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At least 145 records · Page 8

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DOE OSTI2024

High-throughput reaction discovery for Cs–Pb–Br nanocrystal synthesis

High-throughput reaction discovery is necessary to understand complex reaction spaces for inorganic nanocrystal synthesis. Here, we implemented a high-throughput continuous flow millifluidic reactor to perform reaction discovery for Cs–Pb–Br nanocrystal synthesis using a ligand assisted reprecipitation (LARP)-type approach. 3D-printed flow resistors enable the screening of up to 16 different mixing ratios within a single 90 s run, allowing for >270 different precursor concentration ratios to be quickly tested to explore the phase space that results in CsPbBr 3 , Cs 4 PbBr 6 , a biphasic mixture, or no product. To construct a full phase map from these high-throughput experiments, a neural network was trained and validated to predict the product composition (~500 000 points in precursor concentration space). The phase map predicts product composition/phase as a function of Cs–Pb–Br feed ratio. As a result, this approach demonstrates how high-throughput flow chemistry can be used in tandem with machine learning to rapidly explore nanocrystal reaction spaces in flow.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Production of drop-in biodiesel blendstocks via competitive acid-catalyzed dehydration reactions using ethanol oligomerization products

Ethanol can be converted into diesel fuel ethers using a three-step catalytic approach that involves ethanol oligomerization to larger alcohols, hydrogenolysis of the esters followed by dehydration of the C4 to C8 alcohols into ethers. In this paper we report results for the dehydration of a mixture of C4 – C8 alcohols using a zeolite Y catalyst in a continuous flow reactor. Mono-molecular dehydration of the alcohols produces olefins while bi-molecular dehydration of the alcohol produces ethers. Increasing the pressure increases the ether selectivity while decreasing the pressure produces more olefins. Linear alcohol feeds produce more C8+ ethers, while branched and secondary alcohols lead to more olefins. Olefin and coke selectivities increase with increasing carbon chain length of alcohols. Secondary alcohols lead to higher coke selectivities. Furthermore, ethanol/Butanol oligomerization experiments showed that the incoming dehydration feedstock can be grown to larger C6+ alcohol fractions, leading to higher yields of C10+ diesel-range ethers.

09 BIOMASS FUELS↗

DOE OSTI2022

High-repetition-rate, multi-MeV deuteron acceleration from converging heavy water microjets at laser intensities of 10 21 W/cm 2

Herein we demonstrate high repetition-rate deuteron acceleration by irradiating a continuously flowing, ambient temperature liquid heavy water jet with the high-intensity ALEPH laser. The laser delivered up to 5.5 J (120 TW, 1.2 × 10 21 W/cm 2 ) laser energy on target at 0.5 Hz. A high repetition-rate Thomson parabola spectrometer measured the deuteron beam energy spectra on each shot for 60 sequential shots (two minutes). Peak fluxes of 5 x 10 10 deuterons/sr/pulse, corresponding to an average flux of 1.5 x 10 12 deuterons/sr/min, were demonstrated with deuteron energies reaching up to 4.4 MeV. High shot-to-shot stability is observed up to 40%–50% of the maximum deuteron energy. These deuteron beams are suited for fast neutron production through deuteron breakup in a converter yielding energies similar to deuteron–deuteron (D–D, 2.45 MeV) fusion reactions of importance for material damage studies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Infrared compatible rapid mixer to probe millisecond chemical kinetics

Fast microfluidic mixers are a valuable tool for studying solution-phase chemical reaction kinetics and molecular processes with spectroscopy. However, microfluidic mixers that are compatible with infrared vibrational spectroscopy have seen only limited development due to the poor infrared transparency of the current microfabrication material. We describe the design, fabrication, and characterization of CaF2-based continuous flow turbulent mixers, which are capable of measuring kinetics in the millisecond time window with infrared spectroscopy, when integrated into an infrared microscope. Kinetics measurements demonstrate the ability to resolve relaxation processes with 1 millisecond time resolution, and straightforward improvements are described that should result in sub-100 µs time-resolution.

