Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Cycle Performance”

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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

A Comparative Study on the Environmental Impact of CO2 Supermarket Refrigeration Systems

Supermarket refrigeration systems have high environmental impact due to their large refrigerant charge and high leak rates. Accordingly, the interest in using natural refrigerants, such as carbon dioxide (CO2), and new refrigerant blends with low GWP in such systems is increasing. In this paper, an open-source Life Cycle Climate Performance (LCCP) framework is presented and used to compare the environmental impact of three supermarket refrigeration systems. These systems include a transcritical CO2 booster system, a cascade CO2/N-40 system, and a baseline R-404A multiplex direct expansion system. The study is performed for cities representing different climates within the USA using EnergyPlus to simulate the systems' hourly performance. Finally, a parametric analysis is performed to study the impact of annual leak rate on the systems' LCCP.

LCCP↗
DOE OSTI2019

Water Chemistry and Pressure Effects on Steam Oxidation of Ferritic and Austenitic Steels (EPRI)

Traditional laboratory steam experiments are conducted at ambient pressure with water of variable chemistry. In order to better understand the effect of steam pressure and water chemistry, a new recirculating, controlled chemistry water loop with a 650°C autoclave was constructed. The initial experiments included two different water chemistries at 550° and 650°C. Two 500-h cycles were performed using oxygenated (OT, pH ~9 and ~100 ppb O2) or all-volatile treated (AVT, pH ~9 and <10 ppb O2) water conditions at each temperature. Coupons exposed included Fe-(9-11)%Cr and conventional and advanced austenitic steels as well as shot peened type 304H stainless steel. Compared to ambient steam exposures, the oxides formed after 1,000 h were similar in thickness for each of the alloy classes but appeared to have a different microstructure, particularly for the outer Fe-rich layer. An initial attempt was made to quantify the scale adhesion in the two environments.

Pint, Bruce↗
DOE OSTI2022

Bio-Energy with Carbon Capture and Storage (BECCS): Achieving Net Zero and Beyond

This work evaluates the life cycle environmental performance of Bioenergy with Carbon Capture and Storage (BECCS) across different biomass types, processing technologies, and capture rates. Preliminary results suggest that carbon neutrality could be achieved if 35% biomass is co-fired with 90% carbon capture and sequestration.

Carlson, Derrick R.↗
DOE OSTI2024

Grid Resilience Analysis on Geothermal District Heating and Cooling Implementation Alongside Four Existing Oil and Gas Wells in Tuttle, Oklahoma: Preprint

This study builds on the existing techno-economic and environmental life cycle assessments performed for a geothermal district heating and cooling system implementation in Tuttle Oklahoma with four existing oil and gas wells. Its resilience in meeting the peak annual heating and cooling loads of the district assuming a temporary disconnection from the electrical grid is assessed both qualitatively and quantitatively. Attributes of resilience and qualitative criteria established by Kolker et al. (2022) for geothermal district heating systems are applied to the proposed case to highlight its vulnerabilities. Results indicate that increasing the redundancy and diversity in the physical configuration of the distributional piping can considerably increase the system’s resilience. A quantitative assessment executed via the REopt tool predicts that the ancillary electricity required to power the geothermal system’s heating and cooling can be met by an onsite emergency diesel generator during times of grid outages for over 28 days.

district heating and cooling↗
DOE OSTI2025

Grid Resilience Analysis on Geothermal District Heating and Cooling Implementation Alongside Four Existing Oil and Gas Wells in Tuttle, Oklahoma

This study builds on the existing techno economic and environmental life cycle assessments performed for a geothermal district heating and cooling system implementation in Tuttle Oklahoma with four existing oil and gas wells. Its resilience in meeting the peak annual heating and cooling loads of the district assuming a temporary disconnection from the electrical grid is assessed both qualitatively and quantitatively. Attributes of resilience and qualitative criteria established by Kolker et al. (2022) for geothermal district heating systems are applied to the proposed case to highlight its vulnerabilities. Results indicate that increasing the redundancy and diversity in the physical configuration of the distributional piping can considerably increase the system's resilience. A quantitative assessment executed via the REopt tool predicts that the ancillary electricity required to power the geothermal system's heating and cooling can be met by an onsite emergency diesel generator during times of grid outages for over 28 days.

district heating and cooling↗
NASA NTRS1985

Thermal stress cycling of GaAs solar cells

A thermal cycling experiment was performed on GaAs solar cells to establish the electrical and structural integrity of these cells under the temperature conditions of a simulated low-Earth orbit of 3-year duration. Thirty single junction GaAs cells were obtained and tests were performed to establish the beginning-of-life characteristics of these cells. The tests consisted of cell I-V power output curves, from which were obtained short-circuit current, open circuit voltage, fill factor, and cell efficiency, and optical micrographs, spectral response, and ion microprobe mass analysis (IMMA) depth profiles on both the front surfaces and the front metallic contacts of the cells. Following 5,000 thermal cycles, the performance of the cells was reexamined in addition to any factors which might contribute to performance degradation. It is established that, after 5,000 thermal cycles, the cells retain their power output with no loss of structural integrity or change in physical appearance.

