Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Temperature checks”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Influence of dissolved salts and impurities on seawater on heat transfer and fluid flow through fuel channels and debris bed

This project aims to better understand this mechanism and its effect on heat transfer. Specifically, experimental research was conducted to investigate the long term coolability issues in scaled test setups. Advanced diagnostic and measurement techniques were investigated and incorporated into an annular test facility and a debris bed test facility. The diagnostic techniques investigated included: radioactively tagged salt solution, Frisch collar radiation detector array, neutron and x-ray imaging systems, and a Rayleigh backscatter-based fiber-optic temperature system. Models were checked against the in-situ experimental data and recommendations were made for modeling purposes.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1991

The magnitude of the magnetic field near the surface of a high-T(sub c) superconductor with a trapped flux

In 1986, much excitement was caused by the discovery of a class of materials that conducted electricity with zero resistance at temperatures above the boiling temperature of liquid nitrogen. This excitement was checked by the difficulties of manufacturing ceramics and the usefulness of high temperature superconductors that were restricted by their becoming high resistive conductors at small current densities. A lack of pinning of the magnetic field flux caused the return of high resistance as the current was increased in these materials. A study of the magnetic field near the surface of a high temperature superconductor is the first step in the search for a means of pinning the flux lines and increasing their critical current densities. The author found that a comparison between the defects in the surface of the superconductor and the magnetic field showed only a change in the field near the notch and the edge. No correlation was found between the surface grain or structure and the oscillations in the magnetic field. The observed changes in the magnetic field show resonances which may give an indication of the non-flux pinning in these superconductors. A flux pinning mechanism will increase the critical current densities; therefore, other methods of determining this field should be tried. The author proposes using a flux gate magnetometer with a detector wound on a ferrite core to measure the magnitude and direction of the magnetic field.

Overcash, Dan R.↗
NASA NTRS1973

Observations of 7.9-micron limb brightening on Jupiter.

Gillett et al. (1969) observed that the brightness temperature in the strong 7.7-micron CH4 band was higher than at the neighboring wavelengths (where the absorption was expected to be less) in the Jovian spectrum from 2.8 to 13 microns. This observation was interpreted as being caused by a temperature inversion in the upper atmosphere of Jupiter. This interpretation is checked by measuring the variation of the brightness temperature from the center to the limb of the disk, and is confirmed by the observation of limb brightening, rather than the usual limb darkening, at a certain wavelength within the 7.7-micron CH4 band.

Gillett, F. C.↗
DOE OSTI2021

Performance and flexibility improvements of Staged Pressurized Oxy-Combustion

Staged Pressurized Oxy-Combustion (SPOC) is a low-carbon coal combustion power technology being developed by Washington University in St. Louis (WUSTL). Oxy-combustion plants enable straightforward capture of carbon dioxide (CO 2 ) by removing most of the nitrogen in the combustion air prior to use, thereby burning fuel in near-pure oxygen instead of air, producing a flue gas containing primarily CO 2 and water. CO 2 capture at amounts > 90% is possible, often using cryogenic air separation. Oxy-combustion typically relies on flue gas recycle (FGR) to reduce the peak temperature and radiation that would otherwise occur in a fuel/oxygen only flame. SPOC reduces the peak temperatures of combustion by utilizing two or more pressurized boiler modules connected in series to produce fuel staging; hence, only a portion of the fuel is combusted in any given furnace module. This means that the thermal energy released at each stage can be captured and removed from the gases prior to subsequent stages, when more fuel is introduced. This allows the SPOC process to operate with minimal FGR, avoiding the associated efficiency losses and additional costs. Also, the process operates at an elevated gas-side pressure, reducing boiler size, enhancing heat transfer to achieve a compact boiler configuration as compared to an atmospheric-pressure boiler design, and allowing for recovery of the latent heat of the water from the flue gas at a temperature useful to the steam cycle. The resultant net efficiency of the system is over 3 percentage points greater than traditional atmospheric-pressure oxy-combustion, and 7 percentage points greater than the post combustion variant, representing a step-change improvement over first-generation capture technologies. To further develop the concept, WUSTL and the Electric Power Research Institute, Inc., organized a project with American Air Liquide, Inc., Doosan Babcock Limited, and the U.S. Department of Energy to investigate a practicable and workable boiler design. The team has identified the potential for enhanced process flexibility for controlling power generation over a wider load range than is normally available to conventional coal-fired power plants due to the staged nature of the heat release. With increasing intermittent renewable generator contribution, on-demand generators need to be highly flexible to participate in the future energy market, requiring extensive operation at reduced load. Conventional coal-fired steam generators typically face challenges in maintaining temperature control of the reheat steam and main steam at reduced loads. This results in inefficient operation, both in terms of the boiler efficiency and steam turbine heat rate. The results of this project show the SPOC process is capable of exceptional turndown, both on a stage basis and with the ability to bypass entire stages. Oxygen-supply flexibility was also investigated, as this is also a key consideration for the overall flexibility of the SPOC process given the operating constraints of conventional air separation units. A boiler design concept assessment was conducted and was focused on delivering compact and constructible design. The assessment checked appropriate tube operating metal temperatures at full load and at lower operating loads, balanced against the needs of efficient coal combustion, and the resultant slagging and ash environments. Combustion testing in the 100-kWth pressurized combustion test rig at WUSTL was carried out to validate the combustion, heat flux profiles and burnout at multiple loads. Combustion parameters investigated were flame stability, fuel burnout, ash composition, radiative heat flux, and temperature profiles. The results of these tests formed the basis of a full-scale boiler design that will encompass improvements in both efficiency and flexibility over conventional oxy-combustion processes. The air separation unit flexibility was investigated, and associated cost implications were addressed. Detailed economic assessment results for a 550 MWe net power block are also provided, allowing for a comparison against the baseline NETL oxy-combustion and post combustion capture cases.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS2008

