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1.
《Advanced Powder Technology》2022,33(12):103855
In a narrow channel, the apparent relative viscosity of a suspension with finite-size particles is strongly dependent on its microscopic particle arrangement. Relative viscosity increases when suspended particles flow near the channel wall; thus, a suspension in a narrow channel does not always exhibit the same rheological properties even if the concentration is the same. In this study, we focus on the inertia and concentration of particles in a narrow channel and consider their effects on the microscopic particle arrangement and macroscopic suspension rheology. Two-dimensional pressure-driven suspension flow simulations were performed using a two-way coupling scheme, and normalized particle density distribution (PDD) were implemented to consider their particle arrangements. The results demonstrated that the velocity profiles for the particle suspension were changed by the Reynolds number and particle concentration because of the interactions between particles according to the power-law index. These changes affected the particle equilibrium positions in the channel, and the subsequent changes in solvent layer thickness caused changes in the macroscopic apparent viscosity. The behavior of microscopic particles played important roles in determining macroscopic rheology. Thus, we have confirmed that a normalized PDD can be used to estimate and assess the macroscopic rheology of a suspension. 相似文献
2.
《Ceramics International》2022,48(12):17359-17368
In this work, 0.7BaTiO3-0.3Sr0.2Bi0.7TiO3 (0.7BT-0.3SBT) ceramics with 0.15 mol% various rare-earth oxides doped are designed and synthesized by the conventional solid-state route. All prepared samples exhibited a single perovskite phase and dense microstructure with fine grain size (0.2–0.5 μm) after sintering at 1180 °C. Especially, the Gd-doped 0.7BT-0.3SBT ceramics exhibited excellent energy storage performances; the corresponding recoverable energy density and efficiency were 3.2 J/cm3 and 91.5% under an electric field of 330 kV/cm, respectively. Meanwhile, doping with Gd caused the BT-based ceramics to possess excellent temperature (30–150 °C) and outstanding frequency stabilities (10–1000 Hz). Moreover, the pulsed charge-discharge experiments revealed that a high power density of 59 MW/cm3 and a fast discharge speed of 110 ns with outstanding temperature stability could be synchronously obtained in the Gd-doped composition. All these features are attractive for pulsed power applications. 相似文献
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4.
《Ceramics International》2022,48(24):36620-36628
In order to solve the problem of low charging and discharging energy density of dielectric capacitors, the structure design of layered polymer matrix composites is carried out in this paper. Ba0.7Sr0.3TiO3, Ba0.8Sr0.2TiO3 and Ba0.9Sr0.1TiO3 nanoparticles were successfully prepared by the oxalate coprecipitation method. The surface of BaxSr1-xTiO3 was successfully coated with dopamine, which promoted the dispersion of the polymer matrix of the ceramic powder. Monolayer BaxSr1-xTiO3/PVDF composites containing BaxSr1-xTiO3 with different Ba/Sr ratios were successfully prepared by the casting method. Three-layer asymmetric composites with different fillers were successfully prepared by layer-by-layer casting. The phase and microstructure of the as-prepared materials were analyzed by XRD and SEM. The dielectric, electrical conductivity, ferroelectric and energy storage properties of the composites were tested. The effects and laws of the design of the three-layer asymmetric structure on the dielectric properties and energy storage properties of the layered composites are mainly studied. When the structure of the three-layer asymmetric composite is 1-2-3, the breakdown field strength reaches 330 kV/mm, the discharge energy density reaches 8.51 J/cm3, and the charge-discharge efficiency is 67%. This work demonstrates that layered composites with asymmetric properties can facilitate the development of electrical energy storage. 相似文献
5.
研究不同填料类型与不同填充率对氨氮转化能力及亚氮积累效果影响。结果表明,在填充率相同的情况下,比表面积800 m2/m3的PE-03型号填料亚硝化效果最佳,氨氮转化50%,亚氮积累99%,PE-04型号填料比表面积1 200 m2/m3,相比于PE-03,氨氮转化降低5%、亚氮积累降低3%,PE-05型号填料比表面积510 m2/m3,相比于PE-03,氨氮转化30%、亚氮积累92%;随着填料填充率10%增加到30%,氨氮转化能力从20%增长至55%,之后再增加填充料,会小范围减小亚硝化能力,最低降至48%,由于该阶段亚硝化稳定运行,AOB优势生长,填充率的改变对亚氮积累率的影响不大。不同填料类型的影响研究中,PE-03型号的填料效果最佳;在填充率的考察中,随着同种填料填充率的增加,氨氮转化能力先增加后略微减小,对亚氮积累的情况影响较小;综合经济及技术因素,确定悬浮填料取材为PE-03型号,比表面积为800 m2/m3 相似文献
6.