Janousek, B. K.↗
DOE OSTI2015

Economic Evaluation of Promising Options

This report presents the efforts, undertaken in FY15, aimed at enhancing the Fuel Cycle Options (FCO) Campaign’s capability to perform credible fuel cycle cost estimates and evaluation of financial risk. This effort builds on the work performed in FY14 (Ganda 2014), which focused extensively on understanding the principal drivers of Light Water Reactors (LWR) construction costs, based on historical data. That framework has received further confirmation from the work and the extensive data uncovered in FY15.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

LCIO

Performance of file systems shift during their life cycles. Evaluating this performance change over time is not trivial. Complexity arises in the interplay between external (i.e. application I/O workloads) and internal (i.e. the filesystem state) factors. Many benchmarks can test how a filesystem performs at the current snapshot state, but to observe the change over time necessitates that the filesystem state mutate (age) between benchmark runs. For a large-scale HPC parallel filesystem, the sheer scale and amount of interacting components during I/O operations magnify these challenges. LCIO addresses the question - how will the filesystem perform at different stages of its life cycle? LCIO is a synthetic benchmark, which provides the file system aging process to increase the amount of information that existing benchmarks like IOR and MDTest yield, as well as provide additional points of data that will be useful to system architects and engineers.

Bachstein, Matthew↗
DOE OSTI2016

Dynamic estimator for determining operating conditions in an internal combustion engine

Methods and systems are provided for estimating engine performance information for a combustion cycle of an internal combustion engine. Estimated performance information for a previous combustion cycle is retrieved from memory. The estimated performance information includes an estimated value of at least one engine performance variable. Actuator settings applied to engine actuators are also received. The performance information for the current combustion cycle is then estimated based, at least in part, on the estimated performance information for the previous combustion cycle and the actuator settings applied during the previous combustion cycle. The estimated performance information for the current combustion cycle is then stored to the memory to be used in estimating performance information for a subsequent combustion cycle.

42 ENGINEERING↗
DOE OSTI2016

High-temperature electrochemical performance of low-cost La–Ni–Fe based hydrogen storage alloys with different preparation methods

Highlights: • Effects of four different preparation processes were studied at 20/60 °C. • All NS + HT, RS and RS + HT processes can optimize the thermodynamic performance. • The HT process can provoke the precipitation of A{sub 2}B{sub 7} and leads to a poor cycling life. • Al exhibits the most remarkable dissolution for all the alloys, especially at 60 °C. - Abstract: In order to optimize the microstructure and high temperature electrochemical performances of low-cost AB{sub 5}-type Ml(NiMnAl){sub 4.2}Co{sub 0.3}Fe{sub 0.5} hydrogen storage electrode alloys, four different preparation methods including normal solidification (NS), normal solidification and 900 °C heat treatment (NS + HT), rapid solidification (RS), rapid solidification and 900 °C heat treatment (RS + HT) were adopted in this work. All alloys exhibit CaCu{sub 5} type hexagonal structure and there is a small amount of A{sub 2}B{sub 7} phase in NS + HT and RS + HT alloys. It is found the using of HT process can decrease the hydrogen equilibrium plateau pressure, the plateau slope and hysteresis at 40, 60 and 80 °C. The NS + HT and RS + HT alloys also possess better activation, high rate discharge performance, larger discharge capacity, but poor cycling performance due to the existence of A{sub 2}B{sub 7} phase which can accelerate dissolution of Ni, Mn and Fe elements in KOH alkaline electrolyte. The RS process can make alloy exhibit the best cycling performance especially at 60 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Porous CoFe{sub 2}O{sub 4} nanowire arrays on carbon cloth as binder-free anodes for flexible lithium-ion batteries

Highlights: • Hierarchal CoFe{sub 2}O{sub 4} nanowire arrays are directly grown on flexible carbon cloth. • Porous CoFe{sub 2}O{sub 4} nanowires are composed of many nanocrystals of 20–40 nm. • CoFe{sub 2}O{sub 4} nanowire arrays exhibit excellent rate capability and cycling stability. • Integrated CoFe{sub 2}O{sub 4}/carbon cloth electrodes show high flexibility and areal capacity. - Abstract: A three-dimensional CoFe{sub 2}O{sub 4} nanowire array on carbon cloth was fabricated with a hydrothermal method together with a post-annealing treatment. As a binder-free and flexible anode material for LIBs, it showed an improved electrochemical performance with high cycling stability and excellent rate capability. It exhibited an initial discharge capacity of 1615 mAh g{sup −1} and retained a reversible capacity of about 1204 mAh g{sup −1} after 200 cycles at a specific current of 500 mA g{sup −1}. The high capacity, outstanding rate performance and cycling stability can be attributed to the special configuration of hierarchal porous CoFe{sub 2}O{sub 4} nanowires on carbon cloth, which possess many advantages like short diffusion length, easy strain relaxation and fast electron transport. Moreover, the integrated CoFe{sub 2}O{sub 4} nanowires/carbon cloth electrode shows high flexibility and high areal capacity (2.41 mAh cm{sup −2}), which makes it suitable for use as a binder-free anode to build flexible LIBs.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Demand Driven Cycamore Archetypes

