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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Space shuttle electrical power generation and reactant supply system

The design philosophy and development experience of fuel cell power generation and cryogenic reactant supply systems are reviewed, beginning with the state of technology at the conclusion of the Apollo Program. Technology advancements span a period of 10 years from initial definition phase to the most recent space transportation system (STS) flights. The development program encompassed prototype, verification, and qualification hardware, as well as post-STS-1 design improvements. Focus is on the problems encountered, the scientific and engineering approaches employed to meet the technological challenges, and the results obtained. Major technology barriers are discussed, and the evolving technology development paths are traced from their conceptual beginnings to the fully man-rated systems which are now an integral part of the shuttle vehicle.

Simon, W. E.↗
NASA NTRS2000

Heat Transfer Measurements and Predictions on a Power Generation Gas Turbine Blade

Detailed heat transfer measurements and predictions are given for a power generation turbine rotor with 129 deg of nominal turning and an axial chord of 137 mm. Data were obtained for a set of four exit Reynolds numbers comprised of the design point of 628,000, -20%, +20%, and +40%. Three ideal exit pressure ratios were examined including the design point of 1.378, -10%, and +10%. Inlet incidence angles of 0 deg and +/-2 deg were also examined. Measurements were made in a linear cascade with highly three-dimensional blade passage flows that resulted from the high flow turning and thick inlet boundary layers. Inlet turbulence was generated with a blown square bar grid. The purpose of the work is the extension of three-dimensional predictive modeling capability for airfoil external heat transfer to engine specific conditions including blade shape, Reynolds numbers, and Mach numbers. Data were obtained by a steady-state technique using a thin-foil heater wrapped around a low thermal conductivity blade. Surface temperatures were measured using calibrated liquid crystals. The results show the effects of strong secondary vortical flows, laminar-to-turbulent transition, and also show good detail in the stagnation region.

Giel, Paul W.↗
DOE OSTI2023

Disjunctive optimization model and algorithm for long-term capacity expansion planning of reliable power generation systems

This paper proposes a new optimization model and algorithm for long-term capacity expansion planning of reliable power generation systems. The model optimizes both investment decisions (e.g., size, location, and time to install, retire and decommission facilities) and operation decisions (e.g., on/off status, operating capacity, and expected power output). It is also able to optimize reserve systems (or backup systems), as well as the main systems, to improve power systems reliability. An impact of operational strategies of generators (i.e., participating in electricity production vs. remaining as idle units during operation) on power systems reliability is considered. Probability of equipment failures and capacity failure states are used to rigorously estimate the power systems reliability depending on design and operation strategies. The optimization model is formulated with Generalized Disjunctive Programming (GDP), which is reformulated as a mixed-integer linear programming (MILP) model using the Hull relaxation. Two reliability-related penalties, such as downtime penalty and unmet demand penalty, are included in the objective function to maximize reliability while minimizing the total net present cost. Furthermore, a bilevel decomposition with tailored cuts is developed to reduce computational times of the multi-scale optimization model. The effectiveness of the proposed model is shown by comparing the results with the results obtained from the expansion planning models that do not explicitly consider reliability. In conclusion, we also show that the proposed bilevel decomposition is computationally efficient for solving large scale problems through 5-years and 10-years planning case studies.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1981

Applications study of advanced power generation systems utilizing coal-derived fuels, volume 2

Technology readiness and development trends are discussed for three advanced power generation systems: combined cycle gas turbine, fuel cells, and magnetohydrodynamics. Power plants using these technologies are described and their performance either utilizing a medium-Btu coal derived fuel supplied by pipeline from a large central coal gasification facility or integrated with a gasification facility for supplying medium-Btu fuel gas is assessed.

