A Temperature Model for Synchronized Ultrasonic Torrefaction and Pelleting of Biomass for Bioenergy Production

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Mingman Sun ◽  
Yang Yang ◽  
Meng Zhang
Keyword(s):  
Thermal Stability ◽  
Large Scale ◽  
High Energy ◽  
Single Step ◽  
Multistep Method ◽  
Ultrasonic Frequency ◽  
Volumetric Density ◽  
Thermochemical Pretreatment ◽  
Fuel Pellets ◽  
Fuel Upgrading

Low-energy and volumetric density of biomass has been a major challenge, hindering its large-scale utilization as a bioenergy resource. Torrefaction is a thermochemical pretreatment process that can significantly enhance the properties of biomass as a fuel by increasing the heating value and thermal stability of biomass materials. Densification of biomass by pelleting can greatly increase the volumetric density of biomass to improve its handling efficiency. Currently, torrefaction and pelleting are processed separately. So far, there has been little success in dovetailing torrefaction and pelleting, which only requires a single material loading to produce torrefied pellets. Synchronized ultrasonic torrefaction and pelleting has been developed to address this challenge. Synchronized ultrasonic torrefaction and pelleting can produce pellets of high energy and volumetric density in a single step, which tremendously reduces the time and energy consumption compared to that required by the prevailing multistep method. This novel fuel upgrading process can increase the biomass temperature to 473–573 K within tens of seconds to create torrefaction. Studying the temperature distribution is crucial to understand the fuel upgrading mechanism since pellet energy density, thermal stability, volumetric density, and durability are all highly related to temperature. A rheological model was established to instantiate biomass behaviors when undergoing various ultrasonic vibration conditions. Process parameters including ultrasonic amplitude, ultrasonic frequency, and pelleting time were studied to show their effects on temperature at different locations in a pellet. Results indicated that the volumetric heat generation rate was greatly affected by both ultrasonic amplitude and frequency. This model can help to understand the fuel upgrading mechanism in synchronized ultrasonic torrefaction and pelleting and also to give guidelines for process optimization to produce high-quality fuel pellets.

A Temperature Model for Synchronized Ultrasonic Torrefaction and Pelleting of Biomass for Bioenergy Production

2018 ◽  
Author(s):  
Mingman Sun ◽  
Yang Yang ◽  
Meng Zhang
Keyword(s):  
Thermal Stability ◽  
Large Scale ◽  
High Energy ◽  
Single Step ◽  
Cellulosic Biomass ◽  
Temperature Model ◽  
Step Method ◽  
Volumetric Density ◽  
Fuel Upgrading ◽  
Time And Energy

Low energy and volumetric density of cellulosic biomass has been a challenge hindering its large-scale utilization as a bioenergy resource. Torrefaction is a thermochemical pretreatment process that can significantly enhance the properties of biomass as a fuel by increasing the heating value and thermal stability of biomass materials. Densification of cellulosic biomass by pelleting can greatly increase the volumetric density of biomass to improve its handling efficiency. Currently, torrefaction and pelleting are processed separately, which consumes a great amount of time and energy. In addition, it is more difficult to pellet torrefied biomass than untreated biomass. Synchronized ultrasonic torrefaction and pelleting has been developed to address these challenges. Synchronized ultrasonic torrefaction and pelleting can produce pellets of high energy and volumetric density in a single step, which tremendously reduces the time and energy consumption compared to that by the prevailing multi-step method. This novel fuel upgrading process can increase biomass temperature to 473–573 K within tens of seconds to realize torrefaction. Studying the temperature distribution is a crucial key to understand the fuel upgrading mechanism since pellet energy density, thermal stability, volumetric density, and durability are all highly related to temperature. In this research, a physics-based temperature model is developed to explain torrefaction temperatures measured experimentally and to provide guidelines to optimize process variables to produce high quality pellets that can be used as a sustainable fuel.