Future nuclear fuel cycle options may present advantages over today’s once-through fuel cycle. Nuclear fuel cycle simulation tools assess the performance of those fuel cycles as well as the dynamics of long-term technology transitions. In many nuclear fuel cycle simulation tools, it has historically been the responsibility of the user to manually define facility deployment schemes and all facility parameters. While this is straightforward in simple fuel cycles, transitions from one fuel cycle to another can be more complex. In particular, deployment schemes for supportive fuel cycle facilities beyond the reactor become complex if the analyst desires to avoid gaps in the nuclear fuel and power supply chain during those transition scenarios. As nuclear fuel cycle analysis approaches questions regarding the feasibility and performance of the deployment schemes and technology choices during technology transition, automation of this historically manual process is necessary. The main objective of this work was to develop and demonstrate Cyclus automation capabilities toward key nuclear fuel cycle transition scenarios. While deploying reactors to meet power demand is trivial, and existed in the earliest versions of CYCLUS, automated, predictive deployment and decommissioning of other facilities is more complex. These include mining, milling, enrichment, fuel fabrication, reprocessing, and others. For example, a balanced closed fuel cycle may require ensuring that there is enough fast reactor fuel for their operation and may drive deployment of a fleet of light water reactors. This concern comprises the main challenge that drove the project effort. The Demand-Driven Cycamore Archetype project (NEUP-FY16-10512) aimed to develop CYCAMORE demand-driven deployment capabilities and thereby automate transition scenario definition. The developed software package, d3ploy, in the form of a CYCLUS Institution agent, deploys Facilities to meet the front-end and back-end demands of the fuel cycle. The University of South Carolina and the University of Illinois applied multiple algorithmic approaches to this challenge. This project developed an in situ demand-driven development schedule calculation through non-optimizing, deterministic-optimizing, and stochastic-optimizing algorithms as CYCLUS archetypes and demonstrated these new archetypes in program-supporting fuel cycle transition scenarios. Both objectives were achieved. This report documents the results and deliverables obtained toward these achievements in detail.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Trimetallic Oxygen Carriers CuFeMnO 4 , CuFeMn 2 O 4 , and CuFe 0.5 Mn 1.5 O 4 for Chemical Looping Combustion

Several trimetallic ferrites with different ratios of Cu, Fe, and Mn were synthesized by direct decomposition method and tested for chemical looping combustion of methane, synthesis gas, and carbon. For comparison, several bimetallic ferrites were also tested, and NiFe 2 O 4 and CuFe 2 O 4 showed the best performance. During a 55-cycle test, trimetallic CuFeMnO 4 showed better overall performance than both NiFe 2 O 4 and CuFe 2 O 4 , which had shown the best performance among the bimetallic ferrites for CLC of methane. From all the trimetallic oxygen carriers with different atomic ratios of Cu, Fe, and Mn, CuFeMnO 4 , CuFeMn 2 O 4 , and CuFe 0.5 Mn 1.5 O 4 showed the best performance for CLC of methane. The oxygen carriers CuFeMnO 4 , CuFeMn 2 O 4 , and CuFe 0.5 Mn 1.5 O 4 , even without a support, showed very stable performance during a 100-cycle TGA test. The CuFeMnO 4 oxygen carrier also showed excellent performance during a multicycle CLC test with synthesis gas. In conclusion, CuFeMnO 4 is also suitable for CLC of a solid fuel, such as carbon, which showed stable performance during a 10-cycle test.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Structure of the high voltage phase of layered P2-Na 2/3-z [Mn 1/2 Fe 1/2 ]O 2 and the positive effect of Ni substitution on its stability

