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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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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Polysulfone shock compressed above the decomposition threshold: Velocimetry and modeling of two-wave structures

Polysulfone was shock loaded to pressures of 14.6–26.2 GPa in a series of gas gun-driven plate-impact experiments measuring material response with embedded electro-magnetic particle velocity gauges and optical velocimetry. The embedded electro-magnetic particle velocity gauges did not show a distinct two-wave structure but did show rounding that suggested a reaction but not a distinct separation of the reactants and product waves. In contrast, the transmission experiments fielded with optical velocimetry, with product pressures ranging from 21.0 to 26.2 GPa, showed well-defined two-wave structures due to shock-driven chemical decomposition of the polymer to products at a higher density. Distinct two-wave structures have not previously been published in literature during polymer compression; here, we observed these two-wave structures at both the polymer/lithium fluoride and polymer/polymethylmethacrylate interfaces. Hydrodynamic simulations of the experiments were performed using a newly constructed SESAME equation of state (EOS) for the polymer, a thermochemical EOS for the decomposition products, and an Arrhenius reaction rate model for the kinetics of the reaction. Finally, simulation results also demonstrated two-wave structures but were unable to quantitatively reproduce either the embedded gauge or optical velocimetry data.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Frequency Control and Disturbance Containment Using Grid-Forming Embedded Storage Networks

The paper presents a distributed approach for operating a network of inverter-based energy storage resources embedded in a bulk power system. Departing from their traditional role of steady-state reserves, the storage assets in the network are utilized as frequency-responsive resources shaping system dynamics. The power electronics converter systems interfacing the storage resources are equipped with local controllers designed to respond under transient disturbances. To this end, a safety-constrained distributed control strategy is explored. The paper compares the performance of converter-interfaced grid-forming and grid-following storage networks for fast frequency control and disturbance containment/localization. Sensitivity studies are performed to study the impact of storage size, steady-state dispatch, and controller design on dynamic performance. The findings are presented through case studies with results from the IEEE test systems.

Chatterjee, Kaustav (ORCID:0000000153273860)↗
DOE OSTI2021

Numerical and experimental evaluation of mechanical performance of the multifunctional energy storage composites

This work presents numerical simulation methods to model the mechanical behavior of the multifunctional energy storage composites (MESCs), which consist of a stack of multiple thin battery layers reinforced with through-the-hole polymer rivets and embedded inside carbon fiber composite laminates. MESC has been demonstrated through earlier experiments on its exceptional behavior as a structural element as well as a battery. However, the inherent complex infrastructure of the MESC design has created significant challenges in simulation and modeling. A novel homogenization technique was adopted to characterize the multi-layer properties of battery material using physics-based constitutive equations combined with nonlinear deformation theories to handle the interface between the battery layers. Second, mechanical damage and failure modes among battery materials, polymer reinforcements, and carbon fiber-polymer interfaces were characterized through appropriate models and experiments. The model of MESCs has been implemented in a commercial finite element code in ABAQUS. A comparison of structural response and failure modes from numerical simulations and experimental tests are presented. The results of the study showed that the predictions of elastic and damage responses of MESCs at various loading conditions agreed well with the experimental data. © 2021

Materials Science↗
DOE OSTI2026

Influence of CO 2 -Regenerative Film Properties in Enhancing C 2+ Products Selectivity While Mitigating CO 2 Crossover

