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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Thematic Mapper bandpass solar exoatmospheric irradiances

Based on solar irradiance data published by Neckel and Labs (1984) and Iqbal (1983), the solar exoatmospheric irradiances for Thematic Mapper (TM) bands 1, 2, 3, and 4 have been calculated. Results vary by up to 1 percent from previous published values, which were based on the earlier data of Neckel and Labs. For TM bands 5 and 7, integrated solar exoatmospheric irradiances have also been recalculated using solar irradiance data published by Labs and Neckel (1968), Arvesen et al. (1969), and Iqbal (1983). These irradiances vary by up to 6 percent from previously published results, which were based on data published by Thekaekara (1972).

Markham, B. L.↗
DOE OSTI2020

The Case for Custom TMY's: Examples Using the NSRDB

A typical meteorological year (TMY) data set essentially represents an hourly compilation of median months constructed using multi-year datasets. Although TMY data sets are generated from irradiance data in the horizontal plane, they are used in photovoltaic (PV) modeling for systems inclined to various angles. This paper demonstrates that a POA TMY (plane of array TMY) generated by selecting median months from a multi-year POA irradiance timeseries dataset produces significantly different results than a POA TMY generated by transposing a TMY dataset constructed from horizontal data. In some months the differences can be more than 3%. These results point to the need for generating TMY's using POA irradiance timeseries representing the orientation at which PV panels will be deployed.

14 SOLAR ENERGY↗
DOE OSTI2022

A Comparison of Time-Series Gap-Filling Methods to Impute Solar Radiation Data: Preprint

Complete solar resource data sets play a critical role at every stage of solar energy projects; however, measured or modeled solar resource data come with significant uncertainties and usually suffer from several issues, including, but not limited to, data gaps and data quality issues. To mitigate these issues, an appropriate data imputation method should be implemented to build a complete and reliable temporal (and spatial) database. Motivated by this, in this study, we extensively compare the performance of eight different gap-filling methods by creating random and artificial data gaps in (i) hourly irradiance data for 1 year using a few locations of the National Solar Radiation Database (NSRDB) and (ii) 1-minute ground measurement data sets from the Surface Radiation Budget Network (SURFRAD) and the National Renewable Energy Laboratory (NREL) stations.

clearness index↗
DOE OSTI2021

A Comparison of Time Series Gap-Filling Methods to Impute Solar Radiation Data

Complete solar resource datasets play a critical role at every stage of solar project phases. However, measured or modeled solar resource data come with significant uncertainties and usually suffer from several issues, including but not limited to, data gaps, data quality issue, etc. In order to mitigate these issues an appropriate data imputation method should be implemented to build a complete and reliable temporal (and spatial) database. Being motivated by this, in this study we compare the performances of eight different gap filling methods extensively by creating random and artificial data gaps in (i) hourly irradiance data for one year using a few locations of the National Solar Radiation Database (NSRDB) and (ii) one-minute ground measurement dataset from Surface Radiation Budget Network (SURFRAD) stations.

