Contents:
Summary
Overview & Organization
Technologies
& Programs
This report details findings about technology and technology transfer opportunities at the NASA Lewis Research Center that might be of strategic interest to electric utilities. It is based on a visit to the lab in June 1997 and subsequent contacts, as part of the UFTO multiclient project.
Background
Noting the tremendous scope of research underway in the research facilities of the U.S. government, and a very strong impetus on the government's part to foster commercial partnering with industry and applications of the technology it has developed, the UFTO program has been established as a multi-client study of the opportunities thus afforded electric utilities.
NASA
The material presented here represents only a tiny fraction of NASA technology (and a small fraction of the work at Lewis). In addition to Lewis Research Center, NASA operates many other major R&D facilities: Ames Research Center, Dryden Flight Research Center, Goddard Space Flight Center, Jet Propulsion Lab, Johnson Space Center, Kennedy Space Center, Langley Research Center, Marshall Space Flight Center, and Stennis Space Center.
While the work is focused on propulsion, space systems, space missions, avionics, etc, there is considerable overlap with commercial industrial needs, and with energy in particular. NASA's work has led to over 30,000 spin offs, as a dividend on the nation's investment in aerospace research, in medicine, energy, environment, public safety, transportation and manufacturing.
NASA has an extensive network for technology transfer, including Offices
of Commercial Technology at Headquarters and at each of the major centers
listed above; ten regional Industrial Application Centers; over two dozen
affiliate centers, a number of publications including the monthly "Tech
Briefs" magazine; the annual Technology 200X Conferences which showcase
a great many government and private technology providers; and a major presence
on the internet, including a number of searchable databases.
http://www.hq.nasa.gov NASA Headquarters
http://nctn.hq.nasa.gov NASA Commercial Technology Network
Overview of the NASA Lewis Research Center (LeRC)
(adapted from materials on the LeRC website at http://www.lerc.nasa.gov)
LeRC was established in 1941 by the National Advisory committee for Aeronautics (NACA). It was one of three such centers nationwide. Named for George W. Lewis, NACA's Director of Research from 1924 to 1947, the Center developed an international reputation for its research on jet propulsion systems. In October 1958, the NACA Centers became the nucleus of the National Aeronautics and Space Administration.
Over 3700 people staff LeRC, including civil service employees and support service contractors. Over half of them are scientists and engineers. The budget for FY 97 was $711 Million, out of NASA's total budget of $13.7 Billion. Located adjacent to the Cleveland Airport, LeRC comprises more than 140 buildings that include 24 major facilities and over 500 specialized research and test facilities. LeRC has 63 R&D 100 awards out of the 94 awarded to NASA between 1963 and 1994.
LeRC works on advanced technology for high priority national needs in new propulsion, power, and communications technologies for application to aeronautics and space. The end product is knowledge, usually in a report, that is made fully available to potential users-- the aircraft engine industry, the energy industry, the automotive industry, the space industry, and other NASA centers. LeRC states that part of its mission is to transfer critical technologies to aerospace and non-aerospace industries, universities, and government institutions.
- Aeropropulsion (NASA Lead Center)
Major efforts are in subsonic, supersonic, hypersonic, general aviation,
and high-performance aircraft propulsion systems as well as in materials,
structures, internal fluid mechanics, instrumentation and controls, interdisciplinary
technologies, and aircraft icing research.
- Turbomachinery (Center of Excellence)
Areas of focus are air-breathing propulsion and power systems, primary
and auxiliary propulsion and power systems, onboard propulsion systems,
and rotating machinery for the pumping of fuels. Related technologies include
fans, compressors, turbines, pumps, combustors, bearings, seals, gears,
inlets, nozzles, sensors, and actuators. Related disciplines include materials,
structures, lubrication, acoustics, heat transfer, computational fluid
dynamics, combustion, cryogenics, icing, and controls.
- Other Key Roles and Responsibilities
In addition, LeRC supports other critical NASA roles. Recently, LeRC
was designated the Lead Center for Commercial Communications, Aeronautics
Propulsion Research and Technology, Commercial Technology, and a new General
Aviation Propulsion Initiative. The Center has also been given a lead role
in the microgravity program as the Program Manager for Fluid Physics and
Combustion Microgravity Research.
