助燃空气对乙烯裂解炉NOx排放的影响

乙烯裂解炉内复杂物理化学过程耦合模拟与优化能够满足乙烯装置对高效率、低污染和低成本的设计和操作要求，对提高乙烯工业的竞争力具有重要意义。针对简单燃烧机理难以准确预测炉膛燃烧生成NO_x浓度分布的弊端，提出了在裂解炉使用更准确的简化GRI-Mesh 3.0机理结合涡耗散概念(EDC)模型的方法，并对Sandia Flame D的燃烧过程进行计算流体力学(CFD)模拟，验证了此耦合模型的可靠性。在已建立的燃烧模型的基础上，研究了助燃空气对降低裂解炉NO排放的影响，结果表明：在满足裂解炉热效率的情况下，空气预热温度为300~600 K、过量空气系数为1.1时降低NO的效果最佳。     

Dynamic optimization for gas blending in pipeline networks with gas interchangeability control

The increasing penetration of unconventional gas and liquefied natural gas poses an operational challenge on existing regional gas networks for gas quality problems. A new dynamic model for natural gas pipeline network with multiple supplies is presented with a special emphasis on gas interchangeability control. Wobbe index serves as gas interchangeability indicator and is calculated by equations derived from rigorous composition-based partial differential equations. Disjunctive formulation is applied to represent different modes of gas blending due to gas reversal, and the disjunctive model is then reformulated as a nonsmooth model with min/max and absolute value functions, which is solved by a gradient-based nonlinear program solver after smooth approximation. Moreover, a heuristic algorithm is proposed to tune the penalty parameters in order to focus on different penalty terms while keeping the model well-conditioned. The developed model and strategy are first tested with a small pipeline network model and then extended to a large model. The results show that the model can effectively manage gas interchangeability issues in pipeline networks within reasonable CPU time.     

NSGA-Ⅱ和NSGA-Ⅲ应用于换热网络多目标优化的对比

针对换热网络多目标优化问题，采用目前应用较广泛的两种多目标遗传算法，即NSGA-Ⅱ和NSGA-Ⅲ，对两种算法的性能进行对比研究。案例研究结果表明，NSGA-Ⅱ算法比NSGA-Ⅲ算法运行效率更高，NSGA-Ⅲ的运行时间是NSGA-Ⅱ的2倍以上；NSGA-Ⅱ算法的应用并不严格地受限于3个目标的最大目标数量，NSGA-Ⅱ在求解大于3个目标的多目标优化问题时也可能具有良好的性能，目标数量并非选择NSGA-Ⅱ和NSGA-Ⅲ算法的严格标准。对10×5换热网络案例进行4个相关目标改造优化时，从换热网络的单一性能指标来看，NSGA-Ⅱ算法更容易获得各目标的极值。从最小年度总费用的评价指标来看，两种算法的最优方案效果相近。对7×3换热网络案例进行6个目标的优化时，NSGA-Ⅲ算法得到各目标的极值较优。从最小年度总费用的评价指标来看，NSGA-Ⅲ算法获得的投资费用和年度总费用更小。对于目标函数数量不超过3个，或者3个以上具有一定相关性的多目标优化问题，推荐优先使用NSGA-Ⅱ算法实现快速寻优；而NSGA-Ⅲ算法由于其基于参考点的选择机制，运行效率较慢，更适合用于收敛困难的高维多目标优化问题。     

2 500 t/d生产线煅烧高镁熟料的生产应用

四川省兆迪水泥有限责任公司2500t/d新型干法熟料生产线,于2014年7月11日重建点火投产。生产过程中针对工厂高镁石灰石的原料特点,注意总结工艺操作、熟料质量等方面的经验,采取了积极有效的措施,取得了较好的效果。     

Numerical study of flow distribution uniformity for the optimization of gradient porosity configuration of porous copper fiber sintered felt for hydrogen production through methanol steam reforming micro-reactor