Robson, F. L.↗
DOE OSTI2021

Conformal High-Power-Density Half-Heusler Thermoelectric Modules: A Pathway toward Practical Power Generators

Thermoelectric generators (TEGs) exploiting the Seebeck effect provide a promising solution for waste heat recovery. Among the large number of thermoelectric (TE) materials, half-Heusler (hH) alloys are leading candidates for medium- to high-temperature power generation applications. However, the fundamental challenge in this field has been inhomogeneous material properties at large wafer diameters, insufficient power output from the modules, and rigid form factors of TE modules. This has restricted the transition of TEGs in practical applications for over three decades. Here, we successfully demonstrate large diameter wafers with uniform TE properties, high-power conformal hH TE modules for high-temperature application, and their direct integration on flue gas platforms, such as cylindrical tubes, to form large area flexible TEGs. This new conformal architecture design provides a breakthrough toward medium-/high-temperature TEGs over the conventional BiTe- and polymer-based flexible TEG design. In this work, a variable fill factor and greater flexibility due to the conformal design result in higher device performance as compared to conventional rigid TEG devices. Modules with 72-couple hH legs exhibit a device high-power-density of 3.13 W cm-2 and a total output power of 56.6 W under a temperature difference of 570 degrees C. These results provide a promising pathway toward widespread utilization of thermoelectric technology into the waste heat recovery application and will have a significant impact on the development of practical thermal to electrical converters.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1988

Microwave and millimeter-wave power generation in silicon carbide avalanche devices

Numerical simulations were performed to investigate the typical power-generating capabilities of SiC IMPATT diodes. Using available material parameters, SiC double-drift IMPATT diodes were simulated at 10, 35, 60, and 94 GHz, and the operating characteristics of these devices were compared to those of Si and GaAs devices. Compared to the Si and GaAs IMPATT performances in the pulsed mode, the SiC IMPATT performance was found to be far superior. The performance of SiC devices in the CW mode was also superior to that of GaAs devices, especially at lower frequencies. At a high frequency (94 GHz), the performance of the SiC device was found to be comparable to that of Si devices.

Mehdi, I.↗
NASA NTRS1974

Electrical power generation subsystem for Space Shuttle Orbiter

The requirements, capabilities, and design of the Space Shuttle Orbiter electrical power generation (EPG) subsystem are presented. The Orbiter EPG subsystem is designed to have the flexibility to supply the basic Orbiter electrical loads and the power requirements of the payloads which, in some cases, are completely dependent on the Orbiter for both power and heat rejection. These needs are supplied by three hydrogen/oxygen fuel cell powerplants (FCPs), having the capability of providing a total of 14 kW average and up to 24 kW peak in the basic Orbiter configuration. Kits permit dedication of one FCP to the payload by providing an additional reactant tank pair for a seven-day mission and additional heat rejection capability.

Blaski, M. F.↗
NASA NTRS1979

Supplementary steam - A viable hydrogen power generation concept

Technical and economic aspects of a supplementary steam generation for peaking power applications are discussed. Preliminary designs of the hydrogen/oxygen combustors to be used for such applications are described. The integration of the hydrogen/oxygen steam-generating equipment into a typical coal-fired steam station is studied. The basic steam generation system was designed as a 20 MW supplementary system to be added to the existing 160 MW system. An analysis of the operating and design requirements of the supplementary system is conducted. Estimates were made for additional steam and fuel supply lines and for additional control required to operate the combustors and to integrate the combustor system into the facility.

Wright, D. E.↗
DOE OSTI2025

Life‐cycle greenhouse gas emissions associated with nuclear power generation in the United States

