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At least 667 records · Page 37

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Ultrasonic measurement of temperature distributions in extreme environments: Electrical power plants testing in utility-scale steam generators

Thermal heterogeneities within energy conversion and storage, material processing, nuclear processes, aerospace, and military applications are often inaccessible to characterization by insertion sensors. When sensor deployment is possible, conventional pointwise temperature probes quickly degrade when inserted into harsh environments typical of such processes. We developed spatially-resolved ultrasonic thermometry to noninvasively measure the spatial distributions of thermal properties in such applications, even when sizable thermal gradients are present. Our method divides the path of ultrasonic propagation into segments bound by echogenic features, which create echoes in pulse-echo mode, encoding the information about interior temperature distributions. We use the acquired ultrasonic responses to estimate the internal temperature distributions by solving an inverse problem or concatenating segmental estimates. This work describes the implementation and industrial testing of the developed method at a coal-fired electrical power generation plant. We inserted an echogenically segmented Inconel 625 waveguide into the combustion zone of the utility-scale boiler and continuously acquired ultrasonic data while keeping sensitive components away from the damaging combustion environment. The accuracy of the time-dependent temperature distributions reconstructed from the ultrasonic measurements was comparable to that of thermocouples. The resiliency of ultrasonic thermometry to harsh combustion conditions was far superior to conventional insertion sensors. The measurements obtained during plant operation captured daily steam generation cycles in response to changing customer demand and intermittent contributions of renewable power sources to the power grid. These measurements have revealed new insights into the relationship between the dynamic power generation load and the conditions inside the steam generator. As a result, the successful industrial testing of spatially-resolved ultrasonic thermometry in solids indicates that the developed technology has matured to become an attractive alternative to conventional sensing in solving challenging problems of long-term thermal characterizations in extreme environments.

42 ENGINEERING↗

NASA NTRS1987

Total strain version of strainrange partitioning for thermomechanical fatigue at low strains

A new method is proposed for characterizing and predicting the thermal fatigue behavior of materials. The method is based on three innovations in characterizing high temperature material behavior: (1) the bithermal concept of fatigue testing; (2) advanced, nonlinear, cyclic constitutive models; and (3) the total strain version of traditional strainrange partitioning.

Halford, G. R.↗

NASA NTRS1989

Thrust chamber material technology program

This report covers work performed at Pratt & Whitney on development of copper-based materials for long-life, reusable, regeneratively cooled rocket engine thrust chambers. The program approached the goal of enhanced cyclic life through the application of rapid solidification to alloy development, to introduce fine dispersions to strengthen and stabilize the alloys at elevated temperatures. After screening of alloy systems, copper-based alloys containing Cr, Co, Hf, Ag, Ti, and Zr were processed by rapid-solidification atomization in bulk quantities. Those bulk alloys showing the most promise were characterized by tensile testing, thermal conductivity testing, and elevated-temperature, low-cycle fatigue (LFC) testing. Characterization indicated that Cu- 1.1 percent Hf exhibited the greatest potential as an improved-life thrust chamber material, exhibiting LCF life about four times that of NASA-Z. Other alloys (Cu- 0.6 percent Zr, and Cu- 0.6 percent Zr- 1.0 percent Cr) exhibited promise for use in this application, but needed more development work to balance properties.

Andrus, J. S.↗

NASA NTRS1986

Developmental testing of a programmable multizone furnace

A multizone furnace was evaluated for its potential utilization for process experimentation on board the Space Shuttle. A temperature gradient can be created through the use of a series of connected temperature zones and can be translated by the coordinated sequencing of zone temperatures. The Bridgman-Stockbarger thermal configuration for directional solidification was implemented so that neither the sample nor furnace was translated. The thermal behavior of the furnace was measured and characterized. Limitations due to both thermal and electronic (computer) factors are identified. The results indicate that the multizone design is limited to low temperature gradients because of the indirect furnace-to-sample thermal coupling needed to blend the discrete thermal zones. The multizone furnace design inherently consumes more power than a similar (two temperature) conventional Bridgman type directional solidification furnace because every zone must be capable of the high cooling rates needed to produce the maximum desired temperature drop. Typical achievable static temperature gradients for the furnace tested were between 6 and 75 C/in. The maximum gradient velocity was approximately 10 in./hr. Several aspects of the tested system could be improved, but the dependence of the multizone design on high heat loss will limit Space Shuttle applications in the form tested unless additional power is available. The multizone furnace offers great flexibility but requires a high level of operator understanding for full advantage to be obtained.