Cluster/Peace Electrons Velocity Distribution Function: Modeling the Strahl in the Solar Wind

We present a study of kinetic properties of the strahl electron velocity distribution functions (VDF's) in the solar wind. These are used to investigate the pitch-angle scattering and stability of the population to interactions with electromagnetic (whistler) fluctuations. The study is based on high time resolution data from the Cluster/PEACE electron spectrometer. Our study focuses on the mechanisms that control and regulate the pitch-angle and stability of strahl electrons in the solar wind; mechanisms that are not yet well understood. Various parameters are investigated such as the electron heat-flux and temperature anisotropy. The goal is to check whether the strahl electrons are constrained by some instability (e.g., the whistler instability), or are maintained by other types of processes. The electron heat-flux and temperature anisotropy are determined by fitting the VDF's to a spectral spherical harmonic model from which the moments are derived directly from the model coefficients.

Figueroa-Vinas, Adolfo↗
DOE OSTI2026

EPWgen (EPW generator) [SWR-26-017]

EPWgen fetches hourly station observations (NOAA/Meteostat), fills gaps with MERRA2 reanalysis, merges data, and writes EPW files with computed headers (HDD/CDD, ground temperatures). It also runs QC checks, supports CSV-driven batch and metered-variable exports, and provides a PyQt5 GUI with mapping and progress tracking for single/multi-year workflows.

Bianchi, Carlo [National Laboratory of the Rockies↗
NASA NTRS1993

Results of thermal vacuum tests for the PASP+ flight modules

The PASP PLUS (Photovoltaic Array Space Power Plus Diagnostics) program is a photovoltaic experiment which will be flown on the Air Force satellite APEX (Advanced Photovoltaic And Electronic Experiment). APEX will be launched with a Pegasus during the summer of 1993. There are two other small experiments on APEX but PASP+ is the largest, uses the most power, and accounts for over 90 percent of the data requirements. The orbit is elliptical with apogee and perigee of 1050 and 190 nautical miles respectively. The inclination is 70 deg. The two main objectives of PASP+ are to determine the interactions between high voltage arrays and the space plasma environment and to determine the radiation damage characteristics of several newer types of solar cells. In order to determine the interactions with the space plasma, several of the individual cell strings will be biased to voltages up to plus or minus 500 V, and leakage currents and arcing rates will be measured. The radiation degradation characteristics will be determined by the continuous monitoring of I-V data for all of the cell strings. As part of an overall testing program, the PASP+ panels and controller were put through a thermal vacuum test in order to check the thermal analysis, obtain temperature coefficients for the individual modules, and have an end-to-end test of the entire PASP+ experiment. This thermal vacuum test is described briefly and the results obtained during that testing are discussed.

