Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “kW”

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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Study of fuel cell powerplant with heat recovery

It was shown that heat can be recovered from fuel cell power plants by replacing the air-cooled heat exchangers in present designs with units which transfer the heat to the integrated utility system. Energy availability for a 40-kW power plant was studied and showed that the total usable energy at rated power represents 84 percent of the fuel lower heating value. The effects of design variables on heat availability proved to be small. Design requirements were established for the heat recovery heat exchangers, including measurement of the characteristics of two candidate fuel cell coolants after exposure to fuel cell operating conditions. A heat exchanger test program was defined to assess fouling and other characteristics of fuel cell heat exchangers needed to confirm heat exchanger designs for heat recovery.

King, J. M.↗
NASA NTRS1975

Electrical characteristics of a free-burning direct-current argon arc operating between 90 and 563 kilowatts with two types of cathodes

The electrical characteristics of a high-power, long-lived, free-burning dc argon arc are presented. Empirical formulas relating voltage to current, electrode separation, and operating pressure are given for two types of cathodes: a typical point tip cathode and a cathode with a 1.27-cm-(0.5-in.-) diameter crater in the tip. Power was varied from 90 to 563 kW. A discussion of the cathode with the crater tip is given.

Curtis, H. B.↗
NASA NTRS1975

Analytic solution for low thrust out of ecliptic mission design

Description of an analytic trajectory solution for low thrust out of ecliptic mission design based on the two-variable asymptotic expansion technique. A practical steering program utilizing normal thrusting symmetrical about the nodes is assumed. A two-term expansion yields an essentially exact solution of the problem which is in a form suitable for evaluation on small desk-top computers. It is shown that for a circular base orbit at 1 AU, a 15-kw solar electric system with a specific impulse of 3000 sec is capable of delivering an 1100-kg net payload to a heliographic latitude of about 63 deg.

Flandro, G. A.↗
NASA NTRS1974

High voltage series resonant inverter ion engine screen supply

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

Biess, J. J.↗
NASA NTRS1975

Design synthesis of the SEPS

This paper summarizes the most current configuration of the Solar Electric Propulsion Stage (SEPS) design resulting from the synthesis of key tradeoff analyses. The baseline SEPS is a 21-kW propulsion-power vehicle using the Shuttle/Interim Upper Stage (IUS) launch vehicle for planetary and geosynchronous missions. The trade analyses supporting the baseline configuration include ion thruster array pattern, solar array stowage concepts, and number of thrusters and power processors (PP). In addition, an integrated thermal control and structural system was optimized and designed to meet flight loads and dynamics requirements. Payload provisions, mercury propellant refueling, and design compatibility of the SEPS and Shuttle/IUS are presented.

Horio, S. P.↗
NASA NTRS1975

The attitude control of a solar electric propulsion /SEP/ spacecraft for an out-of-the-ecliptic mission

A computer-controlled attitude and articulation control system is proposed for a spacecraft of extremely soft structure that uses two 8-kW solar arrays with an area of nearly 100 sq m each to power six electric propulsion thrusters. The purpose of the articulation control is to point the scientific instruments, to orient the antenna toward the earth, and to reorient the thrust vector as required for trajectory control. The attitude control system provides control both during the low-thrust phase of the mission and during long-term spinning modes.

Marsh, E. L.↗
NASA NTRS1975

Optimal orbit transfer for out-of-ecliptic mission using a solar electric spacecraft

This paper analyzes the performance capability of a Titan IIIE/Centaur/SEP (15 kw) for out-of-ecliptic missions. Two classes of orbital transfer modes are considered; circular-to-circular and circular-to-elliptic. The results presented compare the achievable heliographic inclination using these different transfer modes and also show the degradations in performance due to constrained launch azimuth and thruster life. It is observed that the latter transfer mode could deliver a spacecraft to a much higher inclination than the former, but the final orbit is very eccentric and could come very close to the sun. In view of the existence of many trajectories by which this mission can be performed, it is suggested that a trajectory other than IAU circular out-of-ecliptic type be used to explore more scientifically rewarding missions.

Yen, C.-W. L.↗
NASA NTRS1975

Trajectory design of a solar electric propulsion Encke slow flyby mission

A slow flyby of the periodic comet, Encke, prior to its perihelion passage in 1980 has been shown to be a feasible mission for a solar electric propulsion spacecraft using a moderate power level of around 15 kw. The mission is accomplished in slightly less than two years with a planned miss distance and flyby speed of 1000 km and 4 km/s respectively. The results of a performance tradeoff study are presented together with a description of the nominal trajectory. The trajectories used in these mission studies were calculated using an updated model of the 30 cm mercury bombardment thruster's performance. The trajectory simulations include optimum staging of operating thrusters as a function of input power level constraints and limits on the variation of thruster specific impulse and efficiency as a function of thruster input power.

Sauer, C. G., Jr.↗
NASA NTRS1975

The Skylab program - An overview

A brief survey is made of significant aspects of the Skylab missions, with emphasis on atmospheric control, electrical power, stabilization and attitude control, prevention of instrument contamination, habitability of the spacecraft, in-flight maintenance and repair, and crew training. Skylab, unlike previous manned spacecraft, had a two-gas atmosphere of oxygen and nitrogen. The station's 25-kW capability was the largest electrical system ever flown in space. Skylab was the first flight application of large control-moment gyroscopes for attitude control. The missions provided significant scientific data in the fields of solar physics, biomedicine, earth resources, and materials processing. Particularly important was the finding of no physical limitation to men's ability to work in space for long periods.