Instruments & Instrumentation↗

DOE OSTI2023

Correlating chemistry and mass transport in sustainable iron production

Steelmaking contributes 8% to the total CO 2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas–solid reduction mechanism is set by the defects and pores inside the mm- to nm-sized oxide particles that change significantly as the reaction progresses. While these governing dynamics are essential to establish continuous flow of iron and its ores through reactors, the direct link between agglomeration and chemistry is still contested due to missing measurements. In this work, we directly measure the connection between chemistry and agglomeration in the smallest iron oxides relevant to magnetite ores. Using synthesized spherical 10-nm magnetite particles reacting in H 2 , we resolve the formation and consumption of wüstite (Fe 1-x O)—the step most commonly attributed to whiskering. Using X-ray diffraction, we resolve crystallographic anisotropy in the rate of the initial reaction. Complementary imaging demonstrated how the particles self-assemble, subsequently react, and grow into elongated “whisker” structures. Our insights into how morphologically uniform iron oxide particles react and agglomerate in H 2 reduction enable future size-dependent models to effectively describe the multiscale aspects of iron ore reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Adsorption of Radioactive Iodine Using Nanocarbon on ETS-10 as Adsorbent

Here, laboratory-synthesized nanocarbon pelletized with titanosilicate (ETS-10) as a support matrix has been investigated for the capture of radioactive iodine present as methyl iodide (CH 3 I) in the off-gas streams produced during aqueous reprocessing of used nuclear fuel. The mass fraction of carbon in the sorbent matrix was 0.10. The effects of residence time and CH 3 I concentration were investigated using a continuous flow column setup to quantify the adsorption and desorption capacities of adsorbent under dynamic conditions from an air stream containing CH 3 I present at concentrations representative of those expected in the off-gas streams. Air with CH 3 I gas as a source in the column resulted in quantifiable CH 3 I adsorption with 0.98 mg/g of adsorption capacity. Laboratory-made nanocarbons had a larger adsorption capacity than those of the other carbons reported in the literature. Additionally, the adsorption capacity of nanocarbon on ETS-10 is compared to that of nanocarbon coated on cordierite in previous studies.

ETS-10↗

DOE OSTI2021

Design and evaluation of an open-source, conformable skin-cooling system for body magnetic resonance guided focused ultrasound treatments

Magnetic resonance guided focused ultrasound (MRgFUS) treatment of tumors uses inter-sonication delays to allow heat to dissipate from the skin and other near-field tissues. Despite inter-sonication delays, treatment of tumors close to the skin risks skin burns. This work has designed and evaluated an open-source, conformable, skin-cooling system for body MRgFUS treatments to reduce skin burns and enable ablation closer to the skin. A MR-compatible skin cooling system is described that features a conformable skin-cooling pad assembly with feedback control allowing continuous flow and pressure maintenance during the procedure. System performance was evaluated with hydrophone, phantom and in vivo porcine studies. Sonications were performed 10 and 5 mm from the skin surface under both control and forced convective skin-cooling conditions. 3D MR temperature imaging was acquired in real time and the accumulated thermal dose volume was measured. Gross analysis of the skin post-sonication was further performed. Device conformability was demonstrated at several body locations. Hydrophone studies demonstrated no beam aberration, but a 5–12% reduction of the peak pressure due to the presence of the skin-cooling pad assembly in the acoustic near field. Phantom evaluation demonstrated there is no MR temperature imaging precision reduction or any other artifacts present due to the coolant flow during MRgFUS sonication. The porcine studies demonstrated skin burns were reduced in size or eliminated when compared to the control condition. An open-source design of an MRgFUS active skin cooling system demonstrates device conformability with a reduction of skin burns while ablating superficial tissues.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

Understanding the depletion of electrons in dusty plasmas at atmospheric pressure

