Effect Of Carbon Particles Research Articles

Numerical study on the effect of carbon particles on flow field characteristics of rotating detonation engine

Rotating detonation engines have high thermal efficiency and thus have been extensively studied. Using solid particles as fuel can reduce costs, and experiments have demonstrated the feasibility of gas-solid two-phase rotating detonation. However, numerical simulation research is required that examines the flow field characteristics of a rotating detonation engine. In order to explore the role of carbon particle fuel in a gas-solid two-phase rotating detonation wave, the weighted essentially non-oscillating scheme and third-order total variation diminishing Runge-Kutta scheme are used to solve the gas-solid unsteady Eulerian–Eulerian equations. Finite rate chemical and surface reaction models are used to simulate the combustion of gaseous substances and carbon particles. The influence of the proportion of carbon particles in the fuel and the diameter of the carbon particles on the rotating detonation flow field characteristics is analyzed. The results indicate that when the size of carbon particles is in the micrometer scale or below, the two-phase rotating detonation waves exhibit double-front or single-front detonation structures, respectively. Adding carbon particles to the fuel enables the rotating detonation engine to achieve a total pressure gain.

Effect of Carbon Particles on Aerodynamic Performance of a Radial Inflow Turbine in Closed Brayton Cycle

Effect of Carbon Particles on Aerodynamic Performance of a Radial Inflow Turbine in Closed Brayton Cycle

Study on the Generation of Carbon Particles in Oil and its Effect on the Breakdown Characteristics of Oil‐Paper Insulation

AbstractThe partial discharge in the converter transformer will cause the carbonization of the insulating paper. The high concentration of free carbon particles generated from the insulating paper during the operation of the converter transformer will cause partial discharge, which will aggravate the insulation performance deterioration. For the bi‐directional interaction of carbon particles and partial discharge, the mechanism of insulating paper carbonization caused by partial discharge and the effect of carbon particles on the dielectric strength of oil paper are studied. In this paper, we construct a simulation system of amorphous cellulose to study the carbonization mechanism of insulating paper from the microscopic level. Furthermore, we build a DC voltage experimental platform to carry out partial discharge damage tests of oil‐paper insulation models and to measure the changes in the breakdown voltage with different carbon particle concentrations and diameters. The results show that partial discharge speeds up the cleavage rate of cellulose, generates low molecular hydrocarbon gas and water molecules, and the carbon atoms rearrange into PAH‐like molecules with aliphatic side chains. The surface of the insulating paper will carbonize, then form free carbon particles after peeling off. Afterward, the carbon particles in insulating oil accumulate in the high electric field area and attach to the insulating paper, which will cause electric field distortion and reduce the dielectric strength of oil‐paper insulation. With the increase of carbon particle concentration and diameter, the breakdown voltage of oil‐paper insulation decreases gradually. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Effect of Carbon Particles with Different Topological Shape on the Rheological Behavior of PVA Aqueous Dispersion

Effect of Carbon Particles with Different Topological Shape on the Rheological Behavior of PVA Aqueous Dispersion

Ionomer and Carbon Aggregate Structure in Catalyst Ink Using Coarse-Grained Molecular Dynamics Simulations