Disher, J. H.↗
NASA NTRS1975

The measurement of meteor winds over Atlanta /34 N, 84 W/

An all-sky, continuous wave radio meteor wind facility has been installed in Atlanta. A double sideband suppressed carrier CW transmitter, operating at around 32.5 MHz, with an rms output of 2 kW, has been installed, and a receiving site was established at 27 km away. Details of the equipment, together with height/time profiles of mean wind circulation and tides between 80 and 100 km, measured from August 9 to September 4, 1974, are presented.

Roper, R. G.↗
NASA NTRS1974

Current NASA ion propulsion technology

The current status of technology and the developmental trends in the field of ion propulsion systems and components for primary and auxiliary applications in advanced earth-orbital and interplanetary missions are reviewed. Particular attention is given to the (electrostatic) 30-cm electron bombardment ion thruster being developed with the aim of achieving an overall efficiency of 73% at full power (2.75 kW) and 64% at half power.

Finke, R. C.↗
NASA NTRS1974

Mercury bombardment ion thrusters - Development status, performance levels, and test history

The present work describes the development status, performance levels, and life test history of 5-cm, 8-cm, and 30-cm mercury bombardment ion thrusters and their respective power processors. A 2.6 kW, 30-cm thruster module and its power processor unit are now available that established the performance required by interplanetary and geosynchronous orbit raising missions. An 8-cm thruster with nominal 4.5 mN thrust level capability has demonstrated a high performance over a wide range of thrust and operational life.

Molitor, J. H.↗
NASA NTRS1974

Interplanetary spacecraft design using solar electric propulsion - A circular 1.0 AU out-of-the-ecliptic mission

A preliminary study has been conducted to investigate the utility of solar electric propelled spacecraft for delivering a scientific payload to high heliographic latitudes to study cosmic rays, the sun, and its influence on environments within our solar system. The mission is considered a candidate for launch in the early 1980's by both the United States and Europe and has the potential of becoming a cooperative space venture. A brief description of the science objectives, mission design and spacecraft design is presented for a circular 1.0 AU heliocentric orbit and a 15 kW solar electric propulsion module. Particular emphasis is placed upon the performance available from this approach.

Duxbury, J. H.↗
NASA NTRS1975

SEPS solar array design and technology evaluation

The technology developments required and a preliminary design of a lightweight 25 kW solar array for the solar electric propulsion stage (SEPS) have been defined. The requirements for a 65 W/Kg SEPS solar array system requires significant component weight reductions over present state-of-the-art flexible solar arrays in both electrical and structural-mechanical designs. A requirement for operation from 0.3 au to 6.0 au presents a wide range of temperature environments as well as severe combined thermal/vacuum/UV radiation environments. Additional requirements are capability for partial array retraction operation, and capability for full retraction and automatic preloading for survival of the Shuttle reentry environment. An assessment of current lightweight flexible solar array technology is made against the SEPS solar array requirements and new technology requirements are defined. A preliminary design and the operating characteristics of a flat-fold solar array system meeting the SEPS requirements is presented. A full-width, 10-ft-tall functional array model, including representative welded electrical modules and a model astromast, was fabricated and tested.

Elms, R. V., Jr.↗
NASA NTRS1975

Preliminary results of the large experimental wind turbine phase of the national wind energy program

A major phase of the wind energy program is the development of reliable wind turbines for supplying cost-competitive electrical energy. This paper discusses the preliminary results of two projects in this phase of the program. First an experimental 100 kW wind turbine design and its status are reviewed. Also discussed are the results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs. These studies show wind energy costs of 7 to 1.5 c/kWH for wind turbines produced in quantities of 100 to 1000 a year and located at sites having average winds of 12 to 18 mph.

Thomas, R. L.↗
NASA NTRS1975

Plans and status of the NASA-Lewis Research Center wind energy project

This report describes that portion of the national five-year wind energy program that is being managed by the NASA-Lewis Research Center for the ERDA. The Lewis Research Center's Wind Power Office, its organization and plans and status are briefly described. The three major elements of the wind energy project at Lewis are the experimental 100 kW wind-turbine generator; the first generation industry-built and user-operated wind turbine generators; and the supporting research and technology tasks which are each briefly described.

Thomas, R.↗
NASA NTRS1975

Evaluation of a microwave high-power reception-conversion array for wireless power transmission

Initial performance tests of a 24-sq m area array of rectenna elements are presented. The array is used as the receiving portion of a wireless microwave power transmission engineering verification test system. The transmitting antenna was located at a range of 1.54 km. Output dc voltage and power, input RF power, efficiency, and operating temperatures were obtained for a variety of dc load and RF incident power levels at 2388 MHz. Incident peak RF intensities of up to 170 mW/sq cm yielded up to 30.4 kW of dc output power. The highest derived collection-conversion efficiency of the array was greater than 80 percent.

Dickinson, R. M.↗
NASA NTRS1975

DSS 14 X-band radar feedcone

A high-power 400-kW continuous-wave (CW) X-band radar feed system was described for use with the Goldstone, California, 64-m DSS 14 antenna system. Design considerations, their solutions, and final system testing are discussed. The radar system, unique in terms of antenna size, radiated power, and efficiency, became operational in December 1974.

Neff, D. E.↗