Curtis, Henry↗
NASA NTRS1999

Mars Global Reference Atmospheric Model (Mars-GRAM) Version 3.8: Users Guide

Mars Global Reference Atmospheric Model (Mars-GRAM) Version 3.8 is presented and its new features are discussed. Mars-GRAM uses new values of planetary reference ellipsoid radii, gravity term, and rotation rate (consistent with current JPL values) and includes centrifugal effects on gravity. The model now uses NASA Ames Global Circulation Model low resolution topography. Curvature corrections are applied to winds and limits based on speed of sound are applied. Altitude of the F1 ionization peak and density scale height, including effects of change of molecular weight with altitude are computed. A check is performed to disallow temperatures below CO2 sublimination. This memorandum includes instructions on obtaining Mars-GRAM source code and data files and running the program. Sample input and output are provided. An example of incorporating Mars-GRAM as an atmospheric subroutine in a trajectory code is also given.

Justus, C. G.↗
NASA NTRS2002

Assimilation of TES Water Vapor Observations

The Thermal Emission Spectrometer (TES) on the Mars Global Surveyor has made extensive observations of the Martian atmospheric water vapor column since the beginning of its mapping mission in early 1999. The results show broad agreement with the earlier Viking Mars Atmospheric Water Detector (MAWD) results (though column amounts in southern summer are higher, perhaps due to dust obscuration during the Viking mission). General circulation model (GCM) simulations of the annual Martian water cycle also show broad agreement with the TES observations. Details of the simulations depend on cloud and boundary layer parameterizations and on the adsorbing properties of the regolith. In order to make quantitative assessments of this agreement and to obtain observational values for the required physical parameters, a tracer transport data assimilation model has been developed. Model winds are derived from both tracer measurements and retrieved atmospheric temperature structures, providing a useful check of the underlying dynamical core of the GCM. By allowing detailed intercomparison between spacecraft and ground-based observations of Martian water vapor, the model should also contribute significantly to our understanding of the diurnal water cycle.

Houben, Howard↗
NASA NTRS2020

Full Aerothermal Characterization of the 6- by 9-Foot Icing Research Tunnel (2019 Test)

A full aerothermal characterization of the NASA Glenn Icing Research Tunnel (IRT) was completed in August 2019. A mandatory maintenance period required the test entry to be separated into two phases: the first occurring in April 2019 and the second in August 2019. The hardware used during this test entry consisted of the 6-foot quick-check rake, 6-foot traversing rake, RTD array, and hot-wire rake. The 6-foot quick check rake collects static pressure, total pressure, total temperature, and flow angularity data along the centerline of the test section. The data from the 6-foot quick-check rake were used to generate test section calibration relationships for total and static pressure as well as implement statistical process control. The 6-foot traversing rake collects flow uniformity data across the test section for various flow parameters, such as static pressure, total pressure, and flow angularity. Total temperature flow uniformity data is mapped by the RTD array and is used to generate the test section calibration relationship for total temperature. The hot-wire rake measures turbulence intensity at three lateral locations and characterizes airspeed unsteadiness in the test section. The test entry resulted in updated calibration relationships and a full characterization of test section flow quality and flow uniformity in the IRT.

Wind↗
NASA NTRS1973

Determination of the distribution of sound source intensities in subsonic and supersonic jets

Equations relating crossed beam space-time correlations to the sound source strength per unit length of an idealized jet are presented and applied to actual measurements in unheated jets at M = 0.71 and M = 1.0. The infrared crossed beam system was assembled and checked out. The prediction of the system's insensitivity to temperature fluctuations when set at 4.31 microns with a 0.08 micron bandpass was checked. Relative intensity profiles of density fluctuations for jets at M = 0.71, 1.0 and 1.94 were measured. These profiles differ considerably from velocity fluctuation profiles measured by other investigators with hotwires. The convection speeds also differ. Finally, the sound source strengths per unit length are obtained at various axial distances for the subsonic and sonic jet. The sonic jet shows peak source strength at an axial distance of six diameters.

