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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Improving Silicon Solar Cell Efficiency Through Advanced Cell Processing, Highly Uniform Texturing, and Thinner Cells

This CRADA is aimed at developing silicon solar cell technologies that can yield higher efficiency solar cells. Specifically, this CRADA cover three technologies: (i) developing a high temperature process for dissolution of oxygen precipitates, (ii) uniform texturization of diamond wire sawn wafers, and (iii) evaluation of techniques to bond techniques thin wafers and thin films.

14 SOLAR ENERGY↗
DOE OSTI2023

Sandwich gasification process for high-efficiency conversion of carbonaceous fuels to clean syngas with zero residual carbon discharge

gasifier and a gasification process provides a long, uniform temperature zone in the gasifier, regardless of the particle size, chemical composition, and moisture content of the fuel by sandwiching a reduction zones between two oxidation zones. The gasifier and gasification process produces a char that is more energy-dense and almost devoid of moisture, affording an additional (char) oxidation zone with a temperature that is higher than a first oxidation zone which is closer to an evaporation and devolatilization zone. As such, the additional (char) oxidation zone contributes to augmenting the reduction zone temperature, providing a favorable dual impact in improving syngas composition and near-complete conversion of the tar.

Patel, Nikhil Manubhai↗
DOE OSTI2022

CFD-DEM Modeling of Autothermal Pyrolysis of Corn Stover with a Coupled Particle- and Reactor-Scale Framework

Autothermal operation of fast pyrolysis is an efficient process-intensification technique wherein exothermic oxidation reactions are used to overcome the heat-transfer bottleneck of conventional pyrolysis. The development of accurate, reliable modeling toolsets is imperative to generating a deeper understanding of biomass autothermal pyrolysis systems to support scale-up and industrial deployment. This modeling effort describes the development of single-particle and reactor models which incorporate detailed reaction schemes and simultaneous exothermic oxidation reactions. The particle-scale model was parameterized for corn stover feedstock with particle morphology, density, ash content, and biopolymer composition, all of which impact the emergent conversion characteristics during pyrolysis. Results were then used to parameterize a reactor-scale autothermal pyrolysis model, which was developed using a coarse-grained computational fluid dynamic-discrete element method. The simulation results compared well with experimental results, with the predicted bio-oil, light gas, and biochar yield within 3.0 wt% of the experimental yields. Further analyses were performed to test the influence of equivalence ratio, biomass injection position, and particle size distribution on autothermal pyrolysis. The analysis of the physio-chemical properties of the fluid and solid phase inside the reactor and at the reactor outlet help reveal important process interactions of autothermal pyrolysis.

BIOMASS FUELS,INORGANIC, ORGANIC, PHYSICAL, AND AN↗
DOE OSTI2024

Small‐Molecule Mixed Ionic‐Electronic Conductors for Efficient N‐Type Electrochemical Transistors: Structure‐Function Correlations

Abstract The fundamental challenge in electron‐transporting organic mixed ionic‐electronic conductors (OMIECs) is simultaneous optimization of electron and ion transport. Beginning from Y6‐type/U‐shaped non‐fullerene solar cell acceptors, we systematically synthesize and characterize molecular structures that address the aforementioned challenge, progressively introducing increasing numbers of oligoethyleneglycol (OEG; g) sidechains from 1 g to 3 g, affording OMIECs 1gY, 2gY, and 3gY, respectively. The crystal structure of 1gY preserves key structural features of the Y n series: a U‐shaped/planar core, close π–π molecular stacking, and interlocked acceptor groups. Versus inactive Y6 and Y11, all of the new glycolated compounds exhibit mixed ion‐electron transport in both conventional organic electrochemical transistor (cOECT) and vertical OECT (vOECT) architectures. Notably, 3gY with the highest OEG density achieves a high transconductance of 16.5 mS, an on/off current ratio of ~10 6 , and a turn‐on/off response time of 94.7/5.7 ms in vOECTs. Systematic optoelectronic, electrochemical, architectural, and crystallographic analysis explains the superior 3gY‐based OECT performance in terms of denser n gY OEG content, increased crystallite dimensions with decreased long‐range crystalline order, and enhanced film hydrophilicity which facilitates ion transport and efficient redox processes. Finally, we demonstrate an efficient small‐molecule‐based complementary inverter using 3gY vOECTs, showcasing the bioelectronic applicability of these new small‐molecule OMIECs.

