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NASA NTRS2016

Features of the Upgraded Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) Software

The Imaging for Hypersonic Experimental Aeroheating Testing (IHEAT) software is used at the NASA Langley Research Center to analyze global aeroheating data on wind tunnel models tested in the Langley Aerothermodynamics Laboratory. One-dimensional, semi-infinite heating data derived from IHEAT are used in the design of thermal protection systems for hypersonic vehicles that are exposed to severe aeroheating loads, such as reentry vehicles during descent and landing procedures. This software program originally was written in the PV-WAVE(Registered Trademark) programming language to analyze phosphor thermography data from the two-color, relative-intensity system developed at Langley. To increase the efficiency, functionality, and reliability of IHEAT, the program was migrated to MATLAB(Registered Trademark) syntax and compiled as a stand-alone executable file labeled version 4.0. New features of IHEAT 4.0 include the options to perform diagnostic checks of the accuracy of the acquired data during a wind tunnel test, to extract data along a specified multi-segment line following a feature such as a leading edge or a streamline, and to batch process all of the temporal frame data from a wind tunnel run. Results from IHEAT 4.0 were compared on a pixel level to the output images from the legacy software to validate the program. The absolute differences between the heat transfer data output from the two programs were on the order of 10(exp -5) to 10(exp -7). IHEAT 4.0 replaces the PV-WAVE(Registered Trademark) version as the production software for aeroheating experiments conducted in the hypersonic facilities at NASA Langley.

Mason, Michelle L.↗

NASA NTRS1987

Overview of NASA Lewis Research Center free-piston Stirling engine technology activities applicable to space power systems

A brief overview is presented of the development and technological activities of the free-piston Stirling engine. The engine started as a small scale fractional horsepower engine which demonstrated basic engine operating principles and the advantages of being hermetically sealed, highly efficient, and simple. It eventually developed into the free piston Stirling engine driven heat pump, and then into the SP-100 Space Reactor Power Program from which came the Space Power Demonstrator Engine (SPDE). The SPDE successfully operated for over 300 hr and delivered 20 kW of PV power to an alternator plunger. The SPDE demonstrated that a dynamic power conversion system can, with proper design, be balanced; and the engine performed well with externally pumped hydrostatic gas bearings.

Slaby, Jack G.↗

NASA NTRS1985

FSA future directions: Reliability and engineering sciences FY85-FY86 activities and plans

Objectives were listed for four areas: engineering science, reliability physics, module development, and module performance and failure analysis. The engineering science efforts are to develop module design requirements for large-scale photovoltaic (PV) applications and to develop generic module and array design and construction technology to meet the needed performance, safety, reliability, and system interfaces. The reliability physics effort is to develop the technology for 30-year life modules. The module development efforts are to transfer new technology to PV manufacturers and their products, and to evaluate these advanced modules. The module performance and failure analysis efforts are to determine PV module performance, to identify needed development, and to assess suitability for large-scale use.

Ross, R. G., Jr.↗

NASA NTRS1999

PV-Diesel Hybrid SCADA Experiment Network Design

The essential features of an experimental network for renewable power system satellite based supervisory, control and data acquisition (SCADA) are communication links, controllers, diagnostic equipment and a hybrid power system. Required components for implementing the network consist of two satellite ground stations, to satellite modems, two 486 PCs, two telephone receivers, two telephone modems, two analog telephone lines, one digital telephone line, a hybrid-power system equipped with controller and a satellite spacecraft. In the technology verification experiment (TVE) conducted by Savannah State University and Florida Solar Energy Center, the renewable energy hybrid system is the Apex-1000 Mini-Hybrid which is equipped with NGC3188 for user interface and remote control and the NGC2010 for monitoring and basic control tasks. This power system is connected to a satellite modem via a smart interface, RS232. Commands are sent to the power system control unit through a control PC designed as PC1. PC1 is thus connected to a satellite model through RS232. A second PC, designated PC2, the diagnostic PC is connected to both satellite modems via separate analog telephone lines for checking modems'health. PC2 is also connected to PC1 via a telephone line. Due to the unavailability of a second ground station for the ACTS, one ground station is used to serve both the sending and receiving functions in this experiment. Signal is sent from the control PC to the Hybrid system at a frequency f(sub 1), different from f(sub 2), the signal from the hybrid system to the control PC. f(sub l) and f(sub 2) are sufficiently separated to avoid interference.