Zero-gap anion-exchange membrane electrode assembly (AEMEA) electrolyzers operating in alkaline media face challenges such as CO 2 crossover and salting-out. The bipolar membrane electrode assembly (BPMEA) electrolyzer, using DI water as the electrolyte, addresses both CO 2 crossover and salting-out issues. As cations, which are crucial in stabilizing the CO 2 R intermediates, are absent in the electrolyte, cations embedded in the AEM play an important role in dictating the CO 2 R selectivity and activity in BPMEA systems. So far, no systematic study has been conducted on the influence of cations embedded in AEMs on CO 2 selectivity and activity in BPMEA systems. Moreover, BPMEA systems impose an additional challenge: low stability due to delamination of the bipolar membrane caused by CO 2 regeneration at the membrane-membrane interface. To enhance the stability of the electrolyzer, a simple yet highly reproducible strategy for coating a porous CO 2 regenerative film on smooth Nafion 117 is demonstrated in this work, along with a systematic study of four different commercially available AEMs, composed of different cations and cation densities, for use in combination with Nafion 117 and copper catalyst at the cathode. We found that the PiperION membrane delivers selectivity and activity comparable to those of alkali-metal cations, owing to the enhanced local electric field resulting from the combined effects of a high positive charge on the N atom of the piperidinium cation and the high ion-exchange capacity. Further, we studied the influence of the thickness of the PiperION porous layer over Nafion 117 on CO 2 R selectivity and found that 70 μm is the minimum thickness to achieve maximum C 2+ products selectivity, reduced the CO 2 crossover to 5% from 25% at 4 SCCM and 150 mA cm –2 , and was stable for operation beyond 100 h. The selectivity of this system, compared with AEMEA, and stability outperformed both AEMEA and BPMEA. This study helps design more effective BPMs to inhibit CO 2 crossover while enabling stable and selective electrochemical CO 2 reduction to C 2+ hydrocarbons.

Cations↗
DOE OSTI2022

Bifacial all-perovskite tandem solar cells

The efficiency of all-perovskite tandem devices falls far below theoretical efficiency limits, mainly because a widening bandgap fails to increase open-circuit voltage. We report on a bifacial all-perovskite tandem structures with an equivalent efficiency of 29.3% under back-to-front irradiance ratio of 30. This increases energy yield and reduces the required bandgap of a wide-bandgap cell. Open-circuit voltage deficit is therefore minimized, although its performance under only front irradiance is not ideal. The bifacial device needs a sputtered rear transparent electrode, which could reduce photon path length and deteriorate stability of Pb-Sn perovskites. Embedding a light-scattering micrometer-sized particle layer into perovskite to trap light, effectively increases absorptance by 5 to 15% in the infrared region. Using a nonacidic hole transport layer markedly stabilizes the hole-extraction interface by avoiding proton-accelerated formation of iodine. These two strategies together increase efficiency of semitransparent Pb-Sn cells from 15.6 to 19.4%, enabling fabrication of efficient bifacial all-perovskite tandem devices.

14 SOLAR ENERGY↗
DOE OSTI2025

A Block-Structured Adaptive Mesh Framework to Solve Radiation Transfer Equation in Irregular Embedded Geometries

Radiation transport arises in various scientific, industrial, and medical fields, and understanding its effect in applications is needed to make accurate predictions, safety assessments and performance optimizations. Solving the Radiation Transport Equation (RTE) is challenging due to its integro-differential nature, which involves both differential and integral terms. The differential term describes the change in radiation intensity due to absorption and emission, while the integral term accounts for scattering. The accurate modeling of radiation is further complicated in many applications due to the complex, irregular geometries. Various methods exist for solving the RTE, including the zonal, Monte Carlo, spherical harmonics, discrete ordinates, and finite volume methods. Traditional mesh-based approaches, which rely on structured or unstructured meshes, struggle with irregular geometries due to: a) the difficulty of conforming structured grids to irregular domains, b) challenges in enforcing boundary conditions correctly, and c) the additional computational cost of unstructured mesh methods. This work presents a second-order accurate method for solving the RTE in irregular geometries. The radiation intensity is discretized using the finite-volume method in both spatial and angular directions on regular Cartesian grid blocks. Leveraging the block-structured adaptive mesh refinement (AMR) framework provided by AMReX, our method refines the grid locally to reduce spatial discretization error, ensuring a converged numerical solution while minimizing computational costs elsewhere. A two-stage deferred correction approach is employed: First, a first-order discretization on grid blocks is solved using an algebraic multigrid method in HYPRE. Second, a correction term is applied explicitly to achieve second-order accuracy. The correction term is calculated by approximating the radiation flux on cell faces using a Total Variation Diminishing (TVD) scheme. This approach ensures quick convergence of the multigrid method while preserving higher-order accuracy of the numerical solution. Irregular geometries are resolved as embedded boundaries (EB), resulting in both cut cells and regular cells. In cut cells, we modify the fluxes using face fractions and incorporate additional contributions from EB boundary conditions. To ensure higher-order convergence near the EB interface, the correction term is modified by interpolating the radiation intensity to fictitious ghost points. The implementation takes advantage of modern supercomputers by leveraging AMReX’sMPI/X parallelization strategy where X can be MPI or a GPU accelerator including CUDA, HIP and DPC++. We validate our solver using classical test cases, both with and without EB, demonstrating accuracy and efficiency. Additionally, we analyze the impact of adaptive mesh refinement on solution accuracy and computational cost, highlighting the advantages of our approach for high-resolution radiation transport simulations.