A combination of operando X-ray diffraction, pair distribution function (PDF) analysis coupled with electrochemical measurements and Mössbauer spectroscopy elucidates the nature of the phase transitions induced by insertion and extraction of sodium ions in P2-Na 0.67 [Ni y Mn 0.5 + y Fe 0.5 -2 y ]O 2 (y = 0, 0.10, 0.15). When phase transitions are avoided, the optimal cathode material – P2-Na 0.67 Fe 0.2 Mn 0.65 Ni 0.15 O 2 - delivers 25% more energy than the unsubstituted material, sustaining high specific energy (350 Wh kg -1 ) at moderate rates and maintains 80% of the original energy density after 150 cycles - a significant improvement in performance vs. the unsubstituted analogue. The crystal structure of the high voltage phase is solved for the first time by X-ray PDF analysis of P2-Na 0.67 -z Fe0.5Mn 0.5 O 2 (where z~0.5), revealing that migration of the transition metals – particularly Fe 3+ - into tetrahedral sites in the interlayer space occurs at high potential. This results in new short range order between two adjacent layers. Although the transition metal migration is reversible as proven by electrochemical performance, it induces a large disfavourable cell polarization. The deleterious high voltage transition is mitigated by substitution of Fe 3+ by Mn 4+ /Ni 2+ , giving rise to better cycling performance. Moreover, as demonstrated by 57 Fe Mössbauer spectroscopy, the much lower ratio of Fe 4+ O6 to Fe 3+ O 6 observed systematically across the range of Ni content – compared to the values expected from a purely ionic model – suggests redox activity involves the O-2p orbitals owing to their overlap with the transition metal-3d orbitals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Degradation Characterization of Thermal Interface Greases

Thermal interface materials (TIMs) are used in power electronics packaging to minimize thermal resistance between the heat generating component and the heat sink. Thermal greases are one such class. The conformability and thin bond line thickness (BLT) of these TIMs can potentially provide low thermal resistance throughout the operation lifetime of a component. However, their performance degrades over time due to pump-out and dry-out during thermal and power cycling. The reliability performance of greases through operational cycling needs to be quantified to develop new materials with superior properties. NREL, in collaboration with DuPont, has performed thermal and reliability characterization of several commercially available thermal greases. Initial bulk and contact thermal resistance of grease samples were measured, and then the thermal degradation that occurred due to pump-out and dry-out during temperature cycling was monitored. The thermal resistances of five different grease materials were evaluated using NREL's steady-state thermal resistance tester based on the ASTM test method D5470. Greases were then applied, utilizing a 2.5 cm x 2.5 cm stencil, between invar and aluminum plates to compare the thermomechanical performance of the materials in a representative test fixture. Scanning Acoustic microscopy, thermal, and compositional analyses were performed periodically during thermal cycling from -40 degrees C to 125 degrees C. Completion of this characterization has allowed for a comprehensive evaluation of thermal greases both for their initial bulk and contact thermal performance, as well as their degradation mechanisms under accelerated thermal cycling conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1999

Inlet Development for a Rocket Based Combined Cycle, Single Stage to Orbit Vehicle Using Computational Fluid Dynamics

Design and analysis of the inlet for a rocket based combined cycle engine is discussed. Computational fluid dynamics was used in both the design and subsequent analysis. Reynolds averaged Navier-Stokes simulations were performed using both perfect gas and real gas assumptions. An inlet design that operates over the required Mach number range from 0 to 12 was produced. Performance data for cycle analysis was post processed using a stream thrust averaging technique. A detailed performance database for cycle analysis is presented. The effect ot vehicle forebody compression on air capture is also examined.

DeBonis, J. R.↗
DOE OSTI2020

Design and Development of Low Weight, Titanium Aluminide Airfoils for High Performance Industrial Gas Turbines meeting 65% Combined Cycle Efficiency (Final Report)

This project funded under DOE-FOA-0001816 was performed with the intent of evaluating the potential of utilizing a low density, high specific strength Titanium Aluminide (TiAl) alloy in a large annulus last stage gas turbine blade with the intent of improving combined cycle gas turbine efficiency toward a goal of reaching 65% efficiency. The project consisted of identifying a potentially suitable TiAl material for manufacture of such a large blade by investment casting. This included estimation of design properties for the selected alloy, trade studies using a baseline design created for a nickel based alloy cast in the TiAl alloy to evaluate potential design changes required for the use of this material and optimization of a prototype design for the same baseline application using the selected TiAl alloy. Several rounds of optimization were completed with the intent of meeting the baseline design targets with a resulting design that showed at least equivalent performance in terms of creep, LCF/TMF, HCF and aerodynamic damping potential. While it was found that significant reductions in blade loading on the disk were possible, the design resulting from the optimization met most lifing targets at the baseline size, but showed a reduction in margins in some areas in comparison to the Ni-based baseline design. Additionally, it was found that the low strain tolerance of the TiAl alloy for temperatures at and below the operational temperature of the attachment resulted in marginal, although still acceptable, creep rupture performance of the design. Due to results indicating the reduced potential for increasing turbine annulus compared to expectations a Phase II award was not proposed and it is not recommended to pursue additional design optimization efforts until further material advances with TiAl materials are achieved.

03 NATURAL GAS↗