Ting, E. Y.↗

DOE OSTI2020

Collaborative Research: Understanding Nanoparticle-Plasma Interactions in Dusty Non-Thermal Plasmas by Nanoparticle Probes and Online Aerosol Characterization (Final Technical Report)

This report describes results from the University of Minnesota’s contribution to studies performed under the award DE-SC0018202 (principal Investigator: Christopher J. Hogan Jr.. This award is a collaborative research grant with support equally provided to Case Western Reserve University and to the University of Illinois (with principal investigator R. Mohan Sankaran). To date ten peer-reviewed published papers have resulted from the studies performed with University of Minnesota personnel contributing; this report describes the results of these studies as well as several unpublished studies, grouped into seven separate study types. The overarching goal of the carried out studies was to understand nanoparticle behavior and dynamics in non-thermal plasma synthesis reactors, specifically adapting aerosol measurement technology to provide online measurements of particle size, charge, and structure in plasma reactor systems.

42 ENGINEERING↗

NASA NTRS2023

Using Dome Concordia to Characterize the Long-Term Stability of VIIRS Thermal Emissive Bands

The Visible Infrared Imaging Radiometer Suite (VIIRS) instruments aboard the Suomi NPP and NOAA-20 spacecraft have successfully provided Earth image products since 2011 and 2017, respectively. Maintaining accurate radiometric calibration and calibration consistency between the two sensors is a necessity for the continued quality of long-term data records. In this work, the use of frequent VIIRS measurements of brightness temperature over the area surrounding Dome Concordia (Dome C), Antarctica (75.1 °S, 123.4°E) to track the long-term stability of its thermal emissive bands (TEB) is presented. The extremely dry, cold, and rarefied atmosphere of the site makes it ideal to track and detect long-term changes in the TEB responses via analysis of near-nadir and off-nadir VIIRS overpasses in reference to the surface temperature measurements provided by an automated weather station (AWS). Multi-year Dome C measurements have been used to assess the stability of the VIIRS response-versus-scan-angle (RVS) of the half-angle-mirror (HAM), derived from prelaunch characterization, and detector differences at multiple scan angles. Also, included in this work is the RVS stability assessments using the Dome C overpasses. The methodology developed via this work will also be applied to the recently launched VIIRS instrument onboard the NOAA-21 satellite (previously JPSS-2) in the future.

Amit Angal↗

DOE OSTI2025

An Optothermal Raman Model Accounting for Convection, Radiation, and Substrate Effects for Evaluation of the Thermal Conductivity of Two‐Dimensional Coatings

Thermal conductivity of two‐dimensional (2D) materials is important to characterize as this will govern thermal transport physics in the various thermal and energy applications benefitting from the unique properties of these materials. Here, analytical and numerical techniques are presented to determine the thermal conductivity and interfacial conductance of a 2D material coating using confocal micro‐Raman spectroscopy as a noncontact diagnostic. While several methods have been proposed for calculating the values of thermal conductivity, interfacial conductance, and spatial temperature profile, these models often do not consider effects of radiation, convection, and substrate resistance on the temperature and heat flux profiles. We present a model to calculate the thermal conductivity and interfacial conductance which accounts for convection, radiation, and substrate effects to characterize a variety of 2D material coatings, which is demonstrated using large area graphene transferred onto copper and nickel substrates. Convection and radiation effects are found to have a negligible effect on the temperature profile of supported coatings, while the substrate effects have a considerable effect and therefore impact the quantification of thermal conductivity and interfacial conductance in addition to limiting the spatial resolution of the technique. These findings will allow for more accurate and reproducible extraction of the thermal conductivity of graphene and other 2D material coatings when employing noncontact optothermal Raman spectroscopy methods.

2D coatings↗

NASA NTRSDate not supplied

TPSAS-NF1676L-31522-DND

Currently, there are limitations in launch capability regarding requisite payload volume and mass for long duration extra-terrestrial missions. In-space additive manufacturing may provide a solution to this challenge and is applicable for articles ranging from large system and subsystem architectures to small consumables and replacement articles. For small articles, additive manufacturing is becoming more feasible through advances in instrumentation and novel manufacturing strategies capable of generating complex shapes. Many approaches, however, utilize feedstock materials that, once consumed, must be replenished before additional architectures can be generated. Thus, although promising, a major challenge with additive manufacturing is the required starting materials to support on-demand article generation. This presentation describes research toward reversibly assembling materials that can revert to the starting material state for subsequent fabrication. Polyimides were synthesized with thermally reversible Diels-Alder reaction functionalities, furan or maleimide moieties. These materials were characterized utilizing typical spectroscopic, thermal, and mechanical techniques. Amine hardener-enriched epoxy microparticles were synthesized for use as a mechanically robust substrate. Integration of these technologies into a single system and application toward generation of secondary structures on a launch vehicle as a means of in-situ resource utilization will be described.