computational fluid dynamics (CFD)↗
DOE OSTI2024

Cryogenic aspects of a 20 MW class low-temperature superconducting generator for the renewables industry

In this paper we give a progress update on the cryogenic design for cooling a 20 MW class, partially superconducting generator with stationary field coils for offshore wind renewables industry [1-2]. This is a continuation of an earlier program on a 10 MW system dating back ten years. Whereas this new power rating increase leads to a radial diameter expansion of the superconducting field coils from 4 to > 9.5 m, it maintains the axial length. We show the design based on this scaled up with enlarged diameter. The field coil size increase asks for higher cooling power that leads to a bigger cold box size to accommodate the cryocoolers. In the design, as many as 8 cryocoolers can be accessed and serviced from the nacelle that houses the main cryogenic components. A typical thermal load balance sheet with all components is given and compared against the available cryocooler cooling power at different operating conditions. Due to the cryocoolers’ local point of contact cooling within the nacelle, the temperature gradient of the thermal shield that fully encloses the cold mass with its embedded field coils needs to be balanced out to minimize the heat burden on the field coils. This requires additional analytical efforts and implementation of further design features. The extended nacelle houses the cold box with its cryogenic infrastructure. The interface for the envisaged cryogenic pushbutton closed-loop circulating system remains invisible, requires no handling of cryogenic liquids and is hermetically closed. The field coil diameter increase also leads to a greater initial helium gas storage volume. In addition, it requires higher initial room temperature fill pressure within the toroidal helium vapor storage tanks and in cooling tubes connecting to the cryocoolers. The toroidal helium gas tanks are thermally coupled with the thermal shield so that helium convection inside the storage tank can improve heat transfer and reduce the temperature gradient of the thermal shield. Besides those heat transfer challenges, additional mechanical strain within this large structure is exerted on the torque tubes during initial cooldown and when energizing field coils. Some of those design challenges are quite unexpected, leading to novel workarounds in order to maintain the chosen cooling strategy. Finally, we assess those design limitations in view of further cryogenic scalability with emphasis on manufacturability and assembly.

cryogenics↗
DOE OSTI2022

Ig-VAE: Generative modeling of protein structure by direct 3D coordinate generation

While deep learning models have seen increasing applications in protein science, few have been implemented for protein backbone generation—an important task in structure-based problems such as active site and interface design. We present a new approach to building class-specific backbones, using a variational auto-encoder to directly generate the 3D coordinates of immunoglobulins. Our model is torsion- and distance-aware, learns a high-resolution embedding of the dataset, and generates novel, high-quality structures compatible with existing design tools. We show that the Ig-VAE can be used with Rosetta to create a computational model of a SARS-CoV2-RBD binder via latent space sampling. We further demonstrate that the model’s generative prior is a powerful tool for guiding computational protein design, motivating a new paradigm under which backbone design is solved as constrained optimization problem in the latent space of a generative model.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Olympus System Backplane Definition