clearness index↗
NASA NTRS1995

Long-term total solar irradiance variability during sunspot cycle 22

Total solar irradiance measurements from the 1984-1993 Earth Radiation Budget Satellite (ERBS) active cavity radiometer and 1978-1993 Nimbus 7 transfer cavity radiometer spacecraft experiments are analyzed to detect the presence of 11-, 22-, and 80-year irradiance variability components. The analyses confirmed the existence of a significant 11-year irradiance variability component, associated with solar magnetic activity and the sunspot cycle. The analyses also suggest the presence of a 22- or 80-year variability component. The earlier Nimbus 7 and Solar Maximum Mission (SMM) spacecraft irradiance measurements decreased approximately 1.2 and 1.3 W/sq m, respectively, between 1980 and 1986. The Nimbus 7 values increased 1.2 W/sq m between 1986 and 1989. The ERBS irradiance measurements increased 1.3 W/sq m during 1986-1989, and then decreased 0.4 W/sq m (at an annual rate of 0.14 W/sq. m/yr) during 1990-1993. Considering the correlations between ERBS, Nimbus 7, and SMM irradiance trends and solar magnetic activity, the total solar irradiance should decrease to minimum levels by 1997 as solar activity decreases to minimum levels, and then increase to maximum levels by the year 2000 as solar activity rises. The ERBS measurements yielded 165.4 +/- 0.7 W/sq m as the mean irradiance value with measurement accuracies and precisions of 0.2% and 0.02%, respectively. The ERBS mean irradiance value is within 0.2% of the 1367.4, 1365.9, and 1366.9 W/sq m mean values for the SMM, Upper Atmosphere Research Satellite (UARS), and Space Shuttle Atmospheric Laboratory for Applications and Science (ATLAS 1) Solar Constant (SOLCON) active cavity radiometer spacecraft experiments, respectively. The Nimbus 7 measurements yielded 1372.1 W/sq m as the mean value with a measurement accuracy of 0.5%. Empirical irradiance model fits, based upon 10.7 -cm solar radio flux (F10) and photometric sunspot index (PSI), were used to assess the quality of the ERBS, Numbus 7, SMM, and the UARS irradiance data sets and to identify irradiance variability trends which may be caused by drifts or shifts in the spacecraft sensor responses. Comparisons among the fits and measured irradiances indicate that the Nimbus 7 radiometer response shifted by a total of 0.8 W/sq m between September 1989 and April 1990 and that the ERBS and UARS radiometers each drifted approximately 0.5 W/sq m during the first 5 months in orbit.

Lee, Robert B., III↗
NASA NTRS1990

Solar Constant Data from Earth Radiation Budget Measurements

At present, solar total irradiance measurements are made from four satellites using electrically self calibrating pyrheliometers, as a part of the earth radiation budget measurement programs. The Earth Radiation Budget (ERB) mission onboard Nimbus-7 spacecraft (Nimbus/ERB) started solar total irradiance measurements in November 1978, and is still obtaining irradiance data on every orbit, daily. The Earth Radiation Budget Experiment (ERBE) solar monitors onboard Earth Radiation Budget Satellite (ERBS), NOAA-9 and NOAA-10 started solar total irradiance measurements in October 1984, January 1985, and October 1986, respectively. Our knowledge of solar total irradiance and its variability has grown remarkably during the past few years, as a result of the above measurements, and the high precision data obtained from Solar Maximum Mission/Active Cavity Radiometer Irradiance Monitor-1 (SMM/ACRIM-1). The results from a comparative study of the solar constant data available from the above missions are presented. The solar constant value derived from the sensors agree within the uncertainty associated with absolute pyrheliometers available at present. An attempt will be made to correlate the solar irradiance variability with other solar parameters. The measurements from Nimbus-7/ERB started November 1978, as the solar cycle 21 was increasing in activity. The solar luminosity reached a maximum in the spring of 1979. The irradiance then decreased slowly to a minimum which lasted from 1984 through 1986. The irradiance is presently increasing towards a new maximum. It appears that the solar constant value follow an eleven year cycle.

Mecherikunnel, A. T.↗
DOE OSTI2020

GET-Solar (Generation forecasting and parameter Estimation Tool for Solar) [SWR-20-115]

GET-Solar (Generation forecasting and parameter Estimation Tool for Solar) can be used to estimate behind the meter (BTM) solar generation from limited datasets. Using distributed sets of diverse solar sites, but with close spatial proximity, and/or limited historical PV generation information can be used to generate of solar profiles. This is useful for applications where partial solar generation data is available, and on-site irradiance data is not available. GET-Solar calculates PV technical data parameters and calculates output by modeling shading and cloud cover impacts. Clear sky irradiance profiles are used to calculate base generation profiles on which the local shading and cloud cover layers are added. In order to arrive at clear sky generation data, PV mounting information like panel tilt and and angle is needed. For cases where PV mounting information is missing, panel tilt and azimuth angle can be estimated using a non-linear optimization algorithm. GET-Solar can also be used for forecasting applications where historical PV data is available to estimate local shading at various solar positions. This overall framework can be used for estimation of solar parameters, and assisting in analyzing and modeling diverse sets of DER where solar generation is also present in utility meter data. GET-Solar has been developed in Python and uses the Pyomo optimization language.