Christopher J. Wohl↗

DOE OSTI2021

Design, synthesis, and characterization of vinyl-addition polynorbornenes with tunable thermal properties

Unfunctionalized vinyl-addition polynorbornene (VAPNB) possesses many outstanding properties such as high thermal, chemical, and oxidative stability. These features make VAPNB a promising candidate for many engineering applications. However, VAPNB has a small service window between its glass transition temperature (T g ) and decomposition temperature (T d ), and it cannot be readily processed in a melt state. In this work, we demonstrate that the service window of VAPNBs can be tailored through the use of norbornene monomers bearing alkyl, aryl, and aryl ether substituents. The vinyl addition homopolymerization and copolymerization of these functionalized norbornyl-based monomers yielded VAPNBs with high T' g s (>150 °C) and large service windows (T d –T g > 100 °C), which are comparable to other commercial engineering thermoplastics. To further establish the feasibility of melt processing, a functionalized VAPNB material with T g = 209 °C and a service window of 170 °C was successfully extruded and molded into bars. Subsequent characterization of the bars by dynamic mechanical analysis (DMA), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC) revealed only minor signs of polymer degradation. Furthermore, these studies suggest that substituted VAPNBs could be developed into a new class of engineering thermoplastics that is compatible with workhorse melt processing techniques such as extrusion and injection molding, as well as emerging techniques such as extrusion-based 3D printing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

In situ characterization of phase transformations in petroleum pitch by high temperature X-ray diffraction

The phase transformation from isotropic to mesophase of a petroleum-derived pitch was monitored by in situ X-ray diffraction at 410 °C. The kinetics of the transformation were characterized by monitoring the growth of a broad peak at 2θ~24° and could be described by Avrami’s equation. The volatilization of low molecular weight components originally present in the pitch, or produced during the condensation reaction, was assessed by thermal gravimetry analysis, following the same thermal history. Ex situ characterizations of the pitch precursor before and after thermal treatment provided insight into the evolution of the molecular structure associated with mesophase generation (optical polarized microscopy, molecular weight distribution by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, X-ray photoelectron spectroscopy, Auger spectroscopy, and thermal stability). Here, this investigation demonstrates the value of using complementary in situ and ex situ experimental techniques to characterize complex mechanisms during the processing of organic materials.

02 PETROLEUM↗

DOE OSTI2026

Experimental characterization and analysis of phase change material-based thermal energy storage system for refrigerated display case

Refrigerated display cases that are used to store and exhibit food products in supermarkets and retail spaces consume a significant portion of the buildings’ total electricity. Importantly, the refrigeration-related energy cost and demand charges are greatly affected by the time-of-use electricity pricing and demand rates, which are at their maximum during peak hours, typically when refrigeration energy consumption is also high. Using energy storage to shift the refrigeration load from peak to off-peak hours can greatly reduce the operational costs in the supermarket. This study demonstrates a phase change material-based thermal energy storage (TES) system, specifically designed in stackable units, that can be integrated with an open vertical refrigerated display case. We perform numerical and experimental characterization that includes finite-difference modeling for the TES, prototype fabrication, and laboratory evaluation, followed by a preliminary system-level analysis to predict the impact of TES on the refrigerated case performance, energy use, and energy cost. The results show that the dedicated latent TES for refrigerated cases can provide a specific energy of 50.4 Wh/kg and a specific power of 15.5 W/kg. The TES can be charged during 12 h of the off-peak period and discharged at various rates during 4 to 6 h of the peak period, thereby shifting the refrigeration load from the peak to the off-peak period. Consequently, annual cost savings up to 19% can be achieved, depending on the thermal load, the summer/winter peak electricity pricing, and the transition temperature of the phase change material used.

25 ENERGY STORAGE↗

NASA NTRS1988

Characterization of microcomposite polyimide films

Thermally stable microcomposite polyimide films were prepared by the homogeneous incorporation of either a soluble metal salt or a metal complex into a poly(amide-acid)/N,N-dimethylacetamide solution. The thermal processing of films solvent cast onto glass substrates and cured in an appropriate atmosphere yields films containing not only a fairly uniform dispersion of submicrometer particles, but also a new surface layer of metal or metal oxide. These polymeric systems have been characterized using X-ray photoelectron spectroscopy, Auger electron spectroscopy with depth profiling via argon ion etching, transmission electron microscopy of ultramicrotomed cross-sections, scanning electron microscopy, elemental analysis, thermal analysis, and variable temperature electrical resistivity determinations. The data from these techniques were used cooperatively to develop a model for these microcomposite polyimide films.