The Center continues to support space power, onboard propulsion, advanced subsonic, high-speed and high-performance computing research activities at other NASA Lead Centers as well as to retain responsibility for the launch of assigned Atlas and Titan missions. Lewis also is involved in negotiations to have a major role in the proposed Advanced Space Transportation System at Marshall Space Flight Center and to participate in the planning for the Lunar/Mars Initiative at the Johnson Space Center. In addition, Lewis has been recognized as the Lead Center for Workgroup Hardware and Software as well as for Spectrum Management.
LeRC Organization
The technical work at LeRC is organized into four major Directorates:
- Aeronautics
- Research and Technology
- Space
- Engineering and Technical Services
- External Programs
The focus here is on the Research and Technology Directorate, which has six divisions:
- Materials
- Power and On-Board Propulsion Technology
- Instrumentation and Controls
- Communications Technology
- Turbomachinery and Propulsion Systems
- Structures and Acoustics.
The NASA Lewis Research Center takse a broad and aggressive approach to their tech transfer responsibilities, with a number of innovative programs varying in the level of formality and resource commitment by each partner. The partnering mechanisms include Space Act Agreements (similar to CRADAs), the NASA Lewis Incubator for Technology (LIFT), the Small Business Innovation Research (SBIR) program, formal agreements such as contracts, grants and cooperative agreements, licensing of inventions, the Commercial Technology Consultants Program (CommTech), hosting of technical conferences, and informal technical assistance
In addition, LeRC engages with a number of local entities to foster regional growth and technology startups. For example, they work with the Great Lakes Industrial Technology Center (GLITEC) and Enterprise Development Inc (EDI) to present informal dialogues with small groups, focused on a specific area of technology. They also work with other Technology Brokers: the Ohio Aerospace Institute (OAI); Ohio's Edison Program, which has technology centers and incubators; the Cleveland Advanced Manufacturing Program (CAMP). The idea is to leverage LeRC resources.
Contact: cto@lerc.nasa.gov
Larry Viterna, 216-433-3484, fax 216-433-5531
--> LeRC Home Page
http://www.lerc.nasa.gov
--> Opportunities for Business and Industry
http://www.lerc.nasa.gov/Doc/LeRC_opportunities.html
--> Technology Transfer at NASA Lewis Research Center
http://www.lerc.nasa.gov/WWW/TU/techtran.html
Covered in this report:
Advanced Refrigerator/Freezer
Technology
Solar
Dynamic Power System (solar thermal electric)
Thermal
to Electric Conversion (Stirling, AMTEC, TPV)
Photovoltaic
Power Management
Batteries
The Series Connected
Boost Converter (DC Power Regulator)
Regenerative PEM Fuel
Cell Testbed
Shuttle Fuel Cell Upgrade
Program
UFTO Principal Point of Contact:
Diane M. Chapman, Customer Focal Point, R&T Directorate
216-433-2309,
dchapman@lerc.nasa.gov
Available on request from Ms. Chapman:
Organization charts and "Technical Points of Contact" booklet give
broad insight into the nature of LeRC's work and how to access it.
Contact: Jim Cairelli, 216-433-6142, james.e.cairelli@lerc.nasa.gov
Orbital and deep space missions place a demanding set of requirements for refrigerator/freezer (R/F) systems, particularly for Life and Biomedical Science experiments (i.e. to preserve samples). System power consumption, weight, and utilization of available space are primary considerations. Starting in 1993, LeRC undertook a focused project for advanced R/F technology assessment and development. A broad array of cooling technologies was narrowed to Stirling, Turbo Brayton, Orifice Pulse Tube, Thermoelectric, and Enhanced Stirling. Stirling cycle coolers are highly efficient, compact, light weight and particularly well suited for R/F applications over a broad range of temperatures. Thermal transport methods considered included heat pipes, Thermal Pyrolytic Graphite (TPG) and copper conductor. Heat pipes provide the highest thermal conductivity and also can be designed to act as thermal diodes. This minimizes the conductive heating of the storage volume during periods without electrical power. However, their working fluids are hazardous and require special containment to ensure spacecraft crew safety. TPG has higher thermal conductivity and lower density than copper, and is anisotropic. It would require considerable development, but could lead to as much as a 10% system efficiency improvement over copper. Enclosure insulation technologies were considered in two broad categories: cylindrical dewars and rectangular cabinets. Although a dewar can have a very high thermal resistance (R2300), a cabinet provides greater internal volume for a given external envelope. Current technology low vacuum (0.1 torr) panels with plastic or metal skins filled with powders or fiberglass have overall R-values of 15-35 per inch thickness. Design analysis indicates that moderate vacuum (0.001 torr) plastic panel insulation with rigidized multilayer insulation should be capable of R>100/inch including edge losses.
