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A comparison of predicted and observed turbulent wind fields present in natural and internal wind park environments

Description: This paper assesses the accuracy of simulated wind fields for both the natural flow and that within a wind park environment. The simulated fields are compared with the observed ones in both the time and frequency domains. Actual measurements of the wind fields and the derived kinematic scaling parameters upwind and downwind of a large San Gorgonio Pass wind park are used. The deviations in the modeled wind field from the observed are discussed. 10 refs., 6 figs., 2 tabs.
Date: October 1, 1991
Creator: Kelly, N D & Wright, A D
Partner: UNT Libraries Government Documents Department
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A comparison of spanwise aerodynamic loads estimated from measured bending moments versus direct pressure measurements on horizontal axis wind turbine blades

Description: Two methods can be used to determine aerodynamic loads on a rotating wind turbine blade. The first is to make direct pressure measurements on the blade surface. This is a difficult process requiring costly pressure instrumentation. The second method uses measured flap bending moments in conjunction with analytical techniques to estimate airloads. This method, called ALEST, was originally developed for use on helicopter rotors and was modified for use on horizontal axis wind turbine blades. Estimating airloads using flap bending moments in much simpler and less costly because measurements can be made with conventional strain gages and equipment. This paper presents results of airload estimates obtained using both methods under a variety of operating conditions. Insights on the limitations and usefulness of the ALEST bending moment technique are also included. 10 refs., 6 figs.
Date: October 1, 1991
Creator: Simms, D A & Butterfield, C P
Partner: UNT Libraries Government Documents Department
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Improved tunnel resistance of silvered-polymer mirrors

Description: This report documents the research performed at the Solar Energy Research Institute during fiscal year (FY) 1991 to develop ways to prevent delamination failure (known as tunneling) of silvered-polymer reflector materials. Several promising approaches have been identified and demonstrated that substantially reduce such failures. These approaches include (1) use of Tedlar edge tape rather than the manufacturer-recommended ECP-244 tape, (2) thermal treatment of laminated reflector/substrate constructions, and (3) application of silver to the polymer film through an alternative deposition process. Approaches 1 and 2 offer readily available engineering solutions to the delamination problem. Approaches 2 and 3 provide tunnel resistance over the entire surface of the reflector material, including the edges. Tedlar (a polyvinyl fluoride from DuPont) tape is an opaque white tape available in different widths from 3M Company. The base material has demonstrated outstanding outdoor durability. Thermal treatment of ECP-305 laminated to substrate materials has demonstrated outstanding resistance to tunneling. Alternative silver deposition techniques such as sputtering (rather than thermal evaporation) offer increased resistance to tunneling. 15 refs., 10 figs.
Date: October 1, 1991
Creator: Jorgensen, G.; Schissel, P.; Kennedy, C.; Shinton, Y.; Powell, D. & Siebarth, J.
Partner: UNT Libraries Government Documents Department
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Thermal testing of the proposed HUD energy efficiency standard for new manufactured homes

Description: Thermal testing of two manufactured homes was performed at the National Renewable Energy Laboratory's (NREL's) Collaborative Manufactured Buildings Facility for Energy Research and Testing (CMFERT) environmental enclosure in the winter and spring of 1991. The primary objective of the study was to directly measure the thermal performance of the two homes, each built according to a proposed new US Department of Housing and Urban Development (HUD) standard. Secondary objectives were to test the accuracy of an accompanying compliance calculation method and to help manufacturers find cost-effective ways to meet the new standard. Both homes performed within the standard without major design or production line modifications. Their performance fell within 8% of predictions based on the new draft HUD calculation manual; however, models with minimum window area were selected by the manufacturer. Models with more typical window area would have required substantive design changes to meet the standard. Several other tests were also performed on the homes by both NREL and the Florida Solar Energy Center (FSEC) to uncover potential thermal anomalies and to explore the degradation in thermal performance that might occur because of (a) penetrations in the rodent barrier from field hookups and repairs, (b) closing of interior doors with and without operation of the furnace blower, and (c) exposure to winds.
Date: June 1, 1992
Creator: Judkoff, R.D. & Barker, G.M.
Partner: UNT Libraries Government Documents Department
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Aquatic species project report: FY 1991