The purpose of this document is to define the backplane of the Olympus firing system, a modular system based on SpaceWire communication between modules. The backplane provides the connection between the modules, controller (embedded in the front module), the SpaceWire router, and an alternative switch. Those connections include SpaceWire links, interlocks, a key, a dead-man switch (DMS)/charge, timing lines, power distribution, geographical addresses, and communication to the human-machine interface (HMI). This backplane is based on the VMEBus International Trade Association (VITA) 46 Specification (VPX) and OpenVPX standards for a 3U backplane. Unless otherwise specified, those standards apply for signal definitions and mechanical specifications.

42 ENGINEERING↗
DOE OSTI2022

Stable Cuprous Hydroxide Nanostructures by Organic Ligand Functionalization

Abstract Copper compounds have been extensively investigated for diverse applications. However, studies of cuprous hydroxide (CuOH) have been scarce due to structural metastability. Herein, a facile, wet‐chemistry procedure is reported for the preparation of stable CuOH nanostructures via deliberate functionalization with select organic ligands, such as acetylene and mercapto derivatives. The resulting nanostructures are found to exhibit a nanoribbon morphology consisting of small nanocrystals embedded within a largely amorphous nanosheet‐like scaffold. The acetylene derivatives are found to anchor onto the CuOH forming CuC linkages, whereas CuS interfacial bonds are formed with the mercapto ligands. Effective electronic coupling occurs at the ligand‐core interface in the former, in contrast to mostly non‐conjugated interfacial bonds in the latter, as manifested in spectroscopic measurements and confirmed in theoretical studies based on first principles calculations. Notably, the acetylene‐capped CuOH nanostructures exhibit markedly enhanced photodynamic activity in the inhibition of bacteria growth, as compared to the mercapto‐capped counterparts due to a reduced material bandgap and effective photocatalytic generation of reactive oxygen species. Results from this study demonstrate that deliberate structural engineering with select organic ligands is an effective strategy in the stabilization and functionalization of CuOH nanostructures, a critical first step in exploring their diverse applications.

Liu, Qiming↗
DOE OSTI2019

Affordable Estimation of Solvation Contributions to the Adsorption Energies of Oxygenates on Metal Nanoparticles

Electrocatalysts are mainly characterized by their intrinsic adsorption properties. However, the observed electrocatalytic activity ultimately results from the interplay between such properties and various additional interactions within the electrified solid–liquid interface. One of such phenomena is solvation, which can substantially affect the stability of adsorbates. The incorporation of solvation in computational electrocatalysis models can be fully implicit (inaccurate for H-bonded adsorbates), fully explicit (challenging computation of free energies), or embedded. Here, we show that without any need for explicit or implicit media, a microsolvation approach with just three water molecules captures the contribution of co-adsorbed water to the adsorption energies of *OH and *OOH (two important adsorbates for oxygen reduction) on platinum nanoparticles of various sizes. The approach enables an accurate yet inexpensive explicit modeling of solvent–adsorbate interactions in nanoparticles and the calculation of solvation corrections, estimated as -0.59 ± 0.14 and -0.47 ± 0.13 eV for *OH and *OOH adsorption on Pt, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Multi-plane moment-of-fluid interface reconstruction in 3D