Cho, Yongjoon↗
DOE OSTI2024

Small‐Molecule Mixed Ionic‐Electronic Conductors for Efficient N‐Type Electrochemical Transistors: Structure‐Function Correlations

Abstract The fundamental challenge in electron‐transporting organic mixed ionic‐electronic conductors (OMIECs) is simultaneous optimization of electron and ion transport. Beginning from Y6‐type/U‐shaped non‐fullerene solar cell acceptors, we systematically synthesize and characterize molecular structures that address the aforementioned challenge, progressively introducing increasing numbers of oligoethyleneglycol (OEG; g) sidechains from 1 g to 3 g, affording OMIECs 1gY, 2gY, and 3gY, respectively. The crystal structure of 1gY preserves key structural features of the Y n series: a U‐shaped/planar core, close π–π molecular stacking, and interlocked acceptor groups. Versus inactive Y6 and Y11, all of the new glycolated compounds exhibit mixed ion‐electron transport in both conventional organic electrochemical transistor (cOECT) and vertical OECT (vOECT) architectures. Notably, 3gY with the highest OEG density achieves a high transconductance of 16.5 mS, an on/off current ratio of ~10 6 , and a turn‐on/off response time of 94.7/5.7 ms in vOECTs. Systematic optoelectronic, electrochemical, architectural, and crystallographic analysis explains the superior 3gY‐based OECT performance in terms of denser n gY OEG content, increased crystallite dimensions with decreased long‐range crystalline order, and enhanced film hydrophilicity which facilitates ion transport and efficient redox processes. Finally, we demonstrate an efficient small‐molecule‐based complementary inverter using 3gY vOECTs, showcasing the bioelectronic applicability of these new small‐molecule OMIECs.

Cho, Yongjoon↗
DOE OSTI2022

Intramolecular charge-transfer enhances energy transfer efficiency in carotenoid-reconstituted light-harvesting 1 complex of purple photosynthetic bacteria

In bacterial photosynthesis, the excitation energy transfer (EET) from carotenoids to bacteriochlorophyll a has a significant impact on the overall efficiency of the primary photosynthetic process. This efficiency can be enhanced when the involved carotenoid has intramolecular charge-transfer (ICT) character, as found in light-harvesting systems of marine alga and diatoms. Here, we provide insights into the significance of ICT excited states following the incorporation of a higher plant carotenoid, β-apo-8'-carotenal, into the carotenoidless light-harvesting 1 (LH1) complex of the purple photosynthetic bacterium Rhodospirillum rubrum strain G9+. β-apo-8'-carotenal generates the ICT excited state in the reconstituted LH1 complex, achieving an efficiency of EET of up to 79%, which exceeds that found in the wild-type LH1 complex.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Production of Copper-Plated Beamline Bellows and Spools for LCLS-II

The SLAC National Accelerator Laboratory is currently constructing a major upgrade to its accelerator, the Linac Coherent Light Source II (LCLS-II). Several Department of Energy national laboratories, including the Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Laboratory (FNAL), are participating in this project. The 1.3-GHz cryomodules for this project consist of eight cavities separated by bellows (expansion joints) and spools (tube sections), which are copper plated for RF conduction. JLab is responsible for procurement of these bellows and spools, which are delivered to JLab and FNAL for assembly into cryomodules. Achieving accelerator-grade copper plating is always a challenge and requires careful specification of requirements and application of quality control processes. Due to the demanding technical requirements of this part, JLab implemented procurement strategies to make the process more efficient as well as provide process redundancy. This paper discusses the manufacturing challenges that were encountered and resolved, as well as the strategies that were employed to minimize the impact of any technical issues.

Wilson, Katherine M.↗
DOE OSTI2018

Sandwich gasification process for high-efficiency conversion of carbonaceous fuels to clean syngas with zero residual carbon discharge

The present invention discloses a gasifier and/or a gasification process that provides a long, uniform temperature zone in the gasifier, regardless of the particle size, chemical composition, and moisture content of the fuel by sandwiching a reduction zones between two oxidation zones. The gasifier and/or gasification process has a char that is more energy-dense and almost devoid of moisture that affords for an additional (or char) oxidation zone with a temperature that is higher than a first oxidation zone which is closer to a evaporation and devolatilization zone. As such, the additional (or char) oxidation zone contributes to augmenting the reduction zone temperature, thereby providing a favorable dual impact in improving syngas composition and near-complete conversion of the tar.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Sandwich gasification process for high-efficiency conversion of carbonaceous fuels to clean syngas with zero residual carbon discharge

The present invention discloses a gasifier and/or a gasification process that provides a long, uniform temperature zone in the gasifier, regardless of the particle size, chemical composition, and moisture content of the fuel by sandwiching a reduction zones between two oxidation zones. The gasifier and/or gasification process has a char that is more energy-dense and almost devoid of moisture that affords for an additional (or char) oxidation zone with a temperature that is higher than a first oxidation zone which is closer to a evaporation and devolatilization zone. As such, the additional (or char) oxidation zone contributes to augmenting the reduction zone temperature, thereby providing a favorable dual impact in improving syngas composition and near-complete conversion of the tar.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Sandwich gasification process for high-efficiency conversion of carbonaceous fuels to clean syngas with zero residual carbon discharge

The present invention discloses a gasifier and/or a gasification process that provides a long, uniform temperature zone in the gasifier, regardless of the particle size, chemical composition, and moisture content of the fuel by sandwiching a reduction zones between two oxidation zones. The gasifier and/or gasification process has a char that is more energy-dense and almost devoid of moisture that affords for an additional (or char) oxidation zone with a temperature that is higher than a first oxidation zone which is closer to an evaporation and devolatilization zone. As such, the additional (or char) oxidation zone contributes to augmenting the reduction zone temperature, thereby providing a favorable dual impact in improving syngas composition and near-complete conversion of the tar.