Recommendations were made for which technologies should be pursued for each of several classes of freezers, depending on temperature range. These include plasic panel insulation, TPG cooler cold finger, phase change thermal storage, and brush carbon thermal quick disconnect.
NASA Contractor Report 198484, Advanced Refrigerator Freezer Technology
Development, Technology Assessment, Oct. 1996
Contractor: Oceaneering Space Systems, Houston TX
LeRC is investigating a liquefaction and cryogenic support system for use on Mars, using Stirling cryocoolers. Engineering model tests in a simulated Mars environment began in early 1997.
Stirling cycle cooler suppliers:
- Global Cooling Manufacturing Co., Athens, OH
- Sunpower, Inc., Athens, OH
- Stirling Technology Company, Kennewick, WA
Heat Pipe supplier:
- Thermacore, Inc., Lancaster, PA
Thermal pyrolitic graphite supplier:
- Advanced Ceramics, Inc., Cleveland, OH
Phase change panels and brush carbon quick disconnect supplier:
- Energy Sciences Laboratories, Inc., San Diego, CA
Plastic panel insulation developer:
- Oceaneering Space Systems, Inc., Houston, TX
A SD power system converts solar thermal energy to mechanical energy, which is then converted into electrical energy. The thermal-to-mechanical energy conversion process is usually carried out by using a Brayton, Rankine, or Stirling cycle. The working fluid is heated by a concentrating solar collector, which focuses the energy into a receiver. The receiver may also include thermal energy storage that will allow the SD system to continue to operate at constant output while the collector is in eclipse. Closed Brayton Cycle (CBC) engines are related to open cycle gas turbines found on aircraft as engines or auxiliary power units. CBC engines are capable of high thermodynamic cycle efficiencies-approaching 40 percent-which makes them ideal for use in electrical power generation systems for space.
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Researchers have found that solar dynamic power with thermal energy storage can provide significant savings in life cycle costs and launch mass when compared to conventional photovoltaic power systems with battery storage for providing continuous electric power for near-Earth orbits. Lewis has been collaborating with industry in space power systems to design, fabricate and test a solar dynamic power system that is capable of storing energy to ensure continuous operation.
During testing, a large reflective surface known as a concentrator focuses simulated sunlight onto a receiver to heat the working gas, which is a helium-xenon mixture. The resulting energy powers a turboalternatorcompressor (TAC) providing electric power for various orbit operations. Radiators then release waste heat from the TAC into space.
A salt storage material contained in the receiver captures the Sun's energy and provides the stored energy to the system throughout the sun/shade orbit. The storage material absorbs and returns the energy by melting and freezing, thereby providing the heat at a constant temperature throughout the complete orbit.
Working in partnership with industry, Lewis is responsible for the overall project management. The industry team led by AlliedSignal includes Harris Corp., LORAL Vought Systems, Rockwell International, Aerospace Design & Development, and Solar Kinetics Inc., who initially received funding for this project through the NASA SBIR Program.
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A complete Solar Dynamic (SD) space power system has been tested in a large thermal/vacuum facility with a simulated sun at Lewis. The Lewis facility provides an accurate simulation of temperatures, high vacuum and the solar flux encountered in low-Earth orbit (LEO). The SD space power system includes the solar concentrator, solar receiver with thermal energy storage integrated with the power conversion unit in the Lewis facility.