Description: This report summarizes the progress and research accomplishments of the Aquatic Species Project, which is managed by the National Renewable Energy Laboratory for the US Department of Energy. The project is focused on applying genetic engineering techniques to enhance the lipid, or oil, production of microalgae. Those lipids can be extracted and processed into high-energy liquid fuels such as diesel. Because microalgae require carbon dioxide, a major greenhouse'' gas, as a nutrient, project researchers also study the role that microalgae could play in a possible global climate change mitigation strategy.
Date: April 1, 1992
Creator: Brown, L.M. (National Renewable Energy Lab., Golden, CO (United States)) & Sprague, S. (USDOE, Washington, DC (United States))
Partner: UNT Libraries Government Documents Department
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Evaluation of Wastewater Treatment Requirements for Thermochemical Biomass Liquefaction

Description: Biomass can provide a substantial energy source. Liquids are preferred for use as transportation fuels because of their high energy density and handling ease and safety. Liquid fuel production from biomass can be accomplished by any of several different processes including hydrolysis and fermentation of the carbohydrates to alcohol fuels, thermal gasification and synthesis of alcohol or hydrocarbon fuels, direct extraction of biologically produced hydrocarbons such as seed oils or algae lipids, or direct thermochemical conversion of the biomass to liquids and catalytic upgrading to hydrocarbon fuels. This report discusses direct thermochemical conversion to achieve biomass liquefaction and the requirements for wastewater treatment inherent in such processing. 21 refs.
Date: April 1, 1992
Creator: Elliott, D. C.
Partner: UNT Libraries Government Documents Department
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Cooperative field test program for wind systems

Description: The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.
Date: March 1, 1992
Creator: Bollmeier, W.S. II & Dodge, D.M.
Partner: UNT Libraries Government Documents Department
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Comparison of Predicted Optical Performance With Measured Results for Dish Concentrators

Description: Several optical design tools have been developed at the National Renewable Energy Laboratory (NREL) during the past two years. These have been used extensively both in-house and by industry to analyze dish concentrator systems and to optimize performance of such designs. The first program, OPTDSH, models single-element dish concentrators. The second code, ODMF, allows multifacet dish arrays to be modeled. The accuracy of performance simulations by these programs has been established by comparing predicted results with measured on-sun data. ODMF evolved from NREL's High-Flux Solar Furnace (HFSF) design tool, SOLFUR, and in fact is a special case of SOLFUR in which the primary facet array is on sun.'' Consequently, confirmation of the accuracy of SOLFUR would verify the results from ODMF as well. Furthermore, because OPTDSH can be viewed as a single-facet case of ODMF, determination of the precision of SOLFUR/ODMF would also substantiate OPTDSH. Thus, the approach to verifying the correctness of all three codes was to compare flux patterns as predicted by SOLFUR with those actually measured at NREL's HFSF. Measured vs. calculated data have been compared on the basis of flux distribution (in terms of contour plots) and peak flux for both single-facet and multiple-facet cases. Agreement in measured vs. predicted peak flux values has been obtained within the uncertainty associated with the measurement/calibration process. Excellent agreement has also been demonstrated by comparing contour maps of measured vs. computed flux levels. 7 refs.
Date: April 1, 1991
Creator: Jorgensen, G.
Partner: UNT Libraries Government Documents Department
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Shining On: A primer on solar radiation data

Description: This document is a primer on solar radiation data. General uses of solar energy are presented. The manner in which solar radiation data is used to aid engineers in optimizing the use of solar thermal conversion and photovoltaic conversion is discussed. Methods for acquiring and assimilating the solar radiation data are illustrated. This would include the design and use of pyranometers and pyrheliometers. Seasonal and geographical variations in solar flux reaching the earth are evaluated. Other uses of compiled data include the determination of meteorological impacts of atmospheric disturbances such as volcano eruptions.
Date: May 1, 1992
Creator: Dunlap, M.A.; Cook, G. (eds.); Marion, B.; Riordan, C. & Renne, D.
Partner: UNT Libraries Government Documents Department
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NREL PV AR D 11th review meeting, May 13--15, 1992, Denver Marriott City Center, Denver, Colorado