Damkevala, R. J.↗
NASA NTRS1974

Digital temperature sensor performance assessment report

Performance assessment data accumulated during exposure of the digital temperature sensor to simulated shuttle flight type environments are presented. The test parameters were specifically designed to check the sensor for its: (1) ability to resolve temperature relative to the design specifications; (2) ability to maintain accuracy after interchanging the temperature probes with each electronics interface assembly; (3) stability (i.e., satisfactory operation and accuracy during and after exposure to flight environments); and (4) repeatability, or its ability to produce the same output on subsequent exposures to the identical stimulus. Equipment list, test descriptions, data summary, and conclusions are included.

Canniff, J. H.↗
DOE OSTI2020

Progress Toward Simulating Departure from Nucleate Boiling at High-Pressure Applications with Selected Wall Boiling Closures

Recently, a Eulerian-based two-fluid computational fluid dynamics (CFD) framework with a wall heat flux partitioning approach has been intensively investigated for departure from nucleate boiling (DNB) simulation under the U.S. Department of Energy–funded Consortium for Advanced Simulation of Light Water Reactors (CASL) program. Understanding of the DNB characteristics over a range of pressurized water reactor–like operating conditions and accurate prediction of boiling crisis in the nuclear power system have been grand challenges because of the large impact of DNB on reactor safety and operational economics. The ultimate goal of this task in the CASL program is to introduce a robust multiphase CFD–based DNB modeling framework that is capable of characterizing an entire boiling history in which the wall boiling mode experiences the following through multiple stages of heat transfer mode: (1) single-phase convective heat transfer, (2) nucleate boiling heat transfer, and (3) identification of the departure of nucleate boiling. To validate the CASL boiling model, we have benchmarked simulated DNB over three different flow channel configurations (pipe flow, 5 × 5 fuel bundle with mixing vane tests, and 5 × 5 fuel bundle without mixing vane tests) against experimental measurements, and the validation result with open literature is reported. The DNB detection criteria in the simulation are checked by monitoring the peak wall temperature, wall dryout factor, and net energy balance. In addition to the DNB performance test, some preliminary sensitivity results on closure model selection are reported to address the prediction capability of local void profile against measurements. The boiling simulation tested in this study exhibits a maximum deviation of 24% from the measured DNB value in a high-pressure (i.e., 138 bars) subcooled pipe flow test. The ranges of operating conditions are as follows: 1650 to 2650 kg/m 2 ·s for mass flux and 8.5 to 96 K for subcooled inlet temperature. The deviation is even reduced to 7% when the subcooled temperature is less than 40 K. Besides accuracy, base practice guidelines for DNB detection criteria are tested by monitoring three simulation variables: (1) maximum wall temperature, (2) wall dryout factor (i.e., K-value), and (3) energy balance. Numerical robustness of DNB simulation is largely achieved in most of the validation test except for a few high subcooled test cases.

42 ENGINEERING↗
NASA NTRS1965

Simulator produces physiological waveforms

Physiological waveform simulator is capable of producing signals to simulate an axiliary and a sternal electrocardiogram, blood pressure, respiratory rate and body temperature. This may be used to check out bioinstrumentation.

Ekeroot, S.↗
NASA NTRS1971

A neutral particle wake method for measuring the atmospheric temperature from a satellite

A method is described that permits a satellite-borne neutral mass spectrometer to perform measurements of the atmospheric temperature. The method employs the spectrometer to examine the partial pressure variations that occur as the wake of a small rectangular baffle is swept across the entrance orifice of the spectrometer. For a given baffle size and mounting distance from the orifice the depth of the resulting pressure minimum depends only upon the thermal velocity, or temperature, of the observed species. A check upon the validity of the method is obtained by measuring the wake characteristics of more than one species and/or by employing each of several baffle sizes.

Brace, L. H.↗
NASA NTRS1978

One-millimeter brightness temperatures of the planets

Results are reported for a bolometric determination of the relative brightness at a wavelength of 1 mm of Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. The relative measurements are converted to absolute temperatures by using a thermal model for Mars, which was checked by observations of Mars and Jupiter at two different epochs. The mean planetary disk temperatures are found to be 320 + or 16 K for Mercury, 276 + or - 14 K for Venus, 145 + or - 7 K for Saturn, 168 + or - 8 K for Jupiter, 87 + or - 7 K for Uranus, and 96 + or - 10 K for Neptune. These results are compared with previous determinations at other wavelengths, and some aspects of the observations of the individual planets are briefly discussed.

Werner, M. W.↗