Electrospinning and hydrothermal synthesis of recyclable MoS2/CNFs hybrid with enhanced visible-light photocatalytic performance

In this work, a two-step synthesis route combining an electrospinning method and a hydrothermal process was used to prepare MoS₂/CNFs hybrid. CNFs was applied as the matrix for the nucleation and growth of MoS₂ nanosheets. In this hybrid, the crisscrossed MoS₂ nanosheets were randomly aligned and densely packed over the surface of CNFs. We probed the photocatalytic activity of MoS₂/CNFs hybrid to degrade rhodamine B (Rh B) in an aqueous solution under visible light irradiation. The hybrid displayed higher photodegradation performance relative to MoS₂ and mechanical mixture of MoS₂ with CNFs, with 67% Rh B completely degraded over 5 h-period. We attributed such enhancement in photocatalytic activity to the enhanced absorption property and electrical conductivity due to the synergy between MoS₂ and CNFs. The hybrid can furthermore be easily separated from the solution and reused for the subsequent photodegradation cycles. We verified the negligible loss in the photodegradation activity of MoS₂/CNFs hybrid towards Rh B during the three subsequent cycles. The high photocatalytic activity and recyclability of the hybrid render its practical application to degrade organic pollutants (i.e., dye compounds) in industrial wastewater.     

高温灰渣在斜面冷渣器中的流动分析

为了分析工业生产中的高温灰渣在斜面上的流动特性,采用基于离散单元法的颗粒流动程序(PFC2D),建立料仓和斜面的仿真模型,首先分析颗粒通过斜面的临界角,然后针对颗粒在不同斜面倾角,进行了颗粒运动的数值模拟,为下一步分析颗粒传热做准备。通过模拟发现:1颗粒通过斜面的临界角为28°~29°;2在斜面倾角大于临界角的前提下,颗粒的堆积厚度随着通过斜面的距离的增大而减小,堆积厚度拟合直线的斜率逐渐增大,在40°之前呈现直线增长的趋势,40°~50°增长速度逐渐平缓,拟合直线的截距随着倾角的增大,逐渐较小。     

急冷器波纹管设计与非线性有限元分析

针对某急冷器集流管中波纹管设计强度的理论计算结果,应用Ansys软件,通过非线性有限元分析对其进行了验证,并将二者的结果进行比较,获得了该波纹管受力的特点,确认了该波纹管设计强度理论计算结果的安全可靠性。     

固体氧化物燃料电池钎焊自适应密封研究进展

平板式固体氧化物燃料电池(Solid oxide fuel cell,SOFC)是一种直接将储存在燃料和氧化剂中的化学能转化为电能的发电装置,具有能量转化效率高、结构紧凑、对环境污染小等优点,成为替代现有石化燃料的最佳选择。SOFC要通过封接防止泄漏,由于其工作温度高,对封接要求苛刻。在高温下,要求封接材料具有良好的化学稳定性、热稳定性、气密性以及绝缘性等,因此密封技术一直是制约其商业化应用的瓶颈问题。钎焊自适应密封是近几年发展起来的一种平板式SOFC密封技术,利用金属箔片钎焊连接电池和金属框架,具有封接强度高、密封性能好、能吸收热应力等优点,具有较好的应用前景。介绍自适应密封的原理、特点和应用,从结构设计、钎焊技术、残余应力等方面的研究进展进行综述,指出该技术存在的问题,并对其今后的发展方向进行预测和展望。     

金属垫片密封表面形貌的分形表征

引言 金属垫片密封结构常见于石油、化工、核能等装置中,广泛应用于高温、高压及强腐蚀介质等操作条件恶劣、密封要求高、一般的垫片无法满足要求的场合.     

Enhanced thermal properties of silica-based ceramic cores prepared by coating alumina/mullite on the surface of fused silica powders

In this study, an alumina/mullite coating was synthesized on the surface of fused silica powders to form an alumina/mullite-silica core-shell structure. The effects of the alumina/mullite coating on the cristobalite crystallization, thermal properties, and leachability of the silica-based ceramic cores were investigated using the simulated casting process. The X-ray diffraction results indicated that the crystallization of cristobalite was significant at the simulated casting temperature of approximately 1400 °C. An increase in the cristobalite content during this stage resulted in a large thermal expansion because of its higher coefficient of thermal expansion compared with that for fused silica. The addition of optimum amounts of the alumina/mullite powders resulted in an increase in the initial shrinkage temperature and a decrease in the shrinkage of the specimens. When the coating powders were added at 43 wt%, the initial shrinkage temperature increased from 1092 °C to 1200 °C and the shrinkage decreased sharply. Leaching tests showed that the silica-based ceramic cores were removed in the form of stripped layers. The washing and shaking process accelerated the disintegration of the ceramic core and improved its leachability.     

Methanation of carbon dioxide and fluidization quality in a fluid bed reactor—the influence of a decrease in gas volume

A large decrease of fluidization quality was observed when methanation of carbon dioxide was carried out in a fluid-bed reactor even if the catalyst particles had the optimal properties for good fluidization. The cause of this phenomenon was explored by measuring pressure fluctuations, bubble frequency and extent of CO₂ conversions. The results indicated that the decrease of the fluidity was caused by a reduction in volume of reactant gases due to the reaction. The voidage in the emulsion phase is considered to be an important factor affecting the fluidity. The fluidization quality and contacting efficiency could be improved by such devices as baffle internals or two-stage spargers.     

小冲孔试样弹塑性蠕变损伤的有限元分析

综合考虑了小冲孔试样实验过程中的弹性、塑性及蠕变等因素,采用了Mises型流动法则和改进的K-R蠕变损伤本构方程,建立了ABAQUS有限元模型,模拟计算了550℃三种载荷条件下,Cr5Mo试样的弹塑性蠕变过程,分析试样的中心蠕变挠度、蠕变应变随时间的变化规律,当量应力的分布情况,以及试样的蠕变损伤与位置的关系,同时分析了挠度与应力对网格的敏感性。结果表明:模拟结果与实验结果很接近,且与单轴实验的应变曲线十分相似;整个试样在中心损伤比较严重,呈现明显局部化特征;讨论了试样网格的敏感性,试样半径方向0mm~1mm之内应力变化幅度比较大(除约束点),并且应力的最大值也出现在这个区域,在这个区域进行网格细化提高计算的精确性,而其他区域采用粗网格减少计算成本,达到精确性和经济性的平衡。径向上网格大小对挠度影响比较大,应力对网格大小不敏感。     

多层升降横移立体停车库控制系统设计与实现

随着经济的发展,人民生活水平的提高,小汽车数量急剧增加,停车难的问题日益突出.本文分析了立体停车库在生活中的优点、现实意义,介绍了常用立体停车库的种类.以三层立体停车库为例,采用西门子S7-200 PLC作为主控制器,对三层15车位立体升降横移式停车库系统的软硬件结构及安全保护措施,包括电气回路、车极移动、故障自检及处理、人机界面等,做了详细地阐述.