Description: This is a collection of abstracts from papers presented at the National Renewable Energy Laboratory (NREL) Photovoltaic (PV) research and development review meeting held May 1992. Subject areas covered include solar cell and solar module manufacturing and development, materials, polycrystalline thin films, applications, amorphous silicon, solar cell performance and testing, crystalline silicon and other photovoltaic and safety perspectives. (GHH)
Date: January 1, 1992
Partner: UNT Libraries Government Documents Department
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Catalyst and Feedstock Effects in the Thermochemical Conversion of Biomass to Liquid Transportation Fuels

Description: The thermochemical conversion of biomass feedstocks to liquid transportation fuels can be accomplished by three processes, namely gasification, high-pressure liquefaction, and pyrolysis. In this study, the pyrolysis option is selected which is followed by the catalytic upgrading of pyrolysis vapors to aromatic and olefinic hydrocarbons (PYROCAT process). The aromatics constitute a high-octane gasoline blend, while the olefins can be utilized as feedstocks for various chemicals. The PYROCAT process has been studied in a laboratory-scale fixed-bed catalytic reactor. Consecutive biomass samples were pyrolyzed rapidly in steam at 550{degree}C and atmospheric pressure, and then the pyrolysis vapors were passed over a zeolite catalyst. The catalytic upgrading products were monitored in real-time using molecular-beam mass-spectrometry (MBMS). The yields of major products were estimated from mass-spectral data. Several zeolite catalysts were screened in the upgrading process and promising catalysts with high yields were identified. Feedstocks studied included: the woody biomass species aspen (Populus tremuloides), basswood (Tilia americana), and willow (Salix alba); the three isolated components of wood lignin, xylan and cellulose; and the herbaceous species bagasse (Saccharum spp. hybrid), wheat straw (Triticum aestivum), and Sericea lespedeza (Lespedeza cuneata). 17 refs.
Date: May 1992
Creator: Rejai, B.; Agblevor, F. A.; Evans, R. J. & Wang, D.
Partner: UNT Libraries Government Documents Department
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Perspective on photovoltaic amorphous silicon

Description: Amorphous silicon is a thin film option that has the potential for a cost-effective product for large-scale utility photovoltaics application. The initial efficiencies for single-junction and multijunction amorphous silicon cells and modules have increased significantly over the past 10 years. The emphasis of research and development has changed to stabilized efficiency, especially that of multijunction modules. NREL has measured 6.3%--7.2% stabilized amorphous silicon module efficiencies for US products, and 8.1% stable efficiencies have been reported by Fuji Electric. This represents a significant increase over the stabilized efficiencies of modules manufactured only a few years ago. An increasing portion of the amorphous silicon US government funding is now for manufacturing technology development to reduce cost. The funding for amorphous silicon for photovoltaics by Japan over the last 5 years has been about 50% greater than that in the United State, and by Germany in the last 2--3 years more than twice that of the US Amorphous silicon is the only thin-film technology that is selling large-area commercial modules. The cost for amorphous silicon modules is now in the $4.50 range; it is a strong function of plant production capacity and is expected to be reduced to $1.00--1.50/W{sub p} for plants with 10 MW/year capacities. 10 refs.
Date: May 1, 1992
Creator: Luft, W.; Stafford, B. & von Roedern, B.
Partner: UNT Libraries Government Documents Department
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A surface definition code for turbine blade surfaces