Moment-of-fluid (MOF) methods for interface reconstruction approximate the region occupied by material in each mesh element only through reference to its geometric moments. Here, we present a 3D MOF method that represents the material (POM) in each cell as the convex intersection of the cell and multiple half-spaces, each selected to minimize the least-squares error between computed moments of the approximated material and provided reference moments. This optimization problem is highly non-linear and non-convex, making the numerical result very sensitive to the initial guess. To create an effective initial guess in each cell, we construct an ellipsoid from 0th–2nd order reference moments such that its shape corresponds with that of the POM. Within this ellipsoid we inscribe a polyhedron, and initialize the minimization problem with the half-spaces defined by each of its faces. The inscribed polyhedron has minimally 4 faces, and using up to 3rd order moments permits optimization over up to 20 unknown values. We therefore define MOF methods that utilize 4, 5, or 6 half-spaces, correspondingly initialized with the faces of a single inscribed tetrahedron, triangular prism, or hexahedron. Stability of the non-linear optimization is further improved with a prepossessing step that normalizes the reference moments according to the axes of the reference ellipsoid. Using this approach, the non-linear least-squares solver reliably converges to a near-global minimum from a single initial guess. We demonstrate accuracy and robustness using single-cell and multi-cell examples over a wide spectrum of geometry. In particular, we demonstrate our ability to exactly reproduce several important and complex features defined by up to four half-spaces, such as corners, filaments, filament tips, and embedded material in the cell.

3D interface reconstruction↗
DOE OSTI2020

Integrated Dynamic Facade Control with an Agent-based Architecture for Commercial Buildings

Dynamic façades have significant technical potential to minimize heating, cooling, and lighting energy use and peak electric demand in the perimeter zone of commercial buildings, but the performance of these systems is reliant on being able to balance complex trade-offs between solar control, daylight admission, comfort, and view over the life of the installation. As the context for controllable energy-efficiency technologies grows more complex with the increased use of intermittent renewable energy resources on the grid, it has become increasingly important to look ahead towards more advanced approaches to integrated systems control in order to achieve optimum life-cycle performance at a lower cost. This study examines the feasibility of a model predictive control system for low-cost autonomous dynamic façades. A system architecture designed around lightweight, simple agents is proposed. The architecture accommodates whole building and grid level demands through its modular, hierarchical approach. Automatically-generated models for computing window heat gains, daylight illuminance, and discomfort glare are described. The open source Modelica and JModelica software tools were used to determine the optimum state of control given inputs of window heat gains and lighting loads for a 24-hour optimization horizon. Penalty functions for glare and view/ daylight quality were implemented as constraints. The control system was tested on a low-power controller (1.4 GHz single core with 2 GB of RAM) to evaluate feasibility. The target platform is a low-cost ($35/unit) embedded controller with 1.2 GHz dual-core cpu and 1 GB of RAM. Configuration and commissioning of the curtainwall unit was designed to be largely plug and play with minimal inputs required by the manufacturer through a web-based user interface. An example application was used to demonstrate optimal control of a three-zone electrochromic window for a south-facing zone. The overall approach was deemed to be promising. Further engineering is required to enable scalable, turnkey solutions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Heat exchanger assemblies having embedded sensors

Heat exchanger assemblies are provided that can include: a heat exchanger housing; at least one primary conduit operably coupled to the heat exchanger housing and configured to convey a primary heat exchange fluid; at least one secondary conduit operably coupled to the heat exchanger housing and configured to convey a secondary heat exchange fluid; at least one thermal interface between the primary and secondary fluids; and at least one sensor operably engaged with the thermal interface. Heat exchanger assemblies including molten salt, liquid metal, or water/steam as part of the heat exchange fluids of the heat exchanger assembly are provided. The heat exchanger assemblies can include: at least one thermal interface between primary and secondary heat exchange fluids of the heat exchanger assembly; and a sensor operably engaged with the at least one interface.