The cathode catalyst layer (CL) is one of the principal components for proton exchange membrane fuel cells. CL is typically prepared by drying a catalyst ink consisting of Pt-C (platinum on a carbon power support), ionomer, and solvents (water/alcohol mixtures). Under good solvent conditions for the polymer backbone, where solvents dissolve the backbone chains, ionomers exhibit polyelectrolyte-type behavior, forming loose ionic aggregates. The interaction between ionomer and solvents controls the ionomer conformations in the solutions, which determines the final microstructure of ionomer in CLs. The characterization of ionomer structures has been extensively studied using experimental measurements such as small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS).1-2 They observed that hydrophobic backbones of Nafion form the cylindrical-like core of self-assembled ionomer structures while ionic groups are located at the periphery of this aggregates. Theoretically, while most of studies have primarily focused on the solid membrane state with water volume fraction significantly below 50%, ionomer and carbon aggregations in solutions are also an important phenomenon to understand the self-assembly behaviors of ionomers as key structure-forming elements in CL. In this study, ionomer and carbon aggregations in a mixture of 1-propanol (NPA) and water have been investigated using coarse-grained molecular dynamics simulations. To perform simulations of larger systems and longer time spans compared with atomistic simulations, the reduced spatial resolution of the bead representation based on the relative free energy difference was used as a coarse-grained model. The dependence of NPA content on the ionomer structures was studied by systematically changing the NPA content in the system. The self-assembly behavior of ionomers into cylindrical bundle-like aggregates was observed for all NPA content solutions (Figure 1). Ionomer aggregates showed different behavior of formation at different NPA contents. The radius of an ionomer bundle was found to become smaller as NPA content increases, which is in good agreement with the trend seen in experimental measurements.3 The effects of carbon particles on the ionomer aggregation for various ionomer concentrations will also be discussed in the presentation. References Gebel, G.; Loppinet, B.; Hara, H.; Hirasawa, E., Small-Angle Neutron Scattering Study of Polyethylene-Co-Methacrylate Ionomer Aqueous Solutions. J. Phys. Chem. B 1997, 101, 3980-3987.Jiang, S.; Xia, K.-Q.; Xu, G., Effect of Additives on Self-Assembling Behavior of Nafion in Aqueous Media. Macromolecules 2001, 34, 7783-7788.Yamaguchi, M.; Matsunaga, T.; Amemiya, K.; Ohira, A.; Hasegawa, N.; Shinohara, K.; Ando, M.; Yoshida, T., Dispersion of Rod-Like Particles of Nafion in Salt-Free Water/1-Propanol and Water/Ethanol Solutions. J. Phys. Chem. B 2014, 118, 14922-14928. Figure 1

Synthesis and catalytic performance of hierarchical MCM-22 zeolite aggregates with the assistance of carbon particles and fluoride ions

Hierarchical MCM-22 zeolite aggregates (MCM-22-FC) were prepared by one-pot hydrothermal synthesis with the assistance of carbon particles and fluoride ions. The effects of carbon particles and fluoride ions on the morphology and catalytic properties of the MCM-22 zeolite were investigated. The hierarchical MCM-22-FC zeolite aggregates were constructed by intergrown and stacked thin MCM-22 lamellas and possessed macro-/mesopores and inherent micropores. The MCM-22-FC zeolite was modified to form the Mo/MCM-22-FC catalyst, which exhibited an improved benzene yield and aromatic selectivity as well as catalyst life in the methane dehydroaromatization (MDA) reaction. Based on NH 3 -TPD and pyridine-Fourier transform infrared spectroscopy measurements together with thermogravimetric analysis, we found that the improved MDA catalytic performance of Mo/MCM-22-FC resulted from the formation of more active MoC x or MoO x C y species that evolved from increased amounts of Brönsted acids with the assistance of fluoride ions. This promoted the diffusion of large molecule products because of the thin MCM-22 lamellas. Less excess Brönsted acid sites were retained in the Mo/HMCM-22-FC catalyst because the formation of active centers inhibited the formation of coke, which contributed to its improved aromatic selectivity Hierarchical MCM-22 zeolite aggregates constructed by intergrown and stacked thin MCM-22 lamellas were prepared by one-pot hydrothermal synthesis with the assistance of carbon particles and fluoride ions. The Mo/MCM-22-FC catalyst exhibited an improved benzene yield and aromatic selectivity as well as catalyst life in the methane dehydroaromatization reaction.