Patel, Nikhil Manubhai↗
DOE OSTI2018

Efficient Technology for Combined Processing of Silicate and Carbonate Uranium Ores

The results of studies on the processing of carbonate ores with extraction of uranium and molybdenum by means of autoclave and atmospheric leaching and sorption extraction of valuable components using carboxyl cationionites and strongly basic anionites are presented. The most stable and highest indices for the extraction of uranium and molybdenum into solution were obtained for autoclave leaching with the following process parameters: pressure 12–14 psig, temperature ~140°C, pulp processing time 4–6 h, and initial sodium carbonate concentration 40–50 g/dm{sup 3}. The degree of extraction of uranium and molybdenum into solution was ≥96%. Almost complete separation of uranium from molybdenum was obtained on carboxyl cationites without bicarbonate solutions in the pH range 6.5–7.5. An efficient technology is proposed for combined processing of silicate and carbonate ores using a unified sorption scheme making it possible to extract uranium and molybdenum separately while obtaining ammonium uranyl tricarbonate and ammonium paramolybdate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

The fabrication of polyfluorene and polycarbazole-based photovoltaic devices using an air-stable process route

We report a comparative study based on the fabrication of polymer:fullerene photovoltaic (PV) devices incorporating carbazole, fluorene, and a PTB based co-polymer. We have explored the efficiency and performance of such devices when the active polymer:fullerene layer is deposited by spin-casting either under nitrogen or ambient conditions. We show that PV devices based on carbazole and fluorene based materials have very similar power conversion efficiencies when processed under both air and nitrogen, with other photobleaching measurements suggesting that such materials have comparatively enhanced photostability. Devices based on the PTB co-polymer, however, have reduced efficiency when processed in air.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Progress toward Biomass and Coal-Derived Syngas Warm Cleanup: Proof-of-Concept Process Demonstration of Multicontaminant Removal for Biomass Application

Systems comprising of multiple sorbent and catalytic beds have been developed for the warm syngas cleanup of coal- and biomass-derived syngas. Tailored specifically for biomass application the process described here consists of six primary unit operations: 1) Na2CO3 bed for HCl removal, 2) two regenerable ZnO beds for bulk H2S removal, 3) ZnO bed for H2S polishing, 4) NiCu/SBA-16 sorbent for trace metal (e.g. AsH3) removal, 5) steam reforming catalyst bed for tars and light hydrocarbons reformation and NH3 decomposition, and a 6) Cu-based LT-WGS catalyst bed. Simulated biomass-derived syngas containing a multitude of inorganic contaminants (H2S, AsH3, HCl, and NH3) and hydrocarbon additives (methane, ethylene, benzene, and naphthalene) was used to demonstrate process effectiveness. The efficiency of the process was demonstrated for a period of 175 hours, during which no signs of deactivation were observed. Post-run analysis revealed small levels of sulfur slipped through the sorbent bed train to the two downstream catalytic beds. Future improvements could be made to the trace metal polishing sorbent to ensure complete inorganic contaminant removal (to low ppb level) prior to the catalytic steps. However, dual, regenerating ZnO beds were effective for continuous removal for the vast majority of the sulfur present in the feed gas. The process was effective for complete AsH3 and HCl removal. The steam reforming catalyst completely reformed all the hydrocarbons present in the feed (methane, ethylene, benzene, and naphthalene) to additional syngas. However, post-run evaluation, under kinetically-controlled conditions, indicates deactivation of the steam reforming catalyst. Spent material characterization suggests this is attributed, in part, to coke formation, likely due to the presence of benzene and/or naphthalene in the feed. Future adaptation of this technology may require dual, regenerable steam reformers. The process and materials described in this report hold promise for a warm cleanup of a variety of contaminant species within warm syngas.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2011

IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. II. DUST-INDUCED COLLISIONAL IONIZATION