The nucleation and growth of NPs in the gas phase using atmospheric-pressure plasma systems is an important approach to synthesizing novel dimensionally-controlled materials. In this paper, we investigated the effect of the NPs on a typical type of continuous-flow, substrate-free plasma at atmospheric pressure to understand their potential contribution to electron density changes. A tandem plasma system was set up consisting of one plasma reactor that produced carbonaceous NPs from mixtures of argon and hexane, and another identical plasma reactor where the as-grown particles were injected and non-intrusive electrical and optical measurements were performed. The electron densities obtained from conductivity measurements and a plasma fluid model were found to decrease in the presence of NPs. However, control experiments revealed that the main source of the electron depletion was residual vapor or reaction byproducts in the form of molecular species or nanoclusters and not the particles themselves. These results were validated by constant number Monte Carlo simulations which showed that at the experimentally-measured conditions, the NPs were not of sufficiently high enough concentration to reduce the electron density; however, if molecules or clusters are ionizable, they remain in sufficient concentration to deplete electron densities. Our study shows that at atmospheric pressure, because of their typically larger electron density values, particle-producing plasmas are distinct from those at low pressure, and nanoparticle formation does not have the same impact while molecular-scale species may be a more important consideration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2021

Selective Biosorption of Valuable Rare Earth Elements Among Co-Occurring Lanthanides

To meet the increasing demand for rare earth elements (REEs) essential for low carbon-intensity energy technologies, new methods are needed for selective REE extraction from unconventional resources. Only a few REEs have significant economic value, but isolation of target rare earths from co-occurring lanthanides is challenging due to their similar chemical behavior. We present a novel approach to enhance separation of specific REEs from lanthanide mixtures. Escherichia coli cells engineered with lanthanide binding tags (LBTs) were immobilized in nonadsorbing, permeable polyethylene glycol diacrylate beads and packed into continuous flow, fixed-bed columns. Breakthrough of 15 rare earths in the +3 oxidation state resulted in notable differences in adsorption selectivity, with greatest separation between europium (Eu) and lanthanum (La) due to competitive displacement. REE adsorption onto fixed-bed columns was predicted by coupling a surface complexation model to a calibrated one-dimensional dual porosity transport model that accounts for interbead advective and intrabead diffusive transport. A tradeoff between high-abundance, low-affinity native carboxyl sites and low-abundance, high-affinity engineered LBT sites dictates process recovery efficiency and selectivity. Key chemical and operational parameters are identified to maximize selective extraction of high-value lanthanides, achieving a threefold enhancement of Eu recovery relative to La in a mixed REE solution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Time-Resolved Stochastic Dynamics of Quantum Thermal Machines

Steady-state quantum thermal machines are typically characterized by a continuous flow of heat between different reservoirs. However, at the level of discrete stochastic realizations, heat flow is unraveled as a series of abrupt quantum jumps, each representing an exchange of finite quanta with the environment. Here, in this work, we present a framework that resolves the dynamics of quantum thermal machines into cycles classified as enginelike, coolinglike, or idle. We analyze the statistics of individual cycle types and their durations, enabling us to determine both the fraction of cycles useful for thermodynamic tasks and the average waiting time between cycles of a given type. Central to our analysis is the notion of intermittency, which captures the operational consistency of the machine by assessing the frequency and distribution of idle cycles. Our framework offers a novel approach to characterizing thermal machines, with significant relevance to experiments involving mesoscopic transport through quantum dots.

full counting statistics↗

DOE OSTI2022

Effects of frequency and pulse width on electron density, hydrogen peroxide generation, and perfluorooctanoic acid mineralization in a nanosecond pulsed discharge gas-liquid plasma reactor

Plasma electron density and temperature were characterized in a continuous flowing gas-liquid film reactor with argon carrier gas by time-resolved optical emission spectroscopy. The plasma parameters were studied as a function of time for varying pulse widths and frequencies. Pulse frequency was varied between 1 and 10 kHz at 16 kV (input voltage) and 40 ns (pulse width) using an Eagle Harbor Technologies, Inc. (EHT) power supply and 5–100 kHz using an Airity Technologies, LLC (AT) power supply. The pulse width was varied between 40 and 200 ns at 16 kV, 2 kHz with the EHT power supply. Optimal frequencies of 5 and 20 kHz were observed for peak electron density with EHT and AT power supplies, respectively. The peak electron density increased with increasing pulse width between 40 and 200 ns using the EHT power supply. Hydrogen peroxide exiting the reactor in the liquid phase increased with discharge power irrespective of the power supply or pulse parameters. Mineralization of 12.5, 50, and 200 ppm perfluorooctanoic acid (PFOA) dissolved in DI water to fluoride (F - ) correlated to the peak electron density. Glycerol, a liquid-phase hydroxyl radical scavenger, depleted hydrogen peroxide but did not affect PFOA mineralization. CO, a gas-phase hydroxyl radical scavenger, led to a reduction in the formation of F - production, suggesting hydroxyl radicals in the gas-liquid film play a necessary, but not singular, role in mineralization of PFOA.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