Effect of Carbon Particles on the Permittivity and Acoustic Performance of Epoxy Compounds

Effect of Carbon Particles on the Permittivity and Acoustic Performance of Epoxy Compounds

The Effect of Carbon Particles on Styropore Solvent by Benzene

The Effect of Carbon Particles on Styropore Solvent by Benzene

Effect of carbon particles on heavy metal emissions under ash-melting conditions

In Japan, incineration ash is subjected to a melting process to reduce waste volume and to stabilize hazardous heavy metals. In previous articles, we reported that large quantities of volatile metals are emitted under ash-melting conditions at temperatures higher than 1200°C and that such emissions are considerably increased under reducing conditions. However, the emission behavior in the presence of large amounts of char particles was unclear, and we suspected that emissions under these conditions might differ from emissions under the previous conditions. Therefore, we investigated heavy metal emissions and the melting characteristics of ash in the presence of carbon particles. In this experiment, a small crucible with ash and carbon was rapidly heated using a high-frequency induction-heating furnace to simulate the melting ash gasification with carbon. As a result, it was found that additive carbon can promote emissions of heavy metals such as zinc and lead and control the melt of the ash.

Microstructure, characterisation, and superplasticity of alumina/carbon nanocomposite

A nanocomposite formed of a fine-grained alumina matrix and of carbon nanoparticles was produced by hot-pressing. Compressive deformation tests were performed on this material at T = 1400°C up to true strains of -70 %. In all cases true strain rates of up to 2 x 10 -4 s 1 corresponded to low flow stresses (< 50 MPa). No cavitation was observed at grain boundaries and few microstructural changes were found to accompany the deformation. Grain boundary sliding accommodated by diffusional mechanism contributed to the main part of deformation. It is shown that the deformation results are consistent with a diffusivity of the grain boundaries not being affected by the presence of the carbon nanoparticles. The effect of carbon particles lies primarily in a reduction in grain growth without increase in flow stress.

PULMONARY INFLAMMATORY RESPONSE TO INHALED ULTRAFINE PARTICLES IS MODIFIED BY AGE, OZONE EXPOSURE, AND BACTERIAL TOXIN

Epidemiological studies demonstrate associations between increasing levels of ambient particles and morbidity in the elderly with cardiopulmonary disease. Such findings have been challenged partly because particles may not act alone to cause these effects. Wehypothesized that carbonaceous ambient ultrafine particles and ozone can act together to induce greater oxidative stress and inflammation in the lung than when administered alone and that these effects would be amplified in the compromised, aging lung. Two models of a compromised lung were used: endotoxin priming and old-age emphysema (TSK mice). Young (10 wk) and old (22 mo) male F344 rats and male TSK mice (14-17 mo) were exposed to ultrafine carbon particles (count median diameter 25 nm, 110 μg/m3) and to ozone (1 ppm) alone and in combination for 6 h. Inhalation of low-dose endotoxin (70 and 7.5 units estimated alveolar deposited dose in rats and mice, respectively) was used to model respiratorytract infection. Cellular and biochemical lavage parameters and oxidant release from lung lavage cells were assessed 24 h after exposure. Inflammatory cell influx into the alveolar space was observed for both species and age groups: The combination of inhaled ultrafine carbon and ozone after endotoxin priming resulted in the greatest increase in lavage-fluid neutrophils. In general, the unstimulated and stimulated release of reactive oxygen species (ROS) from lavage inflammatory cells correlated well with the neutrophil response. There were significant effects of carbon particles as wellas a consistent interaction between carbon and ozone as determined by analysis of variance (ANOVA). However, this interaction was in the opposite direction in young rats versus old rats and old TSK mice: Carbon and ozone interacted such that ROS activity was depressed in young rats, whereas it was enhanced in old rats and old TSK mice, indicating age-dependent functional differences in elicited pulmonary inflammatory cells. These results demonstrate that ultrafine carbonaceous particles inhaled for short periods of time can induce significant pulmonary inflammation and oxidative stress that are modified by age, copollutants, and a compromised respiratory tract.

Micro‐Raman Analysis of Carbon Inclusions in Heavy‐Metal Fluoride Glasses

While vitreous carbon crucibles can be used to produce high‐quality heavy‐metal fluoride glasses using low concentrations of SF6 gas (15%), pure SF6 gas produces low‐quality and high‐scattering glasses. This has been attributed to contamination by vitreous carbon particles by a fallback mechanism due to reaction of SF6 gas with the crucible walls above the melt. The detrimental effect of carbon particles is further highlighted by their high scattering efficiency factor which indicates that only 37 particles of 1‐μm diameter can be tolerated in an optical fiber for attaining 0.01 dB/km loss.