生物质基喷气燃料是指全部或大部分来源于生物资源的喷气燃料,符合清洁低碳、安全高效的现代能源体系的要求。以生物质基喷气燃料替代传统石油基喷气燃料有助于我国早日实现“碳达峰、碳中和”的远大目标。在阐述生物质基喷气燃料生产工艺的发展历程及生物质基喷气燃料应用现状的基础上,提出高密度的生物质基喷气燃料是未来喷气燃料的发展方向,具有多环结构的生物质是合成高密度生物质基喷气燃料组分的优质原料;同时,总结了高密度生物质基喷气燃料组分生产工艺的研究进展,展望了生物质基喷气燃料未来的发展及挑战。 相似文献
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8.
Jinming Wang Meng Yang Guodong Zou Di Liu Qiuming Peng 《Advanced functional materials》2021,31(21):2101180
Lithium (Li) metal, as an appealing candidate for the next-generation of high-energy-density batteries, is plagued by its safety issue mainly caused by uncontrolled dendrite growth and infinite volume expansion. Developing new materials that can improve the performance of Li-metal anode is one of the urgent tasks. Herein, a new MXene derivative containing pure rutile TiO2 and N-doped carbon prepared by heat-treating MXene under a mixing gas, exhibiting high chemical activity in molten Li, is reported. The lithiation MXene derivative with a hybrid of LiTiO2-Li3N-C and Li offers outstanding electrochemical properties. The symmetrical cell assembling lithiation MXene derivative hybrid anode exhibits an ultra-long cycle lifespan of 2000 h with an overpotential of ≈30 mV at 1 mA cm−2, which overwhelms Li-based anodes reported so far. Additionally, long-term operations of 34, 350, and 500 h at 10 mA cm−2 can be achieved in symmetrical cells at temperatures of −10, 25, and 50 °C, respectively. Both experimental tests and density functional theory calculations confirm that the LiTiO2-Li3N-C skeleton serves as a promising host for Li infusion by alleviating volume variation. Simultaneously, the superlithiophilic interphase of Li3N guides Li deposition along the LiTiO2-Li3N-C skeleton to avoid dendrite growth. 相似文献
9.
The phase shift characteristics reflect the state change of electromagnetic wave in plasma sheath and can be used to reveal deeply the action mechanism between electromagnetic wave and plasma sheath. In this paper, the phase shift characteristics of electromagnetic wave propagation in plasma were investigated. Firstly, the impact factors of phase shift including electron density,collision frequency and incident frequency were discussed. Then, the plasma with different electron density distribution profiles were employed to investigate the influence on the phase shift characteristics. In a real case, the plasma sheath around the hypersonic vehicle will affect and even break down the communication. Based on the hypersonic vehicle model, we studied the electromagnetic wave phase shift under different flight altitude, speed, and attack angle. The results indicate that the phase shift is inversely proportional to the flight altitude and positively proportional to the flight speed and attack angle. Our work provides a theoretical guidance for the further research of phase shift characteristics and parameters inversion in plasma. 相似文献
10.
《Ceramics International》2021,47(24):34521-34528
Aiming at the problem that power density and energy density are difficult to obtain simultaneously under low field, a novel composition (1-x)Na0·5Bi0·5TiO3-xBaZn1/3Ta2/3O3((1-x)NBT-xBZT) was designed and fabricated via solid-state methods. With the addition of BZT, the crystal lattice, structural symmetry, grain size, and dense degree were all increased proved by XRD, Raman, and Archimedes drainage method et al. Because of the enhancement of relaxor behavior, the x=0.10 sample displayed a high permittivity εr of 2871±15% and a low dielectric loss tan δ ≤ 0.025 in the wide temperature range of 60–400 oC. This ceramic also showed maximum recoverable energy density Wd (2.07 J/cm3) with high efficiency η (71.5%) under a low field of 150 kV/cm. Moreover, pulse discharge testing proved that this ceramic possessed both a significant discharge energy density WD (0.96 J/cm3) and a record high power density PD (108.54 MW/cm3). This work provided a promising material for high power and energy applications. 相似文献