Evolution of the microstructure of Cu(Ti)/SiO2 layers annealed in NH3

1995 ◽  
Vol 53 ◽  
pp. 452-453
Author(s):  
J. Liu ◽  
N. D. Theodore ◽  
D. Adams ◽  
S. Russell ◽  
T. L. Alford ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Titanium Nitride ◽  
Large Scale ◽  
Standard Procedure ◽  
Alloy Film ◽  
Electron Beam Evaporation ◽  
Copper Metallization ◽  
Nominal Composition ◽  
Ti Alloy ◽  
Thermally Grown

Copper-based metallization has recently attracted extensive research because of its potential application in ultra-large-scale integration (ULSI) of semiconductor devices. The feasibility of copper metallization is, however, limited due to its thermal stability issues. In order to utilize copper in metallization systems diffusion barriers such as titanium nitride and other refractory materials, have been employed to enhance the thermal stability of copper. Titanium nitride layers can be formed by annealing Cu(Ti) alloy film evaporated on thermally grown SiO2 substrates in an ammonia ambient. We report here the microstructural evolution of Cu(Ti)/SiO2 layers during annealing in NH3 flowing ambient.The Cu(Ti) films used in this experiment were prepared by electron beam evaporation onto thermally grown SiO2 substrates. The nominal composition of the Cu(Ti) alloy was Cu73Ti27. Thermal treatments were conducted in NH3 flowing ambient for 30 minutes at temperatures ranging from 450°C to 650°C. Cross-section TEM specimens were prepared by the standard procedure.

Organic solvent-assisted free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 on 3D graphene as a high energy density cathode

2015 ◽  
Vol 51 (91) ◽  
pp. 16381-16384 ◽  
Author(s):  
Yuelong Xin ◽  
Liya Qi ◽  
Yiwei Zhang ◽  
Zicheng Zuo ◽  
Henghui Zhou ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Solvent ◽  
Freeze Drying ◽  
Large Scale ◽  
High Energy ◽  
High Energy Density ◽  
Free Standing ◽  
3D Graphene ◽  
Active Particles

A novel organic solvent-assisted freeze-drying pathway, which can effectively protect and uniformly distribute active particles, is developed to fabricate a free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 (LR)/rGO electrode on a large scale.

High energy density aqueous zinc–benzoquinone batteries enabled by carbon cloth with multiple anchoring effects

2021 ◽  
Author(s):  
Zhiqiang Luo ◽  
Silin Zheng ◽  
Shuo Zhao ◽  
Xin Jiao ◽  
Zongshuai Gong ◽  
...  
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Porous Carbon ◽  
Large Scale ◽  
High Energy ◽  
High Energy Density ◽  
Carbon Cloth ◽  
Anchoring Effects ◽  
High Theoretical Capacity ◽  
Energy Storage Applications

Benzoquinone with high theoretical capacity is anchored on N-plasma engraved porous carbon as a desirable cathode for rechargeable aqueous Zn-ion batteries. Such batteries display tremendous potential in large-scale energy storage applications.

scholarly journals 1.5 °C degrowth scenarios suggest the need for new mitigation pathways

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lorenz T. Keyßer ◽  
Manfred Lenzen
Keyword(s):  
Technological Change ◽  
High Speed ◽  
Large Scale ◽  
High Energy ◽  
Climate Mitigation ◽  
Intergovernmental Panel ◽  
Economic Output ◽  
Integrated Assessment Modelling ◽  
Negative Emissions ◽  
Energy Emissions

Abstract1.5  °C scenarios reported by the Intergovernmental Panel on Climate Change (IPCC) rely on combinations of controversial negative emissions and unprecedented technological change, while assuming continued growth in gross domestic product (GDP). Thus far, the integrated assessment modelling community and the IPCC have neglected to consider degrowth scenarios, where economic output declines due to stringent climate mitigation. Hence, their potential to avoid reliance on negative emissions and speculative rates of technological change remains unexplored. As a first step to address this gap, this paper compares 1.5  °C degrowth scenarios with IPCC archetype scenarios, using a simplified quantitative representation of the fuel-energy-emissions nexus. Here we find that the degrowth scenarios minimize many key risks for feasibility and sustainability compared to technology-driven pathways, such as the reliance on high energy-GDP decoupling, large-scale carbon dioxide removal and large-scale and high-speed renewable energy transformation. However, substantial challenges remain regarding political feasibility. Nevertheless, degrowth pathways should be thoroughly considered.