Over 2 kW of electrical power was achieved in early 1995 while operating at 52,000 rpm with a turbine inlet temperature of 790.5 and a compressor inlet temperature of -2.8 degC. Orbital operation was demonstrated (66 minutes of insolation/28 minutes of eclipse) at 48,000 rpm. SD system testing has accumulated over 365 hours of power operation, ranging from 300 watts to 2.0 kW, including 187 simulated LEO's, 16 cold (ambient) starts, and two hot restarts.
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NASA Lewis' objective is to commercialize this technology and make it an alternative to conventional photovoltaic/battery power systems, and is actively pursing interested partners to participate in the development of advanced SD designs.. Among the applications where SD technology can be used are commercial and DoD satellites in low-to- medium Earth orbits.
Contact: Jim Calogeras, 216-433-5278, james.e.calogeras@lerc.nasa.gov
Contact: Jim Dudenhoefer, 216-433-6140, james.dudenhoefer@lerc.nasa.gov
For Thermal to Electric Conversion, the goals are cost, simplicity, reliability and of course efficiency, for use with radio isotope heat, solar thermal heat, combustion, and waste heat utilization. Many approaches have been under development for many years, and LeRC is a key player.
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Stirling Engines --
LeRC has been deeply involved in Stirling engine development for over 20 years, working closely with developers for a variety of applications. Major efforts were conducted with the Department of Energy (DOE) for the Automotive Stirling Engine Development Project with Mechanical Technology Inc. (MTI) (developed 60-kW Mod II kinematic engine with 38% efficiency and multi-fuel capability) and for the Advanced Stirling Conversion System (ASCS) for distributed dish solar terrestrial power generation with Cummins Power Generation and Stirling Technology Company (STC). Under the NASA Civil Space Technology Initiative, another major project with MTI developed a 12.5-kWe free-piston Stirling power convertor for the SP-100 space power program; this convertor met its performance goals on its first startup and has been tested for over 1500 continuous hours.
Currently, LeRC and DOE are developing a 30-40We free-piston Stirling convertor with STC for a 150-We Advanced Radioisotope Power Source for deep-space missions, using multiple convertors for reliability and modularity. STC has operated a 10-We Stirling convertor for over 39,000 hours with no maintenance and no degradation in performance.
High-efficiency Stirling terrestrial power systems should be capable of achieving 60% of Carnot or higher - 40-45% overall efficiency at a temperature ratio of 3.
Contact: Lanny Thieme, 216-433-6119, lanny.thieme@lerc.nasa.gov
Stirling Technology Co, Richland WA, makes cryocoolers and engines from 10 watts to 3-5 kW. They have sold several beta units of a 23% efficient 350 watt engine to some European utilities and one US utility. This unit has many parts in common with their BeCool cryocooler, which is in pilot production. They hope ultimately to reach $1/watt, and are looking for investors and partners.
Contact: Maury White, 509-735-4700, x105, http://www.stirlingtech.com
Other suppliers are (in addition to STC):
Sunpower, Inc., Athens, Ohio, contact: John Crawford, 614-594-2221
Stirling Thermal Motors, Inc., Ann Arbor, Michigan, contact:
Lennart Johansson, 313-995-1755
Mechanical Technology, Inc., Latham, New York, contact: Manmohan
Dhar, 518-785-2106
Clever Fellows Innovation Consortium, Troy, New York, contact: John
Corey, 518-272-3565
Thermophotovoltaic (TPV) -
TPV is seen as applicable in radiothermal generators in deep space,
as they offer a 2x efficiency improvement over thermoelectric devices,
and for solar applications for near sun missions, owing to their lighter
weight and radiation hardness. On the ground, the DOD sees field power
unit applications, and solar TPV is under joint development with McDonald-Douglas
LeRC's program includes a 500 W combustion demo unit, and improved power conversion cells. The InFaAs/InP Monolithic Interconnected Module (MIM) allows for high power density and high efficiency. It consists of many individual cells that are series connected on a single substrate. Higher efficiency is obtained by returns unused portion of the spectrum back to the emitter for recycling.
Contact: David Wilt, 216-433-6293, david.wilt@lerc.nasa.gov
Dennis Flood, 216-433-2303, dennis.flood@lerc.nasa.gov
Multi Band Gap Solar Cells -- Efficiencies of 24-26%, and up to 30% Production cells due in 98/99
Advanced Concentrator Arrays -- "Scarlet" Linear refractive concentrators. Joint with BMDO. 2.6 kw Array to be the first use of concentrators in space.
