Hydrogen Production from Catalytic Steam Reforming of Bio-Oils: A Critical Review

In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.     

高温冷凝水的酸性腐蚀分析

冷凝水系统中酸性腐蚀的原因、种类和解决方法；加氨法在实际生产中的应用。     

常规流场和交指型流场的质子交换膜燃料电池传热传质三维模拟

针对常规流场和交指型流场的质子交换膜燃料电池提出了三维非等温数学模型。模型详细考虑了电池内部的传热、传质和电化学反应，重点考察了多孔介质内的组分传递和膜内水的电渗和扩散作用，对氧气传递限制和膜内水迁移对电池性能的影响进行了分析和讨论。结果表明，流道的交指型设计加强了气体在多孔介质内的质量传递，提高了电池的输出性能，但相应地，阴极催化层界面水分的减少也使得膜的水合程度降低，这就需要更有效的水管理来防止膜脱水。     

铝合金连续铸造过程CET位置判据的研究

柱状晶向等轴晶转变(CET)是在一定的凝固过程中必须控制的一种显微组织转变.本文针对铝合金连铸坯凝固过程中柱状晶向等轴晶的转变,综合运用了正交试验研究、数值模拟计算、数学拟合等方法,分析了连铸过程主要工艺因素拉坯速度、一冷水量、二冷水量和浇注温度对连铸坯凝固过程中柱状晶向等轴晶转变位置的影响,提出了柱状晶向等轴晶转变的转变位置判据,即当连铸坯某一位置处的固相率等于0.3时,温度梯度G与冷却速度R满足函数关系G0.8072/R=0.469时,在该位置处将发生柱状晶向等轴晶的转变.     

The mathematical model of solidification latent heat under high cooling rate

Treatment of solidification latent heat is a key point in solidification simulation by the finite difference method. When latent heat is dealt with in a traditional method of equivalent latent heat, it was found that heat was increased when casting with a high cooling rate, and then the simulation result was distorted. In this paper, a new method is proposed to deal with solidification latent heat. Moreover, a mathematical model was suggested, in which the latent heat can be dealt with accurately under high or normal cooling rates. By contrasting the simulation results from this new method with the traditional one, it was indicated that this new model can obtain more accurate simulation results than the traditional model under high or normal cooling rates. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 115–121, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20104     

Performance comparison of three solid oxide fuel cell power systems

An energy analysis of three typical solid oxide fuel cell (SOFC) power systems fed by methane is carried out with detailed thermodynamic model. Simple SOFC system, hybrid SOFC‐gas turbine (GT) power system, and SOFC‐GT‐steam turbine (ST) power system are compared. The influences of air ratio and operative pressure on the performance of SOFC power systems are investigated. The net system electric efficiency and cogeneration efficiency of these power systems are given by the calculation model. The results show that internal reforming SOFC power system can achieve an electrical efficiency of more than 49% and a system cogeneration efficiency including waste heat recovery of 77%. For SOFC‐GT system, the electrical efficiency and cogeneration efficiency are 61% and 80%, respectively. Although SOFC‐GT‐ST system is more complicated and has high investment costs, the electrical efficiency of it is close to that of SOFC‐GT system. Copyright © 2013 John Wiley & Sons, Ltd.     

管式固体氧化物燃料电池单体欧姆极化分析

结合管式固体氧化物燃料电池结构特征和性能特征，建立了电池单体电压、电流和功率与电池长度、各级材料性质关系的数学模型。计算结果表明，减少电解质厚度和提高电池电流收集器的导电性可以减少电池的欧姆极化，提高电池的输出能力。     

支撑形式及多孔电极结构参数对SOFC性能的影响

研究不同结构设计条件下，活化极化、欧姆极化、浓差极化对SOFC性能的影响。在分析浓差极化时，综合考虑了普通扩散和Knudsen扩散，使模型更接近实际。采用灵敏度分析方法，分析了5个结构参数对SOFC性能的影响。结果表明，在该文的分析条件下，阳极支撑的设计具有较好的输出特性。     

不同型式流场的PEMFC内部传质分析

对采用不同型式流场的PEMFC进行建模,并用控制容积法对控制方程进行离散,求解得到PEMFC内部各物理量的分布以及综合水拖带系数、质子交换膜平均电导率等。分析了采用交趾型流场和常规流场时PEMFC的内部传质以及阴极性能、电池性能和膜性能,结果认为采用交趾型流场时,PEMFC阴极性能高于采用常规流场的PEMFC阴极性能,但质子交换膜的平均电导率低于采用常规流场时。在没有液态水产生时常规流场PEMFC性能高于交趾型流场PEMFC。     

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液化石油气是一种成分复杂的混合物，这就大大增加了对其爆炸进行数值计算的难度。采用CFD(Computational Fluid Dynamics，计算流体力学)方法，对石油气的混合成分进行了简化处理，进而对石油气爆炸进行了数值模拟，建立了描述液化石油气爆燃的理论模型，采用SIMPLE算法对模型进行了求解。计算的超压与实验值相比较，球形容器内最大偏差为9.09%，平均偏差为4.58%；开敞空间情况下，最大偏差9.02%，平均偏差3.92%。还对工业上可能产生的液化石油气可燃气云爆燃威力进行了预测，当气云半径为100 m时，最大超压可达48.432 kPa。研究表明，大尺寸气云可以产生具有破坏力的超压。