA NTRS1983

An SCR inverter with an integral battery charger for electric vehicles

The feasibility of incorporating an onboard battery charger into the inverter previously developed under a NASA contract is successfully demonstrated. The rated output power of the resulting isolated battery charger is 3.6 kW at 220 Vac with an 86 percent efficiency and a 95 percent power factor. Also achieved are improved inverter efficiency (from 90 to 93 percent at 15 kW motor shaft power), inverter peak power capability (from 26 to 34 kW), and reduced weight and volume of the combined inverter/charger package (47 kg, 49 x 44 x 24 cm). Some major conclusions are that using the inverter commutation circuitry to perform the battery charging function is advantageous, and that the input-commutated thyristor inverter has the potential to be an excellent inverter and battery charger for use in electric vehicle applications.

Thimmeach, D.↗
NASA NTRS1984

Advanced high-power transfer through rotary interfaces

A roll-ring design that is uniquely suited for rotary signal/power transfer in space applications is described. Two high-power configurations of the roll ring were developed. Present lab-proven hardware is available with power transfer capability of 2 kW at 200 amps and higher power units with 100-kW capability are in the design stage. Theoretical analysis indicated that power levels of kW are possible.

Jacobson, P.↗
NASA NTRS1984

Electrodynamic tethers. I - Power generation in LEO. II - Thrust for propulsion & power storage

The power gain and thrust for plasma engines available by unreeling 10 km of insulated Al wire from a spacecraft are investigated. The wire, unreeling in the vertical, would cut the earth's magnetic field lines, thereby generating 20 kW of power in the wire. A drag loss of 20.4 kJ/sec would reduce the power gain to 18.7 kW, an efficiency of 92 percent. Thicker wires could push the power gain to 1 MW at 95 percent efficiency. Conductive 'balloons' at the ends of the tether would function as ionospheric 'brushes' to complete the circuit. Reversing the IXB force by employing on-board stored power would drive the tether current against the induced voltage, providing a 1 N thrust for 8 kW of energy consumed, which could be supplied by solar panels during the day portion of orbit. The equivalent thrust by conventional stationkeeping means would consume 8000 kg of propellant/yr. Techniques for stabilizing the tether in the presence of variable magnetic fields are discussed.

Mccoy, J. E.↗
NASA NTRS1985

Review of the development of small- and medium-capacity gas turbines at the Motoren- und Turbinen Union

Small- and medium-capacity gas turbines under development for turboprop aircraft and helicopter, as well as for armored and commercial vehicle propulsion, are discussed. Design problems related to axial turbines, ceramic components, regenerative gas turbines, and the optimal expansion ratios for turbines with capacities from 250 to greater than 800 kW are considered; in addition, combustion chamber technology is mentioned. Prototype gas turbines with capacities of 500 to 600 kW or 800 to 1800 kW are described.

Heilmann, W.↗
NASA NTRS1985

Advanced on-site power plant development technology program

A 30-cell stack was tested for 7200 hours. At 6000 hours the stack was successfully refilled with acid with no loss of performance. A second stack containing the advanced Configuration B cell package was fabricated and assembled for testing in 1985. A 200-kW brassboard inverter was successfully evaluated, verifying the design of the two-bridge ASCR circuit design. A fuel processing catalyst train was tested for 2000 hours verifying the catalyst for use in a 200-kW development reformer. The development reformer was fabricated for evaluation in 1985. The initial test plan was prepared for a 200-kW verification test article.

Kemp, F. S.↗
NASA NTRS1984

Space station power system

It is pointed out that space station planning at NASA began when NASA was created in 1958. However, the initiation of the program for a lunar landing delayed the implementation of plans for a space station. The utility of a space station was finally demonstrated with Skylab, which was launched in 1972. In May 1982, the Space Station Task Force was established to provide focus and direction for space station planning activities. The present paper provides a description of the planning activities, giving particular attention to the power system. The initial space station will be required to supply 75 kW of continuous electrical power, 60 kW for the customer and 15 kW for space station needs. Possible alternative energy sources for the space station include solar planar or concentrator arrays of either silicon or gallium arsenide.

Forestieri, A. F.↗
NASA NTRS1985

Space Station power system issues

Issues governing the selection of power systems for long-term manned Space Stations intended solely for earth orbital missions are covered briefly, drawing on trade study results from both in-house and contracted studies that have been conducted over nearly two decades. An involvement, from the Program Development Office at MSFC, with current Space Station concepts began in late 1982 with the NASA-wide Systems Definition Working Group and continued throughout 1984 in support of various planning activities. The premise for this discussion is that, within the confines of the current Space Station concept, there is good reason to consider photovoltaic power systems to be a venerable technology option for both the initial 75 kW and 300 kW (or much greater) growth stations. The issue of large physical size required by photovoltaic power systems is presented considering mass, atmospheric drag, launch packaging and power transmission voltage as being possible practicality limitations. The validity of searching for a cross-over point necessitating the introduction of solar thermal or nuclear power system options as enabling technologies is considered with reference to programs ranging from the 4.8 kW Skylab to the 9.5 gW Space Power Satellite.

Giudici, R. J.↗