Combined with a simple phase change model,the Volume of Fluid(VOF)method is used for simulating the seed bubble triggered boiling in a single circular microchannel with 6.5mm *** results show that the introduction of ...
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Combined with a simple phase change model,the Volume of Fluid(VOF)method is used for simulating the seed bubble triggered boiling in a single circular microchannel with 6.5mm *** results show that the introduction of seed bubbles improves the heat transfer performance and suppresses the flow instability *** seed bubbles are triggered into the microchannel for f=2000 Hz,passing by only about five numbers of periods,the wall superheats remarkably decreased,a complete thermal equilibrium between the liquid and vapor phases is approached,the flow instability can be controlled *** the stable flow stage,the heat transfer which can reach more than 3 times the single liquid phase heat transfer dominated by the local liquid film thickness,which is the actual heat transfer length-scale in the liquid film ***,the liquid bridge region existing between the bubbles produces a week heat transfer mechanism.
Development of non-precious-metal electrocatalysts is believed as the key for realization of scale-up applications of the proton exchange membrane fuel cells. One of the most promising types of non-precious-metal cata...
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Development of non-precious-metal electrocatalysts is believed as the key for realization of scale-up applications of the proton exchange membrane fuel cells. One of the most promising types of non-precious-metal catalysts is carbon-supported transition metal-nitrogen (C/M-N x ) materials (M = Co, Fe, Ni, Mn, etc., and normally x = 2 or 4). In this article, a novel molecular design strategy, in which the multilayers of Co 2+ ions and porphyrin are fabricated onto the surface of the reduced graphene oxide sheets by the layer-by-layer assembly technique, is suggested for production of the cost-effective and high-efficient catalysts. Impressively, compared with commercial carbon-supported Pt catalysts, the prepared multilayers on the surface of the reduced graphene oxide sheets exhibit the comparable electrocatalytic activity, but much better methanol tolerance and long-term stability toward oxygen reduction reaction. This work opens a door toward accurate construction of the low-cost catalysts for high-performance oxygen reduction reaction.
Composite nanoparticles with discrete domains of different materials, which are fused by solid-state interfaces, represent an emerging class of multifunctional lab-on-a particle architectures that underpin future adva...
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Composite nanoparticles with discrete domains of different materials, which are fused by solid-state interfaces, represent an emerging class of multifunctional lab-on-a particle architectures that underpin future advances in diverse *** type of nanostmcture combines materials with distinct physical and chemical properties to yield a unique hybrid nanosystem having multifunctional capabilities and tuned or enhanced useful properties, which may not be attainable in individual materials.
Rechargeable lithium ion batteries (LIBs) have become one of the dominant power sources for portable electronic *** oxide (Co3O4) as LIB anode material receives extensive attention since it is expected to have a high ...
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Rechargeable lithium ion batteries (LIBs) have become one of the dominant power sources for portable electronic *** oxide (Co3O4) as LIB anode material receives extensive attention since it is expected to have a high capacity and excellent cycling performance.
The defined oxidation ability of metallurgical slag based on the ion and molecule coexistence theory (IMCT), i.e., the comprehensive mass action concentration of iron oxides NFetO, was verified by comparing the calcul...
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The defined oxidation ability of metallurgical slag based on the ion and molecule coexistence theory (IMCT), i.e., the comprehensive mass action concentration of iron oxides NFetO, was verified by comparing the calculated NFetO and the reported activity of iron oxides aFetO in selected 14 slag systems. To calculate NFetO in the selected slag systems, a thermodynamic model for calculating the mass action concentrations of structural units in CaO-SiO2-MgO-FeO-Fe2O3-MnO- Al2O3-P2O5 type slag systems, i.e., the IMCT-Nt thermodynamic model was developed. NFetO in the other 13 slag systems can be obtained by simplifing this IMCT-Nt. It is shown that the defined comprehensive mass action concentration of iron oxides NFetO is more accurate than the measured activity of iron oxides aFetO in characterizing the oxidation ability of the selected FetO-containing slag systems.
Zn-doped MgAl layered double hydroxides (LDHs) with M 2+ /M 3+ = 2 and different molar ratios of Mg/Zn have been synthesized by modified homogeneous co-precipitation method and characterized by powder x-ray diffractio...
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Zn-doped MgAl layered double hydroxides (LDHs) with M 2+ /M 3+ = 2 and different molar ratios of Mg/Zn have been synthesized by modified homogeneous co-precipitation method and characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectrum (FT-IR) and thermogravimetry and differential thermal analysis (TG-DTA) techniques. The as-synthesized plate-like LDHs nanoparticles have an average diameter around 90nm and thickness about 20nm. The thermal stabilizing effects of different LDHs on PVC were studied by Congo red test and thermal ageing test. The introduction of Zn increased the average bond length and area of the layers of LDHs, therefore enhanced the adsorption ability on HCl gas which is generated during degradation of PVC to improve the thermal stability of PVC. LDHs with molar ratio of Mg/Zn = 1.0 shows the best thermal stabilizing effect on PVC. Such Zn-doped MgAl-LDHs could be a promising class of thermal stabilizer with non-toxicity, environmental friendliness and economy.
Despite the promising application of porous Si‐based anodes in future Li ion batteries, the large‐scale synthesis of these materials is still a great challenge. A scalable synthesis of porous Si materials is present...
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Despite the promising application of porous Si‐based anodes in future Li ion batteries, the large‐scale synthesis of these materials is still a great challenge. A scalable synthesis of porous Si materials is presented by the Rochow reaction, which is commonly used to produce organosilane monomers for synthesizing organosilane products in chemical industry. Commercial Si microparticles reacted with gas CH 3 Cl over various Cu‐based catalyst particles to substantially create macropores within the unreacted Si accompanying with carbon deposition to generate porous Si/C composites. Taking advantage of the interconnected porous structure and conductive carbon‐coated layer after simple post treatment, these composites as anodes exhibit high reversible capacity and long cycle life. It is expected that by integrating the organosilane synthesis process and controlling reaction conditions, the manufacture of porous Si‐based anodes on an industrial scale is highly possible.
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