MatLab Package for Whispering Gallery Mode Data

Dye-doped whispering gallery mode resonator (WGMR) microspheres yield highly structured emission spectra that are extremely sensitive to their environment and are of intense interest for use in a variety of sensing applications. Efforts to leverage the unique sensitivities of WGMRs have relied on stringent experimental requirements to correlate specific spectral shifts/changes to an analyte/stimulus such as 1) precise positional knowledge, 2) reference spectra for each microsphere, and 3) high mechanical stability. Consequently, these can hinder adequate mixing or incorporation of analytes and creates challenges for remote sensing. The MATLAB codes provided here are to be used in conjunction with a continuous flow technique for measuring WGM spectra of dye-doped microspheres suspended in solution. One MATLAB script, smooths the data, automatically baseline corrects it to isolate the whispering gallery modes (WGM) from the unwanted bulk emission, and assesses the similarity of each spectrum to aid in selecting a set of unique WGM spectra for further analysis. The next script is designed to analyze WGM spectra to determine the size of the resonator and the refractive index (RI) of its local environment without a priori knowledge of the individual microsphere. The final script allows the user to cluster spheres based on the product of their RI and radius and the contrast ratio of the RI of the sphere material and that of its environment by using a shared nearest neighbor spectral clustering algorithm.

Lilley, Laura↗

DOE OSTI2023

system2atoms

system2atoms is a suite of models that can simulate the performance of hydrogen infrastructure across multiple scales. Examples of the different scale levels include: 1. System Scale - techno-economic analysis for hydrogen applications, integration of hydrogen infrastructure with the electrical grid, and supply and demand constraints across applications 2. Component Scale - continuous-flow catalyst beds, electrochemical conversion units, gas-phase separators, pumps, compressors, storage tanks, evaporators, heaters, and coolers 3. Material Scale - surface reactions, degradation mechanisms, and catalyst poisoning

Mcnenly, MatthewJ↗

DOE OSTI2025

Optimization of spray breakup model parameters for predicting fuel spray and film characteristics in gasoline direct injection engines

This study investigated the behavior of gasoline direct injection (GDI) sprays using computational fluid dynamics (CFD). The authors developed an approach to identify optimal spray breakup model parameters by evaluating an error function across numerous simulations, with the goal of minimizing discrepancies from experimental data. Using the optimal setup, the simulated spray matched well with projected liquid volume distributions, liquid penetration, and spray width measured in a constant-pressure continuous-flow chamber. To further validate the approach, the same setup was tested across various fuels, injectors, and operating conditions. Subsequently, the optimal setup, along with a recently developed spray-wall interaction model, were applied to a direct-injection spark-ignited engine under late-injection conditions to predict and evaluate fuel film formation and evolution at varying engine coolant temperatures. Here, with the centrally mounted injector directing the spray toward the piston, simulations indicated that the spray tends to impinge on the piston surface. The proposed simulation framework also accurately captured the aggregate film area on the piston surface, aligning with previously published experimental results. Moreover, simulations showed that increasing the coolant temperature from cold start conditions (333 K) to warm conditions (363 K) reduced the fuel mass deposited on the piston by roughly 50%. Furthermore, for the spray-guided engine configuration studied in this work, the CFD model predicted minimal film deposition on the spark plug electrodes regardless of the coolant temperatures due to a relatively weak in-cylinder flow during the compression phase.