Glass, III, Samuel W.↗
DOE OSTI2022

Finite boundary effects on the spherical Rayleigh–Taylor instability between viscous fluids

For the Rayleigh–Taylor unstable arrangement of a viscous fluid sphere embedded in a finite viscous fluid spherical shell with a rigid boundary and a radially directed acceleration, a dispersion relation is developed from a linear stability analysis using the method of normal modes. [Formula: see text] is the radially directed acceleration at the interface. ρ i denotes the density, μ i is the viscosity, and R i is the radius, where i = 1 is the inner sphere and i = 2 is the outer sphere. The dispersion relation is a function of the following dimensionless variables: viscosity ratio [Formula: see text], density ratio [Formula: see text], spherical harmonic mode n, [Formula: see text], [Formula: see text], and the dimensionless growth rate [Formula: see text], where σ is the exponential growth rate. We show that the boundedness provided by the outer spherical shell has a strong influence on the instability behavior, which is reflected not only in the modulation of the growth rate but also in the selection of the most unstable modes that are physically possible. This outer boundary effect is quantified by the relative magnitude of the radius ratio H. We find that when H is close to unity, lower order harmonics are excluded from becoming the most unstable within a vast region of the parameter space. In other words, the effect of H has precedence over the other controlling parameters d, B, and a wide range of s in establishing what the lowest most unstable mode can be. When H ~ 1, low order harmonics can become the most unstable only for s >> 1. However, in the limit when s → ∞, we show that the most unstable mode is n = 1 and derive the dispersion relation in this limit. The exclusion of most unstable low order harmonics caused by a finite outer boundary is not realized when the outer boundary extends beyond a certain threshold length-scale in which case all modes are equally possible depending on the value of B.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

CRISPR-COPIES: Web Tool

CRISPR/Cas system has emerged as a powerful genome-editing tool for metabolic engineering and human gene therapy. However, the conundrum of where to integrate heterologous genes on the chromosome using the CRISPR/Cas system remains an open question. Selecting a site for gene integration requires incorporation of complex criteria such as factors involved in CRISPR/Cas-mediated integration, genetic stability, and gene expression and therefore, usually requires strenuous characterization of sites on particular or different chromosomal locations. To address these issues, we developed CRISPR-COPIES, a COmputational Pipeline for the Identification of CRISPR/Cas-facilitated intEgration Sites. The tool applies ScaNN, a state-of-the-art model on the embedding-based nearest neighbor search for fast and accurate off-target search and can identify genome-wide intergenic sites for most bacterial and fungal genomes within minutes. This submission contains the code we developed to create a user-friendly web interface for CRISPR-COPIES (https://biofoundry.web.illinois.edu/copies/). We anticipate CRISPR-COPIES will serve as a useful tool for targeted DNA integration and aid in the characterization of synthetic biology toolkits, rapid strain construction to produce valuable biochemicals, and human gene and cell therapy.

Bioinformatics↗
DOE OSTI2019

Cobalt-Based Nonprecious Metal Catalysts Derived from Metal–Organic Frameworks for High-Rate Hydrogenation of Carbon Dioxide

The development of cost-effective catalysts with both high activity and selectivity for carbon–oxygen bond activation is a major challenge and has important ramifications for making value-added chemicals from carbon dioxide (CO 2 ). Herein, we present a one-step pyrolysis of metal organic frameworks that yields highly dispersed cobalt nanoparticles embedded in a carbon matrix which shows exceptional catalytic activity in the reverse water gas shift reaction. Incorporation of nitrogen into the carbon-based supports resulted in increased reaction activity and selectivity toward carbon monoxide (CO), likely because of the formation of a Mott–Schottky interface. At 300 °C and a high space velocity of 300 000 mL g –1 h –1 , the catalyst exhibited a CO 2 conversion rate of 122 μmolCO 2 g –1 s –1 , eight times higher than that of a reference Cu/ZnO/Al 2 O 3 catalyst. Our experimental and computational results suggest that nitrogen-doping lowers the energy barrier for the formation of formate intermediates (CO 2 * + H* → COOH* + *), in addition to the redox mechanism (CO 2 * + * → CO* + O*). This enhancement is attributed to the efficient electron transfer at the cobalt–support interface, leading to higher hydrogenation activity and opening new avenues for the development of CO 2 conversion technology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