超小型密封继电器推动杆部件烧结后的主要缺陷及探讨

超小型密封继电器推动杆部件烧结后的主要缺陷有歪头、平头和气泡,这些缺陷的存在降低了玻璃绝缘子的电性能和机械性能,如何控制和减少上述缺陷是推动杆部件烧结研究的重要课题。本文从玻坯密度、可伐合金的预氧化、玻璃绝缘子与烧结模的润湿等方面,对推动杆部件烧结后的主要缺陷进行了较详细的探讨。     

加成型高温硫化液体硅橡胶的气泡消除及性能研究

研究了交联剂、催化剂和消泡剂等对加成型高温硫化(HTV)液体硅橡胶气泡消除及性能的影响。结果表明：随着交联剂与催化剂用量增加,硅橡胶的固化时间变短,产生气泡增多;使用消泡剂可有效抑制硅橡胶中气泡的产生。当交联剂用量为0.95phr、催化剂用量为1.05phr、消泡剂4用量为4‰时,加成型HTV液体硅橡胶的综合性能最佳。     

鹤管气阻与泵汽蚀的对比分析

长期以来,鹤管气阻与泵汽蚀一直困扰着油料储运界,尽管人们在实践中找到一些行之有效的解决办法,但仍有不少同志对这两个问题认识不清。因此,很有必要对两者进行对比分析,以利于澄清错误认识,更好解决鹤管气阻与泵汽蚀问题。本文阐述了鹤管气阻与泵汽蚀发生的机理及解决措施;从发生部位、形成机理、产生危害及防治措施四个方面对鹤管气阻与泵汽蚀进行了对比分析。     

Experimental determination of maximum effective hydrodynamic stress in multiphase flow using shear sensitive aggregates

Maximum effective hydrodynamic stress, , responsible for the breakup of aggregates with size comparable to Kolmogorov eddies, was experimentally determined in an aerated stirred tank. The proposed method is based on the measurement of the maximum stable aggregates size consisting of poly(methyl methacrylate) nanoparticles. The fractal aggregates were broken under various operating conditions in an aerated stirred tank and calibrated with known flow conditions using contracting nozzles to convert the measured aggregate sizes into hydrodynamic stress. It was found that can vary substantially among studied conditions and its magnitude depends on the controlling mechanism including gas jet during bubble formation, bubble rise, bubble burst at the gas–liquid interface or the turbulence generated by the impeller. The measured values are in good agreement with literature data which supports the applicability of this method to characterize the maximum effective hydrodynamic stress in complicated multiphase flow. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1735–1744, 2015     

微纳米气泡曝气技术在生活污水处理中的应用研究

微纳米气泡曝气作为一种新型的曝气技术,已被逐渐运用在水处理中。本文从实际出发,对比研究了微气泡曝气和底部曝气对生活污水的处理效果。实验结果表明,在相同的曝气强度下,微气泡曝气技术对污水中CODCr的降解效率要明显高于底部曝气,前者的去除率为90.8%,后者仅为86.4%。使用微气泡曝气时,SS的浓度在8 h内达到最低值,去除率为96.3%,而使用底部曝气时,污水中的SS在第12 h才达到最低值,去除率仅为89%。使用微气泡曝气时,污水中氨氮的浓度在14 h左右(底部曝气需20 h)基本达到最低值,去除率为82%,比同时间段使用底部曝气时水中氨氮的去除率要高约15%,低温时更要高出20%以上。此外,使用微气泡曝气对TN和TP的最大去除率分别比底部曝气高7.5%和6%。     

直接接触冷凝器中流动及传热特性

利用SV型和SK型静态混合器,并以粉末烧结的微孔钛曝气器为气体分布器,开发出一种新型直接接触冷凝器。在空气-水和水蒸气-水体系中测试并比较2种新型直接接触冷凝器的流体力学性能及冷凝传热性能。结果表明:装有SV型静态混合器的新型直接接触冷凝器较装有SK型静态混合器的新型冷凝器对水蒸气的分布更加均匀,具有更好的吸收效果,钛曝气器的利用可有效提高换热效率,并降低水蒸气冷凝所引起的振动与噪声。     

柱状气液分离器液相带气特性分析

分析了柱状气液分离器(GLCC)内气相的运动轨迹。通过实验得到了不同操作参数下的液相带气特性,揭示了液相和气相速度对液相带气的影响。同时,采用可视化研究得到了分离器下部气液两相流型图,分析了不同形态气核的特性。证实了气核是造成液相带气的主要原因,揭示了不同稳定性的气核对液相带气的影响。     

In situ characterization of floc morphology by image analysis in a turbulent Taylor–Couette reactor

Flocculation of bentonite was performed in a turbulent Taylor–Couette reactor under various shear rates. Image processing enabled to determine various morphological characteristics of individual flocs. Not only their mean values but also their distributions were studied under various hydrodynamic conditions. Relevant properties were selected. The temporal evolution of radius of gyration and circularity distributions was monitored during the flocculation process. Although size and shape are obviously correlated, this article points out that their dependency to hydrodynamics is different, showing that flocs of similar sizes produced under different hydrodynamic conditions exhibit different shapes. The sizes are calibrated by the turbulence as the double radius of gyration is close to Kolmogorov microscale, whereas the circularity seems correlated to the rotation speed. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2389–2403, 2014     

Hydrodynamic feedback on bubble breakup at a T‐junction within an asymmetric loop

Bubble breakup at a microfluidic T‐junction by taking into consideration the hydrodynamic feedback at the downstream channels is presented. Experiments are conducted in square microchannels with 400 μm in width. The splitting ratio of the bubble size in the bifurcations varies nonmonotonically with the flow rate ratio of gas/liquid phases, and it is also affected by the liquid viscosity. A critical size of the mother bubble determines the variation trend of the splitting ratio of bubble size with flow rates of both phases and the liquid viscosity, which is related to the different breakup mechanisms for long and short bubbles at the junction and the different additional resistances induced by long and short bubbles in downstream channels. A theoretical model is proposed to predict the tailoring size of bubbles at the T‐junction by taking into account of the additional resistance in the presence of bubbles in downstream channels. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1920–1929, 2014     

Hydrodynamics and reactor performance evaluation of a high flux gas‐solids circulating fluidized bed downer: Experimental study

Reactor performance of a high flux circulating fluidized bed (CFB) downer is studied under superficial gas velocities of 3–7 m/s with solids circulation rate up to 300 kg/m²s using ozone decomposition reaction. Results show that the reactant conversion in the downer is closely related to the hydrodynamics, with solids holdup being the most influential parameter on ozone decomposition. High degree of conversion is achieved at the downer entrance region due to strong gas‐solids interaction as well as higher solids holdup and reactant concentration. Ozone conversion increases with the increase of solids circulation rate and/or the decrease of superficial gas velocity. Overall conversion in the CFB downer is less than but very close to that in an ideal plug flow reactor indicating a good reactor performance in the downer because of the nearly “ideal” hydrodynamics in downer reactors. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3412–3423, 2014