Computational fluid dynamics (CFD)↗

DOE OSTI2022

Electrochemical CO2 conversion to formic acid through the Andora Process

Electrochemical utilization or conversion of CO2 can be used to convert waste CO2 into targeted high-value and cost-effective commercial products. Conventional processes for CO2 conversion to fuel sources are challenging and expensive due to their requirement for high temperatures and pressures. Electrochemically, a catalyst can be used at a fixed applied potential to reduce CO2 to form a desired product with less competition at modest operating conditions. Formic acid (FA) has recently become a product of interest for CO2 conversion due to its potential for hydrogen storage and fuel cell applications. Electrochemically, FA is produced through a direct two-electron transfer process involving CO2 with a proton source, requiring less energy input and fewer reaction steps than traditional processes. However, there remain significant obstacles for the broader-scale implementation of CO2 on the market, including competition with unwanted CO and H, the presence of molecular oxygen, and stability of the electrocatalyst. In order to overcome some of these challenges, a new continuous flow Andora Process was developed consisting of two separate cells to decouple electrochemical reduction of the charge carrier with the FA production via an engineered catalyst. Recent experimental results show that with appropriate design changes and operating conditions to the flow system, FA production above 500 mM can be achieved along with efficiencies above 80%. TEA and LCA assessments of the Andora Process show a potential for the reduction in the GWP potential and cost saving compared to the current comparative formic acid production process.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2020

Pool Fire Analysis Methodology for Assessing Damage to Waste Containers

This document provides guidelines, whereby the physical parameters associated with postulated flammable/combustible liquid pool fires are determined (thermal analysis) in order to estimate the number of waste containers impacted. Pool fire damage to waste containers may occur due to a container being fully engulfed (within the periphery of the pool), partially engulfed, or within the critical heat flux distance. The methodology described here for estimating the size of the pool fire is developed using spill characteristics outlined in Chapter 65 of the SFPE Handbook (Ref. 7) and testing done by Hansen (Ref. 25). For exposures, the critical flux height is determined using the detailed method of Shokri and Beyler (Ref. 8) from the flame height, calculated as described by Heskestad (Ref. 7) and the average black body emissive power, determined using the method of Shokri and Beyler (Ref. 8). Three types of liquid pool fires should be considered; unconfined crash/instantaneous spill fires, unconfined continuously flowing (also called metered leak) spill fires, and confined spill fires. All fuel sources should be considered consistent with the facility Fire Hazard Analysis (FHA). However, the most likely liquid fuel sources present in TRU waste facilities are those present on TRU waste handling vehicles (forklifts, pallet movers, transport trucks, etc.). This method can also be used for assessing damage to items other than waste containers or other methods of analysis may be used with appropriate justification.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Development of a Turbulent Liquid Spray Atomization Model for Diesel Engine Simulations (Final Technical Report)

This project addresses the systematic lack of predictive capabilities by spray models within engine CFD codes. We develop a new modeling approach to predict the breakup of diesel sprays based on recent literature showing that liquid turbulence plays a fundamental role in spray atomization. A new body of quantitative validation data is also developed as a critical element of the project, leveraging the joint capabilities of Georgia Tech’s high-pressure continuous-flow spray chamber and Argonne National Lab’s near-nozzle x-ray diagnostics at the Advanced Photon Source. This project contributes spatially-resolved measurements of drop size distribution within well-characterized diesel injectors, Spray A and D, from the Engine Combustion Network (ECN) to the engine combustion community for the first time. Utilizing this new body of measurements, we validate and demonstrate a new spray model for diesel sprays, termed the KH-Faeth model, that predicts global and local spray characteristic more accurately than the widely adopted and employed KH model. Predicted drop size distributions are seen to predict measured drops sizes both quantitatively and predictively, with accurate response in droplet size distributions over a wide range of ambient density, injection pressure, and injector nozzle size (Spray A and D) without model tuning. The KH-Faeth model can reduce error in the predicted centerline droplet size profile by up to 80% for ECN Spray D simulations when compared to use of the widely employed KH model.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2021

Simultaneous Capture and Conversion of CO 2 to Methanol via a Switchable Ionic Liquid and Low-Temperature Metal Catalyst (CRADA 449)

Advance development of the Integrated (Carbon Dioxide) CO 2 Capture and Conversion to Methanol (ICCCM) process, which is based on PNNL’s proprietary Carbon Dioxide Binding Organic Liquids (CO 2 BOLs) capture solvent technology for separating the CO 2 from dilute streams. Design, fabricate, and demonstrate a bench-scale ICCCM prototype for the continuous flow combined capture and catalytic conversion of CO 2 into methanol and assess viability for commercialization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