Under the 2022 Inflation Reduction Act, tax credits of up to $3/kgH 2 are available to hydrogen producers if they generate emissions at levels below 0.45 kgCO 2 e/kgH 2 , spurring producers to explore how hydrogen production via electrolysis using electricity generated by nuclear power may qualify for such tax credits. With uranium as a primary fuel for nuclear power plants (NPPs) and no on-site emissions, the upstream emissions associated with nuclear fuel supply chains largely determine the carbon intensity of nuclear energy. Using the GREET (Greenhouse gases, Regulated Emissions, and Energy use in Technologies) model, we evaluated the life-cycle greenhouse gas (GHG) emissions of uranium production and the use of uranium to generate electricity in light water reactor (LWR) NPPs. We evaluated the process chemicals and energy inputs throughout the nuclear fuel supply chain to identify the major contributors to nuclear fuel cycle GHG emissions. Such emissions are estimated at 3.0 gCO 2 e/kWh at NPPs in the United States. The greatest share of nuclear fuel cycle GHG emissions—comprising 53% of total emissions—are associated with electricity consumption throughout the fuel supply chain. We extended the analysis to include an evaluation of the carbon intensity of H 2 production via electrolysis using nuclear power from LWRs. Finally, we examined the impact of future (2035 and 2050) electricity supply chain scenarios on nuclear fuel cycle GHG emissions. Our analysis revealed a decrease of 33% (2035) and 46% (2050) in the carbon intensity of nuclear electricity relative to current nuclear fuel cycle GHG emissions.

greenhouse gas emissions↗
NASA NTRS1980

High-efficiency concentration/multi-solar-cell system for orbital power generation

An analysis was performed to determine the economic feasibility of a concentrating spectrophotovoltaic orbital electrical power generation system. In this system dichroic beam-splitting mirrors are used to divide the solar spectrum into several wavebands. Absorption of these wavebands by solar cells with matched energy bandgaps increases the cell efficiency while decreasing the amount of heat which must be rejected. The optical concentration is performed in two stages. The first concentration stage employs a Cassegrain-type telescope, resulting in a short system length. The output from this stage is directed to compound parabolic concentrators which comprise the second stage of concentration. Ideal efficiencies for one-, two-, three-, and four-cell systems were calculated under 1000 sun, AMO conditions, and optimum energy bands were determined. Realistic efficiencies were calculated for various combinations of Si, GaAs, Ge and GaP. Efficiencies of 32 to 33 percent were obtained with the multicell systems. The optimum system consists of an f/3.5 optical system, a beam splitter to divide the spectrum at 0.9 microns, and two solar cell arrays, GaAs and Si.

Onffroy, J. R.↗
NASA NTRS1976

Closed cycle MHD power generation experiments using a helium-cesium working fluid in the NASA Lewis Facility

The MHD channel in the NASA Lewis Research Center was redesigned and used in closed cycle power generation experiments with a helium-cesium working fluid. The cross sectional dimensions of the channel were reduced to 5 by 16.5 cm to allow operation over a variety of conditions. Experiments have been run at temperatures of 1900-2100 K and Mach numbers from 0.3 to 0.55 in argon and 0.2 in helium. Improvements in Hall voltage isolation and seed vaporization techniques have resulted in significant improvements in performance. Typical values obtained with helium are Faraday open circuit voltage 141 V (92% of uBh) at a magnetic field strength of 1.7 T, power outputs of 2.2 kw for tests with 28 electrodes and 2.1 kw for tests with 17 electrodes. Power densities of 0.6 MW/cu m and Hall fields of about 1100 V/m were obtained in the tests with 17 electrodes, representing a factor of 18 improvement over previously reported results. The V-I curves and current distribution data indicate that while near ideal equilibrium performance is obtained under some conditions, no nonequilibrium power has been generated to date.

Sovie, R. J.↗
NASA NTRS2003

Optimization of Brayton Cycle Power Generation for In-Space Electric Propulsion Application

A Brayton cycle was analyzed and optimized over the power range 60 - 140 kWe, for application to electric propulsion systems. A gas-cooled reactor heat source with exit temperature 1150 K was assumed. Power generation system specific masses (alpha) from 36 kg/kWe at 60 kWe to 22 kg/kWe at 140 kWe were obtained. These masses do not include the thrust production system, which is predicted to add 6 to 8 kg/kWe. Cycle efficiencies varied from 32% at 60 kWe to 36% at 140 kWe. Cycle minimum temperature, cycle pressure ratio, and heat exchanger design parameters were varied for the optimization. Optimization parameters and methods are described.

Woodcock, Gordon↗