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27th Intersociety Energy Conversion Engineering Conference (1992)
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Electrical Power System Integrated Thermal/Electrical System Simulation

Martin Marietta Astronautics Group-W. Eric Freeman
Published 1992-08-03 by SAE International in United States
This paper adds thermal properties to previously developed [1] [2] [3] electrical Saber templates and incorporates these templates into a functional Electrical Power Subsystem (EPS) simulation. These combined electrical and thermal templates enable the complete and realistic simulation of a vehicle EPS on-orbit. Applications Include on-orbit energy balance determinations for system load changes, initial array and battery EPS sizing for new EPS development, and array and battery technology trade studies. This effort proves the versatility of the Saber simulation program in handling varied and complex simulations accurately and in a reasonable amount of computer time.
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Space Power Subsystem Sizing

Wright-Patterson AFB-Jack W. Geis
Published 1992-08-03 by SAE International in United States
A Space Power Subsystem Sizing program has been developed by the Aerospace Power Division of Wright Laboratory, Wright-Patterson Air Force Base, Ohio. Although a similar computational program has been developed in the Air Force, this program is integrated into a Quattro Pro spreadsheet.The Space Power Subsystem program (SPSS) contains the necessary equations and algorithms to calculate photovoltaic array power performance, including end-of-life (EOL) and beginning-of-life (BOL) specific power (W/kg) and areal power density (W/m2). These can then be displayed parametrically in graph form. Along the way equations are used to determine solar cell temperature effects, and cell performance degradation due to high energy particulate radiation as a function of altitude, orbital inclination, shield thickness and time in orbit.Additional equations and algorithms are included in the spreadsheet for determining maximum eclipse time as a function of orbital altitude, and inclination. The maximum eclipse time is used in sizing the secondary battery power subsystem and in determining this effect on solar array BOL and EOL power requirements. Altogether, approximately 45 equations and algorithms, and 50 variables are…
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The New Environmentalism

New York Power Authority-Herschel Specter
Published 1992-08-03 by SAE International in United States
Almost all discussions of the relationships between energy and the environment concentrate on the impacts of producing energy. We are frequently reminded of effects such as acid rain, atmospheric heating by greenhouse gases, oil spills, Chernobyl, black lung disease, and the loss of habitat for animals from the snail darter to the Alaskan caribou.Often energy production is cast as a conflict; i.e., commercial gain versus inflicting damage to humans and the environment. Such a viewpoint has been the underpinning for many local and national challenges during the past two decades. While such debates have been very valuable in heightening our awareness of the environment and have sometimes led to significant progress, they are, at best, incomplete. As we move through the 1990's we must expand these ideas if the environment is truly to be protected. We need a new environmentalism because it seems that we have overlooked a major challenge to the environment: insufficient energy.
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Projected Impact of Deep Ocean Carbon Dioxide Discharge on Atmospheric CO2 Concentrations

Pacific International Center for High Technology Research-G. C. Nihous, Y. Mori, S. M. Masutani, L. A. Vega
University of Hawaii-C. M. Kinoshita
Published 1992-08-03 by SAE International in United States
An evaluation of oceanic containment strategies for anthropogenic carbon dioxide is presented. Energy conservation is also addressed through an input hydrocarbon-fuel consumption function. The effectiveness of the proposed countermeasures is determined from atmospheric CO2 concentration predictions. A previous box model with a diffusive deep ocean is adapted and applied to the concept of fractional CO2 injection in 500 m deep waters. Next, the contributions of oceanic calcium carbonate sediment dissolution, and of deep seawater renewal, are included. Numerical results show that for CO2 direct removal measures to be effective, large fractions of anthropogenic carbon dioxide have to be processed. This point favors fuel pre-processing concepts. The global model also indicates that energy conservation, i. e. a hydrocarbon-fuel consumption slowdown, remains the most effective way to mitigate the greenhouse effect, because it offers mankind a substantial time delay to implement new energy production alternatives.
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Neural Network Controller Design for a Magnetic Bearing Flywheel Energy Storage System

University of Maryland-Roger L. Fittro, Davinder K. Anand
Published 1992-08-03 by SAE International in United States
The control and analysis of magnetic bearings has been primarily based upon classical linear control theory. This approach does not allow for some important system complexities and nonlinearities to be taken into account. The resulting simplifications degrade the overall system performance. This paper investigates the use of a neural network to control a magnetic bearing flywheel energy storage system. A plant simulation is developed as well as a neural network emulator and controller.
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SP-100 Thermoelectric Converter Technology Development