A macroscopic numerical method is proposed to study the flow distribution uniformity of a novel porous copper fiber sintered felt (PCFSF), which has gradient porosities and was developed as the methanol steam reforming micro-reactor catalyst support for hydrogen production for fuel cell applications. The macroscopic porous media developed by the ANSYS/FLUENT software is used to represent the PCFSF. Our results indicate that the gradient porosity can reshape the flow distribution of PCFSFs greatly, thus producing significant influence on their performance. It is further revealed that, for a PCFSF with a determined gradient porosity configuration but different reactant feed directions, the velocity uniformity can be used as a quantitative criterion to evaluate the performance of hydrogen production. Furthermore, new gradient PCFSFs are produced according to the flow distribution of original gradient PCFSFs. The preliminary experimental results of the new gradient PCFSFs of 0.8-0.9-0.7 and 0.7-0.9-0.8 exhibit better methanol conversion and H₂ flow rate. This indicates that the numerical method can be used for the optimization of PCFSFs' gradient porosity configuration, which consists of the shape and position of the interfaces between different porosity portions, the number of interfaces and the porosity distribution in different portions.     

A comprehensive review of solar thermoelectric cooling systems

The negative environmental impacts of burning fossil fuels have forced the energy research community seriously to consider renewable sources, such as naturally available solar energy. This paper provides an overview of solar thermoelectric (TE) cooling systems. Thus, this review presents the details referring to TE cooling parameters and formulations of the performance indicators and focuses on the development of TE cooling systems in recent decade with particular attention on advances in materials and modeling and design approaches. Additionally, the TE cooling applications have been also reviewed in aspects of electronic cooling, domestic refrigeration, air conditioning, and power generation. Finally, the possibility of solar TE cooling technologies application in “nearly zero” energy buildings is briefly discussed, and some future research directions are included. This research shows that TE cooling systems have advantages over conventional cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no working fluid, being powered by direct current, and easily switching between cooling and heating modes.     

基于随机模型的动车组制动模块稳健优化设计

针对目前产品优化设计中未考虑设计变量随机性和灵敏度指数对产品质量特性的影响及优化求解效率低等问题，提出一种综合考虑灵敏度指数与质量损失函数的稳健优化设计方法。通过假设设计变量的分布类型，得到设计变量的概率分布特征，将设计变量对产品质量特性的灵敏度指数与质量损失函数加权整合，并以此作为优化目标，以设计变量的容差作为约束条件，构建随机稳健优化模型。通过扩大种群数目、改进控制参数及增加惩罚因子的方法对遗传算法进行改进，结合改进的遗传算法对优化模型进行求解，得到优化模型的全局稳健最优解。以某动车组制动模块为例，采用给出的方法对其进行稳健优化设计，验证该方法的有效性与合理性。优化结果表明，该方法能够实现动车组制动模块的稳健优化设计，提高了制动模块的抗干扰能力。     

Extraction optimization and adsorption isotherm kinetics of polyphenols from blossoms of Citrus aurantium L. var. amara Engl

ABSTRACT

Crude extracts were extracted from blossoms of Citrus aurantium L. var. amara Engl. with 50% ethanol (CAVAP-E), 50% methanol (CAVAP-M), and hot water (CAVAP-W). CAVAP-W had the highest polyphenol yield of 3.7%. The optimum values of liquid/solid ratio, ultrasonic time, and ultrasonic power were 34.06 mL/g, 1 h, and 81.04 W, respectively. The adsorption characteristics of polyphenols were investigated using different macroporous resins. AB-8 and HP-20 resins offered higher adsorption and desorption capacities. Langmuir equation was more suitable to predict the adsorption of polyphenols. The pseudo second-order model was satisfactory to describe the kinetic data of polyphenols onto AB-8 and HP-20.     

某污水处理厂MBR膜系统改造与运行管理

某污水处理厂设计规模为10万t/d,采用AAO+MBR工艺,设计出水水质满足《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A标准。由于运行时间较长,MBR运行系统存在产能下降、膜丝断丝脱落、污堵和清洗频次以及强度增加等问题,严重影响正常生产运行。针对MBR系统运行中存在的问题,文中提出具体改造建议,并总结运行经验,进一步优化MBR膜系统的运行维护管理,为其他污水厂MBR膜系统运行问题提供解决思路和维护管理经验。