Kalu, Alex↗

NASA NTRS1995

A quasi-permeable barrier in the equatorial lower stratosphere

Analyses of global isentropic maps of potential vorticity from the United Kingdom Meteorological Office (UKMO) data assimilation system reveal that there is a region of strong meridional potential vorticity (PV) gradients in the equatorial lower stratosphere. A semi-Lagrangian tracer transport model is used to show that this region of strong PV gradients acts as a quasipermeable barrier to cross-equator mass exchange on isentropic surfaces.

Chen, Ping↗

NASA NTRS1999

Solar Power System Analyses for Electric Propulsion Missions

Solar electric propulsion (SEP) mission architectures are applicable to a wide range of NASA missions including human Mars exploration and robotic exploration of the outer planets. In this paper, we discuss the conceptual design and detailed performance analysis of an SEP stage electric power system (EPS). EPS performance, mass and area predictions are compared for several PV array technologies. Based on these studies, an EPS design for a 1-MW class, Human Mars Mission SEP stage was developed with a reasonable mass, 9.4 metric tons, and feasible deployed array area, 5800 sq m. An EPS was also designed for the Europa Mapper spacecraft and had a mass of 151 kg and a deployed array area of 106 sq m.

Kerslake, Thomas W.↗

NASA NTRS1981

Highlights of NASA/DOE photovoltaic market assessment visit to Morocco

A broad range of agricultural, rural development, and other power applications in various regions of Morocco were examined to determine the potential market for photovoltaic products in Moroccan development. The primary focus of the study was the agriculture sector which accounts for approximately 17% of the country's GNP. The country has a clear need for reliable remote power systems, but does not have the financial resources to invest in the relatively high capital cost PV equipment. A modest potential for PV use was identified in nonagricultural rural services, such as refrigerators for rural clinics and rural radio-telephones. The main potential for PV in Morocco in the next five years lies mainly in the telecommunications sector. Applications include rural TV sets, TV repeater stations, microwave relay stations, and railroad, marine, and airline signalling. Market size estimates were derived from development and expansion plans. At an average customer cost for complete installed systems from $18/Wp to $30/Wp the total potential market value is estimated in the range of $6.6 to $11 million over the 1981-1986 period.

Source record↗

NASA NTRS1996

Review of recent thermophotovoltaic (TPV) research at Lewis Research Center

Thermophotovoltaic (TPV) research at NASA Lewis Research Center that began in the late 1980's is reviewed. This work has been concentrated on low bandgap indium gallium arsenide (InGaAs) PV cells and rare earth yttrium aluminum garnet (YAG) thin film selective emitters, as well as, TPV system studies. An emittance theory has been developed for the thin film emitters. Experimental spectral emittance results for erbium Er-YAG and holmium Ho-YAG show excellent emittance (greater than or equal to .7) within the emission bands. The .75 eV InGaAs PV cells fabricated at Lewis have excellent quantum efficiency. An efficiency of 13% has been measured for this cell coupled to an Er-YAG selective emitter and a short pass IR filter.