Description: A numerical interpolation scheme has been developed for generating the three-dimensional geometry of wind turbine blades. The numerical scheme consists of (1) creating the frame of the blade through the input of two or more airfoils at some specific spanwise stations and then scaling and twisting them according to the prescribed distributions of chord, thickness, and twist along the span of the blade; (2) transforming the physical coordinates of the blade frame into a computational domain that complies with the interpolation requirements; and finally (3) applying the bi-tension spline interpolation method, in the computational domain, to determine the coordinates of any point on the blade surface. Detailed descriptions of the overall approach to and philosophy of the code development are given along with the operation of the code. To show the usefulness of the bi-tension spline interpolation code developed, two examples are given, namely CARTER and MICON blade surface generation. Numerical results are presented in both graphic data forms. The solutions obtained in this work show that the computer code developed can be a powerful tool for generating the surface coordinates for any three-dimensional blade.
Date: May 1, 1992
Creator: Yang, S.L. (Michigan Technological Univ., Houghton, MI (United States)); Oryang, D. & Ho, M.J. (Tuskegee Univ., AL (United States))
Partner: UNT Libraries Government Documents Department
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Application Experience and Field Performance of Silvered Polymer Reflectors

Description: The solar-weighted hemispheric reflectance of unweathered silvered acrylic mirrors exceeds 92%, and specular reflectance into a 4- milliradian, full-cone acceptance angle is greater than 90%. Comparison of outdoor and accelerated tests suggests that the protected silver can resist corrosion for the five-year life that is the current goal. An installation of parabolic troughs has been cleaned monthly for two years, and reflectance is regularly returned to within a few percent of the initial reflectance values. In the presence of moisture, the silver/acrylic bond can delaminate to form a maze of tunnels and destroy specular reflectance. Proper edge preparation and protection delay the initiation of tunnels. 6 refs.
Date: April 1, 1991
Creator: Schissel, P.; Jorgensen, G. & Pitts, R.
Partner: UNT Libraries Government Documents Department
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Photovoltaic Subcontract Program, FY 1991

Description: This report summarizes the fiscal year (FY) 1991 (October 1, 1990, through September 30, 1991) progress of the subcontracted photovoltaic (PV) research and development (R D) performed under the Photovoltaic Advanced Research and Development Project at the National Renewable Energy Laboratory (NREL) -- formerly the Solar Energy Research Institute (SERI). The mission of the national PV program is to develop PV technology for large-scale generation of economically competitive electric power in the United States. The technical sections of the report cover the main areas of the subcontract program: the Amorphous Silicon Research Project, Polycrystalline Thin Films, Crystalline Silicon Materials Research, High-Efficiency Concepts, the New Ideas Program, the University Participation Program, and the Photovoltaic Manufacturing Technology (PVMaT) project. Technical summaries of each of the subcontracted programs provide a discussion of approaches, major accomplishments in FY 1991, and future research directions.
Date: March 1, 1992
Partner: UNT Libraries Government Documents Department
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Photoelastic stress analysis on a Phoenix 7. 9-meter blade

Description: Photoelastic tests were conducted on the Phoenix 7.9-meter blade to develop the basic methodology for locating critical strain areas on full-scale composite structures. Under relatively low elastic loading the strain fields over various regions on the blade planform were documented with 35mm photographs under different loading conditions at the Solar Energy Research Institute (SERI) Structural Test Facility (STF). Strain concentrations were easily located and quantified. Principal strain magnitudes and directions were determined at the highest strain areas using separator gages. Results were compared to measured operating loads. This experiment demonstrated the value of experimental stress analysis using the photoelastic technique for the evaluation of composite blade designs. 9 refs., 6 figs., 3 tabs.
Date: October 1, 1991
Creator: Musial, W. D.; Jenks, M. D.; Osgood, R. M. & Johnson, J. A.
Partner: UNT Libraries Government Documents Department
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Geothermal Energy Contract List: Fiscal Year 1990

Description: The Geothermal Division of the US Department of Energy (DOE) is charged with the lead federal role in the research and development (R D) of technologies that will assist industry in economically exploiting the nation's vast geothermal resources. The Geothermal Energy R D Program represents a comprehensive, balanced approach to establishing all forms of geothermal energy as significant contributors to the nation's energy supply. The program is structured both to maintain momentum in the growth of the existing hydrothermal industry and to develop long-term options offering the greatest promise for practical applications. The Geothermal Energy Contract List, Fiscal Year 1990 is a tabulation of geothermal R D contracts that were begun, ongoing, or completed during FY 1990 (October 1, 1989 through September 30, 1990). The R D activities are performed by national laboratories or industrial, academic, and nonprofit research institutions. The contract list is organized in accordance with the Geothermal Division R D work breakdown structure. The structure hierarchy consists of Resource Category (hydrothermal, geopressured-geothermal, hot dry rock, and magma energy), Project (hard rock penetration, reservoir technology, etc.), and Task (lost circulation control, rock penetration mechanics, etc.). For each contract, the contractor, the FY 1990 funding, and a brief description of the milestones planned for FY 1991 are provided.
Date: October 1, 1991
Partner: UNT Libraries Government Documents Department
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Simplified Air Change Effectiveness Modeling