General Electric Co.-D. N. Matteo, J. A. Bond, R. J. Rosko
Published 1992-08-03 by SAE International in United States
As part of the SP-100 Space Reactor Power System Program being undertaken for the U. S. Department of Energy, GE is developing a thermoelectric (T/E) power converter which utilizes reactor delivered heat and transforms it into usable electric power by purely static means. This converter is based to GE's product line of successful thermoelectric space power systems. The SP-100 power converter embodies the next generation improvement over the type of T/E converter successfully flown on the six U. S. space missions. That is, conduction coupling of T/E cell to both the heat source and the heat rejection elements. The current technology utilizes radiation coupling in these areas. The conduction coupling technique offers significant improvements in system specific power since it avoids the losses associated with parasitic ΔT's across the radiation gap between the heat source and the hot junction of the thermoelectric (T/E) cell. However, this advantage brings with it the associated challenges of (1) electrically isolating the voltage developed by a string of T/E cells and spacecraft ground (at which potential the hot side…
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75 AH and 10 Boilerplate Nickel-Hydrogen Battery Designs and Test Results

NASA Lewis Research Center-M. Manzo
Space Systems/Loral-M. E. Daman, R. Chang, E. Cruz
Published 1992-08-03 by SAE International in United States
The 75 Ah actively cooled bipolar battery continues to undergo LEO life testing at 40% DOD and to date has completed 13,000 cycles. The EOC and EOD voltages indicate that there is slight degradation in the overall battery performance. The primary influence in this decline is considered to be one cell's poor performance. The potential for extended cycle life capability of bipolar batteries has been demonstrated.Ten 4-cell passively cooled bipolar batteries are on test at Space Systems/Loral (SS/L). Characterization testing has been completed. The results indicate that high capacity utilizations can be maintained at various discharge rates. Performance differences were noted and seem to be related to battery design variations. Further testing is planned.
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SP-100 Early Flight Mission Designs

General Electric Co.-N. F. Shepard, R. E. Biddiscombe, T. S. Chan, N. A. Deane, A. S. Kirpich, R. Murata, R. Protsik, M. A. Smith, J. D. Stephen
Published 1992-08-03 by SAE International in United States
Early flight mission objectives can be met with a Space Reactor Power System (SRPS) using thermoelectric conversion in conjunction with fast spectrum, lithium-cooled reactors. This paper describes two system design options using thermoelectric technology to accommodate an early launch. In the first of these options, radiatively coupled Radioisotope Thermoelectric Generator (RTG) unicouples are adapted for use with a SP-100-type reactor heat source (Deane 1992). Unicouples have been widely used as the conversion technology in RTGs and have demonstrated the long-life characteristics necessary for a highly reliable SRPS (Hemler 1992). The thermoelectric leg height is optimized in conjunction with the heat rejection temperature to provide a mass optimum 6-kWe system configured for launch on a Delta II launch vehicle. The flight-demonstrated status of this conversion technology provides a high confidence that such a system can be designed, assembled, tested, and launched by 1996. The use of a SP-100-type reactor assures compliance with safety requirements and expedites the flight safety approval process while, at the same time, providing flight performance verification for a heat source technology with…
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Comparison of High Temperature, High Frequency Core Loss and Dynamic B-H Loops of a 2V-49Fe-49Co and a Grain Oriented 3Si-Fe Alloy

NASA Lewis Research Center-G. E. Schwarze
Sverdrup Technology, Inc.-J. M. Niedra
Published 1992-08-03 by SAE International in United States
The design of power magnetic components such as transformers, inductors, motors, and generators, requires specific knowledge about the magnetic and electrical characteristics of the magnetic materials used in these components. Limited experimental data exists that characterizes the performance of soft magnetic materials for the combined conditions of high temperature, and high frequency over a wide flux density range. An experimental investigation of a 2V-49Fe-49Co (Supermendur) and a grain oriented 3 Si-Fe (Magnesil) alloy was conducted over the temperature range of 23 to 300 C and frequency range of 0.1 to 10 kHz. The effects of temperature, frequency, and maximum flux density on the core loss and dynamic B-H loops for sinusoidal voltage excitation conditions are examined for each of these materials. A comparison of the core loss of these two materials is also made over the temperature and frequency range investigated.
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Peak-Power Tracker Versus Direct Energy Transfer Electrical Power Systems

Martin Marietta Astronautics Group-W. Eric Freeman
Published 1992-08-03 by SAE International in United States
The characteristics of Peak-Power Tracker (PPT) and Direct Energy Transfer (DET) satellite Electrical Power Systems (EPS) are compared with respect to: (1) the ratio of DET to PPT array areas, due to the PPT's ability to extract the “cold array power”. The comparisons will be made assuming equal output power systems using array parameters, array technology, and orbit characteristics as parameters, (2) the ratio of array areas for the two approaches vs load profile over life, with array technology as a parameter, (3) power system efficiency vs. array areas for the two approaches, and (4) PPT tracking accuracy of the array peak-power point. System power dissipation is not addressed for the two approaches.
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