Chubb, Donald L.↗

NASA NTRS1995

Review of Recent Thermophotovoltaic (TPV) Research at Lewis Research Center

Thermophotovoltaic (TPV) research at NASA Lewis Research Center that began in the late 1980's is reviewed. This work has been concentrated on low bandgap indium gallium arsenide (InGaAs) PV calls and rare earth - yttrium aluminum garnet (YAG) thin film selective emitters, as well as, TPV system studies. An emittance theory has been developed for the thin film emitters. Experimental spectral emittance results for erbium Er-YAG and holmium Ho-YAG show excellent emittance (greater than or equal to 0.7) within the emission bands. The 0.75 eV InGaAs PV cells fabricated at Lewis have excellent quantum efficiency. An efficiency of 130% has been measured for this cell coupled to an Er-YAG selective emitter and a short pass IR filter.

Chubb, Donald L.↗

NASA NTRS1989

Cryogenic reactant storage for lunar base regenerative fuel cells

There are major advantages to be gained by integrating a cryogenic reactant storage system with a hydrogen-oxygen regenerative fuel cell (RFC) to provide on-site electrical power during the lunar night. Although applicable to any power system using hydrogen-oxygen RFC's for energy storage, cryogenic reactant storage offers a significant benefit whenever the sun/shade cycle and energy storage period approach hundreds of hours. For solar power installations on the moon, cryogenic reactant storage reduces overall specific mass and meteoroid vulnerability of the system. In addition, it offers synergistic benefits to on-site users, such as availability of primary fuel cell reactants for surface rover vehicles and cryogenic propellants for OTV's. The integration involves processing and storing the RFC reactant streams as cryogenic liquids rather than pressurized gases, so that reactant containment (tankage per unit mass of reactants) can be greatly reduced. Hydrogen-oxygen alkaline RFC's, GaAs photovoltaic (PV) arrays, and space cryogenic processing/refrigeration technologies are assumed to be available for the conceptual system design. Advantages are demonstrated by comparing the characteristics of two power system concepts: a conventional lunar surface PV/RFC power system using pressurized gas storage in SOA filament wound pressure vessels and, that same system with gas liquefaction and storage replacing the pressurized storage. Comparisons are made at 20 and 250 kWe. Although cryogenic storage adds a processing plant (drying and liquefaction) to the system plus 30 percent more solar array to provide processing power, the approximate order of magnitude reduction in tankage mass, confirmed by this analysis, results in a reduction in overall total system mass of approximately 50 percent.

Kohout, Lisa L.↗

NASA NTRS1989

Cryogenic reactant storage for lunar base regenerative fuel cells

Kohout, Lisa L.↗

NASA NTRS1982

Residential photovoltaic power conditioning technology for grid connected applications

Major advances in photovoltaic (PV) Power Conditioning (PC) with respect to performance and low-cost potential have been made. Solutions have been obtained to interface and control problems related to adapting available inverter designs to the grid-connected, residential photovoltaic experiments. A description is presented to contributing research and development activities. Attention is given to aspects of residential systems experience, conceptual design studies, questions of optimum topology development, and promising advanced designs for residential PV provided by development efforts of the private sector.

Key, T. S.↗

NASA NTRS1989

Energy storage and thermal control system design status

The Space Station Freedom electric power system (EPS) will initially rely on photovoltaics for power generation and Ni/H2 batteries for electrical energy storage. The current design for the development status of two major subsystems in the PV Power Module is discussed. The energy storage subsystem comprised of high capacity Ni/H2 batteries and the single-phase thermal control system that rejects the excess heat generated by the batteries and other components associated with power generation andstorage is described.