Description: This paper describes recent progress in developing practical air change effectiveness modeling techniques for the design and analysis of air diffusion in occupied rooms. The ultimate goal of this continuing work is to develop a simple and reliable method for determining heating, ventilating, and air-conditioning (HVAC) system compliance with ventilation standards. In the current work, simplified two-region models of rooms are used with six occupancy patterns to find the air change effectiveness. A new measure, the apparent ACH effectiveness, yields the relative ventilation performance of an air diffusion system. This measure can be used for the prediction or evaluation of outside air delivery to the occupants. The required outside air can be greater or less than that specified by ventilation standards such as ASHRAE Standard 62-89.
Date: June 1, 1992
Creator: Rock, B. A.; Anderson, R. & Brandemuehl, M. J.
Partner: UNT Libraries Government Documents Department
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NREL Solar Radiation Resource Assessment Project: Status and Outlook

Description: This report summarizes the activities and accomplishments of NREL's Solar Radiation Resource Assessment Project during fiscal year 1991. Currently, the primary focus of the SRRAP is to produce a 1961--1990 National Solar Radiation Data Base, providing hourly values of global horizontal, diffuse, and direct normal solar radiation at approximately 250 sites around the United States. Because these solar radiation quantities have been measured intermittently at only about 50 of these sites, models were developed and applied to the majority of the stations to provide estimates of these parameters. Although approximately 93% of the data base consists of modeled data this represents a significant improvement over the SOLMET/ERSATZ 1952--1975 data base. The magnitude and importance of this activity are such that the majority of SRRAP human and financial in many other activities, which are reported here. These include the continued maintenance of a solar radiation monitoring network in the southeast United States at six Historically Black Colleges and Universities (HBCU's), the transfer of solar radiation resource assessment technology through a variety of activities, participation in international programs, and the maintenance and operation of NREL's Solar Radiation Research Laboratory. 17 refs.
Date: May 1, 1992
Creator: Renne, D.; Riordan, C.; Maxwell, E.; Stoffel, T.; Marion, B.; Rymes, M. et al.
Partner: UNT Libraries Government Documents Department
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Going national with HERS and EEMs: Issues and impacts

Description: This collection of papers is a companion volume to A National Program for Energy-Efficient Mortgages and Home Energy Rating Systems: A Blueprint for Action (NREL/TP-261-4677). The Blueprint reports the findings and recommendations of the National Collaborative on Home Energy Rating Systems and Mortgage Incentives for Energy Efficiency about a voluntary national program linking energy-efficient mortgages and home energy rating systems. This volume provides technical documentation for A Blueprint for Action. It consists of 55 technical issue papers and 13 special papers prepared by the technical advisory committees and some members of the Collaborative Consensus Committee of the National Collaborative. It also contains the bibliography and the glossary written by the members and staff of the National Collaborative.
Date: March 1, 1992
Partner: UNT Libraries Government Documents Department
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Determination of Accuracy of Measurements by NREL's Scanning Hartmann Optical Test instrument

