聚变驱动次临界堆第一壁材料辐照损伤的初步研究

介绍了中子对材料的辐照损伤原理及化合物原子平均离位(DPA)截面计算方法;使用辐照损伤计算程序SPECTER计算了聚变驱动次临界堆(FDS-I)第一壁材料CLAM钢的辐照损伤参数,并将CLAM钢的辐照损伤计算结果与相同条件下316SS、SiC等聚变堆结构材料的计算结果进行了比较.     

Thermal performance of various cross-sectioned rectangular minichannels with water-based phase change nano-suspensions

A numerical study is performed to investigate the influence of geometrical factors on the performance characteristics of a laminar thermally developing flow of phase change nano-suspensions in a rectangular minichannel considering axial wall conduction effects. The phase change material dispersed in the pure water is considered N-eicosane with the onset point of melting of 34.7°C, latent heat of fusion of 243 J/g, and particle size of 200 nm. The volume fractions of the phase change nano-suspensions are 2% and 10%, and the Reynolds number is in the range of 200 to 1500. To evaluate the influences of geometrical parameters on the cooling performance of the minichannel heat sinks, five minichannels are investigated, with aspect ratios (ration between channel height and width) AR_ch of 1, 1.25, and 1.5 and bottom wall thicknesses H_bw of 0.5, 1, and 1.5. The results reveal that the axial wall conduction significantly affects the heat transfer process of a flow in a minichannel at a low Reynolds number, and this effect is more remarkable with a shallower channel and a thicker bottom wall. Five performance indicators are used to systematically evaluate the heat transfer characteristics of the minichannels, including dimensionless heat flux at the bottom wall, temperature suppression, heat transfer effective ratio, heat dissipation of the extended wall, and figure of merit.     

Freestanding graphitic carbon nitride-based carbon nanotubes hybrid membrane as electrode for lithium/polysulfides batteries

Lithium sulfur batteries have drawled worldwide attention in recent years, which benefit of its high-density energetic, low cost, and environmental benignity. Nevertheless, the shuttle effect of polysulfides and resulting self-discharge lead to capacity fade loss and poor electrochemical performance. Herein, graphitic-carbon nitride/carbon nanotubes (g-C₃N₄/CNTs) hybrid membrane is fabricated by the flow-direct vacuum filtration process. The as-prepared 3-D freestanding g-C₃N₄/CNTs membrane employed as positive current collector containing Li₂S₆ catholyte solution for lithium/polysulfides batteries. The fabricated g-C₃N₄/CNTs provide a physical barriers and chemisorption resist polysulfide shuttling. Moreover, the conductive network constructed by CNTs can empower sulfur to be evenly distributed in the cathode and accelerates electron transport. Thus, to further prove the cooperative effect of g-C₃N₄ and CNTs, the freestanding g-C₃N₄/CNTs/Li₂S₆ electrode exhibits more stable electrochemical performance than CNTs/Li₂S₆ electrode, deliver the first discharge capacity of 876 mAh g⁻¹ at 0.5 C and maintained at 633 mAh g⁻¹ after 300 cycles. The sulfur mass in electrode was increased to 7.11 mg, and the g-C₃N₄/CNTs/Li₂S₆ electrode also possess a high capacity retention of 75.5%. Meanwhile, g-C₃N₄ modified CNTs can not only trap polysulfides by strong adsorption but also effectively inhibit the self-discharge behavior of lithium/polysulfides batteries. As a consequence, the g-C₃N₄/CNTs composites for lithium/polysulfides batteries are indicating an excellent electrochemical stability with a long-term storage without obvious capacity degradation.     

Determination of acetaldehyde,methanol and fusel oils in distilled liquors and sakès by headspace gas chromatography

Food Science and Biotechnology - In this study, a headspace gas chromatography (HS-GC) method was carried out to determine the contents of acetaldehyde, methanol and fusel oils in distilled liquors...     

玉米淀粉制糖发酵生产乳酸主要工艺技术分析

分析了玉米淀粉制糖和玉米直接制糖所得糖水的成分,对比后发现,采用玉米淀粉糖清液作为碳源发酵生产乳酸,较玉米糖清液具有更高的糖酸转化率和更低的发酵残糖,L-乳酸光学纯度超过99%,优势显著。研究了玉米淀粉糖液发酵生产乳酸的主要影响因素。酵母粉为氮源,浓度12%～14%的Ca(OH)2为中和剂时,乳酸产量高。通过乳酸发酵原料的改变为我国乳酸行业提升发酵稳定性和产品质量提供一种有效途径。     

A coke deposition self-removal TBCC thermal management with multi-catalyst coating

How to mitigate coke and improve heat sink is the critical factor for thermal management system of turbine-based combined cycle (TBCC). A novel thermal management method using multi-stage coating structure to mitigate coke and improve heat sink is developed in this study. The multi-stage coating structure includes catalytic steam reforming (CSR) and catalytic steam gasification (CSG) catalyst coatings. Coke is removed by CSG, which provides coke self-removal. In addition, the CSG is a strong endothermic reaction, which enables the increase of the chemical heat sink. The numerical study for the multi-stage coating structure was conducted using a heated channel. Results indicate that the multi-stage coating structure can reduce coke by 50% and increase chemical heat sink by 50%, when the mass ratio of secondary steam injection is 2%. In addition, it is found by a comparative study that the increase of secondary steam addition is helpful to remove coke and increase chemical heat sink. Both coke production and chemical heat sink are significantly affected by the rate distribution of CSG. The optimal performance of multi-stage coating structure can be obtained by properly regulating rate distribution of CSG.     

Graphene oxide coated nanosheet-like γ-MnS@KB-S fabricated by spray drying for high energy density Li-S batteries

In order to prohibit the shuttle influence of lithium polysulfides in lithium sulfur battery, a kind of graphene oxide (GO) coated γ-MnS@KB-S (GO@MKB-S) composite cathode material was successfully fabricated. First of all, the γ-MnS@KB (MKB) composite powders were prepared via a solvothermal reaction, then a spray drying method was used to obtain GO@MKB-S composites, which displays core/shell nanostructure. SEM, TEM, XRD as well as Raman spectrum are implemented to look into the microstructures and the functions of the 2D nanosheet-like γ-MnS in setting in KB on the battery performance were carefully analyzed. It is demonstrated that electrochemical discharge capacity and rate performance are clearly improved by using GO@MKB-S composites compared to the cathode electrode of the GO coated KB-S (GO@KB-S). With a sulfur loading of 5 mg cm⁻², the cathode electrode of GO@MKB-S shows a considerable discharge capacity of 749.9 mAh g⁻¹ at 0.36 C. Additionally, the Li-S battery cycle retention of GO@MKB-S sample maintains 97.36% after 100 cycles and 78.69% after 200 cycles.