Effect of carbon particles on the recovery of bone marrow stem cells after irradiation in LPS-resistant C3H/HeJ mice.

Effect of RES-blockade on bone marrow cells was studied serially after irradiation in LPS-resistant mice. Injection of carbon particles reduced damage and accelerated recovery of marrow hemopoietic stem cells, indicating that LPS-resistant mice can react normally to RES-blockade.

Effects of carbon particles on phagocytic activity of reticuloendothelial system in X-irradiated mice.

Effects of carbon particles and x-irradiation on phagocytic activity of reticuloendothelial system (RES) were studied and discussion was made on them in connection with the radioprotective action of carbon particles. Administration of 1 mg of carbon particles per mouse did not decrease the phagocytic activity of RES, but slightly enhanced the activity. A functional blockade of RES was observed in the mice administered more than 5 mg of carbon particles. In the mice given 10 mg of carbon particles, the blockade continued for about a week after the treatment. The degree of blockade caused by the administration of carbon particles was not affected even by X-irradiation with 500 R. The amount of carbon particles required for the blockade of RES coinsides with the dose required to protect mice from radiation-induced death (Radiat. Res., 52, 130 ('72)). It is concluded that RES-blockade is intimately connected with the radioprotective action of carbon particles.

Enhancement of the Recovery of Hemopoietic System with Carbon Particles in Irradiated Mice

Effect of carbon treatment on retention of peripheral erythroches and on hemopoietic recovery following irradiation was studied. Life-span of /sup 51/Cr- labeled erythrocytes was shortened to about three-fourths that of normal mice by irradiation (500 R). By previously blockading RES with carbon particles, this accelerated destruction of erythrocytes was prevented. Proliferation of lymphoreticular tissues after irradiation was significantly enhanced by administration of 10 mg of carbon particles. Similar enhancement of erythropoietic recovery was also observed in the carbon-treated mice. Studies on the survival of endogenous spleen colony forming cells revealed that several times as many cells were protected by carbon treatment before or after irradiation. As a possible mechanism for the radioprotective effect of carbon particles, the following is proposed: elongation of the survival time of slightly injured RBC due to the functional blockade of RES and the prevention of internal hemorrhage by carbon-induced reinforcement of sinuses and sinusoide, higher survival of hemopoietic stem cells and enhancement of hemopoietic recovery which follows the above-mentioned response. (auth)

Effect of Carbon Particles on Hematological Recovery in Irradiated Mice

The effect of carbon particles on survival and hematological recovery of x-irradiated mice was studied. The administration of carbon particles, in the range of 5-15 mg per mouse, 24 hr before irradiation showed good protection against 600 R of x-rays. Similar protection was also observed in the mice which received 5 mg of the particles 3 hr after irradiation. The initial radiation-induced depression in splenic weight was partly prevented in the mice injected intravenously with 10 mg of carbon particles 24 hr before irradiation (500 R). The number of erythrocytes in the protected mice decreased similarly as observed in the irradiated control mice. But carbon particles promoted the subsequent early recovery in the number of erythrocytes. On the other hand, the number of erythrocytes in the unprotected mice was still decreasing. The effect of carbon particles on the decrease in the number of leukocytes was similar to that of erythrocytes except that the former showed a quicker recovery. As a possible explana...

SYNERGISTIC EFFECTS OF AEROSOLS. III. CARBON AND AIR BORNE IONS.

Abstract The learning rates of rats, as determined by means of a Skinner box apparatus, are compared for a control group and five test exposure groups. Exposure to an excess of negative ions yielded an increased learning rate, whereas excess positive ions impeded the learning rate. Exposure to carbon particles, alone and with excess positive or negative ions, resulted in improved learning rates over those from similar exposures in the absence of carbon particles. The synergistic effect of carbon particles is believed due to alteration of the ion balance in the atmosphere.