Abraham, Sherin Ann↗
DOE OSTI2024

Simulative Prediction of Solar Illuminance and Application of the Du-Sharples Model in Estimating Adapted Daylighting Metrics for an Urban Environment

The practice of daylighting in indoor spaces can significantly reduce electricity consumption and carbon emissions, improve human productivity, and enhance mood and cognitive perception. This work discussed the recent developments in daylighting science and practice, computed the periodic variations in average diurnal daylight levels for each month, quantified in terms of global horizontal illuminance and diffuse horizontal illuminance, for Kolkata, India, a city with tropical wet and dry climate, with two empirical luminous efficacy models of estimating solar illuminance, and assessed daylighting metrics with the Du-Sharples model. A program was formulated that could compute and generate daylight data with monthly-hourly solar irradiation data and the Du-Sharples model was utilized to predict dirt-corrected daylighting metrics for three glazing transmittance values and five elemental carbon deposition levels on glazing material. The highest monthly average global horizontal illuminance is recorded in April (64.05 klx for Littlefair model and 66.82 klx for Muneer-Kinghorn model) and the highest monthly average diffuse horizontal illuminance is recorded in July (33.23 klx for Littlefair model and 30.63 klx for Muneer-Kinghorn model). Further, the computed yearly average global and diffuse horizontal illuminance levels agree well with a previous study that applied the Perez model. Yearly average horizontal work surface illuminance level remained >1.5 klx for window-towall area ratio >30 %. The approach adopted in this work and the temporal variation charts of computed exterior daylight level data may assist building service engineers, architects, and indoor lighting practitioners in making informed policy decisions at different stages of building planning.

Engineering↗
NASA NTRS1988

Frequencies of low-degree solar acoustic oscillations and the phase of the solar cycle

A study of the solar total irradiance data of the Active Cavity Radiometer Irradiance Monitor on the SMM satellite shows a small but formally significant shift in the frequencies of solar acoustic (p-mode) oscillations between the epochs of maximum and minimum solar activity. Specifically, the mean frequency of the strongest p-mode resonances of low spherical-harmonic degree (l = 0-2) is approximately 1.3 parts in 10,000 higher in 1980, near the time of sunspot maximum, than at around 1985, near sunspot minimum. The observed frequency shift may be an 11-yr effect but the precise mechanism is not clear.

Woodard, Martin F.↗
NASA NTRS2005

Photolysis Rate Coefficient Calculations in Support of SOLVE II

A quantitative understanding of photolysis rate coefficients (or "j-values") is essential to determining the photochemical reaction rates that define ozone loss and other crucial processes in the atmosphere. j-Values can be calculated with radiative transfer models, derived from actinic flux observations, or inferred from trace gas measurements. The primary objective of the present effort was the accurate calculation of j-values in the Arctic twilight along NASA DC-8 flight tracks during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II), based in Kiruna, Sweden (68 degrees N, 20 degrees E) during January-February 2003. The JHU/APL radiative transfer model was utilized to produce a large suite of j-values for photolysis processes (over 70 reactions) relevant to the upper troposphere and lower stratosphere. The calculations take into account the actual changes in ozone abundance and apparent albedo of clouds and the Earth surface along the aircraft flight tracks as observed by in situ and remote sensing platforms (e.g., EP-TOMS). A secondary objective was to analyze solar irradiance data from NCAR s Direct beam Irradiance Atmospheric Spectrometer (DIAS) on-board the NASA DC-8 and to start the development of a flexible, multi-species spectral fitting technique for the independent retrieval of O3,O2.02, and aerosol optical properties.