scholarly journals Nitrogen-enriched graphene framework from a large-scale magnesiothermic conversion of CO2 with synergistic kinetics for high-power lithium-ion capacitors

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Chen Li ◽  
Xiong Zhang ◽  
Kai Wang ◽  
Xianzhong Sun ◽  
Yanan Xu ◽  
...  
Keyword(s):  
Energy Density ◽  
High Power ◽  
Power Output ◽  
Large Scale ◽  
Electrode Materials ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density ◽  
Chemical Doping ◽  
Lithium Ion Capacitor

AbstractLithium-ion capacitors are envisaged as promising energy-storage devices to simultaneously achieve a large energy density and high-power output at quick charge and discharge rates. However, the mismatched kinetics between capacitive cathodes and faradaic anodes still hinder their practical application for high-power purposes. To tackle this problem, the electron and ion transport of both electrodes should be substantially improved by targeted structural design and controllable chemical doping. Herein, nitrogen-enriched graphene frameworks are prepared via a large-scale and ultrafast magnesiothermic combustion synthesis using CO2 and melamine as precursors, which exhibit a crosslinked porous structure, abundant functional groups and high electrical conductivity (10524 S m−1). The material essentially delivers upgraded kinetics due to enhanced ion diffusion and electron transport. Excellent capacities of 1361 mA h g−1 and 827 mA h g−1 can be achieved at current densities of 0.1 A g−1 and 3 A g−1, respectively, demonstrating its outstanding lithium storage performance at both low and high rates. Moreover, the lithium-ion capacitor based on these nitrogen-enriched graphene frameworks displays a high energy density of 151 Wh kg−1, and still retains 86 Wh kg−1 even at an ultrahigh power output of 49 kW kg−1. This study reveals an effective pathway to achieve synergistic kinetics in carbon electrode materials for achieving high-power lithium-ion capacitors.

scholarly journals Modeling Gamma-Ray SEDs and Angular Extensions of Extreme TeV Blazars from Intergalactic Proton-Initiated Cascades in Contemporary Astrophysical EGMF Models

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 220
Author(s):  
Emil Khalikov
Keyword(s):  
Gamma Rays ◽  
Large Scale ◽  
Gamma Ray ◽  
High Energy ◽  
Cascade Model ◽  
Point Sources ◽  
Spectral Energy ◽  
Observation Data ◽  
Cherenkov Telescopes ◽  
The Universe

The intrinsic spectra of some distant blazars known as “extreme TeV blazars” have shown a hint at an anomalous hardening in the TeV energy region. Several extragalactic propagation models have been proposed to explain this possible excess transparency of the Universe to gamma-rays starting from a model which assumes the existence of so-called axion-like particles (ALPs) and the new process of gamma-ALP oscillations. Alternative models suppose that some of the observable gamma-rays are produced in the intergalactic cascades. This work focuses on investigating the spectral and angular features of one of the cascade models, the Intergalactic Hadronic Cascade Model (IHCM) in the contemporary astrophysical models of Extragalactic Magnetic Field (EGMF). For IHCM, EGMF largely determines the deflection of primary cosmic rays and electrons of intergalactic cascades and, thus, is of vital importance. Contemporary Hackstein models are considered in this paper and compared to the model of Dolag. The models assumed are based on simulations of the local part of large-scale structure of the Universe and differ in the assumptions for the seed field. This work provides spectral energy distributions (SEDs) and angular extensions of two extreme TeV blazars, 1ES 0229+200 and 1ES 0414+009. It is demonstrated that observable SEDs inside a typical point spread function of imaging atmospheric Cherenkov telescopes (IACTs) for IHCM would exhibit a characteristic high-energy attenuation compared to the ones obtained in hadronic models that do not consider EGMF, which makes it possible to distinguish among these models. At the same time, the spectra for IHCM models would have longer high energy tails than some available spectra for the ALP models and the universal spectra for the Electromagnetic Cascade Model (ECM). The analysis of the IHCM observable angular extensions shows that the sources would likely be identified by most IACTs not as point sources but rather as extended ones. These spectra could later be compared with future observation data of such instruments as Cherenkov Telescope Array (CTA) and LHAASO.

