Exergy analysis of the diesel pre-reforming solid oxide fuel cell system with anode off-gas recycling in the SchIBZ project. Part I: Modeling and validation

Solid oxide fuel cell (SOFC) systems with anode off-gas recirculation (AGR) and diesel pre-reforming are advantageous because they can operate with the current fuel infrastructure. In the SchIBZ-project, the prototype of such a SOFC system for maritime applications has already been commissioned. In this first paper, we model the system devices to conduct an exergy analysis of this real SOFC plant and validate them with experimental values from experiments in laboratory scale. The results of our simulation agree well with the experimental values. The calculations with the validated results may be closer to the real thermodynamic behavior of such system components than previous literature.     

Evaluation of metal-supported solid oxide fuel cells (MS-SOFCs) fabricated at low temperature (∼1,000 °C) using wet chemical coating processes and a catalyst wet impregnation method

The objective of this study is to evaluate metal-supported solid oxide fuel cells fabricated at low temperatures (～1000 °C) in oxidizing environments using wet chemical coating processes and a catalyst impregnation method. Typically, applying general wet chemical coating processes and heat treatment at low temperature is desirable for fabricating metal-supported solid oxide fuel cells when considering manufacturing productivity and efficiency. However, in the case of conventional anodes, a well-organized structure for high performance is rarely formed by sintering at low temperatures when using general fabrication processes. For this reason, a catalyst-impregnated anode is designed and applied to overcome the above issue. First, to evaluate the electrochemical performance of the designed anode, the area-specific resistances of half-cells are investigated. Then, the newly designed anode is applied to a single cell, and microstructural analysis and electrochemical performance measurements are performed. These results confirm that the catalysts are well distributed, that the electrolyte is fully dense and that the electrochemical performances are reasonable. Additionally, the high durability is also verified through a long-term test over 1000 h. Finally, the metal-supported solid oxide fuel cell with a catalyst-impregnated anode fabricated at low temperature is completely validated through the evaluation of a large-size single cell.     

APU冷却通风系统温度测量与分析

通过加装在辅助动力装置（APU）舱内和APU附件表面的温度传感器对舱温和附件表面温度测量,研究了一个典型的飞行剖面各温度变化情况。测试数据分析表明,舱内测点的最高温度值都是出现在地面利用APU启动主发时。当APU存在电负载和气负载时,环境温度和附件表面温度比不带负载会有5℃左右的上升。另外,较小的飞行速度对APU舱的冷却通风是有利的,但随着速度的继续增大,冷却通风效果变差。     

Characteristic of (La0.8Sr0.2)0.98MnO3 coating on Crofer22APU used as metallic interconnects for solid oxide fuel cell

This study reports the high temperature oxidation kinetics, area specific resistance (ASR), and interfacial microstructure of metallic interconnects coated by (La_0.8Sr_0.2)_0.98MnO₃ (LSM) in air atmosphere at 800 °C. An efficient LSM conductive layer was fabricated on metallic interconnects for solid oxide fuel cells (SOFCs) by using a wet spray coating method. The optimum conditions for slurries used in the wet spray coating were determined by the measurement of slurry viscosity and coated surface morphology. The surface roughnesses of the substrates were increased through sandblast treatment. The adhesive strength of the interface between the coated layer and the metal substrate increased with increased surface roughness of the metallic interconnects. The electrical conductivities of the coated substrates were measured by using a DC two-point and four-wire method under air atmosphere at 800 °C. Of note, the Crofer22APU treated at 1100 °C in N₂ with 10 vol.% H₂ showed long-term stability and a lower ASR value than other samples(heat-treated at 800 °C and 900 °C). After an 8000-h oxidation experiment the coated Crofer22APU substrate, the ASR showed a low value of 23 mΩ cm². The thickness of the coated conductive oxide layer was about 10-20 μm. These results show that a coated oxide layer prevents the formation and the growth of scale (Cr₂O₃ and (Mn, Cr, Fe)₃O₄ layer) and enhances the long-term stability and electrical performance of metallic interconnects for SOFCs.     