Observations have shown that continuous radio emission and also sporadic H{alpha} and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These activity signatures are interpreted as being caused by coupling of an ionized atmosphere to the stellar magnetic field. What remains a puzzle, however, is the mechanism by which such a cool atmosphere can produce the necessary level of ionization. At these low temperatures, thermal gas processes are insufficient, but the formation of clouds sets in. Cloud particles can act as seeds for electron avalanches in streamers that ionize the ambient gas, and can lead to lightning and indirectly to magnetic field coupling, a combination of processes also expected for protoplanetary disks. However, the precondition is that the cloud particles are charged. We use results from DRIFT-PHOENIX model atmospheres to investigate collisional processes that can lead to the ionization of dust grains inside clouds. We show that ionization by turbulence-induced dust-dust collisions is the most efficient kinetic process. The efficiency is highest in the inner cloud where particles grow quickly and, hence, the dust-to-gas ratio is high. Dust-dust collisions alone are not sufficient to improve the magnetic coupling of the atmosphere inside the cloud layers, but the charges supplied either on grains or within the gas phase as separated electrons can trigger secondary nonlinear processes. Cosmic rays are likely to increase the global level of ionization, but their influence decreases if a strong, large-scale magnetic field is present as on brown dwarfs. We suggest that although thermal gas ionization declines in objects across the fully convective boundary, dust charging by collisional processes can play an important role in the lowest mass objects. The onset of atmospheric dust may therefore correlate with the anomalous X-ray and radio emission in atmospheres that are cool, but charged more than expected by pure thermal ionization.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Pilot Scale Operation and Testing of Syngas Chemical Looping For Hydrogen Production

The Syngas Chemical looping (SCL) process provides efficient and economic means to utilize the abundant fossil reserve of coal. The main problem associated with coal utilization is the CO 2 emissions resulting from its combustion. Even though CO 2 regulation or carbon tax is currently not in place, its enforcement is expected in the near future. Such a greenhouse gas emission control, if adopted in current power plant systems, will drive the efficiency down and increase the cost of electricity, due to the energy and capital-intensive nature of current CO 2 separation techniques. This highlights the need to develop technologies that present a solution to the rising cost of electricity in the future. The integrated gasification combined cycle (IGCC) presents an improvement to the above predicament, but it is capital intensive due to the extensive unit operations involved. The efficiency for a CO 2 capture incorporated IGCC system is around ~32%, resulting in approximately 45% increase in cost of electricity. This is definitely a better path to traverse than the conventional pulverized coal (PC) power plants as it has improved economics and efficiencies accompanied by product flexibility. The SCL process advances the benefits even further when integrated with the IGCC process. The SCL process removes the expensive WGS system and CO 2 separation columns, thereby saving on capital and operational expenses. This integration results in a 12 – 21% increase in efficiency accompanied by a reduction in cost of electricity by 15 – 28%, over conventional IGCC systems. Therefore, SCL process provides the best route to harness the energy from coal. The overall project objective was to construct and operate a syngas chemical looping pilot scale test unit at the NCCC. The project scope of work was divided into 3 phases. In Phase I, cold flow model studies using a 1:1 scale acrylic test unit constructed at Particulate Solids Research, Inc. (PSRI) was successfully completed confirming robust solid flow control is achievable in the non-mechanical system design. In Phase II, the high pressure, high temperature, chemical looping reactor was successfully designed with all necessary equipment and safety instrumentation/controls specified to allow for fabrication, site construction, and assembly to commence in Phase III. In Phase III, the SCL pilot plant was successfully assembled and all necessary functional checks and pre-startup safety reviews completed. During unit commission over the course of 200 hours of testing, operational issues were observed with premix burner used for system startup. With the grants awarded by the National Energy Laboratory (NETL) and the Ohio Development Services Agency (ODSA) under awards DE-FE0023915 and D-14-18, the SCL pilot unit underwent three auxiliary equipment modifications to resolve all of the startup operational issues encountered. The unit was successfully demonstrated with 300+hr continuous operation. Key results obtained include high syngas conversion of 97.95% with 16.03% oxygen carrier conversion in the moving bed reducer and >99% purity H 2 produced from the moving bed oxidizer.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2024

Equally high efficiencies of organic solar cells processed from different solvents reveal key factors for morphology control

The power conversion efficiency of organic solar cells (OSCs) is exceeding 20%, an advance in which morphology optimization has played a significant role. It is generally accepted that the processing solvent (or solvent mixture) can help optimize morphology, impacting the OSC efficiency. Here we develop OSCs that show strong tolerance to a range of processing solvents, with all devices delivering high power conversion efficiencies around 19%. By investigating the solution states, the film formation dynamics and the characteristics of the processed films both experimentally and computationally, we identify the key factors that control morphology, that is, the interactions between the side chains of the acceptor materials and the solvent as well as the interactions between the donor and acceptor materials. Our work provides new understanding on the long-standing question of morphology control and effective guides to design OSC materials towards practical applications, where green solvents are required for large-scale processing.

14 SOLAR ENERGY↗