Swartz, William H.↗
DOE OSTI2023

Simulation of a TRISO MiniFuel irradiation experiment with data-informed uncertainty quantification

An irradiation experiment using tristructural isotropic (TRISO) fuel particles and the miniature fuel (MiniFuel) irradiation vehicle was performed in Oak Ridge National Laboratory’s High Flux Isotope Reactor (HFIR) to support development of the Kairos Power fluoride salt–cooled, high-temperature reactor (KP-FHR). Here, this paper describes modeling predictions of temperatures and fuel burnup for the as-built experiment. An uncertainty quantification (UQ) analysis was performed to determine the effect of TRISO particle volume and position on the temperature predictions at various fuel heat generation rates (HGRs). This UQ study utilized fuel kernel position and volume measurements previously collected using X-ray computed tomography (XCT) techniques and Monte Carlo sampling methods to generate fuel compact cases that were then analyzed using a finite element thermal model. The UQ analysis indicated that uncertainty in calculated temperatures caused by varying TRISO particle arrangement is relatively small, even at high fuel HGR. Final predictions of particle temperatures throughout the irradiation are shown to be relevant to KP-FHR normal and off-normal operating conditions and to previous TRISO irradiation experiments. The combination of XCT with UQ analyses will inform post-irradiation examination (PIE) of the irradiated fuel compacts, and these analyses can be used to develop fuel performance models for coated particle fuel forms. Both PIE of separate-effects irradiation data and enhanced fuel performance modeling support accelerated qualification of TRISO fuels for a broad range of advanced reactor applications. The novel approach demonstrated here of measuring TRISO particle configurations with XCT methods and generating representative fuel compacts for finite element modeling and UQ analysis could be leveraged by the broader particle fuel community in the development of other TRISO fuel experiments in which these variables may have a significant impact on key outcomes.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1997

Long-term variations in total solar and UV irradiances

The variations of total solar and UV irradiances during solar cycles 21 and 22 are compared. The total solar irradiance data used were obtained by the SMM/active cavity radiometer irradiance monitoring (ACRIM) 1, upper atmosphere research satellite (UARS)/ACRIM 2 and ERBS experiments. The space-based irradiance observations are compared to the Mount Wilson Magnetic Plage and Photometric Sunspot Index, which is derived from the area and position of sunspots published by the NOAA World Data Center Solar Geophysical Data Catalog. It is found that the variations in solar UV irradiance were similar during the maximum and minimum of solar cycles 21 and 22. The possible reasons for the differences in the irradiance values during the minima of the two solar cylces are discussed.

Pap, J. M.↗
NASA NTRS1994

Long-term variations in total solar irradiance

For more than a decade total solar irradiance has been monitored simultaneously from space by different satellites. The detection of total solar irradiance variations by satellite-based experiments during the past decade and a half has stimulated modeling efforts to help identify their causes and to provide estimates of irradiance data, using `proxy' indicators of solar activity, for time intervals when no satellite observations exist. In this paper total solar irradiance observed by the Nimbus-7/Earth Radiation Budget (ERB), Solar Maximum Mission (SMM)/Active Cavity Radiometer Irradiance Monitor (ACRIM) 1, and Upper Atmosphere Research Satellite (UARS)/ACRIM 2 radiometers is modeled with the Photometric Sunspot Index and the Mg II core-to-wing ratio. Since the formation of the Mg II line is very similar to that of the Ca II K line, the Mg core-to-wing ratio, derived from the irradiance observations of the Nimbus-7 and NOAA9 satellites, is used as a proxy for the bright magnetic elements. It is shown that the observed changes in solar irradiance are underestimated by the proxy models at the time of maximum and during the beginning of the declining portion of solar cycle 22 similar to behavior just before the maximum of solar cycle 21. This disagreement between total irradiance observations and their model estimates is indicative of the fact that the underlying physical mechanism of the changes observed in the solar radiative output is not well-understood. Furthermore, the uncertainties in the proxy data used for irradiance modeling and the resulting limitation of the models should be taken into account, especially when the irradiance models are used for climatic studies.