Thermal cycling and ageing of a glass-ceramic sealant for planar SOFCs

Thermal cycling and thermal ageing tests were performed on Crofer22APU/glass-ceramic/Anode-Supported-Electrolyte (ASE) joined samples in air at the SOFC operating temperature of 800 °C. The Crofer22APU had been polished and preoxidised at 900 °C for 2 h. The diffusion behaviour at the two interfaces was examined and revealed slight diffusion of chromium and manganese from Crofer22APU into the glass-ceramic. No interactions, failure or crack formation were observed at the Crofer22APU/glass-ceramic interface and between the glass-ceramic and YSZ.     

增程式电动汽车辅助动力单元的建模与仿真

用Matlab/Simulink建立辅助动力单元中的发动机、发电机及其控制系统的仿真模型.采用解耦控制实现发动机的转速控制和发电机的转矩控制,模型最终实现了系统的实际功率快速跟随需求功率的目标.     

增程式电动汽车增程器转速切换/功率跟随协调控制

针对电动汽车增程器系统中的发动机、发电机协调控制问题,提出了一种转速切换/功率跟随增程器协调控制策略。首先根据发动机的最佳制动燃油消耗率曲线设计了发动机的功率-转速切换表。然后,分别设计了基于发动机平均值模型的发动机转速二阶滑模控制系统和基于电压定向直接功率控制的PWM整流器功率控制系统。通过对发动机转速和PWM整流器输出功率的闭环控制,使发动机沿着最佳制动燃油消耗率曲线运行。最后,在AVL Cruise和MATLAB/Simulink仿真环境下搭建了系统的联合仿真模型,仿真结果从增程器功率跟随效果,发动机转速控制效果,动力电池电压、电流和SOC波动范围以及发动机工作点分布等方面验证了该策略的有效性。     

多媒体会议中新型快速实时混音算法

混音处理是多媒体会议系统中的一个关键环节, 直接影响用户之间的相互交流。现有常用的混音算法中存在着音量突变的问题, 通过对这些混音算法的分析, 得出了变化的混音权重是导致音量忽大忽小的主要原因的结论。在此基础上, 该文提出了一种采用与混音输入无关的恒定混音权重的非均匀波形收缩混音算法, 该算法混音结果自然流畅, 避免了音量突变的问题。该算法运算简单, 速度快, 没有乘除法操作, 容易硬件实现。可以广泛应用于大规模的多媒体会议系统中。     

某飞机APU进/排气门控制盒可靠性研究

对某飞机APU进/排气门控制盒的可靠性进行了分析,综合考虑器件、环境、电路设计等可靠性因素,依据国军标GJB/Z299C-2006《电子设备可靠性预计手册》中提供的方法,通过元器件可靠性预计法对控制盒的可靠性进行预计,并根据一般原理对提高控制盒可靠性的方法进行了探讨。对比及验证表明,控制盒设计合理,可靠性满足主机及系统要求。     

High-temperature glassy-ceramic sealants SiO2—Al2O3—BaO—MgO and SiO2—Al2O3—ZrO2—CaO—Na2O for solid oxide electrochemical devices

Glasses of the SiO₂–Al₂O₃–BaO–MgO and SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O systems were synthesized in the perspective to apply them as sealants in SOFC at operating temperatures of 700–900 °C. Thermal properties of the chosen glass compositions and their compatibility with the SOFC materials (YSZ-electrolyte and alloy-interconnector Crofer22APU, 15×25T) were investigated by means of synchronic thermal analysis and high-temperature dilatometry. The elemental analysis was performed by atomic emission spectroscopy. The average values of the temperature coefficients of the linear extension are 10.0×10⁻⁶ °C⁻¹ for glass 45%SiO₂– 15%Al₂O₃–25%BaO–15%MgO and 9.5×10⁻⁶ °C⁻¹ for glass 60%SiO₂–10%Al₂O₃–10%ZrO₂–5%CaO–15%Na₂O. The gluing microstructure in YSZ/glass/Crofer22APU was studied by scanning electron microscopy. The crystallization process of silicate phases was revealed to occur in the SiO₂–Al₂O₃–BaO–MgO glass. The analysis of the crystallization products was performed by Raman spectroscopy and X-ray diffraction. Glassy ceramics was proved to possess better parameters in comparison with amorphous glass to be used as a sealant in electrochemical sensors and oxygen sensors. The SiO₂–Al₂O₃–ZrO₂–CaO–Na₂O low-temperature amorphous glass can be applied in SOFC.