scholarly journals Understanding the origin of the positron annihilation line and the physics of supernova explosions

2021 ◽  
Author(s):  
F. Frontera ◽  
E. Virgilli ◽  
C. Guidorzi ◽  
P. Rosati ◽  
R. Diehl ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Large Scale ◽  
Gamma Ray ◽  
Nuclear Astrophysics ◽  
High Energy ◽  
Radioactive Isotopes ◽  
Fusion Reactions ◽  
Dark Matter Annihilation ◽  
Annihilation Line ◽  
Supernova Explosions

AbstractNuclear astrophysics, and particularly nuclear emission line diagnostics from a variety of cosmic sites, has remained one of the least developed fields in experimental astronomy, despite its central role in addressing a number of outstanding questions in modern astrophysics. Radioactive isotopes are co-produced with stable isotopes in the fusion reactions of nucleosynthesis in supernova explosions and other violent events, such as neutron star mergers. The origin of the 511 keV positron annihilation line observed in the direction of the Galactic Center is a 50-year-long mystery. In fact, we still do not understand whether its diffuse large-scale emission is entirely due to a population of discrete sources, which are unresolved with current poor angular resolution instruments at these energies, or whether dark matter annihilation could contribute to it. From the results obtained in the pioneering decades of this experimentally-challenging window, it has become clear that some of the most pressing issues in high-energy astrophysics and astro-particle physics would greatly benefit from significant progress in the observational capabilities in the keV-to-MeV energy band. Current instrumentation is in fact not sensitive enough to detect radioactive and annihilation lines from a wide variety of phenomena in our and nearby galaxies, let alone study the spatial distribution of their emission. In this White Paper (WP), we discuss how unprecedented studies in this field will become possible with a new low-energy gamma-ray space experiment, called ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics), which combines new imaging, spectroscopic and polarization capabilities. In a separate WP (Guidorzi et al. 39), we discuss how the same mission concept will enable new groundbreaking studies of the physics of Gamma–Ray Bursts and other high-energy transient phenomena over the next decades.

Mullite Diffusion Barriers for SiC-C/C Composites Produced by Pulsed Laser Deposition

1998 ◽  
Vol 555 ◽  
Author(s):  
H. Fritze ◽  
A. Schnittker ◽  
T. Witke ◽  
C. Rüscher ◽  
S. Weber ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Target Material ◽  
High Energy ◽  
Single Step ◽  
Laser Deposition ◽  
Reduced Pressure ◽  
Oxidation Rates ◽  
Energy Impact ◽  
Diffusion Parameters

AbstractPulsed Laser Deposition (PLD) allows the ablation of nonconductive and high melting point target materials and the preparation of films with complex composition. High energy impact leads to melting and evaporation of the target material in a single step. In case of mullite ablation, the flux of the metal components is stoichiometric. Under reduced pressure the oxygen content in the layers decreases. However, after a short oxidation treatment, the formation of mullite in the coating is completed, as confirmed by IR spectroscopy and XRD investigations. For a commercial Si-SiC precoated C/C material, the effectiveness of additional PLD mullite layers as outer oxidation protection is tested in the temperature range 773 K < T < 1873 K. Mullite coatings with a thickness of 2.5 pm improve the oxidation behaviour significantly. Because of SiO2 formation at the mullite-SiC interface, all samples exhibited a mass increase upon oxidation. For oxidation durations of three days, only amorphous SiO2 is formed at the mullite-SiC interface. The inward diffusion of oxygen across the outer mullite-containing layer controls the kinetics of the reaction, as was deduced from 18O diffusivity measurements in PLD mullite layers. At temperatures close to the eutectic temperature (1860 K), mullite can seal defects. The calculated oxidation rates resulting from the diffusion parameters in SiO2 and mullite are close to the thermogravimetric data.

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