Pap, Judit M.↗
NASA NTRS1990

The ACRIM data in the context of stellar variability

The Active Cavity Radiometer Irradiance Monitor (ACRIM) total-irradiance data from the Solar Maximum Mission have given a first comprehensive view of solar variability in the stellar sense. Five types of solar variability have been identified thus far. These have small amplitudes, less than a few tenths of one percent, and are at levels generally not yet detectable on other stars. The possible stellar analogs are interesting physically, and in particular may help us to understand solar behavior on longer time scales. The ACRIM data is described from the stellar point of view. The present state of stellar time-series photometry is discussed.

Hudson, Hugh S.↗
DOE OSTI2021

The status of the Japanese material properties handbook and the challenge to facilitate structural design criteria for DEMO in-vessel components

This work summarizes the current status of the material properties handbook for a structural design using Japanese reduced-activation ferritic/martensitic steel F82H. Specifically, the key structural parameters, e.g. time-independent/dependent design stresses and fatigue design curves, were determined by following the French structural design code RCC-MRx. Moreover, under the Japan–U.S. collaboration, tensile data were newly added to the benchmark heavy irradiation data up to 80 dpa, as critical input information in the intermediate check and review in Japan. Furthermore, the status of structural material data and the near-term and long-term issues were clarified by the evaluation using the attribute guides. In parallel, the structural design approaches, which were newly introduced and extended to cope with the structural design issues under the complex environmental conditions peculiar to the DEMO reactor, were noted with the initial R&D results. Of the many design issues, the multi-axial loading conditions due to the complexity of the DEMO reactor as well as the coolant compatibility and the irradiation effect are mentioned. For example, in the paper, multi-axial fatigue–creep testing and evaluation using the modified universal slope method and brittle/ductile fracture testing and evaluation using the local approach are explained toward DEMO.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Role of microstructure on CO corrosion of SiC layer in UO₂-TRISO fuel

The Advanced Gas Reactor Fuel Qualification and Development (AGR) program has focused on qualification of UCO kernel tristructural-isotropic (TRISO) particle fuel relative to UO₂ kernel TRISO particle fuel. However, a UO₂ kernel variant was included in the second AGR irradiation experiment (AGR-2) for comparison and to connect to historic fuel irradiation data. The development of a multiscale, post-irradiation examination (PIE) analysis approach through the AGR Program has allowed for a comprehensive understanding of individual particle failure. This approach has been applied to gain an understanding of SiC layer failure in UO₂ kernel TRISO fuel from AGR-2 after safety testing at 1600–1700 °C. Particle failure by intergranular CO corrosion, facilitated by a compromised inner pyrolytic carbon layer, has been confirmed through the combined application of modern x-ray computed tomography and electron microscopy techniques. In addition, a relationship between grain boundary character and CO corrosion has been identified. This finding provides an opportunity to develop mitigating strategies to improve the resilience of the SiC layer to CO corrosion in UO₂ TRISO fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1988

A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer

Temperature data in the mixed layer and net solar irradiance data at the sea surface are used to estimate the vertical turbulent heat flux at the bottom of the daily mixed layer. The method is applied to data obtained in the eastern tropical Pacific, where the daily cycle in the temperature field is confined to the upper 10-25 m. Equatorial turbulence measurements indicate that the turbulent heat flux is much greater during nighttime than daytime.

Imawaki, Shiro↗
NASA NTRS1994

Nimbus-7 Earth Radiation Budjet compact solar data set user's guide

Nimbus-7 Earth Radiation Budget (ERB) solar measurements extend from November 16, 1978, to December 13, 1993, but with data gaps in 1992 and 1993. The measurements include the total solar irradiance plus six broadband spectral components. The Channel 10c total irradiance data appears very stable, and the calibration, well done. A number of characterization problems remain in the spectral measurements. In the original program, the solar and Earth flux measurements were intermixed and spread over about 170 computer tapes. For easier access, the solar data have been collected into two compact data sets. All of the data are collected into 14 Summary Solar Tapes (SST's). In addition, two Channel 10c Solar Tapes (CST's) give a separate listing of the stable total solar irradiance measurements. Channel 10c calibration and orbital irradiance values are given on separate PC disks. This document gives data descriptions and formats, together with quality control and calibration procedures.

Kyle, H. Lee↗