High voltage thin film array -- demo of 1000 volt module in 1998. Monolithic
polycrystalline CuInS2 deposited by vapor deposition into fused SiO2 at
400 deg. C. Goal is 10x reduction in mass of the solar array.
Contact Jim Soeder, 216-433-5328, james.soeder@lerc.nasa.gov
-- Automation-Fault Recovery
Automation of power systems (e.g. for the space station) focuses on dynamic fault recovery, based on fault recognition at the device level, and coordination at the system level. LeRC operates a high power DC electrical test facility, which has been used to test modular system elements from the Power Electronic Building Block (PEBB) program. e.g. a 12-15 HP motor controller (270 V input, 0-400Hz, 3 phase 100V output).
Contact: Dr. Marvin Warshay, (216) 433-6126, marvin.warshay@lerc.nasa.gov
-- Flywheels
For aerospace and satellite applications, flywheels could replace batteries.
Two vendors are focused on this market: U.S. Flywheel and SatCon. Both
have found magnetic bearings to be a big challenge. Two counter rotating
rotors are used, to cancel momentum. US Flywheels was to deliver a 2 KWHr
system last Summer. LeRC has done extensive systems studies, and leads
a major national program. They're also establishing a test facility.
-- Li Polymer Batteries
LeRC is teamed with Lockheed Martin and Ultralife, Rochester NY in
a DARPA funded TRP program. LeRC is working on electrodes, chemically modifying
the molecular structure of the carbon anode so it can intercalate more
lithium ions that would be possible with graphite. The team has demonstrated
100 Whr/kg, and is working towards a target of 200.
-- Bipolar NIMH batteries
LeRC is incorporating technology advances to improve performance and
reliability, working on a cost shared basis with Electro Energy Co.
-- Ni-H2 Battery
With Hughes, working to reduce the weight and cost, and to increase
life. The new designs are now flight qualified, and scheduled on a number
of missions. This technology has been in use in spacecraft for years, and
is highly reliable and has very long cycle life, but the high cost keeps
it from commercial application.
(see: http://powerweb.lerc.nasa.gov/elecsys/DOC/scbc.html )
The Series Connected Boost Converter (SCBC) is a unique interconnect technology for DC-DC converters developed at the NASA Lewis Research Center. It is not a new DC-DC converter topology.
Benefits
- Very High Efficiency (93% - 98%)
- High Power Density (1,000 + W/kg)
- Extended Fault Tolerance Capabilities
- Easily Adapted to Positive Ground Systems
- Inexpensive to design and build
- Makes use of relatively inexpensive commercially available DC/DC
converters
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The SCBC makes use of standard transformer isolated, step-down DC-DC
converters. These are very common devices that are readily available from
several manufacturers.
The Series Connected Boost Converter simply adds a bypass connection to the DC-DC converter. This bypass connection biases the converter's output on top of the input voltage. Current flows into the converter as usual, but it also flows through the bypass connection, back through the transformer secondary winding, through the rectifier diodes, and out to the load. The input ground now becomes the output ground and current is returned back to the source.
- The power density of the converter is increased a by factor of 2-5
times it's original rating.
- The efficiency of the converter is substantially increased. Run-of-the-mill
85% converters can now process power at 93-98% efficiencies.
- The converter now has an inherently fault tolerant configuration.
- Failure of the converter will only result in degraded power delivery.
In a typical application, a 28 Vdc to 12 Vdc isolated converter rated at 72 Watts is connected in theSBS configuration. The resulting SCBC converter has the ability to deliver 240 Watts (330% increase) with an efficiency of 95.2% (11% increase). All these benefits come at the small expense of relinquishing the galvanic isolation of the converter.
The Series Connected Boost Converter has many applications in any DC power system. However, NASA been focusing on using it as a photovoltaic array regulator for small spacecraft. A Series Connected Boost Converter is an essential component in the Photovoltaic Regulator Kit, which LeRC developed as a low cost alternative to custom design.