Rancourt, J. D.↗

NASA NTRS2003

Numerical Modeling, Thermomechanical Testing, and NDE Procedures for Prediction of Microcracking Induced Permeability of Cryogenic Composites

Reusable Space Vehicles will include light cryogenic composite fuel tanks that must not leak excessively even after multiple launches. Damage in cryogenic composite fuel tanks induced during manufacturing and advanced by thermomechanical cycling can accelerate leakage of the propellant. Whether the leakage exceeds tolerable levels depends on many factors, including pressure gradients, microcrack density, other damage such as delamination, connectivity of the cracks, residual stresses from manufacture, service-induced stresses from thermal and mechanical loads, and composite lay-up. Although it is critical to experimentally characterize permeability during various thermal and mechanical load histories, optimal design depends on having analytical models that can predict the effect of various parameters on performance. Our broad goal is to develop such models that are experimentally validated by destructive and non-destructive evaluation means.

Noh, Jae↗

NASA NTRSDate not supplied

Analysis of Hypervelocity-Impacted Thin Films for Space Applications

Exposure to the harsh space environment and hypervelocity impacts from micrometeoroids and small orbital debris can affect space operations through long-term degradation of spacecraft materials, surfaces, or systems. Multi-layer insulation (MLI) and coated, polyimide films are spacecraft materials commonly found on the external surfaces of spacecraft for thermal control and protection. Characterizing the damage to these exposed materials with in situ and laboratory measurements can better inform spacecraft designers and operators in understanding and mitigating surface or system degradation. In this paper, we examine flown Hubble Space Telescope (HST) Equipment Bay 5 MLI and coated, polyimide ground test articles to characterize hypervelocity impact damage. Impact feature cavities are inspected to identify damage, which can validate long-term degradation models, improve thermal management systems, or improve accuracy of damage predictions. An overview of the impact characterization using optical microscopy, narrowband spectroscopy, and Scanning Election Microscopy/Energy Dispersive X- ray (SEM/EDX) of the two materials is presented. Observations of robustness in the space environment, as well as a detailed assessment of cratering and penetration statistics for the space-exposed sample, also are discussed.

Melissa A. Ward↗

DOE OSTI2022

Experimental characterization of extreme temperature granular flows for solar thermal energy transport and storage

High-temperature, dense granular flows along an inclined plane were considered for solar thermal energy transport and storage with sintered bauxite particles. A series of experiments was performed for particle inlet temperatures of ~ 200, 400, 600, and 800 °C to understand the mechanisms of granular flows at extreme temperatures. Mass flow rates were measured using a load cell and free-surface velocities were measured and computed using particle image velocimetry. Surface temperatures were measured using infrared cameras. A significant decrease in steady-state particle mass flow rate was observed with increasing temperature due to changing flow properties. A decrease in bulk particle free-surface velocities was observed at higher temperatures. Free-surface velocity measurement error between experiments were within 20% of the average. The particle surface temperatures decreased from inlet to outlet with larger gradients at higher temperatures observed due to increasing convection and radiative heat losses. Here, a decrease in temperature was observed along the side walls due to a decrease in particle velocities.

14 SOLAR ENERGY↗

DOE OSTI2023

Collaborative Research: Understanding Nanoparticle-Plasma Interactions in Dusty Non-Thermal Plasmas by Nanoparticle Probes and Online Aerosol Characterization

Research Objectives The goal of this research project is to understand the nature of charge interactions between plasmas and aerosol particles. Specifically, the project has the following objectives: 1) Study the effect of solid nanoparticles on properties of an atmospheric pressure plasma. 2) Study the influence of plasma density on the final charge of nanoparticles. 3) Develop a theoretical understanding of charge decay and charge dynamics in the spatial afterglow in support of experimental observations of the final charge of nanoparticles exiting a plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS1988

Characterization of a graphite epoxy optical bench during thermal vacuum cycling

In-situ monitoring of the Wide-Field/Planetary Camera, a Hubble Space Telescope science instrument, was performed in a vacuum environment to better understand the formation of ice on cooled optical detectors. Several diagnostic instruments were mounted on an access plate to view the interior of the instrument housing and the graphite epoxy optical bench. The instrumentation chosen and the rationale for choosing the instrumentation are discussed. In addition, the performance of the instrumentation during monitoring operations is discussed.

Hansen, Patricia A.↗

NASA NTRS2017

Statistical Characterization of 18650-Format Lithium-Ion Cell Thermal Runaway Energy Distributions

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh/kg) and moderate energy (200 Wh/kg) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 1/4m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.

Thermal Runaway Energy Distribution↗