Description: NREL's Scanning Hartmann Optical Test (SHOT) instrument is routinely used to characterize the surface of candidate dish concentration elements for solar thermal applications. An approach was devised to quantify the accuracy of these measurements. Excellent reproducibility was exhibited and high confidence established. The SHOT instrument was designed to allow the surface figure of large optical test articles to be accurately specified. Such test articles are nominally parabolic with an f/D ratio (in which f=focal length and D=aperture diameter) in the range of 0.5--1.0. Recent modifications of SHOT have extended the characterization range out to about f/D=3.0. A series of experiments was designed to investigate and quantify the uncertainties associated with optical characterization performed by SHOT. This approach involved making a series of measurements with an arbitrary test article positioned at a number of locations transverse to the optical axis of SHOT. 3 refs.
Date: April 1, 1991
Creator: Jorgensen, G.; Wendelin, T. & Carasso, M.
Partner: UNT Libraries Government Documents Department
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Outdoor testing of advanced optical materials for solar thermal electric applications

Description: The development of low-cost, durable advanced optical materials is an important element in making solar energy viable for electricity production. It is important to determine the expected lifetime of candidate reflector materials in real-world service conditions. The demonstration of the optical durability of such materials in outdoor environments is critical to the successful commercialization of solar thermal electric technologies. For many years optical performance data have been collected and analyzed by the National Renewable Energy Laboratory (NREL) for candidate reflector materials subjected to simulated outdoor exposure conditions. Much of this testing is accelerated in order to predict service durability. Some outdoor testing has occurred but not in a systematic manner. To date, simulated/accelerated testing has been limited correlation with actual outdoor exposure testing. Such a correlation is desirable to provide confidence in lifetime predictions based upon accelerated weathering methods. To obtain outdoor exposure data for realistic environments and to establish a data base for correlating simulated/accelerated outdoor exposure data with actual outdoor exposure data, the development of an expanded outdoor testing program has recently been initiated by NREL. Several outdoor test sites will be selected based on the solar climate, potential for solar energy utilization by industry, and cost of installation. Test results are site dependent because exposure conditions vary with geographical location. The importance of this program to optical materials development is outlined, and the process used to determine and establish the outdoor test sites is described. Candidate material identification and selection is also discussed. 10 refs.
Date: May 1, 1992
Creator: Wendelin, T.J.; Jorgensen, G. & Goggin, R.M.
Partner: UNT Libraries Government Documents Department
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Solar synthesis of advanced materials: A solar industrial program initiative

Description: This is an initiative for accelerating the use of solar energy in the advanced materials manufacturing industry in the United States. The initiative will be based on government-industry collaborations that will develop the technology and help US industry compete in the rapidly expanding global advanced materials marketplace. Breakthroughs in solar technology over the last 5 years have created exceptional new tools for developing advanced materials. Concentrated sunlight from solar furnaces can produce intensities that approach those on the surface of the sun and can generate temperatures well over 2000{degrees}C. Very thin layers of illuminated surfaces can be driven to remarkably high temperatures in a fraction of a second. Concentrated solar energy can be delivered over large areas, allowing for rapid processing and high production rates. By using this technology, researchers are transforming low-cost raw materials into high-performance products. Solar synthesis of advanced materials uses bulk materials and energy more efficiently, lowers processing costs, and reduces the need for strategic materials -- all with a technology that does not harm the environment. The Solar Industrial Program has built a unique, world class solar furnace at NREL to help meet the growing need for applied research in advanced materials. Many new advanced materials processes have been successfully demonstrated in this facility, including the following: Metalorganic deposition, ceramic powders, diamond-like carbon materials, rapid heat treating, and cladding (hard coating).
Date: June 1, 1992
Creator: Lewandowski, A.
Partner: UNT Libraries Government Documents Department
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Uniform flux dish concentrators for photovoltaic application

Description: Researchers at the National Renewable Energy Laboratory (NREL) have designed a unique and innovative molded dish concentrator capable of producing a uniform flux profile on a flat target plane. Concentration levels of 100--200 suns, which are uniform over an area of several square inches, can be directly achieved for collection apertures of a reasonable size ({approximately}1.5-m diameter). Such performance would be immediately applicable to photovoltaic (PV) use. Economic concerns have shown that the proposed approach would be less expensive thatn Fresnel lens concepts or other dish concentrator designs that require complicated and costly receivers to mix the flux to obtain a uniform distribution. 12 refs.
Date: May 1, 1992
Creator: Jorgensen, G & Wendelin, T
Partner: UNT Libraries Government Documents Department
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