Simons, Stephen N.↗

NASA NTRS1991

Regenerative fuel cell architectures for lunar surface power

Power needs projected for the lunar and Mars exploration missions range from a few kilowatts for initial manned outposts and rovers to hundreds of kilowatts for permanent bases and in-situ resource utilization. The 354 hour lunar night presents a formidable challenge in energy storage systems for non-nuclear power systems. The Photovoltaic/Regenerative Fuel Cell (PV/RFC) power system is currently being considered as an option to meet the initial low power requirements. For lunar applications, the RFC mass can be a critical driver in the overall PV/RFC system mass. For the long duration nighttime operation missions, the hydrogen/oxygen (H2/O2) reactants and storage are the dominant components from a mass standpoint. It is important, therefore, to examine options which may reduce the reactant and storage mass and, thereby, result in mass savings for the overall PV/RFC system. Various RFC configurations for the stationary lunar missions has been examined using Rocketdyne's RFC computer model. For the stationary applications, a GaAs/Ge PV array with a 3000 psi gas storage proton exchange membrane (PEM) RFC providing 25 kWe during the day and 12.5 kWe at night was designed. PV/RFC systems utilizing super-critical H2/O2 storage and Cryogenic H2/O2 storage for the RFCs were then compared with the baseline high pressure gas storage RFC system. Preliminary results indicate that for long duration nighttime operation missions, the super-critical H2/O2 storage RFC systems offer over 20% mass advantage over the high pressure gas storage while the mass savings for the cryogenic H2/O2 storage RFC systems can be as high as 30%.

D W Harris↗

NASA NTRS1988

The evolution of AAOE observed constituents with the polar vortex

One of the difficulties in determining constituent trends from the ER-2 flight data is the large amount of day to day variability generated by the motion of the polar vortex. To reduce this variability, the observations have been transformed into the conservative (Lagrangian) reference frames consisting of the coordinate pairs, potential temperature (PT) and potential vorticity (PV), or PT and N2O. The requirement of only two independent coordinates rests on the assumption that constituent distributions and their chemical processes are nearly zonal in that coordinate system. Flight data is used everywhere for these transformation except for potential vorticity. Potential vorticity is determined from level flight segments, and NMC PV values during flight dives and takeoffs are combined with flight data in a smooth fashion.

Schoeberl, Mark R.↗

NASA NTRS1989

Energy storage and thermal control system design status

The Space Station Freedom electric power system (EPS) will initially rely on photovoltaics for power generation and Ni/H2 batteries for electrical energy storage. The current design for and the development status of two major subsystems in the PV Power Module is discussed. The energy storage subsystem comprised of high capacity Ni/H2 batteries and the single-phase thermal control system that rejects the excess heat generated by the batteries and other components associated with power generation and storage is described.

Simons, Stephen N.↗

NASA NTRS1982

The worldwide market for photovoltaics in the rural sector

The worldwide market for stand-alone photovoltaic power systems in three specific segments of the rural sector were determined. The worldwide market for photovoltaic power systems for village power, cottage industry, and agricultural applications were addressed. The objectives of these studies were to: The market potential for small stand-alone photovoltaic power system in specific application areas was assessed. Technical, social and institutional barriers to PV utilization were identified. Funding sources available to potential users was also identified and marketing strategies appropriate for each sector were recommended to PV product manufacturers. The studies were prepared on the basis of data gathered from domestic sources and from field trips to representative countries. Both country-specific and sector-specific results are discussed, and broadly applicable barriers pertinent to international marketing of PV products are presented.

Brainard, W. A.↗

NASA NTRS1998

A Review of Recent Thermophotovoltaic Energy Conversion Technology Development at NASA Lewis Research Center

NASA Lewis Research Center (LeRC) has had an ongoing research program in TPV since the late 1980's. This effort has included both in-house research programs on critical components such as photovoltaic cells (PV) and emitter materials, as well as an active contracting effort directed toward system, and component development. Of particular note is the in-house development of thin film selective emitters fabricated from rare-earth yttrium aluminum garnets (YAG). Also developed at LeRC is a Monolithic Interconnect Module (MIM) consisting of many small InGaAs cells series interconnected on a single InP substrate. An infrared reflector placed on the rear surface of the substrate returns unabsorbed photons to the emitter for recycling. The current contracted efforts include two TPV system developments by Tecogen, Inc., a solar powered TPV system development, a GaInAsSb cell development and several emitter development efforts (plasma-sprayed selective emitters, flexible SiC and a selective emitting light pipe).

Wilt, David M.↗