Ref: "Small Spacecraft Technology Initiative PV Regulator Kit", Baez,
et.al. 31st IECEC # 96426
"An Advanced PV Array Regulator Module", Button, et.al., 31st IECEC
#96424 (1996)
Contact Robert Button 216-433-8010, robert.m.button@lerc.nasa.gov
NASA Lewis leads a multiagency effort to design, build, and operate a Regenerative Fuel Cell (RFC) system testbed. Key objectives are to evaluate, characterize, and demonstrate fully integrated RFC's. Construction of the 25-kW RFC testbed at the NASA facility at Edwards Air Force Base was completed in January 1995, and the system has been operational since that time. The facility includes the integration of 50 kW PV arrays, a 25 kW PEM electrolysis unit, four 5 kW PEM fuel cells, high pressure hydrogen and oxygen storage vessels, high purity water storage, and computer monitoring, control and data acquisition.
Initially NASA saw RFCs as a closed-loop power plant for future life support operations in space, however the significant potential was recognized for wider use of RFCs in different space, military, and commercial applications. The team encompasses both Government and industry participants, with Jet Propulsion Lab supporting the electrolyzer and fuel cell installation. The fuel cells are Ballard units, loaned by the Canadian Dept. of National Defence.
Fuel cells consume hydrogen and oxygen (or air) to produce electricity, water, and heat. The product water is stored and later dissociated into its hydrogen and oxygen constituents by a solar-powered electrolyzer. The hydrogen and oxygen are then stored for subsequent fuel cell consumption, and the fuel cell waste heat can be utilized in many different ways. If the fuel cell is designed to consume air rather than pure oxygen, then the oxygen from water electrolysis is available for other uses, such as in biological waste purification.
Combined with a solar power system, the RFC takes the place of storage batteries. Despite a "round-trip" electrical storage efficiency of only 50-60% at best, it offers a number of operational advantages, such as lower weight, long term storage (add fuel storage, not cells, to extend), and better integration with other (space vehicle) systems.
(If the fuel cell itself is designed to operate also in reverse as an electrolyzer, then electricity can be used to convert the water back into hydrogen and oxygen. This dual-function system is known as a reversible or unitized regenerative fuel cell (URFC). Lighter than a separate electrolyzer and generator, a URFC is an excellent energy source in situations where weight is a concern, as long as both functions can be adequately performed by one device. Livermore National Lab has developed such a system, ultimately intended for automotive and high altitude solar powered flight applications.)
For many years, individual RFC subsystem components have been under development for nonregenerative applications. The objectives of the Lewis testbed program are to design, test, and evaluate RFC's to characterize system life, performance, and integration issues for candidate RFC system technologies. The testbed is generic in the sense that it can be used to evaluate the different technologies that are specific to space, military, and commercial needs.
(Ref "Operation of the 25kW NASA LeRC Solar Regenerative Fuel Cell Testbed
Facility", G. Voecks, et.al., JPL Report 97295, June 1997)
Contact: Dr. Marvin Warshay, (216) 433-6126, marvin.warshay@lerc.nasa.gov
For over 20 years, space vehicles have relied on Alkaline Fuel Cells as the highest performing low temperature fuel cell technology. It's special requirements were worth the trouble for it's lighter weight, notably for use in the Space Shuttle. However there are very high annual maintenance and subsystem replacement costs, and NASA embarked on a program to remedy the situation.
A team composed of JPL, the Johnson Space Center, and LeRC quickly concluded that PEM fuel cells had made tremendous progress in the years since the decision to use alkaline fuel cells on the Shuttle, so the Shuttle Upgrade program was redirected towards implementing a PEM, rather than attempting to upgrade the AFC technology.
The program includes:
1. Systems analysis
2. Short stack testing of leading contractors' PEM hardware
3. Flight experiments to verify water management and zero gravity operation
4. Selection of a system
5. Development of flight hardware system, including accessory subsystems.
(Ref "The NASA Fuel Cell Upgrade Program for the Space Shuttle Orbiter",
M. Warshay, et.al, LeRC Report # 97294, 1997)
Contact: Dr. Marvin Warshay, (216) 433-6126, marvin.warshay@lerc.nasa.gov